EFFECT OF SUPPLEMENTAION OF WHEY AGAR (AS BASAL MEDIUM) WITH SOME NUTRITIONAL INGREDIENTS ON THE GROWTH OF PURE CULTURES OF LACTIC ACID BACTERIA.

This experiment was carried out as an attempt to improve the nutritional value of  whey agar medium as a cheap and suitable medium for growing some strain of lactic acid bacteria with the addition of peptone, yeast, tomato, or carrot extract either separately or in combination. Applying whey agar (WA) medium gave no growth with any of the examined pure cultures of lactic acid bacteria. The addition of peptone and carrot extract (WPC) to the whey agar resulted in higher numbers of all cultures, compared with whey peptone (WP) agar. The addition of peptone and tomato extract (WPT) further increased the numbers of lactic acid strains. The highest numbers were gained with    Str. lactis, whereas the lowest were detected with L. casei. L. bulgaricus behaved similarly on this medium with Str. lactis. Rather closely numbers were detected with Str. cremoris and Str. thermophilus. Further increase of growth was observed by enriching the (WA) with peptone and yeast extract (WPY). The incorporation of peptone and both yeast extract and carrot extract (WPYC) or peptone and both of yeast and tomato extract (WPYT) resulted in more intensive growth of all examined cultures. Finally, supplementing the (WA) medium with peptone together with both yeast and tomato and carrot extracts yielded almost the highest stimulatory effect on all of the examined cultures of lacticacid bacteria.