Four strains of lactic acid bacteria (LAB) were cultivated on deproteinated whey supplemented with yeast autolysate (YA) and/or de‐lipidated egg yolk (DEY). Growth was compared to that recorded on the widely used MRS medium. The feasibility of the use of YA in place of yeast extract was confirmed. In the presence of YA in the medium, cell numeration gained nearly 1 log for only 0.4% DEY added in the culture medium, namely 0.1 g/L additional nitrogen, showing that DEY also supplies LAB growth in trace elements and growth factors like vitamins. If compared to the MRS medium, final cell numerations were about 1 log lower on deproteinated whey supplemented with YA and DEY, while the protein nitrogen ratio of both media was 2.7, showing the high potential of the tested supplements, and especially DEY. Subsequent works with higher and hydrolysed DEY may be therefore useful.

Six strains of lactic acid bacteria isolated from different biotopes were cultivated on oilseed crop pea-or chickpea-based media, supplemented with the usual nitrogen supplements, yeast extract, meat extract or tryptic casein peptone. Growth was compared to that recorded on the widely used MRS and M17 media. All the media tested favoured growth of the selected strains, since the final c.f.u. gained at least 3 logs. Vegetal substrate (pea) appeared especially efficient for growth of a LAB species isolated from plants, Lactobacillus plantarum, illustrating the relationship between the supplementation used and the natural biotope of the LAB strain; during growth on oilseed crop pea-and chickpea-based media, the final c.f.u. was 0.58 and 1.28 log higher than the final cell numeration recorded on the reference medium MRS. The better efficiency of chickpea to stimulate LAB growth, if compared to oilseed crop pea, must be related to its higher protein content, 24.15 ± 0.1 and 28.2 ± 0.5% respectively. A vegetal substrate with high protein content can be therefore used to replace, at least partially, the usual nitrogen supplements.

Burman design was used to determine the most influential of 9 variables (glucose, lactulose, tween80, K 2 HPO 4 , sodium acetate, MgSO 4 , pH, shaking and inoculum size) on the growth of L. plantarum BH14. Glucose, lactulose, MgSO 4 and shaking had a significant effect on growth of this strain at a 70% confidence level. Glucose, lactulose and MgSO 4 showed positive coefficient but shaking had a negative coefficient, thus shaking was avoided in subsequent experiments. Composite design was used to determine the optimum concentrations of the significant variables. An optimized formulation of nutrition levels was suggested from the software at the following concentrations: 11.59 g LG 1 glucose, 11.59 g LG 1 lactulose and 0.23 g LG 1 MgSO 4. Growth of L plantarum was compared to that recorded on the reference medium 'vegetal MRS'. The results showed that viable counts in the optimized culture medium were significantly higher than those in the vegetal MRS medium.