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

Abstract

F. LEROI AND M. PIDOUX. 1993. 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 s . 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 florentinus supported better survival of Lactobacillus hilgardii and a significant increase in lactic acid production; at the same time, the growth and alcoholic fermentation of S. flurentinus were drastically reduced. T h e 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 of Lact. hilgardii by Candida lambica in 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 system.

Interaction between dairy yeasts and lactic acid bacteria strains during milk fermentation

“…Both positive and negative interactions between yeasts and LAB species have been reported, although the mechanisms underlying neither are well understood. Positive interactions include the stimulation of LAB through the production of carbon dioxide, pyruvate, propionate and succinate (Leroy & Pidoux, 1993 nutritional requirement for many compounds, and can also be stimulated by the synthesis of vitamins or by the production of amino acids by yeasts (Roostita & Fleet, 1996). In addition, some LAB species release galactose, which may favour the growth of lactose-negative yeasts (Marshall & Tamine, 1997).…”

Reducing the bloater spoilage incidence in fermented green olives during storage

“…The presence of L. plantarum in the brine is very important not only for reducing the residual sugars in the medium (competitiveness) but also for ensuring the continuous acidification of the brine, and consequently inhibiting the yeast growth (Leroi and Pidoux, 1993) which would produce carbon dioxide leading to bloaters formation in the olives. Upon the foregoing the bloater level was drastically reduced by the conditions studied: brining at 5% NaCl, pH adjustment to 4 units, potassium sorbate addition (0.05%) and L. plantarum I159 inoculation.…”

Fungal interactions in food fermentations

“…Sugary kefir (43,44) and tibicos (45) are similar mutualistic combinations of yeasts and lactic acid bacteria, embedded in polysaccharide (including dextran). They have some resemblance to "Mother of Vinegar" and tea fungus (Kombucha) (46), although the latter have a higher content of acetic acid bacteria.…”