Abstract:
AIMS : This study investigates the community structure and diversity of terrestrial soil bacterial communities thriving in
four contrasting Köppen climatic zones of India using high-throughput sequencing.
METHODOLOGY AND RESULTS : Soil samples were collected for metagenomic DNA isolation and PCR amplification using
primers targeting the 16S rRNA gene region. Amplicons were subjected to Oxford nanopore sequencing and data
analysis. Bacterial species diversity, evenness and richness were highest in a humid sub-tropical climatic zone (HSCZ).
Firmicutes were the most abundant phylum in the tropical wet climatic zone (TWCZ), arid climatic zone (ACZ) and humid
sub-tropical climatic zone (HSCZ), while Proteobacteria in the mountain climatic zone (MCZ). The predominance of class
Alphaproteobacteria, Actinobacteria with genera Bradyrhizobium, Chthoniobacter and Mycobacterium, was observed in
MCZ in contrast to class Bacilli with genera Bacillus and Paenibacillus in the rest of the zones. OTU abundance was
positively correlated with moisture, TOC (total organic carbon), K, MAP (mean annual precipitation) and negatively
correlated with pH, Ca, N, B, Fe, P, Mg and MAT (mean annual temperature). A significant correlation was only
observed with Fe against Shannon diversity (H’) in multiple regression analysis.
CONCLUSION, SIGNIFICANCE AND IMPACT OF STUDY : The multidirectional relationship between soil, its microbiota and
climate is crucial in modulating bacterial community diversity and its survival in terrestrial ecosystems that significantly
contribute to ecosystem function. This work mapped the occurrence and distribution of terrestrial soil bacterial
communities in contrasting climatic zones for the first time, enabling us to assess the effect of climate in the mentioned
Köppen climatic zones.
