WHEY CRYSTALLINE LACTOSE AS A MAIN CONSTITUENT IN GROWTH AND COUNTINGMEDIA FOR LACTOCOCCI AND STREPTOCOCCUS-THERMOPHILUS

In the present study, a dried whey crystalline lactose (WCL) preparati on was obtained from deproteinized whey by crystallization in an ethan ol-water system. This was used as a major component in Streptococcus W CL (SWCL) broth and in Modified M17 (MM17) agar media. SWCL broth and MM17 agar were used as media for propagating and counting several stra ins of lactococci and Streptococcus thermophilus, respectively. The st udy was carried out to compare the alternative utilization of SWCL bro th to RSM (reconstituted skim milk) and MM17 agar to original M17 agar . The streptococcal cultures tested in this study remained viable thro ugh several transfers in SWCL broth medium. However, high acidity deve lopment was not observed in SWCL broth cultures. The presence of 4 g/l yeast extract in SWCL broth had more effect on growth than on acid pr oduction. Growth in SWCL broth or RSM was dependent upon the type of s treptococcal culture used. MM17 agar gave comparable results to M17 ag ar in terms of counts of the lactococci and Strep thermophilus propaga ted in SWCL broth or in RSM.