Metabolic Profiles of Carbohydrates in Streptococcus thermophilus During pH-Controlled Batch Fermentation

Abstract

Revealing the metabolic profiles of carbohydrates with their regulatory genes and metabolites is conducive to understanding their mechanism of utilization in Streptococcus thermophilus MN-ZLW-002 during pH-controlled batch fermentation. Transcriptomics and metabolomics were used to study carbohydrate metabolism. More than 200 unigenes were involved in carbohydrate transport. Of these unigenes, 55 were involved in the phosphotransferase system (PTS), which had higher expression levels than those involved in ABC protein-dependent systems, permeases, and symporters. The expression levels of the genes involved in the carbohydrate transport systems and phosphate transport system were high at the end-lag and end-exponential growth phases, respectively. In addition, 166 differentially expressed genes (DEGs) associated with carbohydrate metabolism were identified. Most genes had their highest expression levels at the end-lag phase. The pfk, ldh, zwf, and E3.2.1.21 genes involved in the glycolytic pathway had higher expression levels at the end-exponential growth phase than the mid-exponential growth phase. The results showed high expression levels of lacZ and galKTM genes and reabsorption of extracellular galactose. S. thermophilus MN-ZLW-002 can metabolize and utilize galactose. Overall, this comprehensive network of carbohydrate metabolism is useful for further studies of the control of glycolytic pathway during the high-density culture of S. thermophilus.

Impact of Probiotics on the Salivary Microbiota and Salivary Levels of Inflammation-Related Proteins during Short-Term Sugar Stress: A Randomized Controlled Trial

“…Importantly, the carbohydrate metabolism of many Streptococcus species, including Streptococcus salivarius , was thoroughly characterized decades ago using culture-based microbial analysis [ 22 ]. Indeed, when used in combination with modern molecular techniques such as transcriptomics and metabolomics, traditional culture-based techniques provide detailed data on genes and pathways involved in carbohydrate metabolism of Streptococcus species [ 23 ]. However, such analysis most often involves characterization of specific species grown in monoculture in the laboratory, which hampers the possibility to evaluate the phenotypic profile of the species of interest when this is part of a polymicrobial biofilm competing on available nutrients in vivo.…”

Effects of different carbon sources on metabolic profiles of carbohydrates in Streptococcus thermophilus during fermentation

“…The Leloir pathway is a common galactose metabolism pathway in lactic acid bacteria that involves genes such as lacS (encoding lactose permease), lacZ (encoding ⊎-galactosidase) and galKTEM. 21,36 According to our results, the expression of lacSZ and galKTEM was significantly higher from the lag phase to the midexponential growth phase, when CcpA was lower, and lactose was rapidly hydrolyzed. However, when lactose was completely hydrolyzed and glucose and galactose were present in the medium, CcpA exerted a CCR effect with a rapid increase in expression, whereas the expression levels of lacSZ decreased significantly (at T3 stage).…”

“…Lactose (a non‐PTS sugar) is a very good substrate on which microbial growth occurs even faster than on PTS sugars such as sucrose, which is consistent with the results of the present study indicating that S. thermophilus preferred lactose as the main source of carbon and energy. The Leloir pathway is a common galactose metabolism pathway in lactic acid bacteria that involves genes such as lacS (encoding lactose permease), lacZ (encoding β‐galactosidase) and galKTEM 21,36 …”

“…Hence, transcriptome analysis enables comprehension of the relationship between gene expression and host metabolism 19,20 . Using integrated analyses of metabolomic and transcriptomic data, researchers have found that genes involved in lactose transport and metabolism were significantly up‐regulated in S. thermophilus MN‐ZLW‐002 when lactose was used as the carbon source 21 . To guide high‐density fermentation, Huang et al 22 .…”

Time-course analysis of Streptococcus sanguinis after manganese depletion reveals changes in glycolytic and nucleic acid metabolites

“…Diverse mass spectrometry platforms such as LC–MS/MS, GC–MS and CE–MS with and without chromatography, and spectroscopy technologies such as NMR have enabled high-throughput discovery metabolomics in various biological systems, including bacteria, plants, and humans (Misra & Olivier, 2020 ). Recent studies have described the metabolomes of certain streptococci using various mass spectrometry methods: Streptococcus intermedius under various oxygen conditions (Fei et al, 2016 ); Streptococcus pneumoniae in chemically defined medium (Leonard et al, 2018 ); and Streptococcus thermophilus in pH-controlled batch fermentation (Liu et al, 2020 ; Qiao et al, 2019 ). To our knowledge, the metabolome of S. sanguinis has yet to be investigated.…”