Isolation and enumeration of bifidobacteria in fermented milk products: A review

Abstract

Fermented foods containing selected strains of bifidobacteria are claimed to contain several therapeutic benefits. Several media could be used for selective enumeration of bifidobacteria, however, further research is needed to develop a medium to isolate whole spectrum of species within the genus Bifidobacterium from products containing yogurt bacteria, L. acidophilus, and bifidobacteria. If a product contains bifidobacteria only, glucose-blood liver (BL) agar, reinforced clostridial agar (RCA) or brain-heart infusion (BHI) agar could be used for enumeration using anaerobic incubation. If the product contains bifidobacteria and other lactic acid bacteria, neomycin sulphate, nalidixic acid, lithium chloride, and paromomycin sulphate (NNLP) agar may be the medium of choice. "Bifidus-blood" agar could also be used for selective enumeration of bifidobacteria. However, counterchecking the efficacy of the medium with pure cultures of Bifidobacterium spp. before adopting the medium is suggested.