Cleaner production of biosurfactants via bio-waste valorization: A comprehensive review of characteristics, challenges, and opportunities in bio-sector applications

Biosurfactants are a group of amphiphilic compounds biosynthesized by different animals, plants, and microbialbased resources. They possess surface-active properties such as emulsification, molecular self-assembly, and the reduction of surface/interfacial tension. This review aims to summarize green manufacturing of biosurfactants via bio-wastes valorization. Several environmental/nutritional factors influencing the production of biosurfactants (e.g., carbon sources, nitrogen sources, temperature, pH, and salts concentration) have been described. The superior physicochemical properties of biosurfactants make them interesting candidates for broad-scale applications, including bioremediation of hydrocarbons/heavy metals, agricultural formulations, and microbial enhanced oil recovery (MEOR). Over the previous decade, research on biosurfactants has substantially increased due to their environmentally friendly behavior and production capability using low-cost waste biomasses "green technology". However, the industrial-scale synthesis of biosurfactants faces several challenges that need to be addressed before considering commercialization. Herein, existing challenges and possibilities in bioprocessing applications of biosurfactants have been summarized to suggest future research recommendations. Tailored production of biosurfactants can broaden their scope for practical applications to realize the sustainable and circular bioeconomy.