Sustainable Agriculture in a Changing Climate: Harnessing the Potentials of Extremophilic and Extremotolerant Microbes with Plant Growth-promoting Traits

Climate change and agriculture are intrinsically connected, with sudden changes in climatic conditions known to adversely impact global food production and security. With the world’s human population projected to reach 9.7 billion by 2050, there is increased pressure on agricultural land to meet the world’s food demand. However, climate change-linked abiotic stressors like drought and high temperatures already result in crop failure and food insecurity. There is an exigent need for climate-adapted sustainable agricultural practices to sustain food production. Among many options being pursued in this regard, utilising extremophiles as plant growth-promoting rhizobacteria (PGPR) and stress alleviators is gaining momentum due to their unique mechanisms at anatomical, physiological, biochemical, and molecular levels that cope with stresses associated with extreme environments, which can be used to promote stress resilience in crops. Therefore, this review critically assesses research evidence on plant growth and stress resilience promoting potentials of extremophiles as an approach to foster crop tolerance to climate change-induced stress, particularly drought. There is strong scientific evidence to suggest that thermophiles directly promote plant growth through processes, including nutrient fixation, enzyme and phytohormone production, mineral solubilisation, stress alleviation, and/or tolerance-induced differential gene expression. However, while the application of extremophiles holds great potential for sustainable food production, several technological, ethical, and ecological challenges limit their use in agriculture. Consequently, effective collaboration among scientific communities, policymakers, and regulatory agencies is needed to create strong frameworks that both promote and regulate the utilisation of agriculture.