Genome analysis of two virulent Streptococcus thermophilus phages isolated in Argentina
Instituto de Lactología Industrial (INLAIN, UNL-CONICET), Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santa Fe, Argentina. International journal of food microbiology
(Impact Factor: 3.08).
09/2009; 136(1):101-9. DOI: 10.1016/j.ijfoodmicro.2009.09.005
Two Streptococcus thermophilus phages (ALQ13.2 and phiAbc2) were previously isolated from breakdowns of cheese manufacture in Argentina. Complete nucleotide sequence analysis indicated that both phages contained linear double-stranded DNA: 35,525 bp in length for the pac-type phage ALQ13.2 and 34,882 bp for the cos-type phage phiAbc2. Forty-four and 48 open reading frames (ORF) were identified for ALQ13.2 and phiAbc2, respectively. Comparative genomic analysis showed that these isolates shared many similarities with the eight previously studied cos- and pac-phages infecting different S. thermophilus strains. In particular, part of the phiAbc2 genome was highly similar to a region of phage 7201, which was thought to be unique to this latter phage. Protein analysis of the pac-phage ALQ13.2 using SDS polyacrylamide gel electrophoresis (SDS-PAGE) identified three major proteins and seven minor proteins. Parallel structural proteome analysis of phiAbc2 revealed seven protein bands, two of which were related to major structural proteins, as expected for a cos-type phage. Similarities to other S. thermophilus phages suggest that the streptococcal phage diversity is not extensive in worldwide dairy factories possibly because related high-performing bacterial strains are used in starter cultures.
Available from: Chengjie Ma
- "Phage particles were purified by using two consecutive CsCl gradient ultracentrifugation steps according to Guglielmotti et al. (2009b) with slight modifications. Phage lysate was concentrated in 10% (w/v) polyethylene glycol (PEG, molecular weight: 6000) and 0.5 M NaCl. "
Available from: Jennifer Mahony
- "In contrast to the phages of L. lactis, all phages infecting S. thermophilus display a similar morphology with long, non-contractile tails (typically more than 200 nm in length) and isometric capsid structures, thus belonging to the Siphoviridae family (Brussow et al., 1994; Bruttin et al., 1997; Levesque et al., 2005; Guglielmotti et al., 2009; Zinno et al., 2010; Mills et al., 2011). Therefore, electron microscopy and associated morphological analysis provides little scope for differentiation between these phages, thus necessitating the application of other methods of discernment. "
[Show abstract] [Hide abstract]
ABSTRACT: Phages infecting lactic acid bacteria have been the focus of significant research attention over the past three decades. Through the isolation and characterization of hundreds of phage isolates, it has been possible to classify phages of the dairy starter and adjunct bacteria Lactococus lactis, Streptococcus thermophilus, Leuconostoc spp., and Lactobacillus spp. Among these, phages of L. lactis have been most thoroughly scrutinized and serve as an excellent model system to address issues that arise when attempting taxonomic classification of phages infecting other LAB species. Here, we present an overview of the current taxonomy of phages infecting LAB genera of industrial significance, the methods employed in these taxonomic efforts and how these may be employed for the taxonomy of phages of currently underrepresented and emerging phage species.
Available from: Aidan Coffey
- "Most isolated phages harbour the Sfi21-like replication module, which is unusually conserved (Desiere, Lucchini, Bruttin, Zwahlen, & Brussow, 1997). Up until now, phage 7201 and phage Abc2 were the only known S. thermophilus phages to contain the 7201-like DNA replication module (Guglielmotti et al., 2009). However, a comparison of the replication module of phage 5093 with the replication modules of phages Sfi21 and 7201 indicated that phage 5093 also harbours a 7201-type DNA replication module, sharing 79% identity over 2513 base pairs of the 7201-type region but showing no significant similarity to the corresponding region of Sfi21. "
[Show abstract] [Hide abstract]
ABSTRACT: Streptococcus thermophilus bacteriophage 5093 is a virulent phage that infects the industrial Mozzarella starter CSK939. The genome of phage 5093 is 37,184 base pairs (bps) containing 50 open reading frames (orfs). Genetic analysis revealed that the genome of phage 5093 is highly mosaic when compared with other sequenced S. thermophilus phages. This is particularly apparent in the late gene cluster with regions displaying high homology to prophage sequences of non-dairy streptococci and limited homology to either pac or cos-type S. thermophilus phages. In addition, a definitive antireceptor gene was not observed – suggesting that phage 5093 may have developed a different system for host recognition. Interestingly, the phage does contain a methylase domain that probably evolved as a phage counter-defence mechanism. These findings suggest that phage 5093 may represent a third group of S. thermophilus phage and provide the link between phages that infect S. thermophilus and its non-dairy ancestors.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.