Project description:In this study, we investigated the transcriptional response of the human isolate L. reuteri ATCC 55730 during sourdough fermentation by using whole-genome microarrays. Significant changes of mRNA levels were found for 101 genes involved in diverse cellular processes, e.g., carbohydrate and energy metabolism, cell envelope biosynthesis, exopolysaccharide production, stress responses, signal transduction and cobalamin biosynthesis. Our results evidence extensive changes of the organism’s gene expression to the growth in sourdough as compared to the growth in chemically defined medium, and thus allowed us to uncover pathways involved in the adaptation of L. reuteri to the ecological niche of sourdough. An impact of several genes of L. reuteri for effective growth in sourdough was shown by implementation of mutant strains in sourdough fermentation. This study contributes to the understanding of the molecular fundamentals of L. reuteri’s ecological competitiveness, and provides a basis for further exploration of genetic traits involved in adaptation to the food and/or intestinal environment. Keywords: environment-specific gene expression, sourdough fermentation, chemically defined medium, dye swap
Project description:This SuperSeries is composed of the following subset Series: GSE15686: Meta-transcriptome analysis of a natural wheat sourdough ecosystem during a 10-day spontaneous laboratory fermentation (I) GSE15691: Meta-transcriptome analysis of a natural spelt sourdough ecosystem during a 10-day spontaneous laboratory fermentation (I) GSE15692: Meta-transcriptome analysis of a natural spelt sourdough ecosystem during a 10-day spontaneous laboratory fermentation (II) GSE15693: Meta-transcriptome analysis of a natural wheat sourdough ecosystem during a 10-day spontaneous laboratory fermentation (II) Refer to individual Series
Project description: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. 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.
Project description: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.
