Exploring the Bacterial Diversity of Rajgir Hot Spring in India and its Antibacterial Potential.

Hot springs naturally produce geothermally heated water and are renowned for their diverse microbial communities. Metagenomics studies unveil this microbial diversity. In this study, the bacterial community, along with thermophilic actinobacteria from the Rajgir hot spring, located in Bihar, India, was analyzed using 16S rRNA gene metagenomics sequencing. The sediment temperature was recorded at 45 °C. Investigation of the hot spring ecology revealed the presence of 16 bacterial phyla, with actinobacteria being abundant. Streptomyces, Sphingomonas, Gemmatimonas, Paracoccus, Aeromicrobium, and Actinomyces were among the most common genera found in the sediment samples. These six genera exhibited the highest abundance, with Streptomyces being the most prevalent at 19%, followed by other genera at 13%, 11%, 11%, 10%, and 9%, respectively. Actinobacteria isolated from the hot spring samples were further examined for their antibacterial activities against pathogenic bacteria. Isolates from the Rajgir hot spring demonstrated potential antibacterial activity based on their inhibition zones on agar plates. The results of the antimicrobial screening revealed that AIBRSS1 exhibited the most significant inhibition zone, measuring 26 mm, against Listeria monocytogenes. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-025-01482-z.