Screening of microbes for lipases specific for saturated medium and long-chain fatty acids of milk fat

Over 250 microbial strains were screened for lipase activity specific towards saturated medium and long-chain fatty acids. Strains showing trimyristin (C14:0) hydrolysis on agar medium were further streaked on tricaprylin (C8:0) and on olive oil (mostly C18:1) agar to identify strains hydrolysing C12–C15 fatty acids with modest or no activity towards short-chain and unsaturated fatty acids. The twenty strains showing the desired specificity were grown as liquid cultures and analysed for p-nitrophenyl (p-NP) myristate hydrolysis in the presence of Triton X-100. Cells from the cultures showing the highest activity towards p-NP myristate were analysed for specificity towards p-NP esters of different fatty acid chain lengths. On the basis of the p-NP ester profiling, four lipase samples were selected for hydrolysis experiments on butter oil. Of these, the sample obtained from the cultivation of Didpodascus capitatus met the screening criteria: C12:0–C16:0 specificity and no preference towards C18:0 and C18:1 fatty acids.