Impact of selectively enriched microbial communities on long-term fermentative biohydrogen production

Abstract

The effect of selectively enriched inoculum for biohydrogen production and shifts in microbial communities was observed using anaerobic sequencing batch reactor (AnSBR). Significantly, combined pretreatment using acid and iodopropane resulted 3 fold increase in H₂ production (8.65mol/kgCOD_R) over untreated control (2.63mol/kgCOD_R). Pretreatment showed significant shifts in the microbial communities which are thus accounted for enhanced H₂ production. The high-throughput pyrosequence analysis depicted shifts in phylum Firmicutes and Proteobacteria. In the case of Proteobacteria, there was an increase in Betaproteobacterial, decrease in Epsilonproteobacterial and compositional variation in Alphaproteobacterial species. The decreased OTU number after pretreatment indicate, reduction of undesirable microbial populations while favouring conditions for microbiome that are involved in acidogenic, acetogenic and H₂ production.

Keywords: Acid-shock; Biohydrogen production; Microbial dynamics; Pyrosequence analysis; Volatile fatty acids (VFA).