Vol. 9, Issue 12, Part J (2025)

The present study aims to assess the functional properties and biological activities of lipopeptide mixtures produced by Bacillus methylotrophicus DCS1 strain and recovered from Landy medium during fermentation, after 24, 48 and 72 h. These lipopeptide mixtures are composed of different homologues and various isoforms, belonging to surfactin, iturin and fengycin families, identified in our previous study. The purpose of this research was to investigate some physicochemical properties and to test antibacterial, antifungal and antioxidant activities. Lipopeptide DCS1 solutions exert interesting functional properties such as their ability to reduce the surface tension of water down to low values with weak critical micelle concentration (CMC). The best surface tension reduction from 59.53 mN m^-1 (initial surface tension of water) to 30.1 mN m^-1, with a CMC value of 100 mg l^-1, was obtained with LP (48 h). All the LP mixtures are able to emulsify hydrocarbons but with different emulsification indexes, LP (72 h) exhibit the highest emulsifying activity with vegetable oil with an emulsification index of 47.5%. In addition, they are endowed with antibacterial and antifungal activities against several pathogenic microorganisms. A significant antagonistic activity was observed with LP (48 h) against Salmonella typhimurium and Fusarium solani. The different LP mixtures exhibit interesting antioxidant activities using DPPH radical-scavenging and β-carotene bleaching inhibition methods. The highest activity was observed with LP (72 h), the scavenging effect on DPPH radicals at a concentration of 2 mg ml^-1 was 86.27%. Moreover, LP (72 h) exhibited a strong inhibition of β-carotene bleaching by linoleic acid assay with almost 86% at 4 mg ml^-1 concentration. Therefore, these bioactive lipopeptide families mixtures, having a synergistic effect, could be potential for pharmaceutical purposes, cosmetic and food industries applications.