Development and use of tuf gene-based primers for the multiplex PCR detection of Lactobacillus acidophilus, Lactobacillus casei group, Lactobacillus delbrueckii, and Bifidobacterium longum in commercial dairy products.
PCR primers specific for the detection of Lactobacillus acidophilus, Lactobacillus casei group, Lactobacillus delbrueckii, and Bifidobacterium longum were designed based on the elongation factor Tu gene (tuf). The specificity of these four primer sets were confirmed by PCR with 88 bacterial strains of Lactobacillus, Enterococcus, Bifidobacterium, and other bacterial species. Results indicated that these primer sets generated predicted PCR products of 397, 230, 202, and 161 bp for L. acidophilus, L. delbrueckii, L. casei group, and B. longum, respectively. Bacterial species other than the target organisms tested did not generate false-positive results. When these four primer sets were combined for the simultaneous detection of the lactic acid bacteria (LAB) in fermented milk products including yogurt, the LAB species listed on the labels of these products could be identified without the preenrichment step. The identification limit for each LAB strain with this multiplex PCR method was N X 10(3) CFU/ml in milk samples. The results of our multiplex PCR method were confirmed by PCR assay using primers based on the 16S rDNA or the 16S-23S intergenic spacer region and by biochemical tests using the API 50 CHL kit. When this multiplex PCR method was used with the determination of counts of total viable LAB and bifidobacteria, the quality of commercial fermented milk products could be assured.
Sheu
Sen-Je
SJ
Department of Food Science and Biotechnology, National Chung Hsing University, No. 250, Kuo Kuang Road, Taichung City, Taiwan 402, Republic of China.
Hwang
Wen-zhe
WZ
Chen
Hsin-Chih
HC
Chiang
Yu-Cheng
YC
Tsen
Hau-Yang
HY
D000818:Animals; D015373:Bacterial Typing Techniques; D001644:Bifidobacterium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D015169:Colony Count, Microbial; D043302:Cultured Milk Products / Q000382:microbiology; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D021903:DNA, Ribosomal Spacer / Q000032:analysis; D003611:Dairy Products / Q000382:microbiology*; D006801:Humans; D007778:Lactobacillus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D007779:Lactobacillus acidophilus / Q000145:classification / Q000302:isolation & purification; D007780:Lacticaseibacillus casei / Q000302:isolation & purification; D048668:Lactobacillus delbrueckii / Q000302:isolation & purification; D008970:Molecular Weight; D016133:Polymerase Chain Reaction / Q000379:methods*; D019936:Probiotics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013997:Time Factors
D017931:DNA Primers; D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S