LIPASE PRODUCTION BY LACTIC-ACID BACTERIA AND ACTIVITY ON BUTTER OIL

Over 100 different lactic acid bacteria representing the genera, Lacto bacillus, Lactococcus, Leuconostoc, Pediococcus and Streptococcus, wer e screened for lipase production using an agar medium containing rhoda mine b and three different lipid substrates, triolein (C18:1), tributy rin (C4:0), and butter oil. A total of 29 lipase-producing strains wer e identified. Assays using extracellular material (supernatant) and in tracellular extracts (prepared by sonication) showed that lipases were produced as intracellular enzymes in the strains studied. Several dif ferent lipase assays were employed to measure lipase activities of lip ases produced by selected lactic acid bacteria. The best lipase assay was the pH stat titrator, which gave quick, quantitative results of li pase activity toward a number of synthetic triacylglyceride substrates , as well as natural substrates, such as butter oil. Activities for ce ll free extracts ranged from <1.0-55 mu mol free fatty acid released p er minute per milligram of protein. However, lipase activities of extr acts obtained from lactic acid bacteria were substantially lower than those reported for other micro-organisms, such as Pseudomonas spp. and Candida spp. Studies on the substrate specificity of selected lipases indicated the lipases were generally operating in a random fashion wi th regard to fatty acid type, although there was a slight preference f or oleic acid. (C) 1996 Academic Press Limited