cDNA-amplified fragment length polymorphism to study the transcriptional responses of Lactobacillus rhamnosus growing in cheese-like medium.

ABSTRACT

AIMS: Lactobacillus rhamnosus is a dominant species during Parmigiano Reggiano cheese ripening and exhibits a great adaptability to unfavourable growth conditions. Gene expression of a Lact. rhamnosus, isolated from Parmigiano Reggiano cheese, grown in a rich medium (MRS) and in a cheese-like medium (CB) has been compared by a novel cDNA-amplified fragment length polymorphism (cDNA-AFLP) protocol. METHODS AND RESULTS: Two techniques, capillary and gel electrophoresis cDNA-AFLP, were applied to generate unique transcript tags from reverse-transcribed messenger RNA using the immobilization of biotinylated 3'-terminal cDNA fragments on streptavidin-coated Dynabeads. The use of three pairs of primers allowed detecting 64 genes expressed in MRS and 96 in CB. Different transcripts were observed when Lact. rhamnosus was cultured on CB and MRS. CONCLUSIONS: The cDNA-AFLP approach proved to be able to show that Lact. rhamnosus modifies the expression of a large part of genes when cultivated in CB compared with growth under optimal conditions (MRS). In particular, the profiles of the strain grown in CB were more complex probably because the cells activate different metabolic pathways to generate energy and to respond to the environmental changes. SIGNIFICANCE AND IMPACT OF STUDY This is the first research on Lact. rhamnosus isolated from cheese and represents one of the few concerning bacterial transcriptomic analysis towards cDNA-AFLP approaches.