Abundance, community structure and diversity of nitrifying bacterial enrichments from low and high saline brackishwater environments

Abstract

The study reports diversity in nitrifying microbial enrichments from low (0·5–5‰) and high (18–35‰) saline ecosystems. Microbial community profiling of ammonia‐oxidizing bacteria (AOB) and nitrite‐oxidizing bacteria (NOB) enrichments was analysed by sequencing 16S rRNA and was processed using Mothur pipeline. The α‐diversity indices showed the richness of nitrifying bacterial consortia from the high saline environment and were clustering based on the source of the sample. AOB and NOB enrichments from both the environments showed diverse lineages of phyla distributed in both groups with 38 and 34 phyla from low saline and 53 and 40 phyla in high saline sources, respectively. At class level, α‐ and γ‐proteobacteria were found to be more dominant in both the enrichments. AOBs and NOBs in enrichments from low saline environments were dominated by Nitrosomonadaceae, Gallionellaceae (Nitrotoga sp.) and Ectothiorhodospiraceae and Nitrospira, respectively. Though Chromatiaceae were present in both AOB and NOB enrichments, Nitrosoglobus and Nitrosococcus dominated the AOBs while NOBs were dominated by uncultured genera, whereas Rhizobiales were found in both the enrichments. AOBs and NOBs in enrichments from high saline environments were dominated by Nitrospira‐like AOBs, Nitrosomonas and Nitrosococcus genera, whereas ammonia‐oxidizing archaea (AOA) group included Nitrosopumilus and Nitrososphaera genera comprising and Nitrospirae, respectively. The majority of the genera obtained in both the salinities were found to be either uncultured or unclassified groups. Results of the study suggest that the AOB and NOB consortia have unique and diverse microbes in each of the enrichments, capable of functioning in aquaculture systems practised at different salinities (0–60 ppt).

Ammonia-oxidizing archaea adapted better to the dark, alkaline oligotrophic karst cave than their bacterial counterparts

“…Similarly, IZ-W showed higher alpha diversity compared with other niches (Figure 1A). These findings suggest that environmental factors can influence the community composition and diversity of the AOA (Jin et al, 2011;Patil et al, 2021;Kou et al, 2023). The most abundant AOTU1 (Figures 2A) showed a negative correlation with TOC (Figure 6B), while the dominant OTU of AOB exhibited a positive correlation with TOC (Supplementary Figure S1).…”