For

this reason, in the present work, we focused our attention only on this strain, with the aim to identify the genes that could concur to explain its growth ability in CB and its acid acetic production. The physiological HDAC inhibitor adaptation of L. rhamnosus PR1019 in CB was evaluated using a transcriptomic approach, based on cDNA-amplified fragment length polymorphism (cDNA-AFLP) and quantitative real-time reverse transcription-PCR (qPCR). cDNA-AFLP is one of the most robust and sensitive transcriptomic technologies for genome-wide expression studies, with the main advantage of not requiring any prior knowledge of gene sequences while allowing the detection

of lowly expressed genes through transcript amplification Fosbretabulin concentration [19]. Using this approach, we identified a set of genes resulted over-expressed in CB compared to MRS, potentially involved in alternative metabolic pathways. Interesting find more genes were searched in other NSLAB and SLAB genomes with the aim to explore their diversity. Overall, the results described in this work highlight mechanisms of adaptation leading to the production of acetic acid coupled with ATP generation, that could support the L. rhamnosus growth in cheese during ripening. Methods Bacterial growth conditions L. rhamnosus PR1019 was isolated from Parmigiano Reggiano (PR) at 4 months of ripening on cheese based medium [10] plate counts and identified by 16S rDNA gene sequencing [11] and species-specific PCR [20]. The strain was cultivated in MRS broth (Oxoid) or Cheese Broth (CB) at 30°C, under anaerobiosis, for 24 or 48 h, respectively. CB, a culture medium that mimics raw-milk long-ripened cheese, was prepared according to the modified protocol described by Bove et al. [16, 18]. RNA extraction and cDNA synthesis The growth

of L. to rhamnosus PR1019 in MRS and CB broth was monitored by measuring optical density (OD) at 600 nm. About 109 cells at the top of logarithmic phase were harvested, and total RNA, stabilized with RNAprotect Bacteria Reagent (QIAGEN), was isolated using RNeasy Protect Bacteria Mini Kit (QIAGEN). Three independent biological experiment were made. RNA was quantified using a NanoDrop ND-1000 spectrophotometer (NanoDrop Technologies) and visualized by formaldehyde agarose gel electrophoresis according to standard procedures. All RNAs were of sufficient quantity (>350 ng/μl) and high quality (A260/A280 ratio 2.0 to 2.1). After a step of mRNA enrichment and polyadenylation of RNA transcripts, cDNA was synthesized by reverse transcription (RT) using a biotinylated oligo (dT), following the protocol reported by Bove et al. [18].