Characterization of Bacterial Communities during the Production of Bola Cheese by Pyrosequencing

Introduction: Mexican artisanal cheese made with raw milk such as Bola cheese, is considered a high-risk product. Pasteurization eliminates pathogens from raw milk, but also microorganisms that produce desired sensorial characteristics. By knowing the dynamics of microbial communities during a traditional cheese production process, this could help to detect bacteria that can be used as starter cultures to produce desirable sensorial characteristics in cheese produced with pasteurized milk.

Purpose: To characterize bacterial communities through the Bola cheese production process and to identify bacteria that could be used as starter cultures, by pyrosequencing analysis.

Methods: A total of 24 samples consisting of milk, curd and cheese ripened for 50 and 110 days were obtained during dry and rainy season from 3 producers of Bola cheese. Total DNA was extracted from samples and sent to Molecular Research DNA Laboratory (Shallowater, TX) for DNA sequencing of 16S region amplified using primers 27Fmod (5’-AGRGTTTGATMTGGCTCAG-3’) and 530R (CCGCNGCNGCTGGCAC). Pyrosequencing was performed with Roche 454 FLX titanium instruments and reagents. The sequence database was processed using Mothur software.

Results: Dairy samples collected from each producer in both seasons had a different bacteria composition. No pathogenic bacteria were found in any step of the process. Predominant genera in raw milk consisted in Streptococcus, Lactococcus, Lactobacillus, Macrococcus and Staphylococcus; also environmental microorganisms were present. In curd and cheeses, the predominant species were Streptococcus thermophilus, Lactococcus lactis, Lactobacillus helveticus, Lactobacillus plantarum, Lactobacillus delbrueckii and Enterococcus faecium.

Significance: It was possible to identify bacteria that could be used as a starter culture, which in combination with pasteurized milk in production of Bola cheese could generate high quality and safe products with desirable sensorial characteristics. The information generated in this work would be useful for producers of Bola cheese, by helping them standardize the production process, in establishing provenance, and to preserve a traditional food that supports the economy of local producers and their families.