Microbial community dynamics of a blue-veined raw milk cheese from the United Kingdom

摘要

A commercial blue-veined cheese made from unpasteurized milk was examined by conventional culturing and PCR denaturing gradient gel electrophoresis analysis of the bacterial community 16S rRNA genes using 3 primer sets, V3, V4V5, and V6V8. Genomic DNA for amplification was extracted directly from raw milk, starter culture, cheese at different stages of production, fully ripened cheese, and from the cultured cells grown on various media. The outer rind was sampled separately from the inner white core and blue veins. A diverse microbiota containingLactococcus lactisssp.lactis,Lactobacillus plantarum,Lactobacillus curvatus,Staphylococcus gallinarum,Staphylococcus devriesei,Microbacteriumsp.,Sphingobacteriumsp.,Mycetocolasp.,Brevundimonassp.,Enterococcus faecalis, Proteussp., andKocuriasp. was detected in the raw milk using culturing methods, but onlyLactococcus lactisssp.lactis,Lactobacillus plantarum, andEnterococcus faecalissurvived to the final cheese and were detected both in the core and the rind. Using PCR denaturing gradient gel electrophoresis analysis of the cheese process samples,Staphylococcus equorumandEnterococcus duranswere found in the rind of prepiercing samples but not in the core and veins; after piercing, these species were found in all parts of the cheese but survived only in the rind when the cheese was fully ripened.Brevibacteriumsp.,Halomonassp.,Acinetobactersp.,Alkalibacteriumsp., andCorynebacterium caseiwere identified only by PCR denaturing gradient gel electrophoresis and not cultured from the samples.Brevibacteriumsp. was initially identified in the cheese postpiercing (core and veins),Halomonassp. was found in the matured cheese (rind), andAcinetobactersp.,Alkalibacteriumsp., andCorynebacterium caseiwere also found in the prepiercing samples (rind) and then found through the subsequent process stages. The work suggests that in this raw milk cheese, a limited community from the milk survive to the final cheese, with salt addition and handling contributing to the final cheese consortium.