Detection of interactions between yeasts and lactic acid bacteria isolated from sugary kefir grains

摘要

Different techniques were tested for studying the synergism between the micro‐organisms of sugary kefir grains. Agar cultures in Petri dishes did not give reproducible results. In sequential cultures, i.e. growing one organism, sterile filtering and then inoculating the other, 10 of 18 selected lactic acid bacteria/yeast pairs revealed stimulation of bacterial growth in a poor glucose medium. In mixed culture,Saccharomyces florentinussupported better survival ofLactobacillus hilgardiiand a significant increase in lactic acid production; at the same time, the growth and alcoholic fermentation ofS. florentinuswere drastically reduced. The inter‐relationships between these two strains were the same when immobilized in calcium alginate beads, even though total metabolite production was always lower than with free cells. The stimulation ofLact. hilgardiibyCandida lambicain sequential culture was not confirmed in mixed culture, where the two organisms grew as in pure culture, and bacterial growth and lactic acid production were inhibited in the immobilized sys