| Fermentation type for bio-hydrogen production can utilize organic wastewater and biomass to produce hydrogen which is clean and renewable.This technology has paid rising attention because it's environmentally friendly and sustainable.Biohydrogen and ethanol co-production is one of the main fermentation types.As is known to us,Ethanoligenens harbinense YUAN-3 is a mesophilic typical strain of hydrogen and ethanol co-production.It is dominate in efficiency hydrogen production,self-agglutination and acid resistance.There are still many problems remain unsolved for large-scale hydrogen production.The main difficulty is to establish efficient hydrogen-producing strains which can realize rapid start-up of reactors and bioaugmentation to directionally control operation.Revealing the interaction of microbial populations and mechanism between microorganisms and the interface will have great theoretical and practical significance for the development of efficient hydrogen-producing strains and large-scale hydrogen production.In our study,Fe3O4 magnetic nanoparticles were added into the co-culture system of Ethanoligenens harbinense couple with Pseudomonas aeruginosa PAO1 and mono-culture of Ethanoligenens harbinense to strengthen hydrogen and ethanol production.We analysed the effect of L-cysteine and carbon source concentration on the hydrogen and ethanol production.Finally,we compared the effects of different culture systems on hydrogen and ethanol production and developed the efficient hydrogen-producing system.In this study,co-culture PAO1 with YUAN-3 was cultivated under aerobic conditions without L-cysteine.The effect of Fe3O4 magnetic nanoparticles in the coculture condition,ranging from 0.5g/L to 1.5g/L,was studied on hydrogen and ethanol production.The maximum and hydrogen yield of 0.75 mol-H2/mol-glucose was detected at 0.5g/L Fe3O4 magnetic nanoparticles soaring 15.46% without Lcysteine.And ethanol concentration increased rapidly by 51.37% at 0.5g/L Fe3O4 magnetic nanoparticles,but low hydrogen production was attained.This result illustrated L-cysteine is necessary for hydrogen and ethanol production of YUAN-3.Next,the effect of L-cysteine and carbon source concentration on the co-culture system with the addition of Fe3O4 magnetic nanoparticles was investigated.The hydrogen yield increased with increasing Fe3O4 magnetic nanoparticles addition from 0.5 to 1.5 g/L under glucose supplementation of 15g/L,but the maximum hydrogen yield presented 7.13% enhancement because of the lack of carbon source.When increasing the glucose supplementation to 20g/L,a significant enhancement was realized at 0.5g/L Fe3O4 magnetic nanoparticles addition,which showed 10.23% improvement in hydrogen yield and 27.19% enhancement in ethanol concentration.Considering the effect of PAO1 for hydrogen production,we picked Fe3O4 magnetic nanoparticles into mono-culture system of E.harbinense YUAN-3.The hydrgon yield reached the highest at 0.5g/L Fe3O4 magnetic nanoparticles,experiencing 9.6% promotion compared to black test.Similarly,the molar ratio of ethanol to acetate and glucose utilization was obviously impoved.Compared with the different culture methods,it was found that the addition of Fe3O4 magnetic nanoparticles enhanced hydrogen production and ethanol metabolism.The significant improvement were confirmed when Fe3O4 magnetic nanoparticles were added into the co-culture system.The enhancement was obviously higher than the mono-culture system with the addition of Fe3O4 magnetic nanoparticles.The acetate concentration was lower on co-culture system with the addition of Fe3O4 magnetic nanoparticles in favour of hydrogen production.Under different culture conditions,the final p H of the fermentation increased when raising the addition of Fe3O4 magnetic nanoparticles.This result indicates that Fe3O4 magnetic nanoparticles can anesis the culture medium acidification.However,an increase addition of Fe3O4 magnetic nanoparticles can inhibit the bacteria proliferation,resulting in a decrease of biomass.According to the results,it can be drawn that the addition of Fe3O4 magnetic nanoparticles in the co-culture and monoculture can enhance hydrogen and ethanol production and improve utilization of high substrate concentration.It will provide a theoretical significance for rapid start-up of reactors and large-scale hydrogen production... |
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