Polyphasic Characterization of Microbiota of “Mastredda”, a Traditional Wooden Tool Used during the Production of PDO Provola dei Nebrodi Cheese

Abstract

The biofilms of the wooden tables used for the acidification of the curd were investigated for PDO Provola dei Nebrodi cheese, a traditional stretched cheese made in eastern Sicily (southern Italy) from raw cows’ milk. To this purpose the wooden tables of four dairy facilities were analysed for their microbiota by scanning electron microscopy (SEM) analysis and a combined culture-independent and -dependent microbiological approach. SEM inspection showed an almost continuous biofilm formation. MiSeq Illumina analysis identified 8 phyla, 16 classes, 25 orders, 47 families and 50 genera. Corynebacterium, Bifidobacterium and lactic acid bacteria (LAB) were detected in all samples. In particular, the LAB genera detected on all wooden tables were Lactobacillus, Streptococcus and Lactococcus. LAB dominated the surfaces of all wooden tables with levels higher than 7.0 Log CFU/cm2. In particular, the LAB found at the highest levels were mesophilic cocci. Coagulase positive staphylococci, Salmonella spp., Listeria monocytogenes and Shiga-toxigenic Escherichia coli were never detected. Twenty-seven dominating LAB strains were identified within the genera Enterococcus, Lactobacillus, Lacticaseibacillus, Lactiplantibacillus, Levilactobacillus, Lactococcus, Leuconostoc, Pediococcus and Streptococcus. This work showed that the wooden table used during the production of PDO Provola dei Nebrodi cheese is a safe system and a microbiologically active tool.