Bio-augmentation of S2- oxidation for a heavily polluted river by a mixed culture microbial consortium

Abstract The balance of inorganic sulfur redox in heavily polluted rivers could be disrupted, making sulfur reduction a major metabolic pathway regulated by sulfate reducing bacterium (SRB), leading to massive accumulation of S2- and blackening of water bodies. In order to promote S2- oxidation, mixed culture with Citrobacter sp., Ochrobactrum sp. and Stenotrophomonas sp. was used to active native sulfur oxidizing bacterium (SOB) to augment S2- oxidizing process. The results demonstrated that mixed culture microbial consortium had significant sulfur oxidation effect, with 98% of S2- removal efficiency within 50 h. The sulfur chemical forms varied greatly with mixed culture bio-augmentation, and all the sulfides’ species were finally oxidized to SO42-. The mechanism involved was revealed using high throughput sequencing analysis. The microbial diversity indicated that mixed culture could stimulate and simplify the community structure, enabling native microorganisms cope with the sulfides change. Some microorganisms (family level) including Flavobacteriaceae, Enterococcaceae, Sphingomonadaceae, Cryomorphaceae, Rhodobacteraceae, Campylobacteraceae, Burkholderiaceae, Comamonadaceae, Alcaligenaceae, Methylophilaceae, Bacteriovoracaceae and Caulobacteraceae were thought to be associated with sulfides metabolism and their abundance appeared significant difference in two treatments. Further pearson correlation analysis was performed to determine the role played by different strains at different times. This work demonstrated that the mixed culture might have the potential to be used to promote S2- oxidation and clarify water in the heavily polluted rivers.