Detection and classification of Streptococcus thermophilus bacteriophages isolated from industrial milk fermentation

Abstract

In the last 30 years, 81 Streptococcus thermophilus bacteriophage isolates were collected from industrial yogurt (n = 40) and cheese (n = 41) fermentation. Forty-six distinct restriction patterns of phage DNA (11 in yogurt and 35 in cheese) were observed. The phages were investigated for host range, serological properties, and DNA homology to study whether these three independent techniques can be used to classify the phages into taxonomic groups. Yogurt factory-derived phages were classified into the same two subgroups by serology, host range analysis, and hybridization with subgroup-specific DNA sequences. Cheese factory-derived phages, however, could not be classified: the 35 cheese phage isolates with distinct restriction patterns showed 34 different host ranges. All but one cheese phage isolate showed serological cross-reactivity with yogurt phages. A phage DNA fragment that hybridized with all phage DNA samples was cloned, establishing the genetic relatedness of all S. thermophilus phages from our collection. With the sequence information from an unusually conserved S. thermophilus phage DNA element (H. Brüssow, A. Probst, M. Frémont, and J. Sidoti, Virology 200:854-857, 1994), a PCR-based phage detection method was developed for cheese whey from a factory that produced mozzarella cheese with complex undefined starter mixes. PCR allowed the detection of phages in cheese whey (detection limit, 10(3) PFU/ml) which could not be detected by dot blot hybridization techniques (detection limit, 10(7) PFU/ml).

Diversity among Lactobacillus paracasei phages isolated from a probiotic dairy product plant

“…Bacteriophage attacks against starters of lactic acid bacteria represent one of the major risks of acidifying delays, causing technological difficulties and economic losses (Jarvis 1989;Brüssow et al 1994;Bruttin et al 1997;Moineau and Lévesque 2005). Even though probiotic bacteria are mainly included in fermented dairy products as additives (usually as frozen and ⁄ or lyophilized powders) once the main fermentation process is finished, they can also be propagated during this stage, therefore acting as a starter (Watanabe et al 1970;Forsman et al 1993;Saarela et al 2000;Capra et al 2006b).…”

“…Two distinct ecological settings can be distinguished in the industrial dairy fermentation environment, which are the yogurt and cheese factories (Brüssow et al 1994;Brüssow and Kutter 2005). Phages are seldom seen in yogurt production while represent a constant problem in cheese plants (Suárez et al 2002;Brüssow and Kutter 2005).…”

“…Although the dairy industry has accumulated substantial knowledge in the field of phage factory ecology, these data are generally not published. Some authors (Moineau et al 1996;Deveau et al 2006;Szczepań ska et al 2007) have investigated lactococcal phage diversity and not many studies have been performed to elucidate the origin of Streptococcus thermophilus phages in dairy environments (Brüssow et al 1994(Brüssow et al , 1998Bruttin et al 1997;Brüssow and Desiere 2001), despite these latter lactic acid bacteria are widely used as starters.…”

Sensitivity of capsular-producing Streptococcus thermophilus strains to bacteriophage adsorption

“…It has been suggested that EPS from LAB could mask the phage receptors and hence protect LAB against bacteriophage attacks (Forde and Fitzgerald 1999;Looijesteijn et al 2001;Deveau et al 2002). Nevertheless, the presence of EPS does not seem to exert such protection, as Brüssow et al (1994) isolated phages from yoghurt factories active on ropy strains of Strep. thermophilus.…”

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

“…A longitudinal factory survey has documented the ecological dynamics of phage infection (11). 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).…”