Impact of bioaugmentation on psychrophilic anaerobic digestion of corn straw

In order to investigate the mechanisms by which bioaugmentation affects psychrophilic anaerobic digestion (AD), this study introduced a psychrophilic methanogenic culture into the sequencing batch of psychrophilic AD systems. The findings demonstrated that bioaugmentation boosted the abundance of Smithella (790-2220%), Syntrophobacter (120-890%), and Methanothrix (25-43%) in the psychrophilic AD systems, accelerating acetate and propionate degradation and improving methane production (26%). Metagenomic analysis showed that bioaugmentation increased the relative abundance of genes related to propionate degradation and methane production, such as propionyl-CoA synthetase (45%) and acetyl-CoA synthetase (11%). At the cellular level, genes related to prevention of cell damage and promotion of membrane fluidity were upregulated. This study revealed the effect of bioaugmentation on microbial metabolic activities related to conversion of propionate to methane and cold tolerance in psychrophilic AD.