REACTION CONDITIONS INFLUENCING POSITIONAL SPECIFICITY INDEX (PSI) OF MICROBIAL LIPASES

The effect of reaction conditions on the positional specificities shown by six microbial lipases was studied in terms of PSI. The origins of the lipases were Candida cylindracea, Geotrichum candidum, Rhizopus delemar, Chromobacterium viscosum, Pseudomonas sp. and an unidentified microorganism. The effects of the temperature and pH on PSI were slight. The lipase from C. cylindracea was affected largely by organic solvents in the reaction mixture and its positional specificity became 1,3-specific in the presence of 20% ethanol. On the other hand, Pseudomonas lipase changed its specificity with 0.1% Tweens in the reaction mixture. PSI values towards natural oils and fats were varied in some lipases and the most interesting finding was that all the lipases used were 1,3-specific towards castor oil.