Selective enumeration of Lactobacillus acidophilus, Bifidobacterium spp., starter lactic acid bacteria and non-starter lactic acid bacteria from Cheddar cheese

Twelve media were evaluated for selective and/or differential enumeration of Lactobacillus. acidophilus, Bifidobacterium spp., starter lactic acid bacteria (SLAB) and non-starter lactic acid bacteria (NSLAB) from Cheddar cheese. All media showed variation in counts and selectivity. Some reported selective media failed to inhibit SLAB and NSLAB. The media that were selective and/or differential and also gave better recovery were Reinforced Clostridium Agar with bromocresol green and clindamycin (RCABC), which was selective for L. acidophilus spp. and Reinforced Clostridium Agar with aniline blue and dicloxacillin (RCAAD), which was differential for Bifidobacterium spp. and SLAB. Reinforced Clostridium Agar with bromocresol green and vancomycin (RCABV) was found suitable for NSLAB. Apart from pure cultures, these media were also tested with commercial Cheddar cheese containing L. acidophilus. Additionally, Cheddar cheese containing L. acidophilus and B. lactis was manufactured and the selected media were used to monitor the initial survival of probiotic bacteria, SLAB and NSLAB present.