5-12: Characterization of butyrate-producing microbial community using Laminaria

The enrichment culture with brown algae, Laminaria, was performed using the tidal flat sediment from Ganghwa Island, South Korea as an inoculum. The fermentation behaviors and microbial community of the enrichment culture were investigated using pyrosequencing. During the initial phase (1~2 days), the biogas production was observed and the concentration of ethanol, acetate, and butyrate was low. At day 3, the concentration of products was greatly increased: the gas production was almost doubled (20.1 mL_gas/mL_culture to 36.5 mL_gas/mL_culture) and the concentration of ethanol (0.93 g/L to 1.34 g/L), acetate (0.80 g/L to 1.68 g/L) and butyrate (0.27 g/L to 1.39 g/L) was increased. The gas production and the concentration of ethanol did not change much after 3 days, while the concentrations of acetic acid and butyric acid were greatly increased at day 4. The concentration of acetic acid and butyric acid showed different trends after day 4: the concentration of acetic acid was gradually decreased, while the concentration of the butyric acid was gradually increased up to 4.14 g/L after day 4. The microbial community was changed very dramatically, but only one or two genera were dominant in the microbial community of the samples. The genus Vibrio and Propionigenium were dominant at day 1. At day 2, the genus Vibrio and Clostridium became most dominant. The proportion of Clostridium and products were increased at day 3. The Clostridium was single dominant genus at day 4, although proportion of Clostridium was reduced.