Fractionation and Chemical Characterization of Cell-Bound Biosurfactants Produced by a Novel Limosilactobacillus fermentum Strain via Cheese Whey Valorization

Lactic acid bacteria (LAB) have attracted scientific attention as potential producers of biosurfactants (BS); however, there is limited knowledge on the structure of the produced molecules. The aim of this study was to elucidate the individual components comprising the crude BS produced by <i>Limosilactobacillus fermentum</i> ACA-DC 0183. Initially, batch fermentations using substrate recycling were employed, leading to the production of 0.76 g/L of crude BS from cheese whey as the sole carbon and nutrient source. The produced BS maintained their properties under various temperatures, pH values, and salinity levels, signifying their potential uses in food applications. Additionally, the structural components were analyzed after hydrolysis. The lipoic part was mainly composed of palmitic acid, oleic acid, and stearic acid, while 17 amino acids were identified as part of the protein moiety of the molecule. Acid hydrolysis of the carbohydrate moiety revealed that this part consisted of glucose, galactose, and glycerol. Partial purification with column chromatography and characterization using FTIR demonstrated the presence of a glycoprotein and a glycolipid as surface-active molecules. Revealing the structure and specific properties of microbially produced BS can expand their utilization in target applications, while their production from renewable sources contributes towards the sustainable production of LAB-based BS.