Evaluation of culture media for selective enumeration of bifidobacteria and lactic acid bacteria

Abstract

The purpose of this study was to test the suitability of Transgalactosylated oligosaccharides-mupirocin lithium salt (TOS-MUP) and MRS-clindamycin-ciprofloxacin (MRS-CC) agars, along with several other culture media, for selectively enumerating bifidobacteria and lactic acid bacteria (LAB) species commonly used to make fermented milks. Pure culture suspensions of a total of 13 dairy bacteria strains, belonging to eight species and five genera, were tested for growth capability under various incubation conditions. TOS-MUP agar was successfully used for the selective enumeration of both Bifidobacterium animalis subsp. lactis BB-12 and B. breve M-16 V. MRS-CC agar showed relatively good selectivity for Lactobacillus acidophilus, however, it also promoted the growth of Lb. casei strains. For this reason, MRS-CC agar can only be used as a selective medium for the enumeration of Lb. acidophilus if Lb. casei is not present in a product at levels similar to or exceeding those of Lb. acidophilus. Unlike bifidobacteria and coccus-shaped LAB, all the lactobacilli strains involved in this work were found to grow well in MRS pH 5.4 agar incubated under anaerobiosis at 37 °C for 72 h. Therefore, this method proved to be particularly suitable for the selective enumeration of Lactobacillus spp.

The Effect of Cinnamon on Microbiological, Chemical and Sensory Analyses of Probiotic Yogurt

“…The adilution series were prepared up to 10 -7 . One hundred microliters were taken from each dilution and inoculated on agar plates mentioned above (17). Inoculated MRS, MRS-CC and TOS-MUP media were incubated at 37 ºC in anaerobic conditions for 72 hours (Memmert, IN 110, Germany).…”

“…lactis in TOS-MUP agar plate and Lactobacillus acidophilus bacteria in MRS-CC agar plates were identified. Only 25-250 colonies presented agar plates were evaluated (17). The determined bacterial numbers were calculated as colony-forming unit (cfu)/g yogurt with the cfu formula.…”

Specific composition of indigenous microflora (Lactobacillus spp., Bifidobacterium spp., Lactococcus spp.) in farm animals

“…Simple and selective nutrient media were used to isolate microorganisms from biological material and further determine their cultural properties (Basu et al, 2015). To detect and identify lactobacilli and bifidobacteria used MRS medium, Blaurok's medium, improved on their basis for 24-72 hours at 37°C (Süle et al, 2014;Yang et al, 2018;. The biological properties of lactic acid bacteria were studied by tinctorial, cultural-morphological and biochemical characteristics.…”

Probiotic monocultures in fermented goat milk beverages – sensory quality of final product

“…To calculate the number of cells of Lactobacillus and Bifidobacterium types, we used MRS‐CC agar (MRS–clindamycin–ciprofloxacin agar) (Süle et al . ) and BSM agar (Bifidus Selective Medium Agar, Fluka) with a selective agent (BSM supplement, Fluka). Bacterial cultures were incubated at 37 °C for 72 h under anaerobic conditions.…”