Recommending personalized travel routes from sparse,implicit feedback poses a significant challenge,as conventional systems often struggle with information overload and fail to capture the complex,sequential nature of...Recommending personalized travel routes from sparse,implicit feedback poses a significant challenge,as conventional systems often struggle with information overload and fail to capture the complex,sequential nature of user preferences.To address this,we propose a Conditional Generative Adversarial Network(CGAN)that generates diverse and highly relevant itineraries.Our approach begins by constructing a conditional vector that encapsulates a user’s profile.This vector uniquely fuses embeddings from a Heterogeneous Information Network(HIN)to model complex user-place-route relationships,a Recurrent Neural Network(RNN)to capture sequential path dynamics,and Neural Collaborative Filtering(NCF)to incorporate collaborative signals from the wider user base.This comprehensive condition,further enhanced with features representing user interaction confidence and uncertainty,steers a CGAN stabilized by spectral normalization to generate high-fidelity latent route representations,effectively mitigating the data sparsity problem.Recommendations are then formulated using an Anchor-and-Expand algorithm,which selects relevant starting Points of Interest(POI)based on user history,then expands routes through latent similarity matching and geographic coherence optimization,culminating in Traveling Salesman Problem(TSP)-based route optimization for practical travel distances.Experiments on a real-world check-in dataset validate our model’s unique generative capability,achieving F1 scores ranging from 0.163 to 0.305,and near-zero pairs−F1 scores between 0.002 and 0.022.These results confirm the model’s success in generating novel travel routes by recommending new locations and sequences rather than replicating users’past itineraries.This work provides a robust solution for personalized travel planning,capable of generating novel and compelling routes for both new and existing users by learning from collective travel intelligence.展开更多
Background:Therapeutic responses of breast cancer vary among patients and lead to drug resistance and recurrence due to the heterogeneity.Current preclinical models,however,are inadequate for predicting individual pat...Background:Therapeutic responses of breast cancer vary among patients and lead to drug resistance and recurrence due to the heterogeneity.Current preclinical models,however,are inadequate for predicting individual patient responses towards different drugs.This study aimed to investigate the patient-derived breast cancer culture models for drug sensitivity evaluations.Methods:Tumor and adjacent tissues from female breast cancer patients were collected during surgery.Patient-derived breast cancer cells were cultured using the conditional reprogramming technique to establish 2D models.The obtained patient-derived conditional reprogramming breast cancer(CRBC)cells were subsequently embedded in alginate-gelatin methacryloyl hydrogel microspheres to form 3D culture models.Comparisons between 2D and 3D models were made using immunohistochemistry(tumor markers),MTS assays(cell viability),flow cytometry(apoptosis),transwell assays(migration),and Western blotting(protein expression).Drug sensitivity tests were conducted to evaluate patient-specific responses to anti-cancer agents.Results:2D and 3D culture models were successfully established using samples from eight patients.The 3D models retained histological and marker characteristics of the original tumors.Compared to 2D cultures,3D models exhibited increased apoptosis,enhanced drug resistance,elevated stem cell marker expression,and greater migration ability—features more reflective of in vivo tumor behavior.Conclusion:Patient-derived 3D CRBC models effectively mimic the in vivo tumor microenvironment and demonstrate stronger resistance to anti-cancer drugs than 2D models.These hydrogel-based models offer a cost-effective and clinically relevant platform for drug screening and personalized breast cancer treatment.展开更多
bacterium LV-1 which isolated from soil sample were studied bacterium was isolated by serial dilution method, the effects of carbon source, nitrogen source, the initial pH and temperature on producing polysaccharide b...bacterium LV-1 which isolated from soil sample were studied bacterium was isolated by serial dilution method, the effects of carbon source, nitrogen source, the initial pH and temperature on producing polysaccharide by it were discussed to confirm the optimum fermentation conditions. [ Result] The physicochemical properties showed that the polysaccharide was water-soluble, but insoluble in organic solvents including ethanol, butanol, and chloroform. It was neutral polysaccharide with negative charge and without reducing terminal. The pH of its solution was pH =7.5. There were no protein, fructose, uronic acid, sulphate and starch-like structure included in po/ysacchadde molecules. The optimum fermentation conditions for po/ysaccharide produc- tion were 3% mannitol as carbon source, 0.25% yeast extract as nitrogen source, culture temperature 28 ~（3 and pH =7.5. [Coadu^en] The re- search could provide basis for development and utilization of LV-1 and industrialized production of mucopolysaccharide.展开更多
[Objective] The purpose was to study the optimum conditions of Pycnoporus sanguineus for producing ligninase. [Method] A strain of lignindegrading white-rot fungus was selected from 5 strains of collected fungi and it...[Objective] The purpose was to study the optimum conditions of Pycnoporus sanguineus for producing ligninase. [Method] A strain of lignindegrading white-rot fungus was selected from 5 strains of collected fungi and its ligninase production and the optimum conditions for producing ligninolytic enzyme were measured. [Result] It could produce two kinds of ligninase with good thermal stability. Different temperatures, carbon sources, nitrogen sources, acidities, as well as the additions of surfactant had distinct influence on the development of lignin-degrading enzymes of the fungus. The optimum condition was drawn out：38℃, pH = 4.5, 10.0 g/L glucose, 1.0 g/L tartaric acid ammonium. [Conclusion] The aim of research was to provide a basis for lignin degradation in practical production.展开更多
[Objective] The paper was to ascertain the fermentation conditions and medium formula of Bacillus subtilis B-332. [Method] Using single factor and orthogo- nal experimental designs, the fermentation medium and cultu...[Objective] The paper was to ascertain the fermentation conditions and medium formula of Bacillus subtilis B-332. [Method] Using single factor and orthogo- nal experimental designs, the fermentation medium and culture conditions for B. sub- i tills B-332 were optimized through shaking flask culture. [Result] The optimal culture and inoculation time was 18 h, and the optimized medium formula was as follows： soybean powder 0.60 g/L, sucrose 0.25 g/L, ammonium sulfate 0.07 g/L, trisodium citrate 0.03 g/L, dipotassium hydrogen phosphate 0.003 g/L, magnesium sulfate 0.005 g/L, ferrous sulfate 0.000 5%; the fermentation condition was as follows： tem- perature 30 ℃, shaking bed speed 180 r/min, shaking bottle volume 80 ml/500 ml. In the optimal fermentation conditions, the fermented spore quantity was 1.43×10^11 cfu/ml, which was 34.48 times higher than the spore quantity of 4.03×10^9 cfu/ml in initial condition. [Result] The study laid the foundation for factory production of the strain.展开更多
[Objective] The aim was to optimize the fermentation conditions of acid resistant α-amylase producing strain. [Method] Based on the selection of an acid resistant α-amylase producing strain,the fermentation conditio...[Objective] The aim was to optimize the fermentation conditions of acid resistant α-amylase producing strain. [Method] Based on the selection of an acid resistant α-amylase producing strain,the fermentation conditions including C,N contents and initial pH of culture medium,seed age,inoculum size,rotation speed of shake flask and fermentation temperature were optimized. [Result] The optimum fermentation conditions for acid resistant α-amylase producing strain were：seed age 14 h,inoculum size 8%,initial pH 5.5,fermentation temperature 35 ℃,rotation speed 150 r/min,the volume of inoculum broth 25 ml,C content 1.0% and N content 0.5%. [Conclusion] Under the optimum fermentation conditions,α-amylase activity reached 31.4 U/ml,which was 65.3 % higher than that before optimization.展开更多
[Objective] The paper was to study the best fermentation conditions of Trichoderma aureoviride sp. for the production of chitinase, thus provide new enzyme source for chitinsse industry. [Method] Using orthognnal expe...[Objective] The paper was to study the best fermentation conditions of Trichoderma aureoviride sp. for the production of chitinase, thus provide new enzyme source for chitinsse industry. [Method] Using orthognnal experimental design, with the variation of sugar content after enzymatic hydrolysis measured by DNS method as the indicator, the fermentation conditions were optimized. [Result] Taking colloidal chitin as the carbon source and 2% peptone as the nitrogen source with the shaking speed of 170 r/rain, the optimum fermentation conditions of T. aureoviride for the production of chitinase were as follows ： initial pH value of medium, 5.0; inoculation amount, 8% ; bottle volume, 20 ml; 6 d cultivation at 28℃. [Conclusion] The optimum conditions for the production of chitinase were confirmed, which provided basis for the utilization of T. aureoviride.展开更多
[Objective] The paper was to identify stain ZY-19-2 with inhibitory effect against tobacco black shank （Phytophtora parasitica var.nicotianae Tucker）, and study the fermentation condition of the strain. [Method]A st...[Objective] The paper was to identify stain ZY-19-2 with inhibitory effect against tobacco black shank （Phytophtora parasitica var.nicotianae Tucker）, and study the fermentation condition of the strain. [Method]A strain ZY-19-2 with strong inhibitory effect against P. parasitica were isolated and screened from tobacco rhizosphere soil samples, and identified according to its morphological characteristics. The chitinase production activity of the strain under different culture conditions was also studied. [Result] For stain ZY-19-2 Paecilomyces lilacinus, the optimal fermentation conditions were as follows： 1.2% colloidal chitin as carbon source, 1% peptone as nitrogen source, 0.1% Tween 80 as surfactant, initial pH of fermentation broth at 6.0, the fermentation time of 60 h, inoculum amount at 1%, shaker speed at 120 r/min. The highest enzyme activity reached 0.216 U/ml. [Conclusion]The optimization of fermentation condition of strain ZY-19-2 lay foundation for large-scale production of cheap and efficient chitinase and chitin oligosaccharides, as well as application of the strain for control of tobacco black shank.展开更多
[Objective] This study aimed to investigate the sporulation conditions of Tri- choderma reesei by solid fermentation. [Method] With sporulation yield as the response value, single-factor test, Plackett-Burmam design, ...[Objective] This study aimed to investigate the sporulation conditions of Tri- choderma reesei by solid fermentation. [Method] With sporulation yield as the response value, single-factor test, Plackett-Burmam design, steepest ascent test, BoxBehnken design and response surface analysis were employed to optimize the con- ditions for sporulation of Trichoderma reesei by solid fermentation. [Result] Based on single-factor test, the most appropriate carbon source for Trichoderma reesei was straw stalk powder and wheat bran with the ratio of 3：2 and optimal amount of 15 g/L; the most appropriate inorganic nitrogen was （NH4）2O4 with the optimal amount of 3 g/L. According to Plackett-Burmam design, moisture content, initial pH and incubation temperature were identified as significant factors affecting the sporulation yield of Trichoderma reeseL The maximum sporulation yield area was approached by steepest ascent test. Based on Box-Behnken design and response surface analysis, the optimal fermentation conditions for the maximum sporulation yield were determined as： straw stalk powder of 6 g/L, wheat bran of 9 g/L, （NH4）2SO4 of 3 g/L, moisture content of 65%, incubation temperature of 29 ℃, fermentation period of 72 h and initial pH of 5.5, under these conditions, the sporulation yield reached 2×10^10 spores/g, which was improved by 1.4 times compared with that before optimization. [Conclusion] In this study, the conditions for sporulation of Trichoderma reesei by solid fermentation were optimized with low-cost straw stalk powder and wheat bran as carbon sources, which was conducive to reducing the production cost of Trichoderma reesei and increasing the sporulation yield, showing certain social and economic significance.展开更多
[Objective] The aim was to optimize the fermentation medium and conditions of antibiotic active substances produced by Antarctic psychrotrophic bacterium Rheinheimera sp.97.[Method] Single-factor experiment and orthog...[Objective] The aim was to optimize the fermentation medium and conditions of antibiotic active substances produced by Antarctic psychrotrophic bacterium Rheinheimera sp.97.[Method] Single-factor experiment and orthogonal test were adopted to optimize the fermentation medium of antibiotic active substances produced by Antarctic psychrotrophic bacterium R.sp.97,while the fermentation conditions were optimized by single-factor experiment.[Result] The optimum fermentation medium for the antibiotic active substances production was as follows：tryptone 3.0 g/L,ammonium sulfate 1.0 g/L,starch 2.0 g/L,NaCl 15.0 g/L.The optimized fermentation conditions were as follows：the starting pH of medium was 8.0,fermentation temperature was 10 ℃,liquid volume in Erlenmeyer flask was 30 %（V/V）and inoculation amount was 1%（V/V）.Under the optimized fermentation medium and conditions,the antibacterial activity of R.sp.97 was increased by 18.1%.[Conclusion] This study had provided basis for the antibiotic active substances produced by Antarctic psychrotrophic bacterium R.sp.97.展开更多
Objective] The purpose of this study was to evaluate the effects of five variables （steaming time, moisture content before inoculation, inoculation amount, fer-mentation temperature, fermentation time） on the sweetn...Objective] The purpose of this study was to evaluate the effects of five variables （steaming time, moisture content before inoculation, inoculation amount, fer-mentation temperature, fermentation time） on the sweetness of sweet oats, obtained the best fermentation conditions. [Method] Plackett-Burman （PB） was to evaluate the effects of five variables, and selected significant factors. The steepest ascent was used to approach the optimal response surface experimental area. The optimal fer-mentation condition was obtained by central composite design and response surface analysis. [Results] It was indicated that moisture content, inoculation amount and fer-mentation temperature had significant influences on the content of the reducing sugars. The optimal conditions of moisture content, inoculation amount and temper-ature were 45.26%, 0.014%（g/g） and 28 ℃, respectively. The predicted value of the reducing sugar content was 13.16 mg/g. [Conclusion] Under the optimal conditions, the content of the reducing sugars in the sweet oats could be up to 12.91 mg/g, which was on the whole consistent with the predictive maximum value.展开更多
[Objective] The research aimed to study the optimum liquid fermentation condition of Trichoderma hamatum Th12 strain,which provided the theory basis for studying and developing the biological control agent of Trichode...[Objective] The research aimed to study the optimum liquid fermentation condition of Trichoderma hamatum Th12 strain,which provided the theory basis for studying and developing the biological control agent of Trichoderma spp.[Method] By using the diluted soil plate method and the plate confrontation method,Trichoderma hamatum Th12 strain was identified.Moreover,the influences of carbon source,nitrogen source,fermentation time,fermentation temperature,initial pH,inoculation amount,bottling capacity and shaker speed on the mycelium yield of Trichoderma hamatum Th12 were studied.[Result] The optimum liquid fermentation conditions of Trichoderma hamatum Th12 strain were：glucose as the carbon source,peptone as the nitrogen source,fermentation temperature was 25 ℃,initial pH was 6,inoculation amount was 0.8 ml,bottling capacity was 50 ml,shaker speed was 180 r/min.Trichoderma hamatum Th12 strain was cultivated 3 d under the condition,and the mycelium yield was the highest.[Conclusion] Under the optimum liquid cultivation condition,Trichoderma hamatum Th12 strain could provide the mycelium amount which was used for preventing and controlling Fusarium oxysporum and Rhizoctonia solani of lawn to the utmost extent.展开更多
In this study, a xylanase-produeing Aspergillus niger strain, NS-1, was screened and isolated from agricultural and forestry wastes. Based on single-fac- tor experiments, the effects of different carbon sources, compo...In this study, a xylanase-produeing Aspergillus niger strain, NS-1, was screened and isolated from agricultural and forestry wastes. Based on single-fac- tor experiments, the effects of different carbon sources, composite carbon sources, nitrogen sources, calcium carbonate concentrations, initial pH and surfactants on xylanase production by A. niger NS-1 were investigated. The results indicated that the most appropriate carbon source was corncobs ; the best composite carbon source was corncobs ＋ xylan, which was conducive to xylanase secretion; the most suitable nitrogen source was ammonium sulfate. Xylanase activity reached the highest in the medium added with 1.5% calcium carbonate and SDS as a surfactant with an initial pH of 5.0. This study provided the basis for the production of high-activity xylanase.展开更多
[Objectives]To isolate and optimize the potassium releasing bacteria from sugarcane rhizosphere soil in Baitu Town,Gaoyao District,Zhaoqing City,Guangdong Province,and then evaluate their potassium-releasing ability,a...[Objectives]To isolate and optimize the potassium releasing bacteria from sugarcane rhizosphere soil in Baitu Town,Gaoyao District,Zhaoqing City,Guangdong Province,and then evaluate their potassium-releasing ability,and optimize the fermentation conditions of the strains with the best potassium-releasing ability,so as to provide a scientific basis for the development and production of potassium releasing bacteria fertilizer.[Methods]Potassium-solubilizing bacteria were isolated from sugarcane rhizosphere soil using potassium-feldspar powder as the potassium source of isolation medium by dilution coating method and plate streaking method.The isolated strains were identified by 16s rRNA sequence analysis.The potassium-releasing ability of each strain was determined by sodium tetraphenylborate(STPB)method,and the strain GK-37 with the optimal potassium-releasing ability was selected.The fermentation conditions of GK-37 strain were further optimized,and the effects of different carbon sources on its growth were mainly investigated.[Results]Seven strains of potassium-solubilizing bacteria were isolated and purified,and identified by 16s rRNA.They belonged to Pseudomonas knackmussii,Pseudomonas,Pseudomonas insulaes and Caballeronia zhejiangensis.Among the tested strains,strain GK-37 had the best potassium-releasing ability,and its potassium-releasing capacity was 26.99 mg/L.By optimizing the fermentation conditions of GK-37 strain,it was found that when the fermentation medium was sucrose as carbon source,the growth of the strain was the best.[Conclusions]In this study,the potassium releasing bacteria were successfully isolated and identified from the rhizosphere soil of sugarcane,and the strain GK-37 had high potassium-releasing ability.Through the optimization of fermentation conditions of GK-37 strain,sucrose was determined as the optimal carbon source.This study is expected to provide a valuable reference for the further development and production of potassium releasing bacteria fertilizer.展开更多
The work is intended to achieve optimum culture conditions of α-galactosidase production by a mutant strain ,Aspergillusfoetidus ZU-GI in solid-state fermentation （SSF）. Certain fermentation parameters involving mo...The work is intended to achieve optimum culture conditions of α-galactosidase production by a mutant strain ,Aspergillusfoetidus ZU-GI in solid-state fermentation （SSF）. Certain fermentation parameters involving moisture content, incubation temperature, cultivation period of seed, inoculum volume, initial pH value, layers of pledget, load size of medium and period of cultivation were investigated separately. The optimal cultivating conditions of α-galactosidase production in SSF were 60% initial moisture of medium, 28 ℃ incubation temperature, 18^h cultivation period of seed, 10% inoculum volume, 5.0-6.0 initial pH of medium, 6 layers of pledget and 10 g dry matter loadage. Under the optimized cultivation conditions, the maximum α-galactosidase production was 2037.51 U/g dry matter near the 144th hour of fermentation.展开更多
Fungal strain PA-2 was isolated from infected poplar leaves from the Ping’an District, Haidong City of Qinghai Province, China. Based on the culture characteristics and the internal transcribed spacer(ITS) sequence o...Fungal strain PA-2 was isolated from infected poplar leaves from the Ping’an District, Haidong City of Qinghai Province, China. Based on the culture characteristics and the internal transcribed spacer(ITS) sequence of its 16S r DNA, the strain was identified as Aureobasidium pullulans. The culture and metabolites of strain PA-2 showed high herbicidal potential to five tested weeds Galium aparine var. tenerum, Chenopodium album, Malva crispa, Polygonum lapathifolium and Avena fatua. For the in vitro test, 5 days after the detached leaves were inoculated with PA-2 culture, all leaves infected by the hyphae and became black and rotten. For the in vivo test, a metabolite filtrate of PA-2 culture was sprayed over the living weed plants, and five days after inoculation, the weed plants became withered and necrotic. Seven days after inoculation, the fresh weight reductions of G. aparine var. tenerum, C. album, M. crispa, P. lapathifolium and A. fatua were 87.25, 78.46, 82.25, 62.11, and 80.27%, respectively. Galium aparine var. tenerum and M. crispa exhibited significant reductions in fresh weight. The bio-safety test on the five crops showed no significant plant height reductions, which was also observed for wheat(Triticum aestivum), faba bean(Vicia faba), and barley(Hordeum vulgare). By contrast, oilseed rape(Brassica napus) and pea(Pisum sativum) exhibited light spots but no significant reductions in plant height. These results indicated that A. pullulans could be a potential microbial herbicide for the control of the target weeds in crops. Optimization of the carbon and nitrogen sources for cultural media and substances for solid-state fermentation indicated that PA-2 had better colony growth and spore production with the optimal carbon source of glucose(C4), nitrogen source of soybean flour(N2), and the optimal substance was wheat bran. The results in this study provide useful information for the development ofA. pulluans PA-2 as an herbicide for bio-control of the weed.展开更多
Lentinus squarrosulus Mont. is an emerging tropical white rot basidiomycete, with nutritional and medicinal benefits. Low levels of commercial cultivation of the mushrooms limit their availability for use as food and ...Lentinus squarrosulus Mont. is an emerging tropical white rot basidiomycete, with nutritional and medicinal benefits. Low levels of commercial cultivation of the mushrooms limit their availability for use as food and medicine. Mycelia from submerged fermentation are a suitable alternative to the mushroom from L. squarrosulus. Three strains, 340, 339 and 218, were studied to determine optimum growth conditions for mycelia mass and crude exo-polysaccharides (CEPS) production. The experiments were conducted in a completely randomized design (CRD) with a factorial structure. Nutrients involving 8 carbon and 8 nitrogen sources were screened, and concentrations of the best sources were optimized. Optimized nutrients, interaction between strains and other parameters such as agitation and medium volume were investigated to obtain optimum fermentation conditions for biomass and CEPS production. Biomass yield varied among strains depending on carbon or nitrogen nutrient sources. Starch and yeast extract at 30 and 25 g/L were identified as the most important nutrients in mycelia and CEPS production. Nutrient optimization resulted in a 3-fold increase in mycelia mass: 12.8, 10.0 and 15.3 g/L in strains 340, 339 and 218 respectively. There was a significant interaction between strain, agitation, and volume (p p = 0.02). Static conditions favored more polysaccharide production. Optimized fermentation conditions resulted in very high increase in biomass: 238.1, 266.9 and 185.0 g/L in strains 340, 339 and 218 respectively. Results obtained could be useful in modeling fermentation systems for large-scale production of mycelia mass, CEPS and other bio-products from L. squarrosulus.展开更多
[ Objective] This study aimed to optimize the fermentation condition of Lepista sordida mycelium. [ Method ] The effects of carbon sources, nitrogen sources ,pH and incubation time on the dry weight of mycelium in L. ...[ Objective] This study aimed to optimize the fermentation condition of Lepista sordida mycelium. [ Method ] The effects of carbon sources, nitrogen sources ,pH and incubation time on the dry weight of mycelium in L. sordida fermentation were investigated. [ Result] The descending order of the influences on L. sordida mycelium growth was ： carbon sources 〉 incubation time 〉 pH 〉 nitrogen sources. Based on orthogonal experiment, the optimal fermentation condition of L. sordida mycelium was determined as ： fermentation medium of 3% corn powder and 0.2% yeast extract, pH of 6.0, and incubation time of 8 d. [ Conclusion ] This study provides theoretical reference and experimental basis for the development and utilization of L. sordida biological resources.展开更多
A strain isolated from the fruiting body of a fungus parasitized on Elaphomyces was identified as Cordyceps ophioglossoides based on the morphological characteristics and the analysis of ITS-5.8s rDNA sequence. The op...A strain isolated from the fruiting body of a fungus parasitized on Elaphomyces was identified as Cordyceps ophioglossoides based on the morphological characteristics and the analysis of ITS-5.8s rDNA sequence. The optimal medium, composition （g·L^-1）, containing sucrose 66.0, yeast powder 10.0, silkworm chrysalises digest 30.0, MgSO4· 7H2O 0.4, and KH2PO4 0.4, Was found using fractional factorial design ancl a central composite design, and the optimization of cultural conditions obtained a result of seed age 6 days, inoculum size 6% （by volume）, initial pH 5.6, temperature 24℃, shaking speed 160 ·＇min^-1 by one-factor-at-a-time method. The maximum biomass reached about 20.2 g·L^-1 after 90 hours culture under the optimal conditions. Elementary nharmaeclogical actlwtties showed that mycelia of C. ophioglossoides L2 from submerged culture promoted Uterus growth in estrogen- depleted mice. In the 15-litre scale-up fermentation, the mycelial biomass was around 19.1 g·L^-1, indicating a promising prospect for this biotechnoloagy and the potency to develoo its medical value.展开更多
[ Objective] The paper wag to improve the antimicrobial effect of antagonistic Streptomyces on Botryosphaeria dothidea. [ Method ] Different concentrations of DES were adopted for mutagenic treatment of antagonistic S...[ Objective] The paper wag to improve the antimicrobial effect of antagonistic Streptomyces on Botryosphaeria dothidea. [ Method ] Different concentrations of DES were adopted for mutagenic treatment of antagonistic Streptomyces F-58. After fermentation, the mutant strain numbered F-58-06 with genetic stability and good antimicrobial effect was selected among 200 mutant strains; the biological activity of the strain was determined with B. dothidea as the indicator fungus, and the best concentration of DES wag 2%. The fermentation conditions of antagonistic substances of Streptomyces strain F-58-06 produced in shake flasks were opti- mized using the method of single factor and orthogonal experimental design. [ Result] The optimal fermentation conditions were carbon source corn flour, nitrogen source KNO3, initial pH 7, loading volume 30 mL in 250 mL shake flask, inoculation volume 3%, incubation time 132 h. Based on orthogonal experiments, the best cultured medium ratio was corn flour 4%, KNO3 0.5%, CaCO3 0.2%, NaCI 0.35%, MgSO4 · 7H2O 0. 15%. [ Conclusion ] After mutation and optimization of culture medium, the antimicrobial activity of Streptomyces F-58 was greatly improved, and the average inhibition zone diameter was 1.35 times of that of the original strain.展开更多
基金supported by the Chung-Ang University Research Grants in 2023.Alsothe work is supported by the ELLIIT Excellence Center at Linköping–Lund in Information Technology in Sweden.
文摘Recommending personalized travel routes from sparse,implicit feedback poses a significant challenge,as conventional systems often struggle with information overload and fail to capture the complex,sequential nature of user preferences.To address this,we propose a Conditional Generative Adversarial Network(CGAN)that generates diverse and highly relevant itineraries.Our approach begins by constructing a conditional vector that encapsulates a user’s profile.This vector uniquely fuses embeddings from a Heterogeneous Information Network(HIN)to model complex user-place-route relationships,a Recurrent Neural Network(RNN)to capture sequential path dynamics,and Neural Collaborative Filtering(NCF)to incorporate collaborative signals from the wider user base.This comprehensive condition,further enhanced with features representing user interaction confidence and uncertainty,steers a CGAN stabilized by spectral normalization to generate high-fidelity latent route representations,effectively mitigating the data sparsity problem.Recommendations are then formulated using an Anchor-and-Expand algorithm,which selects relevant starting Points of Interest(POI)based on user history,then expands routes through latent similarity matching and geographic coherence optimization,culminating in Traveling Salesman Problem(TSP)-based route optimization for practical travel distances.Experiments on a real-world check-in dataset validate our model’s unique generative capability,achieving F1 scores ranging from 0.163 to 0.305,and near-zero pairs−F1 scores between 0.002 and 0.022.These results confirm the model’s success in generating novel travel routes by recommending new locations and sequences rather than replicating users’past itineraries.This work provides a robust solution for personalized travel planning,capable of generating novel and compelling routes for both new and existing users by learning from collective travel intelligence.
基金supported by the Natural Science Foundation of Guangdong Province(No.2021B1515120053)Guangdong Basic and Applied Basic Research Foundation(Grant No.2024A1515140166).
文摘Background:Therapeutic responses of breast cancer vary among patients and lead to drug resistance and recurrence due to the heterogeneity.Current preclinical models,however,are inadequate for predicting individual patient responses towards different drugs.This study aimed to investigate the patient-derived breast cancer culture models for drug sensitivity evaluations.Methods:Tumor and adjacent tissues from female breast cancer patients were collected during surgery.Patient-derived breast cancer cells were cultured using the conditional reprogramming technique to establish 2D models.The obtained patient-derived conditional reprogramming breast cancer(CRBC)cells were subsequently embedded in alginate-gelatin methacryloyl hydrogel microspheres to form 3D culture models.Comparisons between 2D and 3D models were made using immunohistochemistry(tumor markers),MTS assays(cell viability),flow cytometry(apoptosis),transwell assays(migration),and Western blotting(protein expression).Drug sensitivity tests were conducted to evaluate patient-specific responses to anti-cancer agents.Results:2D and 3D culture models were successfully established using samples from eight patients.The 3D models retained histological and marker characteristics of the original tumors.Compared to 2D cultures,3D models exhibited increased apoptosis,enhanced drug resistance,elevated stem cell marker expression,and greater migration ability—features more reflective of in vivo tumor behavior.Conclusion:Patient-derived 3D CRBC models effectively mimic the in vivo tumor microenvironment and demonstrate stronger resistance to anti-cancer drugs than 2D models.These hydrogel-based models offer a cost-effective and clinically relevant platform for drug screening and personalized breast cancer treatment.
文摘bacterium LV-1 which isolated from soil sample were studied bacterium was isolated by serial dilution method, the effects of carbon source, nitrogen source, the initial pH and temperature on producing polysaccharide by it were discussed to confirm the optimum fermentation conditions. [ Result] The physicochemical properties showed that the polysaccharide was water-soluble, but insoluble in organic solvents including ethanol, butanol, and chloroform. It was neutral polysaccharide with negative charge and without reducing terminal. The pH of its solution was pH =7.5. There were no protein, fructose, uronic acid, sulphate and starch-like structure included in po/ysacchadde molecules. The optimum fermentation conditions for po/ysaccharide produc- tion were 3% mannitol as carbon source, 0.25% yeast extract as nitrogen source, culture temperature 28 ~（3 and pH =7.5. [Coadu^en] The re- search could provide basis for development and utilization of LV-1 and industrialized production of mucopolysaccharide.
文摘[Objective] The purpose was to study the optimum conditions of Pycnoporus sanguineus for producing ligninase. [Method] A strain of lignindegrading white-rot fungus was selected from 5 strains of collected fungi and its ligninase production and the optimum conditions for producing ligninolytic enzyme were measured. [Result] It could produce two kinds of ligninase with good thermal stability. Different temperatures, carbon sources, nitrogen sources, acidities, as well as the additions of surfactant had distinct influence on the development of lignin-degrading enzymes of the fungus. The optimum condition was drawn out：38℃, pH = 4.5, 10.0 g/L glucose, 1.0 g/L tartaric acid ammonium. [Conclusion] The aim of research was to provide a basis for lignin degradation in practical production.
基金Supported by Major Science and Technology Project of National Water Pollution Control and Management "Pollution Control against Agricultural Non-point Source Pollution into River and Ecological Restoration Technology and Engineering Demonstration Project"(2009ZX07103-002) "the Eleventh Five-Year" National Key Technology Support Program "Control Technology and Demonstration of Overall Planning of Urban and Rural Life Rubbish Pollution" (2009BADC2B00-02)~~
文摘[Objective] The paper was to ascertain the fermentation conditions and medium formula of Bacillus subtilis B-332. [Method] Using single factor and orthogo- nal experimental designs, the fermentation medium and culture conditions for B. sub- i tills B-332 were optimized through shaking flask culture. [Result] The optimal culture and inoculation time was 18 h, and the optimized medium formula was as follows： soybean powder 0.60 g/L, sucrose 0.25 g/L, ammonium sulfate 0.07 g/L, trisodium citrate 0.03 g/L, dipotassium hydrogen phosphate 0.003 g/L, magnesium sulfate 0.005 g/L, ferrous sulfate 0.000 5%; the fermentation condition was as follows： tem- perature 30 ℃, shaking bed speed 180 r/min, shaking bottle volume 80 ml/500 ml. In the optimal fermentation conditions, the fermented spore quantity was 1.43×10^11 cfu/ml, which was 34.48 times higher than the spore quantity of 4.03×10^9 cfu/ml in initial condition. [Result] The study laid the foundation for factory production of the strain.
基金Supported by the Project Funded by Biotechnology Key Laboratory of Fermentation and Brewing Engineering of State Ethnic Affairs Commission (2008SY011)~~
文摘[Objective] The aim was to optimize the fermentation conditions of acid resistant α-amylase producing strain. [Method] Based on the selection of an acid resistant α-amylase producing strain,the fermentation conditions including C,N contents and initial pH of culture medium,seed age,inoculum size,rotation speed of shake flask and fermentation temperature were optimized. [Result] The optimum fermentation conditions for acid resistant α-amylase producing strain were：seed age 14 h,inoculum size 8%,initial pH 5.5,fermentation temperature 35 ℃,rotation speed 150 r/min,the volume of inoculum broth 25 ml,C content 1.0% and N content 0.5%. [Conclusion] Under the optimum fermentation conditions,α-amylase activity reached 31.4 U/ml,which was 65.3 % higher than that before optimization.
基金Supported by Science Research Foundation of Henan University(2008YBGG043)~~
文摘[Objective] The paper was to study the best fermentation conditions of Trichoderma aureoviride sp. for the production of chitinase, thus provide new enzyme source for chitinsse industry. [Method] Using orthognnal experimental design, with the variation of sugar content after enzymatic hydrolysis measured by DNS method as the indicator, the fermentation conditions were optimized. [Result] Taking colloidal chitin as the carbon source and 2% peptone as the nitrogen source with the shaking speed of 170 r/rain, the optimum fermentation conditions of T. aureoviride for the production of chitinase were as follows ： initial pH value of medium, 5.0; inoculation amount, 8% ; bottle volume, 20 ml; 6 d cultivation at 28℃. [Conclusion] The optimum conditions for the production of chitinase were confirmed, which provided basis for the utilization of T. aureoviride.
基金Supported by Technology Development Project of Zhengzhou Tobacco Research Institute of CNTC"Isolation,Application and Research of Disease-resistant Endophyte"(122009CZ0420)~~
文摘[Objective] The paper was to identify stain ZY-19-2 with inhibitory effect against tobacco black shank （Phytophtora parasitica var.nicotianae Tucker）, and study the fermentation condition of the strain. [Method]A strain ZY-19-2 with strong inhibitory effect against P. parasitica were isolated and screened from tobacco rhizosphere soil samples, and identified according to its morphological characteristics. The chitinase production activity of the strain under different culture conditions was also studied. [Result] For stain ZY-19-2 Paecilomyces lilacinus, the optimal fermentation conditions were as follows： 1.2% colloidal chitin as carbon source, 1% peptone as nitrogen source, 0.1% Tween 80 as surfactant, initial pH of fermentation broth at 6.0, the fermentation time of 60 h, inoculum amount at 1%, shaker speed at 120 r/min. The highest enzyme activity reached 0.216 U/ml. [Conclusion]The optimization of fermentation condition of strain ZY-19-2 lay foundation for large-scale production of cheap and efficient chitinase and chitin oligosaccharides, as well as application of the strain for control of tobacco black shank.
基金Supported by General Project of Science and Technology in Hunan Province(No.2012NK3080)~~
文摘[Objective] This study aimed to investigate the sporulation conditions of Tri- choderma reesei by solid fermentation. [Method] With sporulation yield as the response value, single-factor test, Plackett-Burmam design, steepest ascent test, BoxBehnken design and response surface analysis were employed to optimize the con- ditions for sporulation of Trichoderma reesei by solid fermentation. [Result] Based on single-factor test, the most appropriate carbon source for Trichoderma reesei was straw stalk powder and wheat bran with the ratio of 3：2 and optimal amount of 15 g/L; the most appropriate inorganic nitrogen was （NH4）2O4 with the optimal amount of 3 g/L. According to Plackett-Burmam design, moisture content, initial pH and incubation temperature were identified as significant factors affecting the sporulation yield of Trichoderma reeseL The maximum sporulation yield area was approached by steepest ascent test. Based on Box-Behnken design and response surface analysis, the optimal fermentation conditions for the maximum sporulation yield were determined as： straw stalk powder of 6 g/L, wheat bran of 9 g/L, （NH4）2SO4 of 3 g/L, moisture content of 65%, incubation temperature of 29 ℃, fermentation period of 72 h and initial pH of 5.5, under these conditions, the sporulation yield reached 2×10^10 spores/g, which was improved by 1.4 times compared with that before optimization. [Conclusion] In this study, the conditions for sporulation of Trichoderma reesei by solid fermentation were optimized with low-cost straw stalk powder and wheat bran as carbon sources, which was conducive to reducing the production cost of Trichoderma reesei and increasing the sporulation yield, showing certain social and economic significance.
基金Supported by National Department Public Benefit Marine Scientific Research Foundation(201005032-2)National High Technology Research and Development Program of China(2007AA091905)~~
文摘[Objective] The aim was to optimize the fermentation medium and conditions of antibiotic active substances produced by Antarctic psychrotrophic bacterium Rheinheimera sp.97.[Method] Single-factor experiment and orthogonal test were adopted to optimize the fermentation medium of antibiotic active substances produced by Antarctic psychrotrophic bacterium R.sp.97,while the fermentation conditions were optimized by single-factor experiment.[Result] The optimum fermentation medium for the antibiotic active substances production was as follows：tryptone 3.0 g/L,ammonium sulfate 1.0 g/L,starch 2.0 g/L,NaCl 15.0 g/L.The optimized fermentation conditions were as follows：the starting pH of medium was 8.0,fermentation temperature was 10 ℃,liquid volume in Erlenmeyer flask was 30 %（V/V）and inoculation amount was 1%（V/V）.Under the optimized fermentation medium and conditions,the antibacterial activity of R.sp.97 was increased by 18.1%.[Conclusion] This study had provided basis for the antibiotic active substances produced by Antarctic psychrotrophic bacterium R.sp.97.
基金Major science and technology projects in jiangxi province(2010ZX0100)Basic scientific research business expenses Incremental projects of Chinese academy of agricultural sciences(2013ZL013)~~
文摘Objective] The purpose of this study was to evaluate the effects of five variables （steaming time, moisture content before inoculation, inoculation amount, fer-mentation temperature, fermentation time） on the sweetness of sweet oats, obtained the best fermentation conditions. [Method] Plackett-Burman （PB） was to evaluate the effects of five variables, and selected significant factors. The steepest ascent was used to approach the optimal response surface experimental area. The optimal fer-mentation condition was obtained by central composite design and response surface analysis. [Results] It was indicated that moisture content, inoculation amount and fer-mentation temperature had significant influences on the content of the reducing sugars. The optimal conditions of moisture content, inoculation amount and temper-ature were 45.26%, 0.014%（g/g） and 28 ℃, respectively. The predicted value of the reducing sugar content was 13.16 mg/g. [Conclusion] Under the optimal conditions, the content of the reducing sugars in the sweet oats could be up to 12.91 mg/g, which was on the whole consistent with the predictive maximum value.
文摘[Objective] The research aimed to study the optimum liquid fermentation condition of Trichoderma hamatum Th12 strain,which provided the theory basis for studying and developing the biological control agent of Trichoderma spp.[Method] By using the diluted soil plate method and the plate confrontation method,Trichoderma hamatum Th12 strain was identified.Moreover,the influences of carbon source,nitrogen source,fermentation time,fermentation temperature,initial pH,inoculation amount,bottling capacity and shaker speed on the mycelium yield of Trichoderma hamatum Th12 were studied.[Result] The optimum liquid fermentation conditions of Trichoderma hamatum Th12 strain were：glucose as the carbon source,peptone as the nitrogen source,fermentation temperature was 25 ℃,initial pH was 6,inoculation amount was 0.8 ml,bottling capacity was 50 ml,shaker speed was 180 r/min.Trichoderma hamatum Th12 strain was cultivated 3 d under the condition,and the mycelium yield was the highest.[Conclusion] Under the optimum liquid cultivation condition,Trichoderma hamatum Th12 strain could provide the mycelium amount which was used for preventing and controlling Fusarium oxysporum and Rhizoctonia solani of lawn to the utmost extent.
基金Supported by Project of Taizhou Science and Technology Bureau(TS019)
文摘In this study, a xylanase-produeing Aspergillus niger strain, NS-1, was screened and isolated from agricultural and forestry wastes. Based on single-fac- tor experiments, the effects of different carbon sources, composite carbon sources, nitrogen sources, calcium carbonate concentrations, initial pH and surfactants on xylanase production by A. niger NS-1 were investigated. The results indicated that the most appropriate carbon source was corncobs ; the best composite carbon source was corncobs ＋ xylan, which was conducive to xylanase secretion; the most suitable nitrogen source was ammonium sulfate. Xylanase activity reached the highest in the medium added with 1.5% calcium carbonate and SDS as a surfactant with an initial pH of 5.0. This study provided the basis for the production of high-activity xylanase.
基金Supported by Guangdong Province Rural Science and Technology Commissioner Project(KTP20240693)Zhaoqing University Project(QN202329)+3 种基金Science and Technology Innovation Guidance Project of Zhaoqing(202304038001)Undergraduate Innovation and Entrepreneurship Training Program(202410580011&X202310580120)The Third Batch of Innovation Research Team of Zhaoqing University(05)Quality Engineering and Teaching Reform Project of Zhaoqing University(zlgc202229,zlgc202261).
文摘[Objectives]To isolate and optimize the potassium releasing bacteria from sugarcane rhizosphere soil in Baitu Town,Gaoyao District,Zhaoqing City,Guangdong Province,and then evaluate their potassium-releasing ability,and optimize the fermentation conditions of the strains with the best potassium-releasing ability,so as to provide a scientific basis for the development and production of potassium releasing bacteria fertilizer.[Methods]Potassium-solubilizing bacteria were isolated from sugarcane rhizosphere soil using potassium-feldspar powder as the potassium source of isolation medium by dilution coating method and plate streaking method.The isolated strains were identified by 16s rRNA sequence analysis.The potassium-releasing ability of each strain was determined by sodium tetraphenylborate(STPB)method,and the strain GK-37 with the optimal potassium-releasing ability was selected.The fermentation conditions of GK-37 strain were further optimized,and the effects of different carbon sources on its growth were mainly investigated.[Results]Seven strains of potassium-solubilizing bacteria were isolated and purified,and identified by 16s rRNA.They belonged to Pseudomonas knackmussii,Pseudomonas,Pseudomonas insulaes and Caballeronia zhejiangensis.Among the tested strains,strain GK-37 had the best potassium-releasing ability,and its potassium-releasing capacity was 26.99 mg/L.By optimizing the fermentation conditions of GK-37 strain,it was found that when the fermentation medium was sucrose as carbon source,the growth of the strain was the best.[Conclusions]In this study,the potassium releasing bacteria were successfully isolated and identified from the rhizosphere soil of sugarcane,and the strain GK-37 had high potassium-releasing ability.Through the optimization of fermentation conditions of GK-37 strain,sucrose was determined as the optimal carbon source.This study is expected to provide a valuable reference for the further development and production of potassium releasing bacteria fertilizer.
文摘The work is intended to achieve optimum culture conditions of α-galactosidase production by a mutant strain ,Aspergillusfoetidus ZU-GI in solid-state fermentation （SSF）. Certain fermentation parameters involving moisture content, incubation temperature, cultivation period of seed, inoculum volume, initial pH value, layers of pledget, load size of medium and period of cultivation were investigated separately. The optimal cultivating conditions of α-galactosidase production in SSF were 60% initial moisture of medium, 28 ℃ incubation temperature, 18^h cultivation period of seed, 10% inoculum volume, 5.0-6.0 initial pH of medium, 6 layers of pledget and 10 g dry matter loadage. Under the optimized cultivation conditions, the maximum α-galactosidase production was 2037.51 U/g dry matter near the 144th hour of fermentation.
基金supported by the National Natural Science Foundation of China (31760539)the Natural Science Foundation of Qinghai Province, China (2018-ZJ-917)
文摘Fungal strain PA-2 was isolated from infected poplar leaves from the Ping’an District, Haidong City of Qinghai Province, China. Based on the culture characteristics and the internal transcribed spacer(ITS) sequence of its 16S r DNA, the strain was identified as Aureobasidium pullulans. The culture and metabolites of strain PA-2 showed high herbicidal potential to five tested weeds Galium aparine var. tenerum, Chenopodium album, Malva crispa, Polygonum lapathifolium and Avena fatua. For the in vitro test, 5 days after the detached leaves were inoculated with PA-2 culture, all leaves infected by the hyphae and became black and rotten. For the in vivo test, a metabolite filtrate of PA-2 culture was sprayed over the living weed plants, and five days after inoculation, the weed plants became withered and necrotic. Seven days after inoculation, the fresh weight reductions of G. aparine var. tenerum, C. album, M. crispa, P. lapathifolium and A. fatua were 87.25, 78.46, 82.25, 62.11, and 80.27%, respectively. Galium aparine var. tenerum and M. crispa exhibited significant reductions in fresh weight. The bio-safety test on the five crops showed no significant plant height reductions, which was also observed for wheat(Triticum aestivum), faba bean(Vicia faba), and barley(Hordeum vulgare). By contrast, oilseed rape(Brassica napus) and pea(Pisum sativum) exhibited light spots but no significant reductions in plant height. These results indicated that A. pullulans could be a potential microbial herbicide for the control of the target weeds in crops. Optimization of the carbon and nitrogen sources for cultural media and substances for solid-state fermentation indicated that PA-2 had better colony growth and spore production with the optimal carbon source of glucose(C4), nitrogen source of soybean flour(N2), and the optimal substance was wheat bran. The results in this study provide useful information for the development ofA. pulluans PA-2 as an herbicide for bio-control of the weed.
文摘Lentinus squarrosulus Mont. is an emerging tropical white rot basidiomycete, with nutritional and medicinal benefits. Low levels of commercial cultivation of the mushrooms limit their availability for use as food and medicine. Mycelia from submerged fermentation are a suitable alternative to the mushroom from L. squarrosulus. Three strains, 340, 339 and 218, were studied to determine optimum growth conditions for mycelia mass and crude exo-polysaccharides (CEPS) production. The experiments were conducted in a completely randomized design (CRD) with a factorial structure. Nutrients involving 8 carbon and 8 nitrogen sources were screened, and concentrations of the best sources were optimized. Optimized nutrients, interaction between strains and other parameters such as agitation and medium volume were investigated to obtain optimum fermentation conditions for biomass and CEPS production. Biomass yield varied among strains depending on carbon or nitrogen nutrient sources. Starch and yeast extract at 30 and 25 g/L were identified as the most important nutrients in mycelia and CEPS production. Nutrient optimization resulted in a 3-fold increase in mycelia mass: 12.8, 10.0 and 15.3 g/L in strains 340, 339 and 218 respectively. There was a significant interaction between strain, agitation, and volume (p p = 0.02). Static conditions favored more polysaccharide production. Optimized fermentation conditions resulted in very high increase in biomass: 238.1, 266.9 and 185.0 g/L in strains 340, 339 and 218 respectively. Results obtained could be useful in modeling fermentation systems for large-scale production of mycelia mass, CEPS and other bio-products from L. squarrosulus.
文摘[ Objective] This study aimed to optimize the fermentation condition of Lepista sordida mycelium. [ Method ] The effects of carbon sources, nitrogen sources ,pH and incubation time on the dry weight of mycelium in L. sordida fermentation were investigated. [ Result] The descending order of the influences on L. sordida mycelium growth was ： carbon sources 〉 incubation time 〉 pH 〉 nitrogen sources. Based on orthogonal experiment, the optimal fermentation condition of L. sordida mycelium was determined as ： fermentation medium of 3% corn powder and 0.2% yeast extract, pH of 6.0, and incubation time of 8 d. [ Conclusion ] This study provides theoretical reference and experimental basis for the development and utilization of L. sordida biological resources.
基金Supported by the Research Project of Science and Technology of Zhejiang Province, China （2005C23027）, the National High Technology Research and Development Program of China （2007AA021506） and the Natural Science Foundation of Zhejiang Province （R207609）. We would like to thank Dr. Birnie from New Zealand for his editing of this manuscript.
文摘A strain isolated from the fruiting body of a fungus parasitized on Elaphomyces was identified as Cordyceps ophioglossoides based on the morphological characteristics and the analysis of ITS-5.8s rDNA sequence. The optimal medium, composition （g·L^-1）, containing sucrose 66.0, yeast powder 10.0, silkworm chrysalises digest 30.0, MgSO4· 7H2O 0.4, and KH2PO4 0.4, Was found using fractional factorial design ancl a central composite design, and the optimization of cultural conditions obtained a result of seed age 6 days, inoculum size 6% （by volume）, initial pH 5.6, temperature 24℃, shaking speed 160 ·＇min^-1 by one-factor-at-a-time method. The maximum biomass reached about 20.2 g·L^-1 after 90 hours culture under the optimal conditions. Elementary nharmaeclogical actlwtties showed that mycelia of C. ophioglossoides L2 from submerged culture promoted Uterus growth in estrogen- depleted mice. In the 15-litre scale-up fermentation, the mycelial biomass was around 19.1 g·L^-1, indicating a promising prospect for this biotechnoloagy and the potency to develoo its medical value.
基金Supported by Special Fund for Forestry Scientific Research in the Public Welfare(201204501)Key Theoretical Basis for Prevention and Control Technology of Forest Diseases and Pests & Key Science and Technology Project of Jilin Province(20110267)+1 种基金Research of New Antibiotics for Poplar Diseases & Science and Technology Research Plan of Forestry Department of Jilin Province(2014-004)Development of Forestry Microbial Agents & Key Projects for Science and Technology in Jilin Province(20150203015NY):Monitoring and Control Technology of Major Pests and Diseases in Industrial Forest
文摘[ Objective] The paper wag to improve the antimicrobial effect of antagonistic Streptomyces on Botryosphaeria dothidea. [ Method ] Different concentrations of DES were adopted for mutagenic treatment of antagonistic Streptomyces F-58. After fermentation, the mutant strain numbered F-58-06 with genetic stability and good antimicrobial effect was selected among 200 mutant strains; the biological activity of the strain was determined with B. dothidea as the indicator fungus, and the best concentration of DES wag 2%. The fermentation conditions of antagonistic substances of Streptomyces strain F-58-06 produced in shake flasks were opti- mized using the method of single factor and orthogonal experimental design. [ Result] The optimal fermentation conditions were carbon source corn flour, nitrogen source KNO3, initial pH 7, loading volume 30 mL in 250 mL shake flask, inoculation volume 3%, incubation time 132 h. Based on orthogonal experiments, the best cultured medium ratio was corn flour 4%, KNO3 0.5%, CaCO3 0.2%, NaCI 0.35%, MgSO4 · 7H2O 0. 15%. [ Conclusion ] After mutation and optimization of culture medium, the antimicrobial activity of Streptomyces F-58 was greatly improved, and the average inhibition zone diameter was 1.35 times of that of the original strain.
