[Isolation and characterization of intracellular lipase from Serratia marcescens 345]

Lipase was extracted from cells of Serratia marcescens 345 treated with 0.8% Na cholate for 30 min at 37 degrees C. The mixture was then centrifuged and lipase was isolated from the supernatant. The preparation was purified by ammonium sulfate protein precipitation and subsequent dialysis, ultrafiltration of the protein solution through the membrane filter UAM-200 and gel filtration through Sephadex G-200. The effect of metal ions, inhibitors and bile salts as well as temperature and pH on the resultant lipase activity was studied. The substrate specificity of the enzyme was examined. The temperature optimum for the lipase activity was 45 degrees C and pH optimum 6.0--6.3. The enzyme was activated only by Mg2+ at a concentration of 1.10(-4)M in the reaction mixture. Lipase was inhibited by Ni2+, Zn2+, Fe2+ and particularly Cu2+ and Hg2+. Out of the inhibitors tested the strongest were EDTA, o-phenanthrolin and alpha,alpha-dipyridil. Lipolysis was activated by bile salts at a concentration over 0.5%. Intracellular lipase from S. marcescens 345 was able to hydrolyze glycerol esters containing both unsaturated fatty acids (vegetable oils) and saturated fatty acids with a short and a long carbon chain.