Microbial characterization and diversity of artisanal Ranchero cheese with emphasis in Lactococcus strains

Abstract

The aim of this work is to characterize the natural microflora of artisanal Ranchero cheese and to identify Lactococcus isolates. Ten artisanal Ranchero cheese samples made with raw milk were obtained from local producers located in different geographical areas. Aerobic mesophilic, Staphylococci, Psychrophilic, total coliforms, molds, yeast and, lactic acid bacteria (LAB) (Lactococcus, Streptococcus mesophilic and thermophilic, Lactobacillus, Enterococcus, Leuconostoc) were numbered through agar plating. LAB isolates were classified by genus. Then, nineteen randomly selected presumptive Lactococcus isolates were assigned to specie by PCR amplification and DNA sequence. A high number of aerobic mesophilic Staphylococci, Psychrophilic, total coliforms, molds, and yeast were found. Lactococci, mesophilic and thermophilic Streptococci and Lactobacilli were the dominant LAB. Enterococci and Leuconostoc were also present. The isolates were identified as L. lactis subsp. lactis and L. garvieae. And both were found to be the dominant Lactococcus species that could be selected and used in a starter culture. Sanitation deficiencies in the production of artisanal Ranchero cheese were evident, which may translate into being a potential consumers health risk factor.