Diversity among lactococci isolated from ewes' raw milk and cheese

The technological and genetic characteristics of lactococci present in ewes ' ram milk and 1-d-old ewes' raw milk cheeses sampled over a 1-year period were investigated. The proportion of lactic acid bacteria isolates from mil k samples able to decrease milk pH by more than 1.25 units after 6 h incuba tion at 30 degrees C reached 14.5% in spring vs 10.7% in summer, 8.3% in au tumn and 3.0% in winter. In 1-d-old cheese samples, the proportion of lacti c acid bacteria able to lower milk pH by more than 1.25 units increased up to 32.3% in spring vs 23.4% in summer, 8.0% in autumn and 10.3% in winter. Fast acid-producing lactic acid bacteria mainly belonged to the genus Lacto coccus. Using polymerase chain reaction protocols, fast acid-producing lact ococci were grouped as 61 Lactococcus lactis subsp. lactis, 13 L. lactis su bsp. cremoris and 14 L. lactis subsp. lactis biovar diacetylactis. Randomly amplified polymorphic DNA (RAPD) fingerprinting of fast acid-producing lac tococci, using two primers, resulted in 21 different RAPD patterns for L. l actis subsp. lactis isolates, nine RAPD patterns for L. lactis subsp. cremo ris isolates and three RAPD patterns for L. lactis subsp. lactis biovar dia cetylactis isolates. Up to 19 different RAPD patterns were found for L. lac tis isolates from cheeses made in a particular month.