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Spread and variability of the integrase gene in Lactobacillus delbrueckii ssp. lactis strains and phages isolated from whey starter cultures
Author(s) -
Zago M.,
Suarez V.,
Reinheimer J.A.,
Carminati D.,
Giraffa G.
Publication year - 2007
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2006.03101.x
Subject(s) - starter , lactobacillus , microbiology and biotechnology , integrase , biology , fermentation starter , gene , bacteria , lactobacillaceae , food science , genetics , lactic acid
Aims: To determine the presence, diffusion and variability of the integrase ( int ) gene in Lactobacillus delbrueckii ssp. lactis isolated from natural whey starters used for the production of Italian hard cheeses. Methods and Results: A PCR‐based protocol aimed to amplify an internal fragment of the int gene was optimized taking into account phage genome sequences available from public databases. Thirty‐seven of the 39 strains tested showed the presence of the putative int gene. Southern blot hybridization experiments confirmed data obtained by PCR. The presence of the putative int gene was observed also in 20 of 23 Lact. delbrueckii ssp. lactis lytic phages isolated from the same starter cultures used to isolate strains. Phylogenetic analysis of partial int gene revealed a high similarity both within and between strain‐ and phage‐derived sequences. Sixty per cent of the int ‐positive strains resulted inducible with mitomycin C, and two of them released active phage particles. Conclusions: Our preliminary findings seem to suggest that an important number of Lact. delbrueckii ssp. lactis strains associated with the whey starters are lysogenic. Significance and Impact of the Study: Further contribution to obtain a clearer picture of the complex relationship between thermophilic lactic acid bacteria phage and host in whey starters for Italian, hard‐cooked cheeses.