Detection and identification ofLactobacillus helveticusbacteriophages by PCR

Abstract
A PCR protocol for detection ofLactobacillus helveticusbacteriophages was optimized. PCR was designed taking into account the sequence of thelysgene of temperate bacteriophage Φ-0303 and optimized to obtain a fragment of 222 bp using differentLb. helveticusphages from our collection. PCR was applied to total phage DNA extracted from 53 natural whey starters used for the production of Grana cheese and all gave the expected fragment. The presence of actively growing phages in the cultures was verified by traditional tests. Several PCR products of thelysgene were sequenced and aligned. The resulting sequences showed variable heterogeneity between the phages.