BioProject

Sourdough is a very competitive and challenging environment for microorganisms. More...

Sourdough is a very competitive and challenging environment for microorganisms. Usually, a stable microbiota composed of lactic acid bacteria (LAB) and yeasts comes to dominate this ecosystem. Although rich in carbohydrates, thus providing an ideal environment to grow, the low pH presents a particular challenge. The nature of the adaptation to this low pH was investigated for Lactobacillus plantarum IMDO 130201, an isolate from a laboratory wheat sourdough fermentation. Batch fermentations were carried out in wheat sourdough simulation medium, and total RNA was isolated from mid-exponential growth phase cultures, followed by differential gene expression analysis using a LAB functional gene microarray. At low pH values, an increased expression of genes involved in peptide and amino acid metabolism was observed as well as of genes involved in plantaricin production and lipoteichoic acid synthesis. The results highlight cellular mechanisms that allow L. plantarum to function at a low environmental pH. Overall design: The labeled aRNA samples were hybridized using a loop design, i.e. two consecutive samples (e.g., pH 3.5 and pH 4.0, pH 4.0 and pH 4.5, etc.) were hybridized on the same microarray slide, each labeled with another fluorescent dye (Cy3 or Cy5), and the loop was closed by hybridizing sample pH 5.5 together with sample pH 3.5. Less...