Shift of microbial community structure by substrate level in dynamic membrane bioreactor for biohydrogen production

The aim of this study was to evaluate the feasibility of biological hydrogen production (BHP) in a dynamic membrane bioreactor. Hydraulic retention time (HRT) was varied from 1 to 12 hours, and the microbial communities were analyzed. The major hydrogen-producing bacterium wasClostridium chromiireducens, which was enriched up to 82% of the total bacteria with a 2 hour HRT, whileEnterobacter cloacaewas also observed in the range of 0.2% to 34.4% of total bacteria. When the level of the substrate in the reactor was low (<0.5 g/L), BHP dropped dramatically, andSporolactobacillus putidusincreased to 8.8% of the total bacteria. Differences in substrate affinity betweenS. putidusandC. chromiireducenslikely promoted the dominance ofS. putidus, which is more favorable for growth and metabolism at low substrate concentrations, and caused changes in the microbial community.

Automated summary

This study evaluated the feasibility of biological hydrogen production in a dynamic membrane bioreactor by varying the hydraulic retention time and analyzing the microbial communities. The dominance of hydrogen-producing bacteriumClostridium chromiireducensshifted with different HRTs, affecting the microbial community. Low substrate concentrations led to a dramatic drop in BHP and a shift in the microbial community towardsSporolactobacillus putidus.