Isolation of a novel alkaline lipase producing fungus Aspergillus fumigatus MTCC 9657 from aged and crude rice bran oil and quantification by HPTLC

Abstract

Screening methods for the isolation of alkaline lipase producing fungi (acylglycerol hydrolases) from aged and crude rice bran oil and quantification of the Free Fatty Acid liberated (FFA) by the enzyme using HPTLC is discussed. Screening using rhodamine B detected lipase production as an orange halo around microbial colonies under UV light at 350 nm. Chromogenic plates incorporated with a lipidic substrate along with phenol red showed a sharp change in color from pink to yellow due to the presence of liberated fatty acids which was also an indication of lipase production. Media having pH in the range of 8.5 to 10.5 along with tributyrin substrate was used for screening an alkaline lipase producing isolate. The hydrolysis of tween opacity medium and production of an opaque halo in alkaline tributyrin agar plates confirmed the production of alkaline lipase by the isolated organism. The isolated fungus was identified as Aspergillus fumigatus MTCC 9657 from IMTECH, Chandigarh. There is no much information of alkaline lipase production by A fumigatus isolated from aged rice bran oil. Positional specificity of the isolated lipase was determined to be non specific by TLC and FTIR. Quantification of lipase activity of A fumigatus was carried out with the aid of High Performance Thin-layer Chromatography (HPTLC) which can detect even micro quantities of FFA produced and are rapid, efficient and easy-to use for simultaneous analysis. © 2011 Academic Journals Inc.