[Objective] This study was to explore the effects of dilute acid hydrolysis on fermentative biohydrogen production capacity of maize stalk. [Method] Using maize stalks subjected to mechanical disintegration,steam expl...[Objective] This study was to explore the effects of dilute acid hydrolysis on fermentative biohydrogen production capacity of maize stalk. [Method] Using maize stalks subjected to mechanical disintegration,steam explosion and dilute acid hydrolysis as experimental materials,we measured and analyzed the effects of different treatments and particle size of maize stalk were analyzed. [Result] The optimal fermentative biohydrogen production was found under following parameters：pretreatment of 0.8% dilute H2SO4 following steam explosion,particle size of maize stalk of 0.425-0.850 mm,liquid-solid ratio [0.8% H2SO4 （M）：stalk （W）] of 10：1. [Conclusion] Post steam explosion,dilute 0.8% dilute H2SO4 intensified hydrolysis on maize stalk could produce fermentative biohydrogen production capacity.展开更多
Five individual pretreatment methods, including three widely-used protocols （heat, acid and base） and two novel attempts （ultrasonic and ultraviolet）, were conducted in batch tests to compare their effects on mixe...Five individual pretreatment methods, including three widely-used protocols （heat, acid and base） and two novel attempts （ultrasonic and ultraviolet）, were conducted in batch tests to compare their effects on mixed microflora to enhance hydrogen （H2） production from corn stover hydrolysate. Experimental results indicated that heat and base pretreatments significantly increased H2 yield with the values of 5.03 and 4.45 mmol H2/g sugar utilized, respectively, followed by acid pretreatment of 3.21 mmol H2/g sugar utilized. However, compared with the control （2.70 mmol H2/g sugar utilized）, ultrasonic and ultraviolet pretreatments caused indistinctive effects on H2 production with the values of 2.92 and 2.87 mmol H2/g sugar utilized, respectively. The changes of soluble metabolites composition caused by pretreatment were in accordance with H2-producing behavior. Concretely, more acetate accumulation and less ethanol production were found in pretreated processes, meaning that more reduced nicotinamide adenine dinucleotide （NADH） might be saved and flowed into H2-producing pathways. PCR-DGGE analysis indicated that the pretreatment led to the enrichment of some species, which appeared in large amounts and even dominated the microbial community. Most of the dominated species were affiliated to Enterobacter spp. and Escherichia spp. As another efflcient H2 producer, Clostridium bifermentan was only found in a large quantity after heat pretreatment. This strain might be mainly responsible for better performance of H2 production in this case.展开更多
Background:Methane production and fatty acids(FA)biohydrogenation in the rumen are two main constraints in ruminant production causing environmental burden and reducing food product quality.Rumen functions can be modu...Background:Methane production and fatty acids(FA)biohydrogenation in the rumen are two main constraints in ruminant production causing environmental burden and reducing food product quality.Rumen functions can be modulated by the biologically active compounds(BACs)of plant origins as shown in several studies e.g.reduction in methane emission,modulation of FA composition with positive impact on the ruminant products.Coleus amboinicus Lour.(CAL)contains high concentration of polyphenols that may potentially reduce methane production and modulate ruminal biohydrogenation of unsaturated FA.This study aimed to investigate the effect of BAC of Coleus amboinicus Lour.(CAL)fed to growing lambs on ruminal methane production,biohydrogenation of unsaturated FA and meat characteristics.In this study,the in vitro experiment aiming at determining the most effective CAL dose for in vivo experiments was followed by two in vivo experiments in rumen-cannulated rams and growing lambs.Experiment 1(RUSITEC)comprised of control and three experimental diets differing in CAL content(10%,15%,and 20%of the total diet).The two in vivo experiments were conducted on six growing,rumen-cannulated lambs(Exp.2)and 16 growing lambs(Exp.3).Animals were assigned into the control(CON)and experimental(20%of CAL)groups.Several parameters were examined in vitro(pH,ammonia and VFA concentrations,protozoa,methanogens and select bacteria populations)and in vivo(methane production,digestibility,ruminal microorganism populations,meat quality,fatty acids profiles in rumen fluid and meat,transcript expression of 5 genes in meat).Results:CAL lowered in vitro methane production by 51%.In the in vivo Exp.3,CAL decreased methane production by 20%compared with the CON group,which corresponded to reduction of total methanogen counts by up to 28%in all experiments,notably Methanobacteriales.In Exp.3,CAL increased or tended to increase populations of some rumen bacteria(Ruminococcus albus,Megasphaera elsdenii,Butyrivibrio proteoclasticus,and Butyrivibrio fibrisolvens).Dietary CAL suppressed the Holotricha population,but increased or tended to increase Entodiniomorpha population in vivo.An increase in the polyunsaturated fatty acid(PUFA)proportion in the rumen of lambs was noted in response to the CAL diet,which was mainly attributable to the increase in C18:3 cis-9 cis-12cis-15(LNA)proportion.CAL reduced the mRNA expression of four out of five genes investigated in meat(fatty acid synthase,stearoyl-CoA desaturase,lipoprotein lipase,and fatty acid desaturase 1).Conclusions:Summarizing,polyphenols of CAL origin(20%in diet)mitigated ruminal methane production by inhibiting the methanogen communities.CAL supplementation also improved ruminal environment by modulating ruminal bacteria involved in fermentation and biohydrogenation of FA.Besides,CAL elevated the LNA concentration,which improved meat quality through increased deposition of n-3 PUFA.Highlight·Coleus amboinicus Lour.(CAL)into sheep diet decreased CH4emission.·CAL did not reduce nutrient digestibility,but inhibited the methanogen community.·CAL increased ruminal propionate proportion and decreased acetate/propionate ratio.·CAL elevated n-3 fatty acid concentration in ruminal fluid and meat.·Supplementation of CAL improved some meat quality traits.展开更多
Expanded granular sludge bed （EGSB） reactor and bioaugmentation were employed to investigate biohydrogen production with molasses wastewater. The start-up experiments consisted of two stages. In the first stage （0 ...Expanded granular sludge bed （EGSB） reactor and bioaugmentation were employed to investigate biohydrogen production with molasses wastewater. The start-up experiments consisted of two stages. In the first stage （0 - 24d） seeded with activated sludge, the butyric acid type-fermentation formed when the initial expanding rate, organic loading rate （OLR）, the initial redox potential （ORP） and hydraulic retention time （HRT） were 10%, 10.0 kg COD/（m^3·d）, -215 mV and 6.7 h, respectively. At the beginning of the second stage on day 25, the novel hydrogen-producing fermentative bacterial strain B49 （AF481148 in EMBL） were inoculated into the reactor under the condition of OLR 16. 0 kg COD/（m^3·d）, ORP and HRT about - 139 mV and 6.7 h, respectively, and then the reaction system transformed to ethanol-type fermentation gradually with the increase in OLR. When OLR, ORP and HRT were about 94.3 kg COD/（m^3·d）, -250 mV and 1.7 h, respectively, the system achieved the maximum hydrogen-producing rate of 282.6 mL H2/L reactor·h and hydrogen percentage of 51% -53% in the biogas.展开更多
The effects of L-cysteine concentration on biohydrogen production by Enterobacterium Bacterium M580 were investigated in batch cultivation.The experimental results showed that L-cysteine could enhance the cell growth,...The effects of L-cysteine concentration on biohydrogen production by Enterobacterium Bacterium M580 were investigated in batch cultivation.The experimental results showed that L-cysteine could enhance the cell growth,hydrogen production rate and hydrogen yield when its concentration was less than 500 mg·L-1,while it had negative effects when its concentration was higher than 500 mg·L-1.The hydrogen production was the highest 1.29 mol·mol-1(H2/glucose) when 300 mg·L-1L-cysteine was added into the culture,and the yield was 9.4% higher than that in the control.The oxidation-reduction potential(ORP) ,which was influenced by L-cysteine,also affected hydrogen production.The ORP values were in the range-300 mV to-150 mV when the L-cysteine concentration was higher than 500 mg·L-1.Although the ORP in this range was favorable for hydrogen production,it was not suitable for the biomass growth.Hence,less hydrogen was produced.When the L-cysteine concentration was lower than 500 mg·L-1,the ORP was more suitable for both biomass growth and hydrogen production.In addition,at least 91%glucose was consumed when L-cysteine was added to the culture media,compared to the 97.37% consumption without L-cysteine added.展开更多
Background： Micro-algae could inhibit the complete rumen BH of dietary 18-carbon unsaturated fatty acid （UFAs）. This study aimed to examine dose and time responses of algae supplementation on rumen fermentation, bi...Background： Micro-algae could inhibit the complete rumen BH of dietary 18-carbon unsaturated fatty acid （UFAs）. This study aimed to examine dose and time responses of algae supplementation on rumen fermentation, biohydrogenation and Butyrivibrio group bacteria in goats. Methods： Six goats were used in a repeated 3 x 3 Latin square design, and offered a fixed diet. Algae were infused through rumen cannule with 0 （Control）, 6.1 （L-AIg）, or 18.3 g （H-AIg） per day. Rumen contents were sampled on d 0, 3, 7, 14 and 20. Results： H-AIg reduced total volatile fatty acid concentration and acetate molar proportion （P 〈 0.05）, and increased propionate molar proportion （P 〈 0.05）, whereas L-AIg had no effect on rumen fermentation. Changes in proportions of acetate and propionate in H-AIg were obvious from d 7 onwards and reached the largest differences with the control on d 14. Algae induced a dose-dependent decrease in 18：0 and increased trons-18：1 in the ruminal content （P 〈 0.05）. H-AIg increased the concentrations of t9, t] 1-18：2 and tl 1, cl 5-18：2 （P 〈 0.05）. L-AIg only seemed to induce a transient change in 18-carbon isomers, while H-AIg induced a rapid elevation, already obvious on d 3, concentrations of these fatty acid rose in some cases again on d 20. Algae had no effect on the abundances of Butyrivibfio spp. and Butyrivibrio proteoclosdcus （P 〉 0.10）, while H-AIg reduced the total bacteria abundance （P 〈 0.05）. However, this was induced by a significant difference between control and H-AIg on d 14 （-4.43 %）. Afterwards, both treatments did not differ as increased variation in the H-AIg repetitions, with in some cases a return of the bacterial abundance to the basal level （d 0）. Conclusions： Changes in rumen fermentation and 18-carbon UFAs metabolism in response to algae were related to the supplementation level, but there was no evidence of shift in ruminal biohydrogenation pathways towards t1 0-18：1 L-AIg mainly induced a transient effect on rumen biohydrogenation of 18-carbon UFAs, while H-AIg showed an acute inhibition and these effects were not associated with the known hydrogenating bacteria.展开更多
The anaerobic process of biohydrogen production was developed recently. The isolation and identification of biohydrogen producing anaerobic bacteria with high evolution rate and yield is an important foundation of the...The anaerobic process of biohydrogen production was developed recently. The isolation and identification of biohydrogen producing anaerobic bacteria with high evolution rate and yield is an important foundation of the fermented biohydrogen production process through which anaerobic bacteria digest organic wastewater. By considering physiological and biochemical traits, morphological characteristics and a 16S rDNA sequence, the isolated Rennanqilyf33 is shown to be a new species.展开更多
Anaerobic process of biohydrogen production was developed. There is a great deal of Lactobacillus bacteria in the activated sludge of biohydrogen reactor. The isolation and identification of different anaerobic bacter...Anaerobic process of biohydrogen production was developed. There is a great deal of Lactobacillus bacteria in the activated sludge of biohydrogen reactor. The isolation and identification of different anaerobic bacteria in the reactor is important for fermented biohydrogen production process by anaerobic digesting organic wastewater. Considering with the physiological and biochemical traits,morphological characteristics and 16SrDNA sequence,the isolated Rennanqilyf13 is a new species in Lactobacillus genus. And the temporary nomenclature of the species is Lactobacillus Strain Rennanqilyf13 sp. nov.展开更多
The biological hydrogen generating from fermentation of low-cost lignocellulosic feedstocks by hydrogen-producing bacteria has attracted many attentions in recent years. In the present investigation, ten hydrogen-prod...The biological hydrogen generating from fermentation of low-cost lignocellulosic feedstocks by hydrogen-producing bacteria has attracted many attentions in recent years. In the present investigation, ten hydrogen-producing bacteria were newly isolated from the intestine of wild common carp (</span><span style="font-family:Verdana;"><i>Cyprinus carpio</i></span><span style="font-family:Verdana;"> L.), and identified belonging to the genera of </span><i><span style="font-family:Verdana;">Enterobacter</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">Klebsiella</span></i><span style="font-family:Verdana;"> based on analysis of the 16S rDNA gene sequence and examination of the physiological and biochemical characteristics. All the isolates inherently owned the ability to metabolize xylose especially the cotton stalk hydrolysate for hydrogen production with hydrogen yield (HY) higher than 100 mL</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">·</span></span><span></span><span></span><span style="font-family:""><span style="font-family:Verdana;">L</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">. In particular, two isolates, WL1306 and WL1305 obtained higher HY, hydrogen production rate (HPR), and hydrogen production potential (HPP) using cotton stalk hydrolysate as sugar substrate than the mixed sugar of glucose & xylose, which obtained the HY of 249.5 ± 29.0, 397.0 ± 36.7 mL</span></span><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">L</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">, HPR of 10.4 ± 1.2, 16.5 ± 1.5 mL</span><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">L</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">h</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">, HPP of 19.5 ± 2.3, 31.0 ± 2.8 mL</span><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">L</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">g</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><sub><span style="font-family:Verdana;">sugar</span></sub><span style="font-family:Verdana;">, separately. The generation of soluble metabolites, such as the lactate, formate, acetate, succinate and ethanol reflected the mixed acid fermentation properties of the hydrogen production pathway.展开更多
Biohydrogen production through dark fermentation is very attractive as a solution to help mitigate the effects of climate change,via cleaner bioenergy production.Dark fermentation is a process where organic substrates...Biohydrogen production through dark fermentation is very attractive as a solution to help mitigate the effects of climate change,via cleaner bioenergy production.Dark fermentation is a process where organic substrates are converted into bioenergy,driven by a complex community of microorganisms of different functional guilds.Understanding of the microbiomes underpinning the fermentation of organic matter and conversion to hydrogen,and the interactions among various distinct trophic groups during the process,is critical in order to assist in the process optimisations.Research in biohydrogen production via dark fermentation is currently advancing rapidly,and various microbiology and molecular biology tools have been used to investigate the microbiomes.We reviewed here the different systems used and the production capacity,together with the diversity of the microbiomes used in the dark fermentation of industrial wastes,with a special emphasis on palm oil mill effluent(POME).The current challenges associated with biohydrogen production were also included.Then,we summarised and discussed the different molecular biology tools employed to investigate the intricacy of the microbial ecology associated with biohydrogen production.Finally,we included a section on the future outlook of how microbiome-based technologies and knowledge can be used effectively in biohydrogen production systems,in order to maximise the production output.展开更多
Biohydrogen technology has drawn much attention due to its many advantages.However,it is still necessary to screen much more strains with stronger hydrogen-producing capacity for future commercialization processes.In ...Biohydrogen technology has drawn much attention due to its many advantages.However,it is still necessary to screen much more strains with stronger hydrogen-producing capacity for future commercialization processes.In this paper,a biohydrogen-producing strain Enterobacter aerogenes EB-06 was isolated,identified,and named.It could convert glycerol to biohydrogen by microorganism fermentation.The effects of oxygen content,initial pH,initial glycerol concentration,and initial nitrogen source content on biohydrogen production process were investigated.The results have shown that biohydrogen generation was more favorable under anaerobic conditions.The optimum specific biohydrogen production rate (Q H_(2)) was obtained as 41.47 mmol H_(2)/g DCW h at 40 g/L initial glycerol concentration.The optimum volume H_(2) yield (C H_(2)) was 83.76 mmol H_(2)/L at initial pH 7.0.It was found that nitrogen source content (0-4 g/L) could promote biohydrogen production and cell growth.The biohydrogen production of Enterobacter aerogenes EB-06 from glycerol was optimized by the orthogonal experimental design.The optimal yield coefficient of biohydrogen from glycerol fermentation (Y H_(2)/glycerol) of EB-06 was obtained as 1.07 mmol H_(2)/ mol glycerol at 10 g/L initial glycerol concentration,initial pH 5.0,and initial C/N ratio 5/3.展开更多
The effect of substrate concentration ranging from 0 to 300 g/L on fermentative hydrogen production by mixed cultures was investigated in batch tests using glucose as substrate. The experimental results showed that, a...The effect of substrate concentration ranging from 0 to 300 g/L on fermentative hydrogen production by mixed cultures was investigated in batch tests using glucose as substrate. The experimental results showed that, at 35 and initial pH 7.0, during the fermentative hydrogen production, the hydrogen °C production potential and hydrogen production rate increased with increasing substrate concentration from 0 to 25 g/L. The maximal hydrogen production potential of 426.8 mL and maximal hydrogen production rate of 15.1 mL/h were obtained at the substrate concentration of 25 g/L. The maximal hydrogen yield and the maximal substrate degradation efficiency were respectively 384.3 mL/g glucose and 97.6%, at the substrate concentration of 2 g/L. The modified Logistic model could be used to describe the progress of cumulative hydrogen production in this study successfully. The Han-Levenspiel model could be used to describe the effect of substrate concentration on fermentative hydrogen production rate.展开更多
The production of bio-hydrogen from raw cassava starch via a mixed-culture dark fermentation process was investigated. The production yield of H2 was optimized by adjusting the substrate concentration and the microorg...The production of bio-hydrogen from raw cassava starch via a mixed-culture dark fermentation process was investigated. The production yield of H2 was optimized by adjusting the substrate concentration and the microorganism mixture ratio. A maximum H2 yield of 1.72 mol H2/mol glucose was obtained with a cassava starch concentration of 10 g/L to give a 90% utilization rate. The kinetics of the substrate utilization and of the generation of both hydrogen and volatile fatty acids were also investigated. The substrate utilization follows pseudo first order reaction kinetics, whereas the production of both H2 and the VFAs correlate with the Gompertz equation. These results show that cassava is a good candidate for the production of biohydrogen.展开更多
To study the structure of microbial communities in the biological hydrogen produc-tion reactor and determine the ecological function of hydrogen producing bacteria,anaerobic sludge was obtained from the continuous sti...To study the structure of microbial communities in the biological hydrogen produc-tion reactor and determine the ecological function of hydrogen producing bacteria,anaerobic sludge was obtained from the continuous stirred tank reactor(CSTR)in different periods of time,and the diversity and dynamics of microbial communities were investigated by denaturing gra-dient gel electrophoresis(DGGE).The results of DGGE demonstrated that an obvious shift of microbial population happened from the beginning of star-up to the 28th day,and the ethanol type fermentation was established.After 28 days the structure of microbial community became stable,and the climax community was formed.Comparative analysis of 16S rDNA sequences from reamplifying and sequencing the prominent bands indicated that the dominant population belonged to low G+C Gram-positive bacteria(Clostridium sp.and Ethanologenbacterium sp.),β-proteobacteria(Acidovorax sp.),γ-proteobacteria(Kluyvera sp.),Bacteroides(uncultured bacte-rium SJA-168),and Spirochaetes(uncultured eubacterium E1-K13),respectively.The hydrogen production rate increased obviously with the increase of Ethanologenbacterium sp.,Clostridium sp.and uncultured Spirochaetes after 21 days,meanwhile the succession of ethanol type fer-mentation was formed.Throughout the succession the microbial diversity increased however it decreased after 21 days.Some types of Clostridium sp.Acidovorax sp.,Kluyvera sp.,and Bac-teroides were dominant populations during all periods of time.These special populations were essential for the construction of climax community.Hydrogen production efficiency was de-pendent on both hydrogen producing bacteria and other populations.It implied that the co-metabolism of microbial community played a great role of biohydrogen production in the reactors.展开更多
The production of biohydrogen from biological processes is cleaner and more sustainable than that of fossil fuel-based hydrogen.The drive for cleaner and sustainable energy sources is an important facet of the bioecon...The production of biohydrogen from biological processes is cleaner and more sustainable than that of fossil fuel-based hydrogen.The drive for cleaner and sustainable energy sources is an important facet of the bioeconomy.Based on these findings,this paper aimed to examine the significance and impact of biohydrogen on the bioeconomy.These bioprocessing strategies are primarily biophotolysis,fermentation and bio-electrolytic systems.Considering that biological processes are slow compared to other thermochemical production processes,production volumes cannot match that of the latter.The inherently slow nature of biochemical reactions taking place in living organisms is a challenge that puts biohydrogen at a disadvantage.Biological processes are also very sensitive to temperature and pH,thereby requiring more intricate process monitoring and control.To obtain equivalent volumes of biohydrogen compared to production strategies,larger and more intricate facilities would be needed,implying more cost implications.It is surmised that biohydrogen will continue to play an important role in the drive for a sustainable bioeconomy despite the current challenges it faces.展开更多
NH^(+)_(4)is typically an inhibitor to hydrogen production from organic wastewater by photo-bacteria.In this experiment,biohydrogen generation with wild-type anoxygenic phototrophic bacterium Rhodobacter sphaeroideswa...NH^(+)_(4)is typically an inhibitor to hydrogen production from organic wastewater by photo-bacteria.In this experiment,biohydrogen generation with wild-type anoxygenic phototrophic bacterium Rhodobacter sphaeroideswas found to be sensitive to NH^(+)_(4)due to the significant inhibition of NH^(+)_(4)to its nitrogenase.In order to avoid the inhibition of NH^(+)_(4)to biohydrogen generation by R.sphaeroides,a glutamine auxotrophic mutant R.sphaeroides AR-3 was obtained by mutagenizing with ethyl methane sulfonate.The AR-3 mutant could generate biohydrogen efficiently in the hydrogen production medium with a higher NH^(+)_(4)concentration,because the inhibition of NH^(+)_(4)to nitrogenase of AR-3 was released.Under suitable conditions,AR-3 effectively produced biohydrogen from tofu wastewater,which normally contains 50–60 mg/L NH^(+)_(4),with an average generation rate of 14.2 mL/L$h.This generation rate was increased by more than 100%compared with that from wild-type R.sphaeroides.展开更多
基金Supported by National Basic Research Program of China(2006CB708407 2009CB220005)+2 种基金National Natural Science Foun-dation of China (90610001 20871106)Program of 211 Projectfor Zhengzhou University from Ministry of Education~~
文摘[Objective] This study was to explore the effects of dilute acid hydrolysis on fermentative biohydrogen production capacity of maize stalk. [Method] Using maize stalks subjected to mechanical disintegration,steam explosion and dilute acid hydrolysis as experimental materials,we measured and analyzed the effects of different treatments and particle size of maize stalk were analyzed. [Result] The optimal fermentative biohydrogen production was found under following parameters：pretreatment of 0.8% dilute H2SO4 following steam explosion,particle size of maize stalk of 0.425-0.850 mm,liquid-solid ratio [0.8% H2SO4 （M）：stalk （W）] of 10：1. [Conclusion] Post steam explosion,dilute 0.8% dilute H2SO4 intensified hydrolysis on maize stalk could produce fermentative biohydrogen production capacity.
基金supported by the National Natural Science Foundation of China (No. 30870037, 30970552)the Funding of the National Creative Research Groups (No.50821002)+1 种基金the Aid Program for Science and Technology Innovative Research Team in Higher Educational Instituions of Heilongjiang Province (No. 2010TD10)the Harbin Normal University (No. KJTD2011-2)
文摘Five individual pretreatment methods, including three widely-used protocols （heat, acid and base） and two novel attempts （ultrasonic and ultraviolet）, were conducted in batch tests to compare their effects on mixed microflora to enhance hydrogen （H2） production from corn stover hydrolysate. Experimental results indicated that heat and base pretreatments significantly increased H2 yield with the values of 5.03 and 4.45 mmol H2/g sugar utilized, respectively, followed by acid pretreatment of 3.21 mmol H2/g sugar utilized. However, compared with the control （2.70 mmol H2/g sugar utilized）, ultrasonic and ultraviolet pretreatments caused indistinctive effects on H2 production with the values of 2.92 and 2.87 mmol H2/g sugar utilized, respectively. The changes of soluble metabolites composition caused by pretreatment were in accordance with H2-producing behavior. Concretely, more acetate accumulation and less ethanol production were found in pretreated processes, meaning that more reduced nicotinamide adenine dinucleotide （NADH） might be saved and flowed into H2-producing pathways. PCR-DGGE analysis indicated that the pretreatment led to the enrichment of some species, which appeared in large amounts and even dominated the microbial community. Most of the dominated species were affiliated to Enterobacter spp. and Escherichia spp. As another efflcient H2 producer, Clostridium bifermentan was only found in a large quantity after heat pretreatment. This strain might be mainly responsible for better performance of H2 production in this case.
基金funded by the National Science Centre funding program Grant 2018/31/N/NZ9/01589。
文摘Background:Methane production and fatty acids(FA)biohydrogenation in the rumen are two main constraints in ruminant production causing environmental burden and reducing food product quality.Rumen functions can be modulated by the biologically active compounds(BACs)of plant origins as shown in several studies e.g.reduction in methane emission,modulation of FA composition with positive impact on the ruminant products.Coleus amboinicus Lour.(CAL)contains high concentration of polyphenols that may potentially reduce methane production and modulate ruminal biohydrogenation of unsaturated FA.This study aimed to investigate the effect of BAC of Coleus amboinicus Lour.(CAL)fed to growing lambs on ruminal methane production,biohydrogenation of unsaturated FA and meat characteristics.In this study,the in vitro experiment aiming at determining the most effective CAL dose for in vivo experiments was followed by two in vivo experiments in rumen-cannulated rams and growing lambs.Experiment 1(RUSITEC)comprised of control and three experimental diets differing in CAL content(10%,15%,and 20%of the total diet).The two in vivo experiments were conducted on six growing,rumen-cannulated lambs(Exp.2)and 16 growing lambs(Exp.3).Animals were assigned into the control(CON)and experimental(20%of CAL)groups.Several parameters were examined in vitro(pH,ammonia and VFA concentrations,protozoa,methanogens and select bacteria populations)and in vivo(methane production,digestibility,ruminal microorganism populations,meat quality,fatty acids profiles in rumen fluid and meat,transcript expression of 5 genes in meat).Results:CAL lowered in vitro methane production by 51%.In the in vivo Exp.3,CAL decreased methane production by 20%compared with the CON group,which corresponded to reduction of total methanogen counts by up to 28%in all experiments,notably Methanobacteriales.In Exp.3,CAL increased or tended to increase populations of some rumen bacteria(Ruminococcus albus,Megasphaera elsdenii,Butyrivibrio proteoclasticus,and Butyrivibrio fibrisolvens).Dietary CAL suppressed the Holotricha population,but increased or tended to increase Entodiniomorpha population in vivo.An increase in the polyunsaturated fatty acid(PUFA)proportion in the rumen of lambs was noted in response to the CAL diet,which was mainly attributable to the increase in C18:3 cis-9 cis-12cis-15(LNA)proportion.CAL reduced the mRNA expression of four out of five genes investigated in meat(fatty acid synthase,stearoyl-CoA desaturase,lipoprotein lipase,and fatty acid desaturase 1).Conclusions:Summarizing,polyphenols of CAL origin(20%in diet)mitigated ruminal methane production by inhibiting the methanogen communities.CAL supplementation also improved ruminal environment by modulating ruminal bacteria involved in fermentation and biohydrogenation of FA.Besides,CAL elevated the LNA concentration,which improved meat quality through increased deposition of n-3 PUFA.Highlight·Coleus amboinicus Lour.(CAL)into sheep diet decreased CH4emission.·CAL did not reduce nutrient digestibility,but inhibited the methanogen community.·CAL increased ruminal propionate proportion and decreased acetate/propionate ratio.·CAL elevated n-3 fatty acid concentration in ruminal fluid and meat.·Supplementation of CAL improved some meat quality traits.
文摘Expanded granular sludge bed （EGSB） reactor and bioaugmentation were employed to investigate biohydrogen production with molasses wastewater. The start-up experiments consisted of two stages. In the first stage （0 - 24d） seeded with activated sludge, the butyric acid type-fermentation formed when the initial expanding rate, organic loading rate （OLR）, the initial redox potential （ORP） and hydraulic retention time （HRT） were 10%, 10.0 kg COD/（m^3·d）, -215 mV and 6.7 h, respectively. At the beginning of the second stage on day 25, the novel hydrogen-producing fermentative bacterial strain B49 （AF481148 in EMBL） were inoculated into the reactor under the condition of OLR 16. 0 kg COD/（m^3·d）, ORP and HRT about - 139 mV and 6.7 h, respectively, and then the reaction system transformed to ethanol-type fermentation gradually with the increase in OLR. When OLR, ORP and HRT were about 94.3 kg COD/（m^3·d）, -250 mV and 1.7 h, respectively, the system achieved the maximum hydrogen-producing rate of 282.6 mL H2/L reactor·h and hydrogen percentage of 51% -53% in the biogas.
基金Supported by the National High Technology Research and Development Program of China（2006AA02Z246 2007AA03Z456） the National Natural Science Foundation of China（20776119）+2 种基金 the Specialized Research Fund for the Doctoral Program of Higher Education of China（20096101120023） Shaanxi Provincial Natural Science Foundation（SJ08B03） Shaanxi Key Subject Program China
文摘The effects of L-cysteine concentration on biohydrogen production by Enterobacterium Bacterium M580 were investigated in batch cultivation.The experimental results showed that L-cysteine could enhance the cell growth,hydrogen production rate and hydrogen yield when its concentration was less than 500 mg·L-1,while it had negative effects when its concentration was higher than 500 mg·L-1.The hydrogen production was the highest 1.29 mol·mol-1(H2/glucose) when 300 mg·L-1L-cysteine was added into the culture,and the yield was 9.4% higher than that in the control.The oxidation-reduction potential(ORP) ,which was influenced by L-cysteine,also affected hydrogen production.The ORP values were in the range-300 mV to-150 mV when the L-cysteine concentration was higher than 500 mg·L-1.Although the ORP in this range was favorable for hydrogen production,it was not suitable for the biomass growth.Hence,less hydrogen was produced.When the L-cysteine concentration was lower than 500 mg·L-1,the ORP was more suitable for both biomass growth and hydrogen production.In addition,at least 91%glucose was consumed when L-cysteine was added to the culture media,compared to the 97.37% consumption without L-cysteine added.
基金funded by the Natural Science Foundation of Jiangsu Province (China)the Research Foundation-Flanders (Belgium)the Special Research Fund of the Ghent University (Belgium)
文摘Background： Micro-algae could inhibit the complete rumen BH of dietary 18-carbon unsaturated fatty acid （UFAs）. This study aimed to examine dose and time responses of algae supplementation on rumen fermentation, biohydrogenation and Butyrivibrio group bacteria in goats. Methods： Six goats were used in a repeated 3 x 3 Latin square design, and offered a fixed diet. Algae were infused through rumen cannule with 0 （Control）, 6.1 （L-AIg）, or 18.3 g （H-AIg） per day. Rumen contents were sampled on d 0, 3, 7, 14 and 20. Results： H-AIg reduced total volatile fatty acid concentration and acetate molar proportion （P 〈 0.05）, and increased propionate molar proportion （P 〈 0.05）, whereas L-AIg had no effect on rumen fermentation. Changes in proportions of acetate and propionate in H-AIg were obvious from d 7 onwards and reached the largest differences with the control on d 14. Algae induced a dose-dependent decrease in 18：0 and increased trons-18：1 in the ruminal content （P 〈 0.05）. H-AIg increased the concentrations of t9, t] 1-18：2 and tl 1, cl 5-18：2 （P 〈 0.05）. L-AIg only seemed to induce a transient change in 18-carbon isomers, while H-AIg induced a rapid elevation, already obvious on d 3, concentrations of these fatty acid rose in some cases again on d 20. Algae had no effect on the abundances of Butyrivibfio spp. and Butyrivibrio proteoclosdcus （P 〉 0.10）, while H-AIg reduced the total bacteria abundance （P 〈 0.05）. However, this was induced by a significant difference between control and H-AIg on d 14 （-4.43 %）. Afterwards, both treatments did not differ as increased variation in the H-AIg repetitions, with in some cases a return of the bacterial abundance to the basal level （d 0）. Conclusions： Changes in rumen fermentation and 18-carbon UFAs metabolism in response to algae were related to the supplementation level, but there was no evidence of shift in ruminal biohydrogenation pathways towards t1 0-18：1 L-AIg mainly induced a transient effect on rumen biohydrogenation of 18-carbon UFAs, while H-AIg showed an acute inhibition and these effects were not associated with the known hydrogenating bacteria.
文摘The anaerobic process of biohydrogen production was developed recently. The isolation and identification of biohydrogen producing anaerobic bacteria with high evolution rate and yield is an important foundation of the fermented biohydrogen production process through which anaerobic bacteria digest organic wastewater. By considering physiological and biochemical traits, morphological characteristics and a 16S rDNA sequence, the isolated Rennanqilyf33 is shown to be a new species.
基金Shanghai Education Committee Foundation (Grant No.N07ZZ156 S0701004 P1402).
文摘Anaerobic process of biohydrogen production was developed. There is a great deal of Lactobacillus bacteria in the activated sludge of biohydrogen reactor. The isolation and identification of different anaerobic bacteria in the reactor is important for fermented biohydrogen production process by anaerobic digesting organic wastewater. Considering with the physiological and biochemical traits,morphological characteristics and 16SrDNA sequence,the isolated Rennanqilyf13 is a new species in Lactobacillus genus. And the temporary nomenclature of the species is Lactobacillus Strain Rennanqilyf13 sp. nov.
文摘The biological hydrogen generating from fermentation of low-cost lignocellulosic feedstocks by hydrogen-producing bacteria has attracted many attentions in recent years. In the present investigation, ten hydrogen-producing bacteria were newly isolated from the intestine of wild common carp (</span><span style="font-family:Verdana;"><i>Cyprinus carpio</i></span><span style="font-family:Verdana;"> L.), and identified belonging to the genera of </span><i><span style="font-family:Verdana;">Enterobacter</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">Klebsiella</span></i><span style="font-family:Verdana;"> based on analysis of the 16S rDNA gene sequence and examination of the physiological and biochemical characteristics. All the isolates inherently owned the ability to metabolize xylose especially the cotton stalk hydrolysate for hydrogen production with hydrogen yield (HY) higher than 100 mL</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">·</span></span><span></span><span></span><span style="font-family:""><span style="font-family:Verdana;">L</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">. In particular, two isolates, WL1306 and WL1305 obtained higher HY, hydrogen production rate (HPR), and hydrogen production potential (HPP) using cotton stalk hydrolysate as sugar substrate than the mixed sugar of glucose & xylose, which obtained the HY of 249.5 ± 29.0, 397.0 ± 36.7 mL</span></span><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">L</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">, HPR of 10.4 ± 1.2, 16.5 ± 1.5 mL</span><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">L</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">h</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">, HPP of 19.5 ± 2.3, 31.0 ± 2.8 mL</span><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">L</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><span style="font-family:Verdana;">·</span><span style="font-family:Verdana;">g</span><sup><span style="font-family:Verdana;">-</span></sup><sup><span style="font-family:Verdana;">1</span></sup><sub><span style="font-family:Verdana;">sugar</span></sub><span style="font-family:Verdana;">, separately. The generation of soluble metabolites, such as the lactate, formate, acetate, succinate and ethanol reflected the mixed acid fermentation properties of the hydrogen production pathway.
基金The Ministry of Higher Education(MOHE)Malaysia for providing financial support through MyBrainSc scholarshipthe Nigerian Tertiary Education Trust Fund for the scholarship providedfunding received from UTM via Transdisciplinary Research Grant no.05G24 and UTMShine Grant No.09G86.
文摘Biohydrogen production through dark fermentation is very attractive as a solution to help mitigate the effects of climate change,via cleaner bioenergy production.Dark fermentation is a process where organic substrates are converted into bioenergy,driven by a complex community of microorganisms of different functional guilds.Understanding of the microbiomes underpinning the fermentation of organic matter and conversion to hydrogen,and the interactions among various distinct trophic groups during the process,is critical in order to assist in the process optimisations.Research in biohydrogen production via dark fermentation is currently advancing rapidly,and various microbiology and molecular biology tools have been used to investigate the microbiomes.We reviewed here the different systems used and the production capacity,together with the diversity of the microbiomes used in the dark fermentation of industrial wastes,with a special emphasis on palm oil mill effluent(POME).The current challenges associated with biohydrogen production were also included.Then,we summarised and discussed the different molecular biology tools employed to investigate the intricacy of the microbial ecology associated with biohydrogen production.Finally,we included a section on the future outlook of how microbiome-based technologies and knowledge can be used effectively in biohydrogen production systems,in order to maximise the production output.
文摘Biohydrogen technology has drawn much attention due to its many advantages.However,it is still necessary to screen much more strains with stronger hydrogen-producing capacity for future commercialization processes.In this paper,a biohydrogen-producing strain Enterobacter aerogenes EB-06 was isolated,identified,and named.It could convert glycerol to biohydrogen by microorganism fermentation.The effects of oxygen content,initial pH,initial glycerol concentration,and initial nitrogen source content on biohydrogen production process were investigated.The results have shown that biohydrogen generation was more favorable under anaerobic conditions.The optimum specific biohydrogen production rate (Q H_(2)) was obtained as 41.47 mmol H_(2)/g DCW h at 40 g/L initial glycerol concentration.The optimum volume H_(2) yield (C H_(2)) was 83.76 mmol H_(2)/L at initial pH 7.0.It was found that nitrogen source content (0-4 g/L) could promote biohydrogen production and cell growth.The biohydrogen production of Enterobacter aerogenes EB-06 from glycerol was optimized by the orthogonal experimental design.The optimal yield coefficient of biohydrogen from glycerol fermentation (Y H_(2)/glycerol) of EB-06 was obtained as 1.07 mmol H_(2)/ mol glycerol at 10 g/L initial glycerol concentration,initial pH 5.0,and initial C/N ratio 5/3.
基金the National Natural Science Foundation of China (Grant No. 50325824)
文摘The effect of substrate concentration ranging from 0 to 300 g/L on fermentative hydrogen production by mixed cultures was investigated in batch tests using glucose as substrate. The experimental results showed that, at 35 and initial pH 7.0, during the fermentative hydrogen production, the hydrogen °C production potential and hydrogen production rate increased with increasing substrate concentration from 0 to 25 g/L. The maximal hydrogen production potential of 426.8 mL and maximal hydrogen production rate of 15.1 mL/h were obtained at the substrate concentration of 25 g/L. The maximal hydrogen yield and the maximal substrate degradation efficiency were respectively 384.3 mL/g glucose and 97.6%, at the substrate concentration of 2 g/L. The modified Logistic model could be used to describe the progress of cumulative hydrogen production in this study successfully. The Han-Levenspiel model could be used to describe the effect of substrate concentration on fermentative hydrogen production rate.
基金The authors express their thanks for the support from the National Natural Science Foundation of China （Grant No. 21525625）, the National Basic Research Program of China （973 Program, Grant No. 2014CB745100）, the National High Technology Research and Development Program of China （863 Program, Grant No. 2013AA020302）.
文摘The production of bio-hydrogen from raw cassava starch via a mixed-culture dark fermentation process was investigated. The production yield of H2 was optimized by adjusting the substrate concentration and the microorganism mixture ratio. A maximum H2 yield of 1.72 mol H2/mol glucose was obtained with a cassava starch concentration of 10 g/L to give a 90% utilization rate. The kinetics of the substrate utilization and of the generation of both hydrogen and volatile fatty acids were also investigated. The substrate utilization follows pseudo first order reaction kinetics, whereas the production of both H2 and the VFAs correlate with the Gompertz equation. These results show that cassava is a good candidate for the production of biohydrogen.
基金This work was supported by the National Science Foundation for Distinguished Young Scholars(No.50125823)National Natural Science Foundation of China(Grant No.30470054)Key Project of Chinese National Programs for Fundamental Research and Development(No.G2000026402).
文摘To study the structure of microbial communities in the biological hydrogen produc-tion reactor and determine the ecological function of hydrogen producing bacteria,anaerobic sludge was obtained from the continuous stirred tank reactor(CSTR)in different periods of time,and the diversity and dynamics of microbial communities were investigated by denaturing gra-dient gel electrophoresis(DGGE).The results of DGGE demonstrated that an obvious shift of microbial population happened from the beginning of star-up to the 28th day,and the ethanol type fermentation was established.After 28 days the structure of microbial community became stable,and the climax community was formed.Comparative analysis of 16S rDNA sequences from reamplifying and sequencing the prominent bands indicated that the dominant population belonged to low G+C Gram-positive bacteria(Clostridium sp.and Ethanologenbacterium sp.),β-proteobacteria(Acidovorax sp.),γ-proteobacteria(Kluyvera sp.),Bacteroides(uncultured bacte-rium SJA-168),and Spirochaetes(uncultured eubacterium E1-K13),respectively.The hydrogen production rate increased obviously with the increase of Ethanologenbacterium sp.,Clostridium sp.and uncultured Spirochaetes after 21 days,meanwhile the succession of ethanol type fer-mentation was formed.Throughout the succession the microbial diversity increased however it decreased after 21 days.Some types of Clostridium sp.Acidovorax sp.,Kluyvera sp.,and Bac-teroides were dominant populations during all periods of time.These special populations were essential for the construction of climax community.Hydrogen production efficiency was de-pendent on both hydrogen producing bacteria and other populations.It implied that the co-metabolism of microbial community played a great role of biohydrogen production in the reactors.
文摘The production of biohydrogen from biological processes is cleaner and more sustainable than that of fossil fuel-based hydrogen.The drive for cleaner and sustainable energy sources is an important facet of the bioeconomy.Based on these findings,this paper aimed to examine the significance and impact of biohydrogen on the bioeconomy.These bioprocessing strategies are primarily biophotolysis,fermentation and bio-electrolytic systems.Considering that biological processes are slow compared to other thermochemical production processes,production volumes cannot match that of the latter.The inherently slow nature of biochemical reactions taking place in living organisms is a challenge that puts biohydrogen at a disadvantage.Biological processes are also very sensitive to temperature and pH,thereby requiring more intricate process monitoring and control.To obtain equivalent volumes of biohydrogen compared to production strategies,larger and more intricate facilities would be needed,implying more cost implications.It is surmised that biohydrogen will continue to play an important role in the drive for a sustainable bioeconomy despite the current challenges it faces.
基金the National Natural Science Foundation of China(Grant Nos.20677043 and 50222204)。
文摘NH^(+)_(4)is typically an inhibitor to hydrogen production from organic wastewater by photo-bacteria.In this experiment,biohydrogen generation with wild-type anoxygenic phototrophic bacterium Rhodobacter sphaeroideswas found to be sensitive to NH^(+)_(4)due to the significant inhibition of NH^(+)_(4)to its nitrogenase.In order to avoid the inhibition of NH^(+)_(4)to biohydrogen generation by R.sphaeroides,a glutamine auxotrophic mutant R.sphaeroides AR-3 was obtained by mutagenizing with ethyl methane sulfonate.The AR-3 mutant could generate biohydrogen efficiently in the hydrogen production medium with a higher NH^(+)_(4)concentration,because the inhibition of NH^(+)_(4)to nitrogenase of AR-3 was released.Under suitable conditions,AR-3 effectively produced biohydrogen from tofu wastewater,which normally contains 50–60 mg/L NH^(+)_(4),with an average generation rate of 14.2 mL/L$h.This generation rate was increased by more than 100%compared with that from wild-type R.sphaeroides.
