Two groups of bacteriophages infecting Streptococcus thermophilus can be distinguished on the basis of mode of packaging and genetic determinants for major structural proteins

Abstract

A comparative study of 30 phages of Streptococcus thermophilus was performed based on DNA restriction profiles, DNA homology, structural proteins, packaging mechanisms, and host range data. All phages exhibited distinct DNA restriction profiles, with some phages displaying similarly sized restriction fragments. DNA homology was shown to be present among all 30 phages. The phages could be divided into two groups on the basis of their packaging mechanism as was derived from the appearance of submolar DNA fragments in restriction enzyme digests and the presence (cos-containing phages) or absence (pac-containing phages) of cohesive genomic extremities. Interestingly, the 19 identified cos-containing phages possessed two major structural proteins (32 and 26 kDa) in contrast to the remaining 11 pac-containing phages, which possessed three major structural proteins (41, 25, and 13 kDa). Southern hybridization demonstrated that all paccontaining phages tested contain homologs of the genes encoding the three major structural proteins of the pac-containing phage O1205, whereas all cos-containing phages tested exhibit homology to the gene specifying one of the structural components of the cos-containing phage ⌽7201. Fifty-seven percent of the phages (both cos and pac containing) possessed the previously identified 2.2-kb EcoRI fragment of the temperate S. thermophilus phage Sfi18 (H. Brüssow, A. Probst, M. Frémont, and J. Sidoti, Virology 200:854-857, 1994). No obvious correlation was detected between grouping based on packaging mechanism and host range data obtained with 39 industrial S. thermophilus strains.

Comparison of the Lysogeny Modules from the TemperateStreptococcus thermophilusBacteriophages TP-J34 and Sfi21: Implications for the Modular Theory of Phage Evolution

“…We decided to address some questions of phage evolution and phage population biology with phages from Streptococcus thermophilus, a Gram-positive bacterium (Mercenier, 1990) used industrially in milk fermentation (lactic acid bacterium). Several phage collections are available for this phage family (Benbadis et al, 1990;Bru Èssow et al, 1994a;Fayard et al, 1993;Larbi et al, 1992;Le Marrec et al, 1997;Neve et al, 1989;Prevots et al, 1989) and the ecology of phage infections has been studied (Bruttin et al, 1997a). Finally, a molecular characterization of the temperate S. thermophilus phage Sfi21 was started (Bru Èssow et al, 1994b;Bru Èssow and Bruttin, 1995;Bruttin and Bru Èssow, 1996;Bruttin et al, 1997b,c;Desiere et al, 1997Desiere et al, , 1998, making this phage system an acceptable subject for the study of phage evolution.…”

Comparative Genomics of Streptococcus thermophilus Phage Species Supports a Modular Evolution Theory

“…All phages characterized so far belong to the same morphological class (Siphoviridae, B1 morphotype) and the same DNA homology group (8,9), but they could be split into two groups: cos-site and pac-site phages. The two DNA-packaging mechanisms correlated with two distinct structural polypeptide patterns (30) and, in yogurt phage isolates, with host range and serotype (8). Four complete S. thermophilus phage genomes have been reported: the temperate pac-site phage O1205 (40), the temperate cos-site phage Sfi21 (32), and two lytic cos-site phages, the French yogurt isolate Sfi19 (17,32), and the Canadian cheese isolate DT1 (45).…”

Isolation and Characterization of Plasmids from Strains ofStreptococcus ThermophilusBulgarian Yogurt Starters

“…S. tlzermoplzilus strains were grown at 42°C in M 17 broth (Difco Laboratories, Detroit, Mich.), supplemented with I% beef L'Xtract (Difco) and 1,9% B-glyceropho:-.l~h.tte (Sigma), (17). Lactobacillus strains were grown in MRS medium (Difco) at 37°C, and E. coli in Luria broth at 37°C (10% bactotryptone, 5% yeast extract, 5% NaCl, Sambrook et al, 1989).…”