The microbial composition and the number of viable bacteria are essential for the quality of fermented milk. This study detected the number of viable count and species composition of different lactic acid bacteria in fermented milk using selective media, MALDI-TOF MS rapid identification system and polyphasic taxonomy methods. The results showed that for the three fermented milk products, the total number of lactic acid bacteria enumerated by the GB 4789.35 method was higher than that of the selective medium, and the total number of Streptococcus thermophilus enumerated by the M17 medium was higher than that of the MC medium. MALDI-TOF MS rapid identification results showed that M17, MRS (containing 50 μg/mL vancomycin) and bifidobacterium medium could selectively isolated Streptococcus thermophilus, Lactobacillus casei and Bifidobacterium spp. But acidified MRS medium had poor selectivity to Lactobacillus delbrueckii, it could not selectively isolate L. delbrueckii from fermented milk containing Bifidobacterium spp. Through polyphasic taxonomy identification, the microbial composition of lactic acid bacteria in the three fermented milk products at the species or subspecies level was further determined, and the identification results were consistent with the product claims of fermented milk. This study compared different selective enumeration methods of lactic acid bacteria in fermented milk and provided a scientific basis for the quality control and regulation of fermented milk products with complex bacteria.
XIE Jiuyan
,
ZHAO Ting
,
GAO Yi
,
XIN Di
,
FENG Huifen
,
LI Hong
,
YAO Su
. Selective enumeration, isolation and identification of lactic acid bacteria in fermented milk[J]. Food and Fermentation Industries, 2022
, 48(10)
: 35
-41
.
DOI: 10.13995/j.cnki.11-1802/ts.029346
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