Effect Of Amino Acids On Photosynthetic Biohydrogen Production From Corn Straw

This paper was financed by the project of National Natural Science Foundation of China entitled "Regulation mechanism and energy cascade coupling characteristics of two-step biological hydrogen production by dark light"(Project No.51676065)and "Enhancement mechanism of photobiochemical hydrogen production by straw based on active disturbance and characteristics of photothermal mass transfer"(Project No.51806061).As a clean and pollution-free renewable energy,hydrogen energy has been paid more and more attention.Photosynthetic biohydrogen production technology can convert biomass such as straw into hydrogen energy,combine the consumption of organic wastes with the production of clean energy,and solve the energy and environmental problems.The specific hydrogen production,hydrogen production rate,energy conversion efficiency,pH value,redox potential value,reducing sugar content and liquid end products of hydrogen-producing fermentation broth were analyzed using corn straw as hydrogen-producing material.The effects of L-cysteine,L-alanine,L-leucine,L-serine and L-threonine on Photosynthetic biohydrogen production were studied to obtain the best results.The optimum hydrogen production conditions can provide references for improving the hydrogen production capacity and process optimization of photosynthetic organisms of corn straw.Amino acid additives have obvious effects on Photosynthetic biohydrogen production.Amino acid additives can increase the specific hydrogen production and hydrogen production rate of photosynthetic biohydrogen production in an appropriate concentration range.when the concentrations of L-cysteine,L-alanine,L-leucine,L-serine and L-threonine were 0.6,0.6,0.9,1.5 and 0.6 g/L respectively,the maximum hydrogen production of photosynthetic organisms was(54.4±0.75)mL/g,(52±0.61)mL/g,(51.4 ±0.65)mL/g,(49.6±0.39)mL/g,(48.6±0.55)mL/g,which were 45%,37.04%higher than that of the control group,respectively.43%,32.62%and 29.95%respectively,and the maximum hydrogen production rates were(48±0.23)mL/g h L,(45±0.33)mL/g h L,(45 ± 0.32)mL/g h L,(42 ± 0.35)mL/g h L,(45 ± 0.32)mL/g h L,respectively.The fitting results were in good agreement with the experimental results through the analysis of hydrogen production kinetics.In addition,the energy conversion efficiency of the five amino acids reached the maximum at the optimum concentration,which were 3.76 ±0.04%,3.59 ±0.04%,3.43±0.03%,3.36±0.0 7%and 3.55±0.05%.In addition,amino acid additives can reduce the pH value of hydrogen-producing fermentation broth,and the addition of amino acids for L-cysteine,L-serine fermentation broth is more obvious.The redox potential of fermentation broth decreases with the increase of L-cysteine concentration,while the effects of L-alanine,L-leucine,L-serine and L-threonine on the redox potential of fermentation broth are not obvious.The reducing sugar content of fermentation broth increased with the increase of L-cysteine concentration,while the initial reducing sugar content could be increased with the low concentration of L-alanine,L-leucine,L-serine and L-threonine,but the high concentration had little effect on the initial reducing sugar content.Amino acid additives had little effect on the pH value,redox potential and reducing sugar content of fermentation broth during the whole photosynthetic hydrogen production process.The content of volatile fatty acids,such as hydroacetic acid,propionic acid and butyric acid,can be increased by appropriate concentration of amino acids.L-cysteine,L-alanine and L-leucine are more effective than L-serine and L-threonine in promoting the production of volatile fatty acids.In conclusion,L-cysteine is superior to L-alanine,L-leucine,L-serine and L-threonine in promoting the photosynthetic biohydrogen production and influencing the fermentation broth.