Project description:Streptococcus gallolyticus subsp. gallolyticus is a commensal of the human gastrointestinal tract and a pathogen of infective endocarditis and other biofilm-associated infections with exposed collagen. Therefore, this study focuses on the characterization of the biofilm formation and collagen adhesion of S. gallolyticus subsp. gallolyticus under different conditions. It has been observed that lysozyme triggers biofilm formation divergently in the analyzed S. gallolyticus subsp. gallolyticus strains. The transcriptome analysis was performed for two strains which form more biofilm in the presence of lysozyme. Lysozyme leads to higher expression of genes of transcription and translation, of the dlt operon (cell wall modification), of hydrogen peroxide resistance proteins and of two immunity proteins which could be involved in biofilm formation. Furthermore, the adhesion ability of 73 different S. gallolyticus subsp. gallolyticus strains to collagen type I and IV was analyzed. High adhesion ability was observed for the strain UCN 34, whereas the strain DSM 16831 adhered only marginally to collagen. The full genome microarray analysis revealed strain-dependent gene expression due to adhesion. The expression of genes of a transposon and a phage region in strain DSM 16831 were increased, which corresponds to lateral gene transfer. Adherence to collagen leads to a change in the expression of genes of nutrients uptake in the strain UCN 34.
Project description:The present work aimed at discovering xylose-inducible and glucose-insensitive promoters from Geobacillus thermoglucosidasius DSM 2542. This strategy enabled the pathway from xylose metabolism to riboflavin production activated by xylose but not glucose, so that glucose was mainly used for cell growth while xylose was used for riboflavin production. By performing whole genome transcriptional analysis of G. thermoglucosidasius DSM 2542 with or without 1% xylose, 71 xylose-activated genes were identified which were controlled by 39 putative promoters. 3 experimentally validated xylose-inducible and glucose-insensitive promoters covering a broad range of transcriptional levels were used to activate the extra pathway from xylose metabolism to riboflavin production. Fermentation results showed the good performance of these promoters for riboflavin production improvement comparing to constitutive promoters. Therefore, our strategy could be applicable to the construction of cell factories that can efficiently use natural carbon sources with glucose and xylose components for the production of high-value chemicals.