Screening strategies and production of biosurfactants (BSs)/bioemulsifiers (BEs) from marine yeasts and fungi

The unique characteristics of the marine ecosystem support the existence of microorganisms with exceptional metabolic potential, enabling them to produce high-value bioactives. Among these, biosurfactants (BSs) and bioemulsifiers (BEs) are notable multifaceted molecules, distinguished by their unique structural, molecular, and functional properties. Marine yeasts and fungi produce BSs/BEs with distinctive properties in terms of stability under extreme conditions. It is important to mention here that in comparison to marine bacteria, yeast and fungi of the same habitat have been explored only intermittently. Some of the BSs/BEs producing bacteria may prove to have some pathogenic or cytotoxic traits or components, while most yeasts are mainly classified as Generally Recognized As Safe (GRAS) (by the Food and Drug Administration-FDA, USA), making their BSs/BEs products more amenable for a wide range of applications. The diverse and unique potential of surface-active agents is further enhanced by the endosymbiotic associations often found in marine yeasts and fungi. These microorganisms are acknowledged to produce glycolipidic (rhamnolipids, sophorolipids, and mannosylerythritol lipids) or glycolipoproteins. The SL have been reported well for their strong antimicrobial activity, including effectiveness against drug-resistant pathogens, making them promising candidates for controlling foodborne pathogens in the food industry. Furthermore, these microorganisms can utilize a broad range of carbon sources from simple substrates, like glucose and glycerol, to complex feedstocks such as food, oil, agricultural waste, and wastewater, which not only support their growth but also promote the production of substantial yields of these BSs/BEs. In this review, we endeavor to explore BSs/BEs from marine yeasts and fungi, including the screening, characterization, identification, production, and importance.