Effects of controlling ripening conditions on the dynamics of the native microbial population of Mexican artisanal Cotija cheese assessed by PCR-DGGE

摘要

Diversity and dynamics of autochthonous microbiota of Cotija, a traditional Mexican raw-milk cheese that resembles Parmesan, were compared in cheeses during 90 days of ripening under traditional and controlled conditions (temperature and relative humidity). Molecular assessments by PCR-DGGE 26S and 16S rRNA encoding regions were performed on various sections of the cheese at different ripening times. A complex microbial profile was found differentially distributed in the cheese. Several spices of lacticacid-bacteria (LAB) from the genera Leuconostoc, Lactobacillus, Weissella, Aerococcus, Enterococcus, Carnobacterium and the yeasts Candida etchellsii, Pichia kudriavzevii and Moniliella suaveolens were found in the cheese matrix, with Leuconostoc mesenteroides being dominant. The cheese surface was populated by some of these microorganisms before the characteristic crust was formed, but Kluyveromyces lactis, Kodamaea ohmeri together with non-lactic-acid-bacteria (nLAB) Psychrobacter celer and Coiynebacter variabile became distinctive in this part of the cheese. The microbial spatial/temporal variations showed similar patterns in samples from both ripening conditions, which suggested a robust ecosystem that is likely responsible for the safety, sensorial richness, and potential bio-functionality of Cotija. This knowledge could open the possibility for standardizing the ripening operation to avoid defects and improve the marketing of the product. (C) 2015 Published by Elsevier Ltd.