Stress-induced proteins enhance thermal endurance in soil bacterium Priestia aryabhattai strain PSK.N2.

Soil microbial communities play vital roles in ecological stability and offer significant potential for biotechnological innovations. These microorganisms frequently encounter abiotic stressors such as heat, which can activate protective mechanisms including the overexpression of heat shock proteins (HSPs). In this study, a resilient soil bacterium, Priestia aryabhattai strain PSK.N2, was isolated from the Western Ghats of India and identified through a polyphasic approach. Growth parameters were optimized before subjecting the strain to heat stress, both alone and in the presence of sub-lethal concentrations of antibiotics that target distinct cellular processes; DNA replication, RNA transcription, protein synthesis, and cell wall biosynthesis. Comparative protein profiling (via SDS-PAGE), protein aggregation assays, and survival assessments (single spot dilution and CFU enumeration) revealed that heat-stressed cells showed enhanced thermal tolerance compared to those grown under optimal conditions. This increased endurance was associated with the transient overexpression of ~ 17-90 kDa stress-related proteins. In contrast, cells treated with transcription and translation-inhibiting antibiotics (rifampicin and chloramphenicol) showed diminished tolerance, likely due to impaired synthesis of stress-response proteins. These findings suggest that pre-exposure to stress enhances cellular preparedness through selective protein induction, offering insights for developing stress-resilient microbial strains for applications in bioprocessing, environmental remediation, and microbial therapeutics.