The distribution of lactococcal bacteriophage in the environment of a cheese manufacturing plant

Abstract

Survival of starter bacteria and their bacteriophages following spray irrigation of whey in the vicinity of a cheese plant was investigated. Phage in environmental samples that attacked starter strains used in the plant were detected infrequently in water, but persisted for up to six weeks in the soil. Enrichment of cow dung, grass and trough water samples was required to detect phage, indicating their presence at low levels. No starter bacteria could be re-isolated from grass samples from whey irrigated pasture. Inside the plant, whey contained the largest numbers of phage and when released into the environment (via irrigation practices) contributed to the recycling of phages through the plant. It did not, however, appear to be the initial source for starter infection by ‘new’ phage. The detection of phages in the bulk raw milk that were not active on starter strains that were being used in the plant, reemphasized raw milk as a potential source of new phage.