Differentiation of Streptococcus thermophilus strains in commercial Direct Vat Set yoghurt starter

• Published in: Food science and biotechnology Vol. 22; no. 4; pp. 987 - 991
• Main Authors: Ma, Chengjie, Wu, Zhengjun, Chen, Zhengjun, Du, Zhaoping, Sun, Kejie, Ma, Aimin
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-08-2013; 한국식품과학회
• Subjects: Chemistry; Chemistry and Materials Science; Food Science; Nutrition; Research Article; Streptococcus thermophilus; 식품과학; randomly amplified polymorphic DNA; phage typing; whole-cell protein profile; inhibition of acid production
• ISSN: 1226-7708; 2092-6456
• DOI: 10.1007/s10068-013-0174-x

Based on inhibition of acid production, 100 individual colonies of
Streptococcus thermophilus
isolated from commercial Direct Vat Set yoghurt starter DVS-M were typed into 2 groups of sensitive and insensitive to phage φ001, which was isolated from the lysis culture of the turbidity test. The ratio between the sensitive and insensitive isolates in DVS-M was calculated at 3:2. Whole-cell protein profile (WCPP) and randomly amplified polymorphic DNA (RAPD) analysis showed that both WCPP and RAPD patterns between sensitive and insensitive isolates were distinct, whereas isolates with the same sensitivity or insensitivity shared common WCPP and RAPD patterns. It suggested that all the sensitive isolates belong to one
S. thermophilus
strain and all the insensitive isolates belong to another one. This study revealed that DVS-M yoghurt starter consists of 2
S. thermophilus
strains with different phage sensitivity.