Characterization of spontaneous phage-resistant variants of Streptococcus thermophilus by randomly amplified polymorphic DNA analysis and identification of phage-resistance mechanisms

A total of 100 spontaneous phage-resistant mutants isolated from nine commercial Streptococcus thermophilus strains were characterized preliminarily by randomly amplified polymorphic DNA (RAPD) and the nature of their phage-resistance mechanisms was investigated. Only for mutants isolated from one s...

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Bibliographic Details
Published in:International dairy journal 2007-09, Vol.17 (9), p.1115-1122
Main Authors: Binetti, A.G., Suárez, V.B., Tailliez, P., Reinheimer, J.A.
Format: Article
Language:English
Subjects:
Agricultural sciences
bacteriophages
Biological and medical sciences
biological resistance
Food industries
Food microbiology
Fundamental and applied biological sciences. Psychology
Life Sciences
lysogeny
Milk and cheese industries. Ice creams
mutants
Phages
random amplified polymorphic DNA technique
RAPD-PCR
strain differences
strains
Streptococcus thermophilus
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Summary:A total of 100 spontaneous phage-resistant mutants isolated from nine commercial Streptococcus thermophilus strains were characterized preliminarily by randomly amplified polymorphic DNA (RAPD) and the nature of their phage-resistance mechanisms was investigated. Only for mutants isolated from one strain, free phages were detected in their culture supernatants when these were titrated on the sensitive strain, suggesting that the mutants could have acquired the resistance phenotype by integrating the phage in their genomes (lysogeny). Adsorption interference was observed in the derivatives isolated from two strains. For mutants isolated from two other strains, restriction–modification (R–M) type systems were detected. In one of these cases, R–M was probably combined with another intracellular anti-phage system. In most cases, the molecular profiles (RAPD fingerprints) obtained with four arbitrary primers showed a high similarity among parent strains and their respective phage-resistant mutants. Some of these mutants were identified as potentially improved strains for industrial use.
ISSN:0958-6946
1879-0143
DOI:10.1016/j.idairyj.2007.01.007