Abstract. This work reports on the development of a psychrophilic and acidophilic sulfate-reducing bacterial (SRB) consortium from Arctic mine sediments and demonstrated to be successful in removing sulfate and metals at low temperature and acidic pH. The enriched inoculum at varying pH (3–7) and temperatures (15–37 °C), with repeated sub-culturing in three successive stages showed high abundance of psychrophilic SRB genera (Desulfiobacterium, Desulfosporosinus, Desulfurispora, Desulfoomaculum) and fermentative bacteria (Streptococcus, Anaerovora, Actinobacteria, Bifidobacterium, Bacteriodes and Enterococcus). There were three stages of microbial succession for sulfate reduction (85-88%), and metal removal (49-99.9%): initial co-fermentation of glycerol to acetic acid at acidic pH by Desulfosporosinus, Desulfotomaculum, Desulfurospora, and fermentative bacteria, oxidation of acetic acid to CO2 and H2 by Desulfitobacterium at neutral pH, and subsequent utilization of H2 by Desulfosporosinus. The intermediate, acetic acid (0.3–0.9 mM) inhibited the SRB activity and favored the fermentative bacteria upon sub-culturing the inoculum in subsequent stages at pH 3-4.5, resulting in lower sulfate reduction and greater acetic acid accumulation. This study provides the structural and functional properties of psychrophilic and acidophilic microbial communities, which is important for developing successful biological treatment of AMD in cold regions.
Keywords. Sulfate-reducing bacteria; acid mine drainage (AMD); psychrophile; extreme acidophile; sulfate removal; metal removal.
