Phenotypic, genotypic and technological characterization of predominant lactic acid bacteria in Pecorino cheese from central Italy

Abstract

Identification and biotyping of lactic acid bacteria (LAB) isolated from raw-milk Pecorino cheese manufactured in the Marche region (central Italy) for selection of suitable starter cultures or adjuncts. Preliminary characterization with morphological and biochemical assays were undertaken for 112 Gram-positive and catalase-negative isolates. Unequivocal identification of the isolates was obtained through restriction analysis of the amplified 16S rRNA gene and sequencing of 360-380 bp amplicons. Fifty-nine isolates belonging to LAB species generally recognized as safe and potentially utilized as starters or flavour-producing adjuncts were preselected and tested for their acidifying, proteolitic and autolytic activities. Fifty-five of these isolates were also subject to RAPD (randomly amplified polymorphic DNA) fingerprinting and unweighted pair-group method with arithmetic averages (UPGMA) cluster analysis for the estimation of genotypic intra-species variation. As a result, in Pecorino cheese, a heterogeneous lactic acid bacteria population, which includes strains with metabolic characteristics of technological interest, was characterized. The polyphasic approach proposed allows the bacterial ecology of Pecorino cheese to be investigated and allows to assess the potential role of autochthonous LAB strains for the dairy industry. The great economic importance of Pecorino cheese encouraged a deeper knowledge of its microbiota, which is known to influence the peculiar sensory properties of this cheese, also in view of its exploitation.