Exploring the therapeutic potential of Bacillus flexus and Bacillus pumilus from Kathkie Caves, Jammu: Antimicrobial efficacy and cytotoxicity against HEK-293 Cells

Abstract

This study explores the cytotoxic and antimicrobial activities of bacterial isolates Bacillus flexus and Bacillus pumilus from Kathkie caves in district Kishtwar of Jammu, India. Cytotoxicity was evaluated using the MTT assay on HEK-293 human embryonic kidney cells, revealing that Bacillus flexus exhibited significant cytotoxicity with an IC50 of 25.77 ± 2.50 µg/mL, while Bacillus pumilus showed moderate cytotoxicity with an IC50 of 65.22 ± 1.40 µg/mL. Both isolates demonstrated notable antimicrobial activity against various human and animal pathogens. Specifically, Bacillus flexus inhibited the growth of Klebsiella spp. (19.6 mm), Streptococcus spp. (20.6 mm), Staphylococcus spp. (22.0 mm), and Escherichia coli (22.3 mm). Meanwhile, Bacillus pumilus inhibited Pseudomonas spp. (23.0 mm), Klebsiella spp. (8.3 mm), Streptococcus spp. (22.0 mm), and Klebsiella pneumoniae (21.6 mm). The observed antimicrobial spectrum suggests these isolates are promising sources of new antimicrobial agents. The high cytotoxicity of Bacillus flexus indicates potential therapeutic challenges, while the relatively lower cytotoxicity of Bacillus pumilus suggests a safer profile, making it a viable candidate for further development. This study contributes to the understanding of the bioactive potential of these isolates, offering insights into their possible applications in biotechnology and medicine.