Profiling of microbial community during in situ remediation of volatile sulfide compounds in river sediment with nitrate by high throughput sequencing

Abstract

The physiological profiling on community level and analysis of 16S rRNA V6 tag based on high throughput sequencing were used to characterize and to compare microbial community structure, diversity, and bacterial phylogeny from sediments before and after remediation with the help of nitrate. The experiment was conducted in situ within a heavily polluted river located in the south of China. Total 2900 m2 area of sediment were selected on river bed for in situ test. The results showed that about 86.5% of nitrate on average can be consumed within 14 days since injection into contaminated sediment in river and about 86.5% on average of the odor matters of AVS (acidic volatile sulfide) can be removed. It was found that the microbial community richness and diversity decreased during remediation process after nitrate injection due to overgrowth of functional bacteria and then revived on the 14th day nearly the end of remediation process. The most abundant phyla were Proteobacteria (44.10%), Firmicutes (7.22%) and Cloroflexi (6.70%) while 24.90% of the sequences were from bacterial domain. Proteobacteria were found significantly abundant in treated sediments on the 7th day, which were resulted from significant abundance of beta-proteobacteria, epsilon-proteobacteria and gamma-proteobacteria. On the contrary, Firmicutes, Cloroflexi, Actinobacteria and Deltaproteobacteria were significantly abundant in untreated sediments and in sediments after 14 days treatment. Microbial community in sediment before remediation was closely adapted to the sediment conditions with serious sulfide pollution. Injection of nitrate into sediment played multi-roles as stimulation of nitrate reducing bacteria (NRB), inhibition of sulfate reducing bacteria (SRB) as well as increase of oxidation-reduction potential (ORP).