Diversity of lactic acid bacteria population in ripened Parmigiano Reggiano cheese

The diversity of dominant lactic acid bacteria population in 12 months ripened Parmigiano Reggiano cheeses was investigated by a polyphasic approach including culture-dependent and independent methods. Traditional plating, isolation of LAB and identification by 16S rDNA analysis showed that strains belonging to Lactobacillus casei group were the most frequently isolated. Lactobacillus helveticus, Lactobacillus delbrueckii subsp. lactis, Lactobacillus parabuchneri, and Lactobacillus buchneri species were detected with lower frequency. PCR-denaturing gradient gel electrophoresis (DGGE) applied to DNA extracted directly from cheese samples and sequencing of rDNA amplicons confirmed the complex microbiological pattern of LAB in ripened Parmigiano Reggiano cheeses, with the significant exception of the Lactobacillus fermentum species, which dominated in several samples, but was not detected by cultivation. The present combination of different approaches can effectively describe the lactic acid bacteria population of Parmigiano Reggiano cheese in advanced stages of ripening, giving useful information for elucidating the role of LAB in determining the final cheese quality.