Stress-Induced Response and Adaptation Mechanisms in Bacillus licheniformis PSKA1 Exposed With Abiotic and Antibiotic Stresses

Soil ecosystems consist of diverse microbial communities with great potential for ecological and biotechnological applications. These communities encounter various abiotic stresses, which expedite the activation of transient overexpression of heat shock proteins (HSPs). In the present study, a soil bacterium was isolated and identified as Bacillus licheniformis strain PSK.A1, and its growth parameters were optimized before exposing it to heat, salt, pH, and antibiotic stress conditions. Comparative protein expression was analyzed using SDS-PAGE, protein stabilization via protein aggregation assays, and survival through single spot dilution and colony-counting methods under various stress conditions. The pre-treatment of short stress dosage showed endured overall tolerance of bacterium to lethal conditions, as evidenced by moderately enhanced total soluble intracellular protein content, better protein stabilization, comparatively over-expressed HSPs, and relatively enhanced cell survival. The findings highlighted that cells grown under optimal conditions were more susceptible to lethal environments than stressed cells, with their enhanced tolerance linked to the overexpression of 20 distinct HSPs of 17–91 kD. These insights offer the potential for developing strategies to enhance microbial resilience for various applications including bacterial bioprocessing, bio-remediation, and infectious disease management.