Unraveling microbial landscapes: high-throughput amplicon sequencing reveals distinct bacterial communities and potential health risks in potable springs of the Indian Himalayas.

Abstract

Spring water is a vital drinking resource for residents in the Eastern Himalayas' Sikkim, India. While our initial investigations into spring water quality highlighted concerning levels of fecal coliform bacteria, the bacterial community composition (BCC) of these springs remains largely unexplored. This study sought to elucidate the BCC of Himalayan spring water, exploring its effects on water quality and delving into the unique bacterial ecology of these high-altitude springs. Bacterial diversity was assessed using 16S rRNA gene amplicon (V3-V4) library sequencing. The Greengenes reference database facilitated the classification of de-novo assembled operational taxonomic units (OTUs). The findings of this study revealed Proteobacteria (39.78%), Planctomycetes (35.76%), Verrucomicrobia (32.65%), and Bacteroidetes (37.04%) as predominant phyla across the four major districts: East, West, South, and North. Additionally, distinct genera emerged as dominant in each district: Emticicia in the East, Prosthecobacter in the South, and Planctomyces in the North and West. Of potential health concern, pathogenic bacteria like Corynebacterium, Acinetobacter, Legionella, Mycobacterium, and Clostridium were detected, albeit in low abundance. Their presence, even in minor quantities, might indicate potential future health risks for the communities relying on these springs. However, a substantial portion of the bacterial sequence remained unidentified (> = 40.0%), showcasing no sequence similarity with the reference database. This intriguing "dark matter" in bacterial DNA hints at a potential treasure trove of yet-to-be-identified species. Future taxonomic profiling of these novel sequences may offer a deeper understanding of Himalayan springs' microbial makeup. Furthermore, these novel bacterial sequences will be instrumental in enhancing our global understanding of bacterial community structures and their ecological adaptations in high-altitude, low-temperature environments.