Glaciers cover a substantial portion of the world and are home to various biological populations. The Himalayas constitute the largest glaciated region outside the poles; hence, they are regarded as "The Third Pole" of the World. There are around 84 glaciers in the Teesta basin (Sikkim Himalaya). There is substantially less data available on the microbial diversity embedded in the glacial ice core samples of the Sikkim Himalaya, as well as their physico-chemistry and potential geomorphological hazards related to their retreat or decrease in snow-line cover. The present study aims to evaluate the microbial diversity in the glacier ice core region and the study area; therefore, two glaciers in the Sikkim Himalaya were chosen: Frey-Peak and Rathong Glacier. The bacterial diversity analysis reveals the prevalence of various phyla, including Pseudomonadota, Actinomycetota, Bacillota, and Bacteroidota. The random forest model reveals the significant contributions of various elements, including Na, Mg, K, Ca, and Zn, to the alpha diversity of the studied glaciers. Among physicochemical parameters, pH was found to contribute the most in shaping bacterial diversity. Cluster of Orthologous Groups (COG) analysis underscored a predominance of genes associated with amino acids (23.5%), carbohydrates (18.93%), lipids (10.88%), energy (17.26%), coenzymes (9.38%), and ion transport/metabolism (14.71%). KEGG (Kyoto Encyclopedia of Genes and Genomes) Orthology (KO) analysis revealed the presence of 4,915 to 96,954 genes. Interestingly, the metagenomic analysis revealed the presence of specific species of Bradyrhizobium, Beijerinckia, Burkholderia, and Corynebacterium, which are associated with nitrogen metabolism, suggesting their potential involvement in biogeochemical processes. Additionally, a total of 59 to 419 bacterial genes related to sulphur metabolism were deduced through the KEGG functional analysis. The study detected the presence of various antibiotic resistance genes corresponding to different classes of antibiotics, including aminoglycoside, tetracycline, fluoroquinolone, macrolide, and erythromycin. Network analysis reveals that antibiotic resistance genes primarily interact with the phyla Pseudomonadota, Bacillota, and Actinomycetota. The melting of glaciers, a significant effect of climate change, may release contaminants, antibiotic resistance genes, and pathogenic bacteria into free-flowing rivers, potentially impacting human health.
Tamang et al. (Mon,) studied this question.