To obtain comparable 2-DE gels between samples issued from bacteria grown on the two carbohydrates in our recent proteomic analysis, growth on ribose was enhanced by adding small amounts of glucose [19]. For the present transcriptome analysis we therefore chose the same growth conditions. Global gene expression patterns A microarray representing the L. sakei 23K genome and an additional set of sequenced L. sakei

genes was used for studying the effect of carbon source on the transcriptome of L. sakei strains 23K, MF1053 and LS 25. Genes displaying a significant differential expression with a log2 ratio > 0.5 or < -0.5 were classified into functional categories according to the L. sakei 23K genome database http://​migale.​jouy.​inra.​fr/​sakei/​genome-server and are listed in Table 1. The 23K strain showed differential expression for 364 genes within these limits, MF1053 and LS 25 for 223 and 316 genes, respectively. find more Among these, 88, 47 and 82, respectively, were ABT 263 genes belonging to the category of genes of ‘unknown’ function. Eighty three genes, the expression of which varied depending on the carbon source, were common to the three strains, among which 52 were up-regulated and 31 down-regulated during growth on ribose (Figure 1). The function of these common regulated genes was mostly related to carbohydrate transport and metabolism (34 genes, Table 1). The reliability of the microarray results Phloretin was assessed by qRT-PCR analysis

using selected regulated genes in the LS 25 strain. As shown in Table S4 in the additional material (Additional file 1), the qRT-PCR results were in agreement with the data obtained by the microarrays. Table 1 Genes with significant differential expression in three L.

sakei strains grown on ribose compared with glucose, FDR adjusted p-value less than 0.01 and log2 of > 0.5 or < -0.5 (log2 values > 1.0 or < -1.0 are shown in bold). Gene locus Gene Description 23K MF1053 LS 25 Carbohydrate transport and metabolism Transport/binding of carbohydrates LSA0185* galP Galactose:cation symporter 1.2   1.7 LSA0200* rbsU Ribose transport protein 2.8 3.5 4.3 LSA0353* lsa0353 Putative cellobiose-specific PTS, enzyme IIB 3.6 1.3 2.5 LSA0449* manL Mannose-specific PTS, enzyme IIAB 2.1 2.5 1.5 LSA0450* manN Mannose-specific PTS, enzyme IIC 1.9 2.0 1.4 LSA0451* manM Mannose-specific PTS, enzyme IID 2.4 1.0 2.1 LSA0651* glpF Glycerol uptake facilitator protein, MIP family 3.4 4.7 3.4 LSA1050* fruA Fructose-specific PTS, enzyme IIABC     0.9 LSA1204* lsa1204 Putative sugar transporter   1.1   LSA1457* lsa1457 Putative cellobiose-specific PTS, enzyme IIC   2.3   LSA1462* ptsI PTS, enzyme I 0.8 1.7 0.9 LSA1463* ptsH Phosphocarrier protein HPr (histidine protein)   1.2 0.9 LSA1533 lsa1533 Putative cellobiose-specific PTS, enzyme IIA   2.5 2.1 LSA1690 lsa1690 Putative cellobiose-specific PTS, enzyme IIC 0.9     LSA1792* scrA Sucrose-specific PTS, enzyme IIBCA 0.8   1.