Assessment of soil health and bacterial diversity across land-use gradients in the Pranmati basin, Himalayan Critical Zone

Abstract Soil microbes are essential for ecosystem functioning, affecting soil health and fertility. The microbial diversity present in soil is influenced by diverse land-use practices and environmental conditions; however, the effects on prokaryotic communities are not yet fully comprehended. This study investigates the physico-chemical parameters and cultivable bacteria present across four different landforms from natural (Forest land and Flood zone) and human managed (Agricultural and Polluted land) environments of Pranmati basin located in Chamoli district of Uttarakhand. The intricate relationship was established between biotic and abiotic factors with respect to varied land use types and providing further insight into local bacterial community indigenous to this region. Notably, six bacterial strains have been isolated and selected from the Pranmati basin’s diverse landforms, based on morphological identification and not on abundance basis and characterized through biochemical and antibiotic tests. The phylogenetic analysis revealed the isolated strains belonging to the phyla, Firmicutes and Pseudomonadota distributed into six genera on the basis of 16 S rRNA sequence similarity with reference sequences in databases: Bacillus (83.74%), Achromobacter (98.78%), Serratia (96.37%), Lysinibacillus (96.48%), Pseudomonas (95.18%) and Proteus (85.22%). Principal component analysis suggested positive correlation of all the abiotic factors where salinity, electric conductivity, total dissolved solids were the main drivers whereas bacterial count (CFU/ml) depicted weak negative correlation to PC1. The forest and agricultural land showed similar soil chemical properties and bacterial composition, whereas the flood zone formed a discrete group, representing variable microbial community structures. This study emphasizes the microbiological significance of the little-studied North-West Himalaya. These findings underscore the significance of comprehending the interaction between sustainable land management and microbial ecology to enhance soil fertility and health. Further, detailed soil microbiological studies are important before it gets changed due to environmental disturbances and climate change occurring in this region.