Biosurfactants production by some Aspergilli species under solid state fermentation

Abstract

BIOSURFACTANTS are active secondary metabolites producing` by certain microorganisms that have the ability to reduce surface and interfacial tension. They have numerous advantages, such as high biodegradability, increased foaming, low toxicity and performance under challenging conditions. Current study was compared between the potential production of biosurfactant by A. carneus OQ152507, A. niger OQ195934 and A. fumigatus OQ195264 using solid state fermentation (SSF) as a low-cost alternative technology. These isolates were cultivated under SSF using different eight agricultural wastes to produce biosurfactants. The optimized bioprocess conditions for the maximum biosurfactant productivity were potato peels waste (20g/l) as a carbon source at 35ºC and pH 7 in glucose peptone medium for A. carneus OQ152507, sun flower seed shells (28g/l) at 35ºC and pH 7 in starch nitrate medium for A. niger OQ195934 and tea wastes (20g/l) at 30ºC and pH 6 in glucose peptone medium for A. fumigatus OQ195264. Their stability was observed at 120°C, 30g/l of NaCl and alkaline pH 10 for A. carneus and pH9 for A. niger and A. fumigatus biosurfactants. The biosurfactants were identified as glycolipid and phospholipids molecules by Phenol-H2 SO4 and phosphate test. GC-MS and FT-IR analysis confirmed that the tested fungi participate in producing three hydrophobic fatty acid chains: Cis-Vaccenic acid, n-Hexadecanoic acid and Hexadecanoic acid 2-hydroxy-1 (hydroxymethyl) ethyl ester in distinct peaks with the highest percentage area. While, each one has at least one specific biosurfactant moiety.