Characterization of new yeast lipases

Abstract

AbstractPreviously, we used a simple, sensitive agar plate method to screen lipase activity from 1229 selected cultures, including 508 bacteria, 479 yeasts, 230 actinomycetes and 12 fungi, that covered many genera and species. About 25% of the cultures tested were lipase‐positive. We also expanded our screening method to focus specifically on the pH dependence and thermostability of these lipase activities. In this report, we have characterized 25 yeast lipases, obtained from our screening program, on the basis of their positional specificity against triglycerides. Lipase was produced by growing cultures on nutrient medium in the presence of vegetable oil at 25°C for 4 d. Of the 25 new yeast lipases analyzed, 19 showed 1,3‐positional specificity and 6 showed random specificity. No 2‐positional specific lipases were found. Among those cultures with highest lipase activity are: Candida silvicola NRRL YB‐2846 (random); Candida sp. 55 (random); Candida sp. 125 (random); Pichia americana NRRL Y‐2156 (1,3‐specific); P. muscicola NRRL Y‐7005 (random); P. petersanii NRRL YB‐3808 (1,3‐specific); and Yarrowia lipolytica NRRL YB‐423 (random). Characterization of Candida sp. strain 55 lipase on its substrate preference showed that this enzyme hydrolyzed soybean oil triglyceride species LLLn, LLL, LLO, and LLP more readily than LOO, LOP, OOO, LOS, and POO, where L=linoleic, Ln=linolenic, O=oleic, P=palmitic, and S=stearin.