Evaluating the influence of Bacillus spp. mediated growth enhancement and antioxidative defence activation in Mentha piperita L

Peppermint ( Mentha piperita L.) is a valuable medicinal and aromatic herb cultivated globally for its essential oil, prized for therapeutic and flavoring properties. Despite increasing global demand projected to rise from USD 230.3 million in 2024 to USD 444.6 million by 2034, its cultivation remains limited due to comparatively lower herb and oil yields than menthol mint ( Mentha arvensis L.). To address this, the present study evaluated the plant growth-promoting potential of rhizobacteria isolated from the menthofuran-rich peppermint variety CIM-Patra, endowed with phosphate solubilization, ammonia production, siderophore production, and Indole acetic acid production efficiencies. The surface sterilized, uniform sized suckers of a menthol-rich peppermint variety CIM-Suras were inoculated with five isolated PGPRs as Bacillus tequilensis (T1), Bacillus subtilis (T2), Bacterium strain BS0393 (T3), Bacillus thuringiensis (T4), and Bacillus cereus (T5), in triplicate manner. The results of the study revealed that T2 ( Bacillus subtilis ) showed maximum improvement in almost all the studied morphological, physiological, and biochemical parameters, followed by T1 ( Bacillus tequilensis ), and T4 ( Bacillus thuringiensis ). The application T2 with the suckers of CIM-Suras depicted to significantly improve the photosynthetic process, contents of chlorophyll (64.71%), accumulation of proline (43.17%), SOD (24.89%), and catalase (56.33%), over the control, in peppermint suggests the potential of the isolate to abdate the oxidative damage of the cells during altering environmental conditions. These findings underscore the significance of the administration of Bacillus spp. based PGPRs as a sustainable approach to escalate the peppermint cultivation through a climate-conscious solution.