Remodeling of the Streptococcus agalactiae transcriptome in response to growth temperature

ABSTRACT: To understand the extent to which GBS modify gene expression in response to temperatures encountered in the various hosts, we conducted a whole genome transcriptome analysis of organisms grown at 30°C and 40°C. We identified extensive transcriptome remodeling at various stages of growth, especially in the stationary phase (significant transcript changes occurred for 25% of the genes). A large proportion of genes involved in metabolism was up-regulated at 30°C in stationary phase, which reflects a slowing of bacterial metabolism in the early stages of its shift to growth at lower temperature followed by an acceleration in the later stages. Conversely, genes up-regulated at 40°C relative to 30°C include those encoding virulence factors such as hemolysins and extracellular secreted proteins with LPXTG motifs. Over-expression of hemolysins was linked to larger zones of hemolysis and enhanced hemolytic activity at 40°C. A key theme identified by our study was that genes involved in purine metabolism and iron acquisition were significantly up-regulated at 40°C. Three cultures of GBS grown in rich Todd-Hewitt Yeast extract medium at 30°C and three cultures grown at 40°C served as a source of RNA samples collected at mid-logarithmic phase, late-logarithmic phase, and stationary growth phase. RNA was isolated using a modified Trizol method, and targets for hybridization with custom Affymetrix chip were generated as we have described previously. Genes with 30°C/40°C ratio greater than 2 and less than 0.5 (P value less than 0.05), were considered differentially expressed.

ORGANISM(S): Streptococcus agalactiae

SUBMITTER: Izabela Sitkiewicz 

PROVIDER: E-GEOD-11666 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress