Evaluation of culture media for counts of Bifidobacterium animalis in the presence of yoghurt bacteria

Abstract

Much attention has been paid to the use of Bifidobacterium sp. in yoghurts due to their excellent therapeutic and nutritional properties. However, in order to present health properties, it is recommended that each commercial product should indicate the minimum daily amount required for it to confer health benefit(s) based on in vitro and human studies. Besides the inherent low growth of Bifidobacterium sp in milk, there is a need for a reliable method for counting Bifidobacterium sp in the presence of yoghurt bacteria. This study evaluated the use of the media M-MRS, MRS-NNLP and RCPB pH5 aimed at counting the number of Bifidobacterium animalis subesp. lactis in the presence of Streptococcus thermophilus and Lactobacillus delbrueckii subsp bulgaricus after yoghurt fermentation. The M-MRS medium was not selective, allowing for the growth of L. delbrueckii subsp bulgaricus. MRS-NNLP medium presented a good selectivity for B. animalis Bb12 with a slight reduction in the cell count of this microrganism when compared it to the standard MRS medium in pure culture. MRS-NNLP medium was considered a good option to enumerate B. animalis Bb12 although the reduction found in pure culture due to the low difference between the counts. The medium RCPB pH5 presented differentiated growth of B. animalis Bb12 in relation to the yoghurt bacteria and a cell recovery equal to that of the standard MRS, being considered the best option to enumerate Bifidobacterium sp in the presence of yoghurt bacteria.

Plant extract enhances the viability of Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus acidophilus in probiotic nonfat yogurt

“…Bifidobacterium animalis counts were enumerated as described by Moriya et al. (2006) with some modifications. MRS agar was prepared and tempered to 45°C in a water bath (Precision model 183; Precision Scientific, Chicago, IL).…”

“…2006; Vasiljevic and Shah 2008). General agreement has not been reached concerning the minimum concentration of live probiotic bacteria at the time of consumption to confer health benefits (Donkor et al.…”

“…The FAO/WHO defines probiotics as live microorganisms, which when consumed in adequate amounts, confer health benefits to the host (Moriya et al 2006;Vasiljevic and Shah 2008). General agreement has not been reached concerning the minimum concentration of live probiotic bacteria at the time of consumption to confer health benefits (Donkor et al 2006); however, the recommended concentrations in foods range from 6 to 8 log cfu/g (Ross et al 2005;Vasiljevic and Shah 2008).…”

Developing a potential prebiotic of yogurt: growth of Bifidobacterium and yogurt cultures with addition of glycomacropeptide hydrolysate

“…The set yogurt was produced with the same 1.0% inoculum of Bb12, S. thermophilus and L. bulgaricus in reconstituted skim milk at 37°C until coagulation. The individual number of Bb12 was enumerated using RCPB (pH5.0) medium (Moriya et al, 2006).…”

Evaluation of different selective media for enumeration of probiotic micro-organisms in combination with yogurt starter cultures in fermented milk

“…A number of health benefits have been claimed for many products containing one or more groups of probiotic organisms (Moriya et al, 2006;Saccaro et al, 2009). Acidophilus-bifidobacteria products (Mortazavian et al, 2006) or yogurts containing Bifidobacterium bifidum and/or Lactobacillus acidophilus are widely available in the world market (Hassan and Amjad, 2010;Lim et al, 1995;Nwamaka and Chike, 2010).…”