Conversion of algal biomass to hydrogen by marine bacterial consortia

在当今社会面临的众多全球性环境问题中，温室效应是公认的最严重的问题之一。为了解决这一问题，微藻固定CO_2被认为是一种环境友好、节能的措施。然而，微藻系统产生大量的废弃生物质，这些废弃生物质很容易转化为CO_2。本研究建立了一个将固定CO_2的藻类生物质中积累的淀粉生物转化为H_2的系统，该系统是未来最有前途的能源之一。（2）从污水处理厂的活性污泥中筛选出2株具有降解淀粉和产氢能力的菌株，其中1株菌株在3%氯化钠溶液中表现出较强的降解淀粉的能力，另1株菌株在3%氯化钠溶液中表现出较强的产氢能力，其中1株菌株在3%氯化钠溶液中表现出较强的降解淀粉的能力。分别地，结果表明：（1）从该菌群中分离到的10株光合细菌中分离到的10株光合细菌中，有1株光合细菌和1株光合细菌组成的混合菌，其对淀粉的转化效率比上述菌株高;（2）混合菌能以较高的转化率和转化率利用淡水或海洋绿色藻类积累的淀粉生产H_2;（3）混合菌能以较高的转化率和转化率利用CO_2-固定化藻类生物质可直接转化为H_2，与以往报道的生物转化系统相比，该系统具有节能、简单等优点。

Among the many global environmental problems facing society today, greenhouse warming is widely recognized as one of the most serious.To address this problem, CO_2 fixation by microalgae is considered as an environmentally friendly, energy-saving measure.However, microalgal systems produce large amounts of waste biomass which would easily revert to CO_2.In this study, we attemped to develop a system in which starch accumulated in C0_2-fixing algal biomass is biologically converted to H_2, one of the most promising future energy mediai) A halotolerant bacterial consortium, which could directly convert starch to H_2, was selected from an activated sludge of a night soil treatment plant having a seawater dilution system.The consortia showed a strong ability to convert raw starch to H_2 in the presence of 3% sodium chloride.ii) Two different bacterial strains, which played roles in starch degradation and H_2 production from the degraded products, respectively, were isolated from the consortium and identified.iii) A pure mixed culture of known lactobacillus and photosynthetic bacterium showed more efficient conversion of raw starch to H_2 compared with the above bacterial consortium.iv) The pure mixed culture could produce H_2 from the algal starch accumulated in freshwater or marine green algae with high conversion yields and rates.We could demonstrate that C0_2-fixing algal biomass can be directly converted to H_2 by using bacterial consortium or mixed culture.This system will have the advantages of energy efficiency and simplicity compared with other biological conversion systems previously reported.