RELEASE AND PARTIAL CHARACTERIZATION OF CELL-ENVELOPE PROTEINASES FROM LACTOCOCCUS-LACTIS SUBSP LACTIS IFPL 359 AND LACTOBACILLUS-CASEI SUBSP CASEI LFPL-731 ISOLATED FROM RAW GOATS-MILK CHEESE

Different methods of releasing the cell-envelope proteinase (CEP) from Lactococcus lactis IFPL 359 (Lc-CEP) and Lactobacillus casei IFPL 731 (Lb-CEP) have been tested. Release of Lc-CEP was higher in Ca2+-free buffer than in the presence of lysozyme and Ca2+. Lb-CEP was not solub le in Ca2+-free buffer, making necessary the use of chelating agents s uch as ethylenediaminetetraacetate (EDTA) to attain release yields of 15-20%. Solubilizing the cell wall of Lb. casei using lysozyme and mut anolysin improved CEP release yields, even in the presence of Ca2+. Tw o differently charged chromophoric peptides were degraded by whole cel ls and the soluble fractions studied at different hydrolysis rates in both the strains considered. Based on the specificity of these CEPs fo r the different substrates, the two proteinases can be placed in the s ame class as the CEP((I/II)) mixed-type variants that have been identi fied in lactococcal proteinases. In both strains beta-casein was hydro lysed more rapidly than alpha(s)-casein.