Extremophiles as Novel Bioinoculants for Improving Crop Tolerance to Drought and Salinity: Implications for Global Food Security

Drought and soil salinity are major environmental stresses that significantly reduce crop productivity worldwide, and their effects are expected to increase under climate change. Conventional approaches, including breeding stress-tolerant varieties and applying chemical amendments, often face limitations related to cost, time, and environmental sustainability. Extremophilic microorganisms, naturally adapted to harsh environments such as saline soils, deserts, hot springs, and polar regions, have emerged as promising bioinoculants for sustainable agriculture. These microorganisms enhance plant tolerance to drought and salinity through mechanisms such as exopolysaccharide production, ACC deaminase activity, osmolyte accumulation, antioxidant stimulation, and phytohormone synthesis. As a result, they improve plant growth, nutrient uptake, water-use efficiency, and stress resilience. This review highlights the role of halophilic, xerophilic, desert-associated, and polar-adapted plant growth-promoting microorganisms in mitigating abiotic stress. It also discusses current challenges, including inoculant stability, field performance variability, and regulatory issues. Overall, extremophile-based bioinoculants offer an ecofriendly and cost-effective strategy for enhancing climate-resilient agriculture and global food security. Keywords: extremophiles; bioinoculants; drought tolerance; salinity stress; plant growth-promoting rhizobacteria (PGPR); halophiles; sustainable agriculture; food security