5-Aminolevulinic acid （ALA） is a common precursor for tetrapyrrole compounds in all kinds of organ isms and has wide applications in agriculture and medicines. In this study, a new strategy, i.e. short-term dissolve...5-Aminolevulinic acid （ALA） is a common precursor for tetrapyrrole compounds in all kinds of organ isms and has wide applications in agriculture and medicines. In this study, a new strategy, i.e. short-term dissolved oxygen （DO） shock during aerobic fermentation, was introduced to produce 5-aminolevulinic acid with a recombi-nant E. coli. Effects of duration time of DO shock operation on plasmid concentration, intracellular ALA synthase （ALAS） activity and ALA production were investigated in Erlenmeyer shake flasks. The results indicated that both ALAS activity and ALA yield were enhanced in an anaerobic operation of 45 rain in the early exponential phase during fermentation, while they decreased when the anaerobic operation time was further increased to 60 rain. The DO shock protocol was confirmed with the fed-batch fermentation in a 15 L fermenter and the ALA production achieved 9.4 g.L-1 （72 mmol.L-1）, which is the highest yield in the fermentation broth reported up to now.展开更多
L-(+)-Lactic acid production from corncob hydrolysate as a cheap carbohydrate source by fed-batch fermentation of Rhizopus oryzaeHZS6 was studied. After 96 h of fermentation in a 5 L fermentor, the final concentration...L-(+)-Lactic acid production from corncob hydrolysate as a cheap carbohydrate source by fed-batch fermentation of Rhizopus oryzaeHZS6 was studied. After 96 h of fermentation in a 5 L fermentor, the final concentration of ammonium L-(+)-lactate, average productivity(based on initial xylose concentration) and maximum dry cell weight were 132.4 g/L, 1.38 g/(L·h), and 8.9 g/L respectively. The optical purity of L-(+)-lactate was 98.8%.展开更多
An iterative optimization strategy for fed-batch fermentation process is presented by combining a run-to-run optimization with swarm energy conservation particle swarm optimization (SEC-PSO). SEC-PSO, which is designe...An iterative optimization strategy for fed-batch fermentation process is presented by combining a run-to-run optimization with swarm energy conservation particle swarm optimization (SEC-PSO). SEC-PSO, which is designed with the concept of energy conservation, can solve the problem of premature convergence frequently appeared in standard PSO algorithm by partitioning its population into several sub-swarms according to the energy of the swarm and is used in the optimization strategy for parameter identification and operation condition optimization. The run-to-run optimization exploits the repetitive nature of fed-batch processes in order to deal with the optimal problems of fed-batch fermentation process with inaccurate process model and unsteady process state. The kinetic model parameters, used in the operation condition optimization of the next run, are adjusted by calculating time-series data obtained from real fed-batch process in the run-to-run optimization. The simulation results show that the strategy can adjust its kinetic model dynamically and overcome the instability of fed-batch process effectively. Run-to-run strategy with SEC-PSO provides an effective method for optimization of fed-batch fermentation process.展开更多
Bioreactor operation requires continuous monitoring of fermentation parameters and real-time control over bioreactor devices. Remote monitoring and control of the bioreactor＇s computer via the Internet avoids the nec...Bioreactor operation requires continuous monitoring of fermentation parameters and real-time control over bioreactor devices. Remote monitoring and control of the bioreactor＇s computer via the Internet avoids the necessity of personnel being continually onsite during operation. A two liter Sartorius-stedim Biostat~ A Plus fermentation system was networked and interfaced with the commercial software from GoToMyPC to allow remote control of the fermentation system utilizing the internet. The fermentation vessel was equipped with hardware calibrated for monitoring and controlling culture parameters during experimentations. The uniform resource locator controlled night-vision web camera allowed continuous monitoring of the glass fermentation vessel during the day and at night. The main window screen of the laboratory computer can be securely accessed from any portable device （i.e. laptop） capable of establishing an Internet connection and executing the commercial software from GoToMyPC. The secured internet protocol address, provided by GoToMyPC, assures that the system can only be controlled by authorized users who have been given access to the account. This interface permits the remote control of the Biostat A Plus fermentation system and possibly other automated or potentially automated culturing systems at the convenience of the user（s）.展开更多
An on-line scheduling algorithm to maximize gross profit of penicillin fed-batch fermentation is proposed. According to the on-line classification method, fed-batch fermentation batches are classified into three categ...An on-line scheduling algorithm to maximize gross profit of penicillin fed-batch fermentation is proposed. According to the on-line classification method, fed-batch fermentation batches are classified into three categories. Using the scheduling strategy, the optimal termination sequence of batches is obtained. Pseudo on-line simulations for testing the proposed algorithm with the data from industrial scale penicillin fermentation are carried out.展开更多
To investigate the in vitro digestion and fermentation properties of soybean oligosaccharides(SBOS)extracted from defatted soybean meal,the changes in monosaccharide composition and molecular mass were analyzed.Subseq...To investigate the in vitro digestion and fermentation properties of soybean oligosaccharides(SBOS)extracted from defatted soybean meal,the changes in monosaccharide composition and molecular mass were analyzed.Subsequently,the effect of SBOS on microbial community structure and metabolites was studied by 16S rRNA gene sequencing and untargeted metabolomics based on liquid chromatography-mass spectrometry.Results showed that SBOS was not easily enzymolyzed during simulated digestion and could reach the large intestine through the digestive system.The significant decrease in the molecular mass of SBOS after in vitro fermentation indicated its utilization by the gut microbiota,which increased the contents of short-chain fatty acids and lactic acid,thereby reducing the pH of the fermentation broth.Moreover,the core community was found to consist of Blautia,Lactobacillaceae,and Pediococcus.SBOS up-regulated beneficial differential metabolites such as myo-inositol,lactose,and glucose,which were closely related to galactose,amino sugar,and nucleotide sugar metabolism.This study will provide a reference for exploring the relationship between the gut microbiota and the metabolites of SBOS,and provide a basis for the development and application of SBOS as an ingredient for functional products.展开更多
Background There is a growing focus on using various plant-derived agricultural by-products to increase the benefits of pig farming,but these feedstuffs are fibrous in nature.This study investigated the relationship b...Background There is a growing focus on using various plant-derived agricultural by-products to increase the benefits of pig farming,but these feedstuffs are fibrous in nature.This study investigated the relationship between dietary fiber physicochemical properties and feedstuff fermentation characteristics and their effects on nutrient utilization,energy metabolism,and gut microbiota in growing pigs.Methods Thirty-six growing barrows(47.2±1.5 kg)were randomly allotted to 6 dietary treatments with 2 apparent viscosity levels and 3β-glucan-to-arabinoxylan ratios.In the experiment,nutrient utilization,energy metabolism,fecal microbial community,and production and absorption of short-chain fatty acid(SCFA)of pigs were investigated.In vitro digestion and fermentation models were used to compare the fermentation characteristics of feedstuffs and ileal digesta in the pig’s hindgut.Results The production dynamics of SCFA and dry matter corrected gas production of different feedstuffs during in vitro fermentation were different and closely related to the physical properties and chemical structure of the fiber.In animal experiments,increasing the dietary apparent viscosity and theβ-glucan-to-arabinoxylan ratios both increased the apparent ileal digestibility(AID),apparent total tract digestibility(ATTD),and hindgut digestibility of fiber components while decreasing the AID and ATTD of dry matter and organic matter(P<0.05).In addition,increasing dietary apparent viscosity andβ-glucan-to-arabinoxylan ratios both increased gas exchange,heat production,and protein oxidation,and decreased energy deposition(P<0.05).The dietary apparent viscosity andβ-glucanto-arabinoxylan ratios had linear interaction effects on the digestible energy,metabolizable energy,retained energy(RE),and net energy(NE)of the diets(P<0.05).At the same time,the increase of dietary apparent viscosity andβ-glucan-to-arabinoxylan ratios both increased SCFA production and absorption(P<0.05).Increasing the dietary apparent viscosity andβ-glucan-to-arabinoxylan ratios increased the diversity and abundance of bacteria(P<0.05)and the relative abundance of beneficial bacteria.Furthermore,increasing the dietaryβ-glucan-to-arabinoxylan ratios led to a linear increase in SCFA production during the in vitro fermentation of ileal digesta(P<0.001).Finally,the prediction equations for RE and NE were established.Conclusion Dietary fiber physicochemical properties alter dietary fermentation patterns and regulate nutrient utilization,energy metabolism,and pig gut microbiota composition and metabolites.展开更多
Erythromycin fermentation residue(EFR)represents a typical hazardous waste produced by the microbial pharmaceutical industry.Although electrolysis is promising for EFR disposal,its microbial threats remain unclear.Her...Erythromycin fermentation residue(EFR)represents a typical hazardous waste produced by the microbial pharmaceutical industry.Although electrolysis is promising for EFR disposal,its microbial threats remain unclear.Herein,metagenomics was coupled with the random forest technique to decipher the antibiotic resistance patterns of electrochemically treated EFR.Results showed that 95.75%of erythromycin could be removed in 2 hr.Electrolysis temporarily influenced EFRmicrobiota,where the relative abundances of Proteobacteria and Actinobacteria increased,while those of Fusobacteria,Firmicutes,and Bacteroidetes decreased.A total of 505 antibiotic resistance gene(ARG)subtypes encoding resistance to 21 antibiotic types and 150 mobile genetic elements(MGEs),mainly including plasmid(72)and transposase(52)were assembled in EFR.Significant linear regression models were identified among microbial richness,ARG subtypes,and MGE numbers(r^(2)=0.50-0.81,p<0.001).Physicochemical factors of EFR(Total nitrogen,total organic carbon,protein,and humus)regulated ARG and MGE assembly(%IncMSE value=5.14-14.85).The core ARG,MGE,and microbe sets(93.08%-99.85%)successfully explained 89.71%-92.92%of total ARG and MGE abundances.Specifically,gene aph(3 )-I,transposase tnpA,and Mycolicibacterium were the primary drivers of the resistance dissemination system.This study also proposes efficient resistance mitigation measures,and provides recommendations for future management of antibiotic fermentation residue.展开更多
Côte d’Ivoire has been the world’s leading producer of cocoa beans for several decades. Apart from this production performance, the quality of the beans, which are mainly exported to the major chocolate-making ...Côte d’Ivoire has been the world’s leading producer of cocoa beans for several decades. Apart from this production performance, the quality of the beans, which are mainly exported to the major chocolate-making countries, presents a quality problem to the point of suffering a discount on the international market. One of these quality problems is the content of ochratoxin A, a mycotoxin produced by fungi. Finally, to verify the level of contamination in beans produced in Côte d’Ivoire, a study was carried out. It consisted of collecting information on fermentation and drying times (The two major post-harvest operations) and collecting beans, which were analyzed by electrophoresis using the High Performance Liquid Chromatography (HPLC) method. The results obtained show ochratoxin A contents of between 0.05 µg/kg and 0.17 µg/kg. The general level of contamination is therefore very low and below the tolerable limit which is 2 µg/kg. In addition, the correlative study between the fermentation and drying times of the beans revealed no significant influence (p < 0.01) of the duration of these operations on the level of ochratoxin A contamination. Major contamination can occur after post-harvest activities carried out by producers. This is certainly due to the development of fungi responsible for the production of ochratoxin A during the period of storage and marketing of cocoa beans in conditions of high humidity in storage enclosures. Producers need to be made more aware of the need to ensure that cocoa beans are properly dried and stored in dry areas to avoid moisture build-up, which is a source of mould growth and ochratoxin A production.展开更多
[Objectives]To explore the effects of fermentation process on the content and functions of flavonoids in Gardenia jasminoides.[Methods]G.jasminoides was fermented by microorganisms,and the fermentation process of tota...[Objectives]To explore the effects of fermentation process on the content and functions of flavonoids in Gardenia jasminoides.[Methods]G.jasminoides was fermented by microorganisms,and the fermentation process of total flavonoids from G.jasminoides was optimized,and the antioxidant activity and hyaluronidase inhibitory activity of the fermentation broth were tested.[Results]The best strain for fermentation of total flavonoids in G.jasminoides was Bacillus subtilis.The optimum fermentation conditions were as follows:the solid-liquid ratio was 1:30,the inoculation amount was 2%,and the fermentation time was 24 h.Under these fermentation conditions,the content of total flavonoids in G.jasminoides reached 36.90 mg/g,which was 45.22%higher than that of the control group without microbial fermentation,and it had good DPPH free radical and hydroxyl free radical scavenging ability,and the inhibition ability of hyaluronidase after fermentation was also improved.[Conclusions]This study provides a technical reference for the comprehensive application of G.jasminoides.展开更多
Background Rumen microorganisms are key regulators of ruminant growth and production performance.Identifying probiotic candidates through microbial culturomics presents a promising strategy for improving ruminant prod...Background Rumen microorganisms are key regulators of ruminant growth and production performance.Identifying probiotic candidates through microbial culturomics presents a promising strategy for improving ruminant production performance.Our previous study identified significant differences in rumen microbial communities of Holstein calves with varying average daily gain(ADG).This study aims to identify a target strain based on the findings from multi-omics analysis and literature review,isolating and evaluating the target microbial strains from both the rumen and hindgut contents for their probiotic potential.Results Parabacteroides distasonis,a strain closely associated with ADG,was successfully isolated from calf rumen content cultured with Fastidious Anaerobe Agar(FAA)medium and named Parabacteroides distasonis F4.Wholegenome sequencing and pan-genome analysis showed that P.distasonis F4 possesses a core functional potential for carbohydrate and amino acid metabolism,with the ability to produce propionate,acetate,and lactate.The results of targeted and untargeted metabolomics further validated the organic acid production and metabolic pathways of P.distasonis F4.An in vitro simulated rumen fermentation test showed that supplementation with P.distasonis F4 significantly altered rumen microbial community structure and increased the molar proportions of propionate and butyrate in the rumen.Furthermore,an in vivo study demonstrated that dietary supplementation with P.distasonis F4 significantly increased the ADG of pre-weaning calves.Conclusions This study represents the first isolation of P.distasonis F4 from rumen,highlighting its potential as a probiotic strain for improving rumen development and growth performance in ruminants.展开更多
The aim of this study was to investigate the effects of dietary fat on energy and nitrogen(N)metabolism efficiency,rumen fermentation,and microbiota in twin suckling lambs.Thirty pairs of twin male lambs were randomly...The aim of this study was to investigate the effects of dietary fat on energy and nitrogen(N)metabolism efficiency,rumen fermentation,and microbiota in twin suckling lambs.Thirty pairs of twin male lambs were randomly divided into two groups with one group receiving a high-fat diet(HF)and the other a normal-fat diet(NF).Two diets(milk replacer and starter)of equal protein and different fat levels.The metabolism test was conducted when the lambs were 50-60 days old,and nine pairs of twin lambs were randomly selected for slaughter to collect rumen fluid at 60 days old.The result showed that fat addition increased the final body weight(BW),ruminal ammonia nitrogen(NH_(3)-N)content,proportion of propionic acid,and estimated methane production(CH_(4e))(P<0.05).The high fat diet tended to improve digestive energy(DE),metabolism energy(ME),DE/ME,utilisation of N(0.05<P<0.1).However,microbial crude protein(MCP)content,total volatile fatty acids(VFA),acetic acid ratio,and the ratio of acetate to propionate(A:P)were lower than that in the NF group(P<0.05).Regardless of whether fat is added or not,no different were observed in blood metabolites between the treatment.High-throughput sequencing revealed that fat addition before weaning increased phyla Proteobacteria and genera of Succinivibrio,but decreased the relative abundance of Clostridium IV,Dialister,Roseburia,Acidaminococcus,and Megasphaera genera.These findings indicated that high fat diet improved body weight,energy and nitrogen utilization may by shifting the rumen toward propionate fermentation via the enrichment of Succinivibrio.展开更多
Biological insecticides have gained importance in modern society because they cause minimal environmental harm and reduce pests’ability to develop resistance.Nomuraea rileyi,a facultative entomopathogenic fungus,is s...Biological insecticides have gained importance in modern society because they cause minimal environmental harm and reduce pests’ability to develop resistance.Nomuraea rileyi,a facultative entomopathogenic fungus,is suitable for infecting lepidopteran pests,including Spodoptera litura and Helicoverpa armigera.This work aims to identify a suitable semi-solid fermentation medium to increase the conidia production of N.rileyi and enhance its biological control ability as mycoinsecticide.Research is carried out on broken rice,wheat,sorghum,and corn as substrates,both with and without nutrient addition.It also covers incubation under set conditions,colony harvesting,and conidial yield and germination determination using a haemocytometer.All the study was conducted using a completely randomized design(CRD)and a test of significance was set at p<0.05 using analysis of variance(ANOVA).This work aimed to establish the effect of various substrates on growth and conidia formation in N.rileyi.The highest conidia count of 10×10^(8)CFU/g on day 15.The result was obtained from BR+Nu followed by sorghum 7×10^(8)CFU/g,corn 7×10^(8)CFU/g and wheat 6.5×10^(8)CFU/g.Thus,post-drying,the highest corresponding viability was observed in the product containing BR+Nu–6.20×10^(8)CFU/g.Adding rice bran(BR+RB,150 g each)still increases conidial yield up to 14×10^(8) CFU/g at 15 DAI.These indings thus assert that broken rice and supplementation affect conidia yield and viability.展开更多
This study was performed to investigate the changes in microbial communities and metabolites during the long-term fermentation of commercially manufactured anchovy sauce.Samples of commercial anchovy sauce were collec...This study was performed to investigate the changes in microbial communities and metabolites during the long-term fermentation of commercially manufactured anchovy sauce.Samples of commercial anchovy sauce were collected from large-scale fermentation tanks with fermentation periods of up to 7.87 years.The complex bacterial community was simplified to two genera,Tetragenococcus and Halanaerobium,after approximately 0.55 years of fermentation.Although genera,such as Saccharomyces,Cladosporium,Candida,and Aspergillus,were relatively dominant,no clear pattern was identified in fungal community analysis.The longitudinal metabolite profile demonstrated that approximately half(55.8%)of the metabolites present in anchovy sauce were produced within a year of fermentation due to rapid fermentation.Despite the static microbial community,the contents of several metabolites including amino acids and biogenic amines changed continuously during the long-term fermentation of anchovy sauce.This study provides novel insights into the changes in microbiota and metabolites in fish sauce produced without any starter inoculation.展开更多
The olive oil fermentation filtrate was prepared by microbial fermentation technology,and the fermentation process was optimized by orthogonal test to screen out the optimal fermentation conditions.At the same time,th...The olive oil fermentation filtrate was prepared by microbial fermentation technology,and the fermentation process was optimized by orthogonal test to screen out the optimal fermentation conditions.At the same time,the effect of olive oil fermentation filtrate to promote the secretion of type I collagen (COL-I) and type VII collagen (COL-VII) by fibroblasts (HFF-1),the inhibitory effect on the secretion of alpha tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) by lipopolysaccharide induced macrophages (RAW264.7),and the inhibitory effect on the induction of reactive oxygen species (ROS) production by immortalized human keratinocytes (HaCaT) were studied through in vitro cell testing methods.The results showed that the optimal fermentation conditions of olive oil fermentation filtrate were as follows,inoculation amount was 3%,inducer amount was 2%,fermentation time was 48 h.Its efficacy can significantly promote the synthesis of COL-I and COL-VII,and significantly inhibit the content of inflammatory factors TNF-α and IL-6 as well as ROS content,it has multiple effects of firming,anti-wrinkle,soothing and antioxidant,providing scientific and effective data support for the development of cosmetic raw materials.展开更多
[Objectives]This study was conducted to elucidate the fermentation characteristics of different bacterial strains and identify the optimal fermentation strain,so as to provide a theoretical basis for the development o...[Objectives]This study was conducted to elucidate the fermentation characteristics of different bacterial strains and identify the optimal fermentation strain,so as to provide a theoretical basis for the development of functional aloe beverages.[Methods]Using fresh juice from Aloe vera L.as the raw material,the proliferation characteristics of Lactobacillus plantarum(LP),Lactobacillus reuteri(LR),Lactobacillus rhamnosus(LGG)and Pediococcus pentosaceus(PP)during fermentation were investigated.Changes in pH,total viable bacterial count,total sugars,acemannan(AC),total flavonoid content(TFC)and total phenol content(TPC),and their effects on antioxidant activity(DPPH,ABTS,FRAP)were measured before and after fermentation.[Results]Aloe juice served as an excellent growth substrate for all four lactic acid bacterial strains,with viable bacterial counts significantly increasing after fermentation.The LGG group achieved the highest viable count(12.82 lg CFU/ml),followed by the LP group(12.77 lg CFU/ml).All four strains significantly enhanced the total phenol content and antioxidant capacity of the aloe juice.The LP group demonstrated the most outstanding performance,achieving the highest increase in TPC,the smallest reduction in TFC(from 0.054 mg/ml to 0.019 mg/ml),and the strongest comprehensive antioxidant activity(DPPH scavenging rate:80.33%,ABTS scavenging rate:93.15%,FRAP value:0.167 mmol/L).Additionally,it also better preserved the functional component AC.[Conclusions]L.plantarum demonstrated optimal performance in enhancing the antioxidant activity and preserving nutritional components of aloe juice,making it an ideal strain for aloe juice fermentation.This study provides a foundation for developing functional aloe beverages.展开更多
[Objectives]This study was conducted to improve the poor water-holding capacity(WHC)and high syneresis rate of fermented soy milk by optimizing fermentation process conditions.[Methods]Based on the results of single f...[Objectives]This study was conducted to improve the poor water-holding capacity(WHC)and high syneresis rate of fermented soy milk by optimizing fermentation process conditions.[Methods]Based on the results of single factor experiments,response surface methodology was employed to optimize the fermentation temperature,fermentation time,and starter culture addition for enhancing WHC.The physicochemical properties of fermented soybean milk were analyzed.[Results]The optimal process parameters were determined as follows:fermentation temperature 36℃,fermentation time 8 h,and starter culture addition 5%.Under these conditions,WHC reached(77.18±0.08)%,which was consistent with the theoretical prediction value of(76.75±0.15)%.During fermentation,the pH decreased from(6.6±0.11)to(4.65±0.09),while acidity increased from(16.5±0.04)°T to(81.5±0.08)°T.The viable cell count rose from 1×10^(7)to 29×10^(7)cfu/ml,and WHC was improved significantly from(10.50±0.18)%to(77.40±0.13)%.[Conclusions]This study optimized the fermentation process parameters and revealed physicochemical characteristic changes during soybean milk fermentation,providing a theoretical foundation for industrial production.展开更多
Cyclosporin A fermentation residue(CFR)is a type of organic waste generated during the production of cyclosporin A,which are abundant in nutrients including organic matter,phosphorus,nitrogen and potassium.Inappropria...Cyclosporin A fermentation residue(CFR)is a type of organic waste generated during the production of cyclosporin A,which are abundant in nutrients including organic matter,phosphorus,nitrogen and potassium.Inappropriate handling of CFR not only waste valuable bioresources,but may also lead to the cyclosporin A and associated resistance genes into the natural environment,posing a significant threat to ecological system and human health.Land application was an effective way to resource recovery of CFR after aerobic composting(CAC).This study investigated the impact of CAC on soil fertility and environmental safety.The results indicated that CAC could improve soil nutrient contents and enhance enzyme activities.CAC altered the diversity and community composition of soil bacteria,resulting in an increase in the abundance of relevant bacteria beneficial for organic matter decomposition and cyclosporin A degradation.The introduced cyclosporin A(71.69μg/kg)completely degraded within 20 days due to soil biodegradation.The significantly increased abundance of intIl,mdr3,pgp,TSR and pmra in the soil cultivation early stage were restored to the soil background level within 90 days,indicating a reduced risk of antimicrobial resistance.The results demonstrated that reasonable land application of CAC could improve soil fertility without antimicrobial resistance risk,which is helpful for evaluating the resource utilization value and environmental risks of antibiotic fermentation residue after aerobic composting.展开更多
In-depth knowledge of the microbes responsible for biogenic amine(BA)production during soy sauce fermentation remains limited.Herein,the variations in the BA profiles,microbial communities,and microbes involved in BA ...In-depth knowledge of the microbes responsible for biogenic amine(BA)production during soy sauce fermentation remains limited.Herein,the variations in the BA profiles,microbial communities,and microbes involved in BA production during the fermentation of soy sauce through Japanese-type(JP)and Cantonese-type(CP)processes were compared.BA analysis revealed that the most abundant BA species were putrescine,tyramine,and histamine in the later three stages(1187.68,785.16,and 193.20 mg/kg on average,respectively).The BA profiles differed significantly,with CP samples containing higher contents of putrescine,tyramine,and histamine(P<0.05)at the end of fermentation.Metagenomic analysis indicated that BA-producing genes exhibited different abundance profiles,with most genes,including spe A,spe B,arg,spe E,and tyr DC,having higher abundances in microbial communities during the CP process.In total,15 high-quality metagenome-assembled genomes(MAGs)were retrieved,of which 10 encoded at BA production-related genes.Enterococcus faecium(MAG10)and Weissella paramesenteroides(MAG5)might be the major tyramine producers.The high putrescine content in CP might be associated with the high abundance of Staphylococcus gallinarum(MAG8).This study provides a comprehensive understanding of the diversity and abundance of genes involved in BA synthesis,especially at the species level,during food fermentation.展开更多
基金Supported by the National Natural Science Foundation of China （20306026 and 20876141） and the National Basic Research program of China （2007CB707805）.
文摘5-Aminolevulinic acid （ALA） is a common precursor for tetrapyrrole compounds in all kinds of organ isms and has wide applications in agriculture and medicines. In this study, a new strategy, i.e. short-term dissolved oxygen （DO） shock during aerobic fermentation, was introduced to produce 5-aminolevulinic acid with a recombi-nant E. coli. Effects of duration time of DO shock operation on plasmid concentration, intracellular ALA synthase （ALAS） activity and ALA production were investigated in Erlenmeyer shake flasks. The results indicated that both ALAS activity and ALA yield were enhanced in an anaerobic operation of 45 rain in the early exponential phase during fermentation, while they decreased when the anaerobic operation time was further increased to 60 rain. The DO shock protocol was confirmed with the fed-batch fermentation in a 15 L fermenter and the ALA production achieved 9.4 g.L-1 （72 mmol.L-1）, which is the highest yield in the fermentation broth reported up to now.
基金Partially suppored by a grant for the U K DTI- China MOST Collaborative Research
文摘L-(+)-Lactic acid production from corncob hydrolysate as a cheap carbohydrate source by fed-batch fermentation of Rhizopus oryzaeHZS6 was studied. After 96 h of fermentation in a 5 L fermentor, the final concentration of ammonium L-(+)-lactate, average productivity(based on initial xylose concentration) and maximum dry cell weight were 132.4 g/L, 1.38 g/(L·h), and 8.9 g/L respectively. The optical purity of L-(+)-lactate was 98.8%.
基金Supported by the National Natural Science Foundation of China （20676013）
文摘An iterative optimization strategy for fed-batch fermentation process is presented by combining a run-to-run optimization with swarm energy conservation particle swarm optimization (SEC-PSO). SEC-PSO, which is designed with the concept of energy conservation, can solve the problem of premature convergence frequently appeared in standard PSO algorithm by partitioning its population into several sub-swarms according to the energy of the swarm and is used in the optimization strategy for parameter identification and operation condition optimization. The run-to-run optimization exploits the repetitive nature of fed-batch processes in order to deal with the optimal problems of fed-batch fermentation process with inaccurate process model and unsteady process state. The kinetic model parameters, used in the operation condition optimization of the next run, are adjusted by calculating time-series data obtained from real fed-batch process in the run-to-run optimization. The simulation results show that the strategy can adjust its kinetic model dynamically and overcome the instability of fed-batch process effectively. Run-to-run strategy with SEC-PSO provides an effective method for optimization of fed-batch fermentation process.
文摘Bioreactor operation requires continuous monitoring of fermentation parameters and real-time control over bioreactor devices. Remote monitoring and control of the bioreactor＇s computer via the Internet avoids the necessity of personnel being continually onsite during operation. A two liter Sartorius-stedim Biostat~ A Plus fermentation system was networked and interfaced with the commercial software from GoToMyPC to allow remote control of the fermentation system utilizing the internet. The fermentation vessel was equipped with hardware calibrated for monitoring and controlling culture parameters during experimentations. The uniform resource locator controlled night-vision web camera allowed continuous monitoring of the glass fermentation vessel during the day and at night. The main window screen of the laboratory computer can be securely accessed from any portable device （i.e. laptop） capable of establishing an Internet connection and executing the commercial software from GoToMyPC. The secured internet protocol address, provided by GoToMyPC, assures that the system can only be controlled by authorized users who have been given access to the account. This interface permits the remote control of the Biostat A Plus fermentation system and possibly other automated or potentially automated culturing systems at the convenience of the user（s）.
基金supported by the Open Project Program,State key Laboratory of Bioreactor Engineering/ECUSTthe Natural Science Foundation of China(No.60174024).
文摘An on-line scheduling algorithm to maximize gross profit of penicillin fed-batch fermentation is proposed. According to the on-line classification method, fed-batch fermentation batches are classified into three categories. Using the scheduling strategy, the optimal termination sequence of batches is obtained. Pseudo on-line simulations for testing the proposed algorithm with the data from industrial scale penicillin fermentation are carried out.
基金supported by the National Natural Science Foundation of China(No.21076148 and No.31270087)Plan of Tianjin Science and Technology Support(11ZCKFSY0100)
文摘To investigate the in vitro digestion and fermentation properties of soybean oligosaccharides(SBOS)extracted from defatted soybean meal,the changes in monosaccharide composition and molecular mass were analyzed.Subsequently,the effect of SBOS on microbial community structure and metabolites was studied by 16S rRNA gene sequencing and untargeted metabolomics based on liquid chromatography-mass spectrometry.Results showed that SBOS was not easily enzymolyzed during simulated digestion and could reach the large intestine through the digestive system.The significant decrease in the molecular mass of SBOS after in vitro fermentation indicated its utilization by the gut microbiota,which increased the contents of short-chain fatty acids and lactic acid,thereby reducing the pH of the fermentation broth.Moreover,the core community was found to consist of Blautia,Lactobacillaceae,and Pediococcus.SBOS up-regulated beneficial differential metabolites such as myo-inositol,lactose,and glucose,which were closely related to galactose,amino sugar,and nucleotide sugar metabolism.This study will provide a reference for exploring the relationship between the gut microbiota and the metabolites of SBOS,and provide a basis for the development and application of SBOS as an ingredient for functional products.
基金supported by the National Key Research and Development Program(No.2021YFD1300201)Jilin Provincial Department of Science and Technology Innovation Platform and Talent Special Project(No.20230508090RC).
文摘Background There is a growing focus on using various plant-derived agricultural by-products to increase the benefits of pig farming,but these feedstuffs are fibrous in nature.This study investigated the relationship between dietary fiber physicochemical properties and feedstuff fermentation characteristics and their effects on nutrient utilization,energy metabolism,and gut microbiota in growing pigs.Methods Thirty-six growing barrows(47.2±1.5 kg)were randomly allotted to 6 dietary treatments with 2 apparent viscosity levels and 3β-glucan-to-arabinoxylan ratios.In the experiment,nutrient utilization,energy metabolism,fecal microbial community,and production and absorption of short-chain fatty acid(SCFA)of pigs were investigated.In vitro digestion and fermentation models were used to compare the fermentation characteristics of feedstuffs and ileal digesta in the pig’s hindgut.Results The production dynamics of SCFA and dry matter corrected gas production of different feedstuffs during in vitro fermentation were different and closely related to the physical properties and chemical structure of the fiber.In animal experiments,increasing the dietary apparent viscosity and theβ-glucan-to-arabinoxylan ratios both increased the apparent ileal digestibility(AID),apparent total tract digestibility(ATTD),and hindgut digestibility of fiber components while decreasing the AID and ATTD of dry matter and organic matter(P<0.05).In addition,increasing dietary apparent viscosity andβ-glucan-to-arabinoxylan ratios both increased gas exchange,heat production,and protein oxidation,and decreased energy deposition(P<0.05).The dietary apparent viscosity andβ-glucanto-arabinoxylan ratios had linear interaction effects on the digestible energy,metabolizable energy,retained energy(RE),and net energy(NE)of the diets(P<0.05).At the same time,the increase of dietary apparent viscosity andβ-glucan-to-arabinoxylan ratios both increased SCFA production and absorption(P<0.05).Increasing the dietary apparent viscosity andβ-glucan-to-arabinoxylan ratios increased the diversity and abundance of bacteria(P<0.05)and the relative abundance of beneficial bacteria.Furthermore,increasing the dietaryβ-glucan-to-arabinoxylan ratios led to a linear increase in SCFA production during the in vitro fermentation of ileal digesta(P<0.001).Finally,the prediction equations for RE and NE were established.Conclusion Dietary fiber physicochemical properties alter dietary fermentation patterns and regulate nutrient utilization,energy metabolism,and pig gut microbiota composition and metabolites.
基金supported by the Special Project of Basic Scientific Research Business of Central Public Welfare Scientific Research Institutes (No.2019YSKY-027).
文摘Erythromycin fermentation residue(EFR)represents a typical hazardous waste produced by the microbial pharmaceutical industry.Although electrolysis is promising for EFR disposal,its microbial threats remain unclear.Herein,metagenomics was coupled with the random forest technique to decipher the antibiotic resistance patterns of electrochemically treated EFR.Results showed that 95.75%of erythromycin could be removed in 2 hr.Electrolysis temporarily influenced EFRmicrobiota,where the relative abundances of Proteobacteria and Actinobacteria increased,while those of Fusobacteria,Firmicutes,and Bacteroidetes decreased.A total of 505 antibiotic resistance gene(ARG)subtypes encoding resistance to 21 antibiotic types and 150 mobile genetic elements(MGEs),mainly including plasmid(72)and transposase(52)were assembled in EFR.Significant linear regression models were identified among microbial richness,ARG subtypes,and MGE numbers(r^(2)=0.50-0.81,p<0.001).Physicochemical factors of EFR(Total nitrogen,total organic carbon,protein,and humus)regulated ARG and MGE assembly(%IncMSE value=5.14-14.85).The core ARG,MGE,and microbe sets(93.08%-99.85%)successfully explained 89.71%-92.92%of total ARG and MGE abundances.Specifically,gene aph(3 )-I,transposase tnpA,and Mycolicibacterium were the primary drivers of the resistance dissemination system.This study also proposes efficient resistance mitigation measures,and provides recommendations for future management of antibiotic fermentation residue.
文摘Côte d’Ivoire has been the world’s leading producer of cocoa beans for several decades. Apart from this production performance, the quality of the beans, which are mainly exported to the major chocolate-making countries, presents a quality problem to the point of suffering a discount on the international market. One of these quality problems is the content of ochratoxin A, a mycotoxin produced by fungi. Finally, to verify the level of contamination in beans produced in Côte d’Ivoire, a study was carried out. It consisted of collecting information on fermentation and drying times (The two major post-harvest operations) and collecting beans, which were analyzed by electrophoresis using the High Performance Liquid Chromatography (HPLC) method. The results obtained show ochratoxin A contents of between 0.05 µg/kg and 0.17 µg/kg. The general level of contamination is therefore very low and below the tolerable limit which is 2 µg/kg. In addition, the correlative study between the fermentation and drying times of the beans revealed no significant influence (p < 0.01) of the duration of these operations on the level of ochratoxin A contamination. Major contamination can occur after post-harvest activities carried out by producers. This is certainly due to the development of fungi responsible for the production of ochratoxin A during the period of storage and marketing of cocoa beans in conditions of high humidity in storage enclosures. Producers need to be made more aware of the need to ensure that cocoa beans are properly dried and stored in dry areas to avoid moisture build-up, which is a source of mould growth and ochratoxin A production.
基金Supported by Shanghai Putuo District R&D Platform Project(2024QX04).
文摘[Objectives]To explore the effects of fermentation process on the content and functions of flavonoids in Gardenia jasminoides.[Methods]G.jasminoides was fermented by microorganisms,and the fermentation process of total flavonoids from G.jasminoides was optimized,and the antioxidant activity and hyaluronidase inhibitory activity of the fermentation broth were tested.[Results]The best strain for fermentation of total flavonoids in G.jasminoides was Bacillus subtilis.The optimum fermentation conditions were as follows:the solid-liquid ratio was 1:30,the inoculation amount was 2%,and the fermentation time was 24 h.Under these fermentation conditions,the content of total flavonoids in G.jasminoides reached 36.90 mg/g,which was 45.22%higher than that of the control group without microbial fermentation,and it had good DPPH free radical and hydroxyl free radical scavenging ability,and the inhibition ability of hyaluronidase after fermentation was also improved.[Conclusions]This study provides a technical reference for the comprehensive application of G.jasminoides.
基金funded by National Key Research and Development Program(2022YFA1304200)Agricultural Science and Technology Innovation Program(CAAS-ASTIP-2023-IFR-04 and CAAS-ZDRW202305)the Beijing Innovation Consortium of Livestock Research System(BAIC05-2023).
文摘Background Rumen microorganisms are key regulators of ruminant growth and production performance.Identifying probiotic candidates through microbial culturomics presents a promising strategy for improving ruminant production performance.Our previous study identified significant differences in rumen microbial communities of Holstein calves with varying average daily gain(ADG).This study aims to identify a target strain based on the findings from multi-omics analysis and literature review,isolating and evaluating the target microbial strains from both the rumen and hindgut contents for their probiotic potential.Results Parabacteroides distasonis,a strain closely associated with ADG,was successfully isolated from calf rumen content cultured with Fastidious Anaerobe Agar(FAA)medium and named Parabacteroides distasonis F4.Wholegenome sequencing and pan-genome analysis showed that P.distasonis F4 possesses a core functional potential for carbohydrate and amino acid metabolism,with the ability to produce propionate,acetate,and lactate.The results of targeted and untargeted metabolomics further validated the organic acid production and metabolic pathways of P.distasonis F4.An in vitro simulated rumen fermentation test showed that supplementation with P.distasonis F4 significantly altered rumen microbial community structure and increased the molar proportions of propionate and butyrate in the rumen.Furthermore,an in vivo study demonstrated that dietary supplementation with P.distasonis F4 significantly increased the ADG of pre-weaning calves.Conclusions This study represents the first isolation of P.distasonis F4 from rumen,highlighting its potential as a probiotic strain for improving rumen development and growth performance in ruminants.
基金supported by China Agriculture Research System of MOF and MARA(CARS-38)。
文摘The aim of this study was to investigate the effects of dietary fat on energy and nitrogen(N)metabolism efficiency,rumen fermentation,and microbiota in twin suckling lambs.Thirty pairs of twin male lambs were randomly divided into two groups with one group receiving a high-fat diet(HF)and the other a normal-fat diet(NF).Two diets(milk replacer and starter)of equal protein and different fat levels.The metabolism test was conducted when the lambs were 50-60 days old,and nine pairs of twin lambs were randomly selected for slaughter to collect rumen fluid at 60 days old.The result showed that fat addition increased the final body weight(BW),ruminal ammonia nitrogen(NH_(3)-N)content,proportion of propionic acid,and estimated methane production(CH_(4e))(P<0.05).The high fat diet tended to improve digestive energy(DE),metabolism energy(ME),DE/ME,utilisation of N(0.05<P<0.1).However,microbial crude protein(MCP)content,total volatile fatty acids(VFA),acetic acid ratio,and the ratio of acetate to propionate(A:P)were lower than that in the NF group(P<0.05).Regardless of whether fat is added or not,no different were observed in blood metabolites between the treatment.High-throughput sequencing revealed that fat addition before weaning increased phyla Proteobacteria and genera of Succinivibrio,but decreased the relative abundance of Clostridium IV,Dialister,Roseburia,Acidaminococcus,and Megasphaera genera.These findings indicated that high fat diet improved body weight,energy and nitrogen utilization may by shifting the rumen toward propionate fermentation via the enrichment of Succinivibrio.
文摘Biological insecticides have gained importance in modern society because they cause minimal environmental harm and reduce pests’ability to develop resistance.Nomuraea rileyi,a facultative entomopathogenic fungus,is suitable for infecting lepidopteran pests,including Spodoptera litura and Helicoverpa armigera.This work aims to identify a suitable semi-solid fermentation medium to increase the conidia production of N.rileyi and enhance its biological control ability as mycoinsecticide.Research is carried out on broken rice,wheat,sorghum,and corn as substrates,both with and without nutrient addition.It also covers incubation under set conditions,colony harvesting,and conidial yield and germination determination using a haemocytometer.All the study was conducted using a completely randomized design(CRD)and a test of significance was set at p<0.05 using analysis of variance(ANOVA).This work aimed to establish the effect of various substrates on growth and conidia formation in N.rileyi.The highest conidia count of 10×10^(8)CFU/g on day 15.The result was obtained from BR+Nu followed by sorghum 7×10^(8)CFU/g,corn 7×10^(8)CFU/g and wheat 6.5×10^(8)CFU/g.Thus,post-drying,the highest corresponding viability was observed in the product containing BR+Nu–6.20×10^(8)CFU/g.Adding rice bran(BR+RB,150 g each)still increases conidial yield up to 14×10^(8) CFU/g at 15 DAI.These indings thus assert that broken rice and supplementation affect conidia yield and viability.
基金supported by the National Research Foundation of Korea(NRF)(RS-2024-00333618 and RS-2023-00240999)a Korea University Grantthe Institute of Biomedical Science&Food Safety,CJ-Korea University Food Safety Hall at Korea University,Republic of Korea。
文摘This study was performed to investigate the changes in microbial communities and metabolites during the long-term fermentation of commercially manufactured anchovy sauce.Samples of commercial anchovy sauce were collected from large-scale fermentation tanks with fermentation periods of up to 7.87 years.The complex bacterial community was simplified to two genera,Tetragenococcus and Halanaerobium,after approximately 0.55 years of fermentation.Although genera,such as Saccharomyces,Cladosporium,Candida,and Aspergillus,were relatively dominant,no clear pattern was identified in fungal community analysis.The longitudinal metabolite profile demonstrated that approximately half(55.8%)of the metabolites present in anchovy sauce were produced within a year of fermentation due to rapid fermentation.Despite the static microbial community,the contents of several metabolites including amino acids and biogenic amines changed continuously during the long-term fermentation of anchovy sauce.This study provides novel insights into the changes in microbiota and metabolites in fish sauce produced without any starter inoculation.
文摘The olive oil fermentation filtrate was prepared by microbial fermentation technology,and the fermentation process was optimized by orthogonal test to screen out the optimal fermentation conditions.At the same time,the effect of olive oil fermentation filtrate to promote the secretion of type I collagen (COL-I) and type VII collagen (COL-VII) by fibroblasts (HFF-1),the inhibitory effect on the secretion of alpha tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) by lipopolysaccharide induced macrophages (RAW264.7),and the inhibitory effect on the induction of reactive oxygen species (ROS) production by immortalized human keratinocytes (HaCaT) were studied through in vitro cell testing methods.The results showed that the optimal fermentation conditions of olive oil fermentation filtrate were as follows,inoculation amount was 3%,inducer amount was 2%,fermentation time was 48 h.Its efficacy can significantly promote the synthesis of COL-I and COL-VII,and significantly inhibit the content of inflammatory factors TNF-α and IL-6 as well as ROS content,it has multiple effects of firming,anti-wrinkle,soothing and antioxidant,providing scientific and effective data support for the development of cosmetic raw materials.
基金Supported by Undergraduate Innovation and Entrepreneurship Training Program of Zhaoqing University(S202410580071X).
文摘[Objectives]This study was conducted to elucidate the fermentation characteristics of different bacterial strains and identify the optimal fermentation strain,so as to provide a theoretical basis for the development of functional aloe beverages.[Methods]Using fresh juice from Aloe vera L.as the raw material,the proliferation characteristics of Lactobacillus plantarum(LP),Lactobacillus reuteri(LR),Lactobacillus rhamnosus(LGG)and Pediococcus pentosaceus(PP)during fermentation were investigated.Changes in pH,total viable bacterial count,total sugars,acemannan(AC),total flavonoid content(TFC)and total phenol content(TPC),and their effects on antioxidant activity(DPPH,ABTS,FRAP)were measured before and after fermentation.[Results]Aloe juice served as an excellent growth substrate for all four lactic acid bacterial strains,with viable bacterial counts significantly increasing after fermentation.The LGG group achieved the highest viable count(12.82 lg CFU/ml),followed by the LP group(12.77 lg CFU/ml).All four strains significantly enhanced the total phenol content and antioxidant capacity of the aloe juice.The LP group demonstrated the most outstanding performance,achieving the highest increase in TPC,the smallest reduction in TFC(from 0.054 mg/ml to 0.019 mg/ml),and the strongest comprehensive antioxidant activity(DPPH scavenging rate:80.33%,ABTS scavenging rate:93.15%,FRAP value:0.167 mmol/L).Additionally,it also better preserved the functional component AC.[Conclusions]L.plantarum demonstrated optimal performance in enhancing the antioxidant activity and preserving nutritional components of aloe juice,making it an ideal strain for aloe juice fermentation.This study provides a foundation for developing functional aloe beverages.
基金Supported by Postgraduate Research Innovation Project of Shaoyang University(CX2023SY026)Natural Science Foundation of Hunan Province(2022JJ50232)Horizontal Scientific Research Project of Shaoyang University(2023HX43).
文摘[Objectives]This study was conducted to improve the poor water-holding capacity(WHC)and high syneresis rate of fermented soy milk by optimizing fermentation process conditions.[Methods]Based on the results of single factor experiments,response surface methodology was employed to optimize the fermentation temperature,fermentation time,and starter culture addition for enhancing WHC.The physicochemical properties of fermented soybean milk were analyzed.[Results]The optimal process parameters were determined as follows:fermentation temperature 36℃,fermentation time 8 h,and starter culture addition 5%.Under these conditions,WHC reached(77.18±0.08)%,which was consistent with the theoretical prediction value of(76.75±0.15)%.During fermentation,the pH decreased from(6.6±0.11)to(4.65±0.09),while acidity increased from(16.5±0.04)°T to(81.5±0.08)°T.The viable cell count rose from 1×10^(7)to 29×10^(7)cfu/ml,and WHC was improved significantly from(10.50±0.18)%to(77.40±0.13)%.[Conclusions]This study optimized the fermentation process parameters and revealed physicochemical characteristic changes during soybean milk fermentation,providing a theoretical foundation for industrial production.
基金supported by the National Natural Science Foundation of China(No.52170138)the National Key Research and Development Program of China(No.2023YFD1900305)+3 种基金Qingdao Agricultural University Doctoral Start-Up Fund(No.6631122003)the Project of Talent IntroductionEducation Program of Youth Innovation Teams in Universities of Shandong Province(2021–05)Shandong Provincial College Youth Innovation Team Program(No.2023KJ169).
文摘Cyclosporin A fermentation residue(CFR)is a type of organic waste generated during the production of cyclosporin A,which are abundant in nutrients including organic matter,phosphorus,nitrogen and potassium.Inappropriate handling of CFR not only waste valuable bioresources,but may also lead to the cyclosporin A and associated resistance genes into the natural environment,posing a significant threat to ecological system and human health.Land application was an effective way to resource recovery of CFR after aerobic composting(CAC).This study investigated the impact of CAC on soil fertility and environmental safety.The results indicated that CAC could improve soil nutrient contents and enhance enzyme activities.CAC altered the diversity and community composition of soil bacteria,resulting in an increase in the abundance of relevant bacteria beneficial for organic matter decomposition and cyclosporin A degradation.The introduced cyclosporin A(71.69μg/kg)completely degraded within 20 days due to soil biodegradation.The significantly increased abundance of intIl,mdr3,pgp,TSR and pmra in the soil cultivation early stage were restored to the soil background level within 90 days,indicating a reduced risk of antimicrobial resistance.The results demonstrated that reasonable land application of CAC could improve soil fertility without antimicrobial resistance risk,which is helpful for evaluating the resource utilization value and environmental risks of antibiotic fermentation residue after aerobic composting.
基金supported by the Natural Science Foundation of Guangdong Province(2022A1515012158)the National Science Foundation of China(41977138)+3 种基金the Construction Project of Teaching Quality and Teaching Reform in Guangdong Province(SJD202001)the General University Project of Guangdong Provincial Department of Education(2021KCXTD070 and 2021ZDZX4072)the Key Project of Social Welfare and Basic Research of Zhongshan City(2020B2010)the Start-up Fund from the Zhongshan Institute at the University of Electronic Science and Technology in China(419YKQN12)。
文摘In-depth knowledge of the microbes responsible for biogenic amine(BA)production during soy sauce fermentation remains limited.Herein,the variations in the BA profiles,microbial communities,and microbes involved in BA production during the fermentation of soy sauce through Japanese-type(JP)and Cantonese-type(CP)processes were compared.BA analysis revealed that the most abundant BA species were putrescine,tyramine,and histamine in the later three stages(1187.68,785.16,and 193.20 mg/kg on average,respectively).The BA profiles differed significantly,with CP samples containing higher contents of putrescine,tyramine,and histamine(P<0.05)at the end of fermentation.Metagenomic analysis indicated that BA-producing genes exhibited different abundance profiles,with most genes,including spe A,spe B,arg,spe E,and tyr DC,having higher abundances in microbial communities during the CP process.In total,15 high-quality metagenome-assembled genomes(MAGs)were retrieved,of which 10 encoded at BA production-related genes.Enterococcus faecium(MAG10)and Weissella paramesenteroides(MAG5)might be the major tyramine producers.The high putrescine content in CP might be associated with the high abundance of Staphylococcus gallinarum(MAG8).This study provides a comprehensive understanding of the diversity and abundance of genes involved in BA synthesis,especially at the species level,during food fermentation.
