Isolation And Identification Of A Stain Of Photosynthetic Bacteria

Because of energy crisis, more and more countries try to exploit alternative energy. Hydrogen is considered as a potential substitute for fossil fuels because of clean, efficiency and reproduction. Bio-hydrogen is considered more environmental friendly and less energy intensive compared to thermochemical and electrochemical processes. Photosynthetic bacteria can utilize small molecular organic acid compounds to produce hydrogen and play an important role in bio-hydrogen technology.Isolation of photosynthetic bacteria is a necessary component in bio-hydrogen process. Traditional anaerobic techniques such as Hungate technique and anaerobic plate were complicate in operation. In this study anaerobic plate was modified and improved. We have developed a more efficient way named "sandwich plate" (solid culture medium-agar-paraffin wax) to isolation photosynthetic bacteria.Firstly, in the past studies malic acid was the carbon source and hydrogen donor in an enrichment medium. In this study, acetic acid, which is the chief constituent of organic wastewater, was selected to replace malic acid. By this way, photosynthetic hydrogen-producing microflora was obtained from NO 1 bathing beach in Qingdao. The experiment results showed that:the hydrogen production yield was from 20.9ml/100ml culture-102.7ml/100ml culture, and the substrate conversion efficiency was 42.71%-19.07% on the condition of 30℃,4000Lx,initial pH8.0,5mM/L-45mM/L (acetate concentration); Secondly,11 photosynthetic bacteria were isolated from photosynthetic hydrogen-producing microflora using a new isolation method. A purple sulfur bacterium strain QD-10 which contains bacteriochlorophyll a with absorption at 830nm has been investigated systematically. According to physiological and biochemical characteristics and phylogenetic analysis of the 16S rRNA gene sequences.(GenBank accession number FJ605318),the strain QD-10 was identified Marichromatium genus. However, It can grow in 1-7% NaCl and 15℃-40℃, use citrate as carbon and energy source, shows it is different from species of Marichromatium purpuratum. So it may be a new strain; The last, the strain QD-10 was able to utilize the fermentation waste of pantoea agglomerans. The concentration of organic acids decreased obviously after culturing with QD-10.In summary, many valuable photosynthetic bacteria strains and photosynthetic hydrogen-producing microflora were isolated. The hydrogen production condition of photosynthetic hydrogen-producing microflora was optimized. The experiment results showed that when the fermentation waste was treated by photosynthetic Bacteria, the concentration of organic acids in the fermentation waste was significant decreased. The result provides valuable information in further study of biological treatment of marine organic wastewater.