Spatially-ordered layer-by-layer biofilms of a two-species microbial consortium promote hydrogen production

Abstract

The low hydrogen production efficiency caused by volatile fatty acids stress is the main technical barrier in the field of biohydrogen production. To enhance the resistance to acid stress and improve the synergistic efficiency of hydrogen-producing bacteria, spatially-ordered layer-by-layer biofilms of a two-species microbial consortium, consisting of Bacillus cereus A1 and Brevumdimonas naejangsanensis B1, were developed. The results showed that the spatially-ordered biofilms (SBs) significantly improved the cooperation efficiency of the two strains, and the hydrogen production increased by 103.27% and 66.50% compared with suspended fermentation and mixed biofilms (MBs) fermentation, respectively. Furthermore, the mixed ratios of the two strains were further optimized, and the highest hydrogen accumulation of 1755 mL L−1 was obtained at the inoculation volume ratio of A1:B1 = 1:1. Finally, the biofilms were used for 5 repeat batches of fermentation, and the hydrogen production performance was stable, with an average hydrogen accumulation of 1736 mL L−1. This study proposed a layer-by-layer biofilm hydrogen production system based on the spatially ordered distribution of functional bacteria, which significantly improved the cooperation efficiency and stability of the two-species microbial consortium.