Continuous hydrogen production of auto-aggregative Ethanoligenens harbinense YUAN-3 in a continuous stirred-tank reactor

A continuous hydrogen production was performed in a continuous stirred-tank reactor by auto-aggregative Ethanoligenens harbinense YUAN-3 under non-sterile conditions. Pure strain YUAN-3 was inoculated into the reactor using glucose as substrate. Bacterial diversity was detected by denaturing gradient gel electrophoresis based on V3 region of 16S rRNA genes. Cells number of strain YUAN-3 was monitored in reactors and effluent by real-time PCR. During 21 days of the continuous operation, cell flocs formed quickly by aggregation in reactor. H₂ yield reached the highest 1.93 mol/ mol-glucose at a dilution rate of 0.4 h^-1, and H₂ production rate reached the highest 32.2 mmol H₂/L-medium·h at a dilution rate of 0.5h^-1. The overflow rate was less than 0.1%, a lot of strain YUAN-3 retained in bioreactor over all. In addition, some bacterial invaders appeared during continuous operation, and formed a stable community with YUAN-3. Dominant populations in continuous-flow reactor were affiliated with Firmicutes and Bacteroides, and the majority of dominant populations belonged to Ethanoligenens harbinense. The above results demonstrated that autoaggregative bacteria could accomplish a continuous hydrogen production.