Streptococcus thermophilus is a bacterium widely used in the production of yogurts and cheeses, where it efficiently ferments lactose, the saccharide naturally present in milk. It is also employed as a starter in dairy- or plant-based fermented foods that contain saccharides other than lactose (e.g., sucrose, glucose). However, little is known about how saccharide use is regulated, in particular when saccharides are mixed. Here, we determine the effect of the 5 sugars that S. thermophilus is able to use, at different concentration and when they are mixed on the promoter activities of the C-metabolism genes. Using a transcriptional fusion approach, we discovered that lactose and glucose modulated the activity of the lacS and scrA promoters in a concentration-dependent manner. When mixed with lactose, glucose also repressed the two promoter activities; when mixed with sucrose, lactose still repressed scrA promoter activity. We determined that catabolite control protein A (CcpA) played a key role in these dynamics. We also showed that promoter activity was linked with glycolytic flux, which varied depending on saccharide type and concentration. Overall, this study identified key mechanisms in carbohydrate metabolism - autoregulation and partial hierarchical control - and demonstrated that they are partly mediated by CcpA.
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http://dx.doi.org/10.1016/j.fm.2024.104487 | DOI Listing |
Microorganisms
December 2024
Food Animal Environmental Systems Research Unit, Agricultural Research Service, United States Department of Agriculture, 2413 Nashville Road, Suite B5, Bowling Green, KY 42101, USA.
In a previous experiment, we showed that the odor of manure slurries could be improved by anaerobic incubation with the sugars glucose, lactose, and sucrose. This improvement was due to reductions in the concentrations of malodorants, including dimethyl disulfide, -cresol, -ethylphenol, indole, and skatole, and a shift to the production of fruity esters, including ethyl butyrate and propyl propanoate. Due to large concentrations of lactic acid produced by the sugar-amended manure slurries, we inferred that lactic acid bacteria were involved in improving the manure slurry odor.
View Article and Find Full Text PDFJ Gastroenterol Hepatol
January 2025
Faculty of Medicine, Division of Gastroenterology, Department of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia.
Background: Gas production due to fermentation from fructose malabsorption (FM) or lactose malabsorption (LM) and small intestinal bacterial overgrowth (SIBO) contribute to the development of gastrointestinal symptoms in patients with irritable bowel syndrome (IBS). However, the impact of the carbohydrate malabsorption, unlike SIBO, is relatively unknown.
Methodology: A multicenter, prospective study of consecutive adults with IBS who underwent a hydrogen breath test (HBT) (glucose, 75 g; lactose, 25 g; or fructose, 25 g) was conducted.
N Biotechnol
January 2025
Institute for Food and Environmental Research (ILU), Bad Belzig, Germany; Leuphana University Lüneburg, Institute of Sustainable Chemistry, Lüneburg, Germany. Electronic address:
of this study was to investigate the by-products acid whey and oat pomace as nutrient sources for succinic acid production by Actinobacillus succinogenes. Both by-products provide carbon sources in form of glucose and/or lactose without any pre-treatment. Yields of succinic acid per g total sugars consumed after 24 h were between 0.
View Article and Find Full Text PDFSci Rep
January 2025
Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran.
The g-C3N4/CS biosensor was designed, fabricated, and tested using compounds such as glucose, urine, lactose, and flutamide at a molarity of 10 µM, which could demonstrate a high sensitivity of 200 μm-1 for flutamide. Powerful effective medium theory and FDTD simulation were used to predict the most favorable mode and plasmonic properties of a graphite carbon nitride and chitosan nanocomposite. The research also explores the characteristics of surface plasmon resonance exhibited by the nanocomposite as the chitosan content is adjusted.
View Article and Find Full Text PDFBioresour Technol
January 2025
State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu 214122, China.
2'-Fucosyllactose (2'-FL) is the most abundant human milk oligosaccharide (HMO) and has been approved to be commercially added to infant formula. Microbial synthesis from exogenous lactose via metabolic engineering is currently the major approach to production of 2'-FL. Replacement of lactose with cheaper sugars such as glucose and sucrose has been studied to reduce the production costs.
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