AUTHOR=Arioli Stefania , Eraclio Giovanni , Della Scala Giulia , Neri Eros , Colombo Stefano , Scaloni Andrea , Fortina Maria Grazia , Mora Diego 

TITLE=Role of Temperate Bacteriophage ϕ20617 on Streptococcus thermophilus DSM 20617T Autolysis and Biology

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02719

DOI=10.3389/fmicb.2018.02719

ISSN=1664-302X

ABSTRACT=<p><italic>Streptococcus thermophilus</italic> DSM 20167<sup>T</sup> showed autolytic behavior when cultured in lactose- and sucrose-limited conditions. The amount of cell lysis induced was inversely related to the energetic status of the cells, as demonstrated by exposing cells to membrane-uncoupling and glycolysis inhibitors. Genome sequence analysis of strain DSM 20617<sup>T</sup> revealed the presence of a <italic>pac</italic>-type temperate bacteriophage, designated Φ20617, whose genomic organization and structure resemble those of temperate streptococcal bacteriophages. The prophage integrated at the 3′-end of the gene encoding the glycolytic enzyme enolase (<italic>eno</italic>), between <italic>eno</italic> and the lipoteichoic acid synthase-encoding gene <italic>ltaS</italic>, affecting their transcription. Comparative experiments conducted on the wild-type strain and a phage-cured derivative strain revealed that the cell-wall integrity of the lysogenic strain was compromised even in the absence of detectable cell lysis. More importantly, adhesion to solid surfaces and heat resistance were significantly higher in the lysogenic strain than in the phage-cured derivative. The characterization of the phenotype of a lysogenic <italic>S. thermophilus</italic> and its phage-cured derivative is relevant to understanding the ecological constraints that drive the stable association between a temperate phage and its bacterial host.</p>