Insights Into the Diversity of Terrestrial Soil Bacterial Communities Associated With Four Contrasting Köppen Climatic Zones.

Abstract Background: The multidirectional relationship between soil, its microbiota, and climate is crucial in modulating the bacterial community diversity and its survival in the terrestrial ecosystem. Therefore, it is imperative to understand the dynamics of soil bacterial communities thriving in geographical areas of varied climatic exposure. Results: The diversity of terrestrial soil bacterial communities thriving in four contrasting Köppen climatic zones of India was investigated for the first time using high-throughput sequencing. The results revealed that the bacterial species diversity, evenness and richness were highest in HSCZ (humid subtropical climatic zone). Firmicutes was the most abundant phylum in TWCZ (tropical wet climatic zone), ACZ (arid climatic zone), and HSCZ (humid subtropical climatic zone) while Proteobacteria in MCZ (Mountain climatic zone). 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. Correlation analysis showed that H’ (Shannon diversity) index, S (species richness), OTU abundance were positively correlated with moisture, TOC, K, MAP (mean annual precipitation) and negatively correlated with pH, Ca, N, B. Fe, P, Mg and MAT (mean annual temperature). Conclusion: This work mapped the occurrence and distribution of terrestrial soil bacterial communities in contrasting climatic zones that enabled us to assess the effect of climate in mentioned Köppen climatic zones on a taxonomic scale.