Effects of Dilute Acid-intensified Hydrolysis on Fermentative Biohydrogen Production Capacity of Maize Stalk

[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.

氮源对Biohydrogenbacterium R3 sp.nov.发酵产氢效能影响

探讨有机氮源和无机氮源对高效产氢新菌种Biohydrogenbacterium R3 sp.nov.的生长和产氢代谢的影响.结果发现,有机氮源(尤其是酵母粉)对Biohydrogenbacterium R3 sp.nov.生长及产氢的促进作用比较明显,无机氮源对菌株Biohydrogenbacterium R3 sp.nov.生长和产氢量等的促进作用极小;在供试试剂中,酵母粉是提高Biohydrogenbacterium R3 sp.nov.产氢量和促进其细胞生长的最有效的氮源供应者,含有酵母粉的培养液(组Ye)中,产氢量、产氢速率和比产氢速率最大,分别为1529.69mL H2/L、16.94 mmol H2/g CDW.h和1.33 mol H2/mol葡萄糖.

The start-up of biohydrogen-producing process by bioaugmentation in the EGSB reactor

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.

Influence of L-Cysteine Concentration on Oxidation-reduction Potential and Biohydrogen Production

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.

Dose and time response of ruminally infused algae on rumen fermentation characteristics,biohydrogenation and Butyrivibrio group bacteria in goats

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.

Dietary Coleus amboinicus Lour. decreases ruminal methanogenesis and biohydrogenation, and improves meat quality and fatty acid composition in longissimus thoracis muscle of lambs

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.

The molecular biological characterization of a strain of biohydrogen-producing anaerobe in Clostridium Genus

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.

Characterization and phylogenetics of a new species of genus Lactobacillus from the activated sludge in biohydrogen production

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.

Fermentative Biohydrogen Production with Enteric Bacteria Isolated from the Intestine of Wild Common Carp Dwelling in Tarim River Basin

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 (Cyprinus carpio L.), and identified belonging to the genera of Enterobacter and Klebsiella 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·L-1. 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·L-1, HPR of 10.4 ± 1.2, 16.5 ± 1.5 mL·L-1·h-1, HPP of 19.5 ± 2.3, 31.0 ± 2.8 mL·L-1·g-1sugar, 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.

碳酸盐与磷酸盐对Biohydrogenbacterium R3 sp.nov.产氢发酵效能的影响

采用NH4HCO3、NaHCO3、Na2CO3、K2HPO4、KH2HPO4、NaH2PO4和Na2HPO4作为碳酸盐和磷酸盐缓冲溶液源,研究其对Biohydrogenbacterium R3 sp.nov.产氢发酵效能的影响.研究发现,碳酸盐对Biohydrogenbacterium R3 sp.nov.反应体系中的pH值都具有较好的缓冲作用,而磷酸盐的添加对其产氢效能的促进作用较明显.反应器内添加了Na2HPO4与K2HPO4的Biohydrogenbacterium R3 sp.nov.的氢气产量与氢气含量达到最高值,分别为1978.56 mL、44.1%与2160.9 mL、45.8%,此时反应器内的pH值分别为3.28和3.41,细胞浓度分别为1.03 g·L-1和1.21 g·L-1,添加了Na2HPO4的Biohydrogenbacterium R3 sp.nov.的乙醇和乙酸产量分别为4841.49 mg·L-1和2064.94 mg·L-1;而添加了Na2CO3的氢气产量、氢气含量、细胞浓度与反应器内pH值分别为1064.42 mL、35.96%、1.23 g·L-1与3.81,此时乙醇、乙酸的产量分别为3862.21 mg·L-1和1930.86mg·L-1.

The effect of substrate concentration on biohydrogen production by using kinetic models

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.

Effects of various pretreatment methods on mixed microflora to enhance biohydrogen production from corn stover hydrolysate

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.

Optimization and modeling of biohydrogen production by mixed bacterial cultures from raw cassava starch

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.

Monitoring of microbial community structure and succession in the biohydrogen production reactor by denaturing gradient gel electrophoresis(DGGE)

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.

Enhanced biohydrogen generation from organic wastewater containing NH^(+)_(4)by phototrophic bacteria Rhodobacter sphaeroides AR-3

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.

Biohydrogen production and its bioeconomic impact:a review

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.

Pore-scale lattice Boltzmann simulation of flow and mass transfer in bioreactor with an immobilized granule for biohydrogen production

The photo bioreaction combined with flow and mass transfer is simulated with pore-scale lattice Boltzmann （LB） method, which is the scenario of a bioreactor filled with a porous granule immobilized photosynthetic bacteria cells for hydrogen production. The quartet structure generation set （QSGS） is used to generate porous structure of the immobilized granule. The effects of porosity of the immobilized granule on flow and concentration fields as well as the hydrogen production performance are investi- gated. Higher porosity facilitates the substrate solution smoothly flowing through the porous granule with increasing velocity, and thus results in higher product concentration inside the immobilized gran- ule. Additionally, the substrate consumption efficiency increases, while hydrogen yield slightly decreases with increasing porosity, and they tend to stable for the porosity larger than 0.5. Furthermore, the LB numerical results have a good agreement with the experimental results. It is demonstrated that the pore-scale LB simulation method coupling with QSGS is available to simulate the photo hydrogen produc- tion in the hioreactor with porous immobilized granules.

Effects of various pretreatments on biohydrogen production from sewage sludge

The sewage sludge of wastewater treatment plant is a kind of biomass which contains many organics, mainly carbohydrates and proteins. Four pretreatments, acid pretreatment, alkaline pretreatment, thermal pretreatment and ultrasonic pretreatment, were used to enhance biohydrogen production from sewage sludge. The experimental results showed that the four pretreatments could all increase the soluble chemical oxygen demand (SCOD) of sludge and decrease the dry solid (DS) and volatile solid (VS) because the pretreatments could disrupt the floc structure and even the microbial cells of sludge. The results of batch anaerobic fermentation experiments demonstrated that all of the four pretreatments could select hydrogen-producing microorganisms from the microflora of sludge and enhance the hydrogen production. The hydrogen yield of the alkaline pretreated sludge at initial pH of 11.5 was the maximal (11.68 mL H2/g VS) and that of the thermal pretreated sludge was the next (8.62 mL H2/g VS). The result showed that the hydrogen yield of pretreated sludge was correlative with its SCOD. The hydrogen yields of acid pretreated sludge and alkaline pretreated sludge were also influenced by their initial pH. No methane could be detected in the anaerobic fermentation of alkaline pretreated sludge and thermal pretreated sludge, which suggested that these pretreatments could fully inhibit the activity of methanogens. The volatile fatty acids (VFA) production in anaerobic fermentation of alkaline pre- treated sludge was the maximum and the next is that of thermal pretreated sludge.

Deep eutectic solvents:Green multi-task agents for sustainable super green hydrogen technologies

While reliance on renewable energy resources has become a reality, there is still a need to deploy greener and more sustainable methods in order to achieve sustainable development goals. Indeed, green hydrogen is currently believed to be a reliable solution for global warming and the pollution challenges arising from fossil fuels, making it the resilient fuel of the future. However, the sustainability of green hydrogen technologies is yet to be achieved. In this context, generation of green hydrogen with the aid of deep eutectic solvents(DESs) as green mixtures has been demonstrated as a promising research area. This systematic review article covers green hydrogen generation through water splitting and biomass fermentation when DESs are utilized within the generation process. It also discusses the incorporation of DESs in fuel cell technologies. DESs can play a variety of roles such as solvent, electrolyte, or precursor;colloidal suspension and reaction medium;galvanic replacement, shape-controlling, decoration, or extractive agent;finally oxidant. These roles are relevant to several methods of green hydrogen generation, including electrocatalysis, photocatalysis, and fermentation. As such, it is of utmost importance to screen potential DES formulations and determine how they can function in and contribute throughout the green hydrogen mobility stages. The realization of super green hydrogen generation stands out as a pivotal milestone in our journey towards achieving a more sustainable form of development;DESs have great potential in making this milestone achievable. Overall, incorporating DESs in hydrogen generation constitutes a promising research area and offers potential scalability for green hydrogen production, storage,transport, and utilization.

生物制氢原理及研究进展

主要综述了光解水、光发酵、暗发酵、暗-光发酵耦合等生物制氢技术,分析各方法的产氢机制、工艺优劣、影响因素和研究现状等,同时对比了生物制氢反应器的类型与特点。结果表明:生物制氢在低品位能源处理与高级能源生产方面具有巨大潜力。最后,给出了目前生物制氢技术的发展建议。