Multiplex PCR to detect bacteriophages from natural whey cultures of buffalo milk and characterisation of two phages active against Lactococcus lactis, φApr-1 and φApr-2

This work investigated bacteriophage induced starter failures in artisanal buffalo Mozzarella production plants in Southern Italy. Two hundred and ten samples of whey starter cultures were screened for bacteriophage infection. Multiplex polymerase chain reaction (PCR) revealed phage infection in 28.56% of samples, all showing acidification problems during cheese making. Based on DNA sequences, bacteriophages for Lactococcus lactis (L. lactis), Lactobacillus delbruekii (L. delbruekii) and Streptococcus thermophilus (S. thermophilus) were detected. Two phages active against L. lactis, φApr-1 and φApr-2, were isolated and characterised. The genomes, approximately 31.4 kb and 31 kb for φApr-1 and φApr-2 respectively, consisted of double-stranded linear DNA with pac-type system. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS--PAGE) showed one major structural protein of approximately 32.5 kDa and several minor proteins. This is the first report of phage isolation in buffalo milk and of the use of multiplex PCR to screen and study the diversity of phages against Lactic Acid Bacteria (LAB) strains in artisanal Water Buffalo Mozzarella starters.