| Abstract: | To study the structure of microbial communities in the biological hydrogen production 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 gradient
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. andEthanologenbacterium sp.), β-proteobacteria (Acidovorax sp.), γ-proteobacteria (Kluyvera sp.), Bacteroides (uncultured bacterium SJA-168), and Spirochaetes (uncultured eubacterium E1-K13), respectively. The hydrogen
production rate increased obviously with the increase ofEthanologenbacterium sp.,Clostridium sp. and uncultured Spirochaetes after 21 days, meanwhile the succession of ethanol type fermentation was formed. Throughout
the succession the microbial diversity increased however it decreased after 21 days. Some types ofClostridium sp.Acidovorax sp.,Kluyvera sp., and Bacteroides were dominant populations during all periods of time. These special populations were essential for the
construction of climax community. Hydrogen production efficiency was dependent on both hydrogen producing bacteria and other
populations. It implied that the cometabolism of microbial community played a great role of biohydrogen production in the
reactors. |
