Anti-fouling poly(lactic)acid membrane incorporating titanium dioxide‐coated biochar composites for the separation of lipopeptides from Bacillus subtilis fermentation broth

Abstract

This study focuses on developing anti-fouling membranes composed of poly(lactic)acid (PLA) incorporating titanium dioxide-coated biochar composites, aiming to separate the lipopeptide biosurfactants from clarified Bacillus subtilis fermentation broth efficiently. The surface area of the Ti-biochar composites, incorporated into the PLA membrane, was measured as 191.69 m2/g and the water contact angle of the optimal PLA/Ti-biochar membrane was determined to be 62.3°, indicating its hydrophilic nature. The PLA membrane's pure water flux, containing 1 wt % Ti-biochar was 174.61±0.5 L m–2h–1 with the water content of 86.73±0.8 %, and porosity of 44.72±0.3 %. Then, Bacillus subtilis lipopeptides were separated by the optimal PLA/Ti-biochar membrane, and their characteristics were compared to the crude sample. Additionally, the purified lipopeptides demonstrated enhanced antimicrobial properties, with a significantly lower minimum inhibitory concentration (MIC) of 1.7±0.52 µg/ml against Staphylococcus aureus and 1.5±0.24 µg/ml against Fusarium oxysporum, compared to the crude lipopeptides, which had MIC values of 5.5±0.26 µg/ml and 4.2 ±0.45 µg/ml, respectively. The purified lipopeptides were confirmed by high-performance liquid chromatography and mass spectrometry. These results underscore the antifouling characteristics of the fabricated PLA/Ti-biochar membrane, positioning it as a promising candidate for the separation of biological molecules.