EFFECT OF KLUYVEROMYCES-MARXIANUS ON THE GROWTH AND SURVIVAL OF BIFIDOBACTERIA IN MILK

Four strains of bifidobacteria (B. bifidum 93, B. infantis ATCC 17 930 , B. longum ATCC 15 707, and B. longum JR) cultivated in MRS broth mod ified by the addition of cysteine-hydrochloride (0.05 %) were serially subcultured in unsupplemented cow milk alone or in combination with K luyveromyces marxianus var. marxianus 269 under aerobic conditions. In monoculture, bifidobacteria did not multiply after the second subcult ure. In contrast, in coculture with yeast bifidobacteria reached count s about 8 log CFU/g even during 15 subcultures. In addition, K. marxia nus var. marxianus 269 significantly prolonged the survival of bifidob acteria in milk at 4 degrees C. The most susceptible strains (B. longu m JR and B. infantis ATCC 17 930) completely lost their viability with in 5 and 12 d of storage, respectively, while in coculture with yeasts all bifidobacteria cultures tested survived for at least 40 d. The re sults could be useful in producing kefir-like fermented milks containi ng bifidobacteria.