Selection and analysis of bacteriophage‐insensitive mutants of Streptococcus thermophilus isolated in Ukraine

Abstract

Bacteriophage-insensitive Streptococcus thermophilus mutants (BIMs) were obtained by treating the phage-sensitive industrial strains with virulent phages. Five BIMs acquired resistance to S. thermophilus phages of two (cos and pac) main groups selected at Ukrainian dairy processing enterprises. In addition, the valuable biotechnological properties of BIMs were characterised. During fermentation, they formed fermented milk curds with a homogeneous, dense consistency, with pleasant taste and flavour. The BIMs were identified as S. thermophilus by phenotypic and species-specific PCR methods. The BIMs could be used as starters to stabilise the fermentation process under phage infection conditions.

Ectopic Spacer Acquisition in Streptococcus thermophilus CRISPR3 Array

“…One important strategy for controlling virulent phages in industrial settings is to select and use natural bacteriophage-insensitive mutant (BIM) strains as starter cultures. It is now well-documented that S. thermophilus strains rely on the CRISPR-Cas system (a prokaryotic adaptive immune system) to protect itself against phage attacks [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. This system is composed of a clustered regularly interspaced short palindromic repeats (CRISPR) array and its associated cas genes [ 16 , 17 , 18 ].…”

Safety assessment of Streptococcus thermophilus IDCC 2201 used for product manufacturing in Korea

“…In particular, S . thermophilus has been used as a starter for dairy products because of rapid acidifying capacity during fermentation process (Naumenko et al., 2019; Santos et al., 2019). It has been also reported to exhibit several health‐beneficial effects such as growth inhibition of many pathogenic bacteria and strong adherence to the gastrointestinal tract (Braun et al., 2020; Iyer et al., 2010; Wu et al., 2014).…”