Bacterial Operational Taxonomic Units Replace the Interactive Roles of Other Operational Taxonomic Units Under Strong Environmental Changes

Abstract

Background: Microorganisms are an important component of an aquatic ecosystem and play a critical role in the biogeochemical cycle which influences the circulation of the materials and maintains the balance in aquatic ecosystems.

Objective: The seasonal variation along with the impact of anthropogenic activities, water quality, bacterial community composition and dynamics in the Loktak Lake, the largest freshwater lake of North East India, located in the Indo-Burma hotspot region was assessed during post-monsoon and winter season through metagenome analysis.

Methods: Five soil samples were collected during Post-monsoon and winter season from the Loktak Lake that had undergone different anthropogenic impacts. The metagenomic DNA of the soil samples was extracted using commercial metagenomic DNA extraction kits following the manufacturer's instruction. The extracted DNA was used to prepare the NGS library and sequenced in the Illumina MiSeq platform.

Results: Metagenomics analysis reveals Proteobacteria as the predominant community followed by Acidobacteria and Actinobacteria. The presence of these groups of bacteria indicates nitrogen fixation, oxidation of iron, sulfur, methane, and source of novel antibiotic candidates. The bacterial members belonging to different groups were involved in various biogeochemical processes, including fixation of carbon and nitrogen, producing streptomycin, gramicidin and perform oxidation of sulfur, sulfide, ammonia, and methane.

Conclusion: The outcome of this study provides a valuable dataset representing a seasonal profile across various land use and analysis, targeting at establishing an understanding of how the microbial communities vary across the land use and the role of keystone taxa. The findings may contribute to searches for microbial bio-indicators as biodiversity markers for improving the aquatic ecosystem of the Loktak Lake.

Keywords: Wetlands; bio-indicators; biogeochemical; keystone; land use; metagenomics; microbial diversity.

Fig. (1)

Study map and sampling sites in the Loktak Lake. (A higher resolution / colour version of this figure is available in the electronic copy of the article).

Fig. (2)

Bacterial community taxonomic structure at phylum level in relation to physicochemical variables. (A higher resolution / colour version of this figure is available in the electronic copy of the article).

Fig. (3)

Co-occurrence microbial interaction sub-network from Post-monsoon season. Blue squared nodes correspond to physicochemical parameters and circle notes correspond to OTUs. The green and red edges represent positive correlation and negative correlation respectively. Physicochemical parameters represent as pH; power of hydrogen, BOD; Biological Oxygen Demand, Ca; Calcium, COD; Chemical Oxygen Demand, Cl; Chlorine, DO; Dissolved oxygen, MoA; Methyl Orange Alkalinity, Mg; Magnesium, SA; Salinity, TDS; Total Dissolved Solids, TH; Total Hardness, Tm; Temperature, TSS; Total Suspended Solids. (A higher resolution / colour version of this figure is available in the electronic copy of the article).

Fig. (4)

Co-occurrence microbial interaction sub-network from winter season. Blue squared nodes correspond to physicochemical parameters and circle notes correspond to OTUs. The green and red edges represent positive correlation and negative correlation respectively. Physicochemical parameters represent as pH; power of hydrogen, BOD; Biological Oxygen Demand, Ca; Calcium, COD; Chemical Oxygen Demand, Cl; Chlorine, DO; Dissolved oxygen, MoA; Methyl Orange Alkalinity, Mg; Magnesium, SA; Salinity, TDS; Total Dissolved Solids, TH; Total Hardness, Tm; Temperature, TSS; Total Suspended Solids. (A higher resolution / colour version of this figure is available in the electronic copy of the article).

Fig. (5)

Heat-map of microbial community composition with cluster analysis. A, post-monsoon, B, winter. The color variation in each panel shows the percentage in a sample, referring to color key at the top. (A higher resolution / colour version of this figure is available in the electronic copy of the article).

Fig. (6)

Species accumulation and rarefaction curves. A, post-monsoon, B, winter. (A higher resolution / colour version of this figure is available in the electronic copy of the article).