Abiotic Stress in Plants: Biosurfactants as Tools to Enhance Plant Resilience

With the intensification of agricultural activities, there has been a persistent release of pollutants into the environment such as metals, hydrocarbons, and pesticides, resulting in the degradation of natural cycles and the imposition of multiple abiotic stresses on plants. These conditions significantly compromise plant growth, productivity, and overall balance. In this context, microbial biosurfactants emerge as promising multifunctional agents, acting both in the bioremediation of contaminated environments and in promoting plant tolerance to adverse conditions. Produced by a wide variety of microorganisms, including bacteria and fungi, these amphiphilic molecules reduce surface and interfacial tension, enhancing the solubilization, mobilization, and bioavailability of contaminants and nutrients in complex ecosystems. These physicochemical properties confer a strategic role to biosurfactants in mitigating the phytotoxic effects caused by excessive levels of metals, persistent organic compounds, and high salinity, promoting a more favorable rhizospheric environment for plant development. Furthermore, recent evidence shows that biosurfactants can alter the structure and activity of plant-associated microbiota, stimulating colonization by plant growth-promoting microorganisms and participating in cellular signaling with the induction of defense responses. Such responses include the regulation of metabolic pathways associated with osmotic balance, antioxidant activity, and the expression of stress-responsive genes. Thus, the application of microbial biosurfactants represents an innovative, sustainable, and biologically integrated strategy to enhance plant resilience against abiotic stress conditions, while contributing to the rehabilitation of degraded environments. Advances in microbial biotechnology have enabled the optimization of production and structural characterization of these compounds, consolidating their applicability in sustainable agricultural and environmental systems, which will be explored in this chapter.