Many industrial cheese starter bacteria, Lactococcus lactis, harbour one or more prophages integrated in their genomes. Prophage induction has varied effects in the cheese making process. For example, phage induction can cause cells to lyse and release enzymes that can speed up cheese ripening process. Conversely, lysis of starter cultures could delay or halt the cheese fermentation process. Lactococci encounter numerous stress conditions during the production of cheese which include temperature extremes, low pH, high osmotic pressure and nutrient starvation. As a response to stresses, temperate prophages can be induced. We tested the effect of industrial extracytoplasmic stressors on prophage induction in two industrial strains as well as the laboratory strain L .lactis MG1363. The strains were exposed to mitomycin C for 1 and 2h periods to induce prophage DNA replication. Genomic DNA was extracted from cells and subsequently sequenced using Illumina HiSeq2000 100bp pair-ended sequencing technology. Mapping of L. lactis MG1363 and the two industrial strains' sequencing reads back onto the reference genome L. lactis MG1363 (RefSeq: NC_009004) and their draft genomes respectively revealed genomic regions with much higher fold coverage than the baseline sequencing coverage level, suggesting phage replication. These regions were identified as phages, which contained up to 332-fold increased copies of DNA, relative to the housekeeping gene, tufA.  Quantitative PCR was used to confirm the sequencing results as well as quantitating the copy number of the inducible prophages following exposure to slightly growth inhibitory levels of various stressors. With the exception of a slight induction (2 to 4-fold) with hydrogen peroxide and starvation on day 21 in one industrial strain, none of the other stressors induced prophage replication.  These findings show that the repression system that maintains prophages in the dormant state in cheese making lactococcal strains is very tight and that industrially encountered stressors like the ones tested are not predicted to be a major inducer of prophage activation.