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Microbiology Spectrum Jun 2017Lactobacilli occupy a unique position in human culture and scientific history. Like brewer's and baker's yeast, lactobacilli have been associated with food production... (Review)
Review
Lactobacilli occupy a unique position in human culture and scientific history. Like brewer's and baker's yeast, lactobacilli have been associated with food production and preservation for thousands of years. species are used in mixed microbial cultures, such as the classical / inoculum for yogurt fermentation, or combinations of diverse lactobacilli/yeasts in kefir grains. The association of lactobacilli consumption with greater longevity and improved health formed the basis for developing lactobacilli as probiotics, whose market has exploded worldwide in the past 10 years. The decade that followed the determination of the first genome sequence of a food-associated species, , saw the application to lactobacilli of a full range of functional genomics methods to identify the genes and gene products that govern their distinctive phenotypes and health associations. In this review, we will briefly remind the reader of the range of beneficial effects attributed to lactobacilli, and then explain the phylogenomic basis for the distribution of these traits across the genus. Recognizing the strain specificity of probiotic effects, we review studies of intraspecific genomic variation and their contributions to identifying probiotic traits. Finally we offer a perspective on classification of lactobacilli into new genera in a scheme that will make attributing probiotic properties to clades, taxa, and species more logical and more robust.
Topics: Fermentation; Food Microbiology; Genetic Variation; Genome, Bacterial; Genomics; Humans; Kefir; Lactobacillus; Membrane Proteins; Phylogeny; Probiotics; Streptococcus thermophilus; Yeasts; Yogurt
PubMed: 28643623
DOI: 10.1128/microbiolspec.BAD-0011-2016 -
Journal of Dairy Science Aug 2022Free exopolysaccharide (f-EPS) produced by Streptococcus thermophilus improves the texture and functionality of fermented dairy foods. Our previous study showed a major...
Free exopolysaccharide (f-EPS) produced by Streptococcus thermophilus improves the texture and functionality of fermented dairy foods. Our previous study showed a major improvement in f-EPS production of Strep. thermophilus 937 by increasing the concentrations of histidine, isoleucine, and glutamate to 15 mM in an optimized chemically defined medium. The aim of this study was to elucidate the effect of His, Ile, and Glu on the growth, f-EPS biosynthesis pathway, and carbohydrate metabolism profiles of Strep. thermophilus 937. The growth kinetics; transcript levels of key genes in the EPS biosynthesis pathway; enzyme activity involved in sugar nucleotide synthesis; concentrations of lactic acid, lactose, and galactose; and extracellular and intracellular pH were analyzed in chemically defined media with different initial histidine, isoleucine, and glutamate concentrations. The results showed that f-EPS production and viable cell counts of Strep. thermophilus 937 increased 2-fold after the concentrations of His, Ile, and Glu were increased. Additionally, increasing the concentrations of His, Ile, and Glu upregulated transcription of EPS biosynthesis genes and increased the activity of key enzymes in sugar nucleotide synthesis. Moreover, the consumption of lactose increased and secretion of galactose decreased, indicating that increasing the concentration of His, Ile, and Glu could enhance f-EPS production by maintaining viable cell counts, promoting sugar nucleotide synthesis, and increasing the transcript levels of the eps gene cluster. Our results provide a better understanding of the effect of AA on EPS biosynthesis in Strep. thermophilus.
Topics: Amino Acids; Animals; Fermentation; Galactose; Glutamates; Histidine; Isoleucine; Lactose; Nucleotides; Polysaccharides, Bacterial; Streptococcus thermophilus; Sugars
PubMed: 35691747
DOI: 10.3168/jds.2022-21814 -
Current Opinion in Biotechnology Feb 2020Streptococcus thermophilus is a microorganism extensively used in cheese and yogurt fermentation. Its economic value, combined with an increasing demand for novel... (Review)
Review
Streptococcus thermophilus is a microorganism extensively used in cheese and yogurt fermentation. Its economic value, combined with an increasing demand for novel starter cultures with improved functionality, foster numerous research efforts to unravel key aspects of S. thermophilus physiology. Several phenotypic traits are linked to industrial applications. These include sugar metabolism, proteolysis and the production of important metabolites such as acetaldehyde, exopolysaccharides, and vitamins, which affect the organoleptic properties of fermented foods and protocooperation with Lactobacillus delbrueckii subsp. bulgaricus. The advent of new molecular tools including a genome editing toolbox facilitates engineering S. thermophilus for physiological studies as well as generating strains with improved technological and/or functional characteristics.
Topics: Biotechnology; Fermentation; Lactobacillus delbrueckii; Streptococcus thermophilus; Yogurt
PubMed: 31945498
DOI: 10.1016/j.copbio.2019.12.019 -
Brazilian Journal of Microbiology :... Mar 2023The growth of the lactic acid bacteria (LAB), Streptococcus thermophilus and Lactobacillus bulgaricus, widely used for yogurt production, results in acid production and...
The growth of the lactic acid bacteria (LAB), Streptococcus thermophilus and Lactobacillus bulgaricus, widely used for yogurt production, results in acid production and the reduction of the milk [Formula: see text]. Industrial processes can show temperature ([Formula: see text]) changes due to the large scale of the equipment. As [Formula: see text] and [Formula: see text] affect the LAB growth, this study aimed to model the dependence of S. thermophilus and L. bulgaricus as a function of temperature and pH and to estimate and internally validate their growth parameters and confidence intervals with different modeling approaches. Twenty-four datasets regarding the growth kinetics of S. thermophilus and L. bulgaricus were used for estimating the kinetic parameters for each pure culture. The classical Baranyi and Roberts (sigmoidal) primary and Rosso and coworkers (cardinal parameter) secondary models successfully described the experimental data. The one-step modeling approach showed better statistical results than the two-step approach. The values of eight growth parameters ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]) for each culture estimated from the fitting with the one-step approach and the Monte-Carlo-based approach were similar. Low averaged root-mean-squared errors ([Formula: see text]) (0.125 and 0.090 log CFU/mL) and percent discrepancy factor [Formula: see text] ([Formula: see text] and [Formula: see text]) values for S. thermophilus and L. bulgaricus were obtained in the internal model validation, reinforcing the predictive ability of the model.
Topics: Lactobacillus delbrueckii; Streptococcus thermophilus; Lactobacillus; Temperature; Hydrogen-Ion Concentration; Fermentation
PubMed: 36740644
DOI: 10.1007/s42770-023-00907-5 -
Applied and Environmental Microbiology Dec 2022The rhamnose-glucose polysaccharide (Rgp) of Streptococcus thermophilus represents a major cell wall component, and the gene cluster responsible for its biosynthesis...
The rhamnose-glucose polysaccharide (Rgp) of Streptococcus thermophilus represents a major cell wall component, and the gene cluster responsible for its biosynthesis (termed ) has recently been identified. Significant genetic diversity among these loci has previously been reported, with five distinct genotypes identified (designated through -). In the present study, two additional genotypes were identified (designated and ) through comparative analysis of the loci of 78 Streptococcus thermophilus genomes. The locus of a given S. thermophilus strain encoded the biosynthetic machinery for a rhamnan-rich backbone and a variable side chain component, the latter being associated with the highly specific interactions with many bacteriophages that infect this species. The chemical structure of the Rgp from three S. thermophilus strains, representing the , , and -4 genotypes, was elucidated, and based on bioinformatic and biochemical analyses we propose a model for Rgp biosynthesis in dairy streptococci. Furthermore, we exploited the genetic diversity within the S. thermophilus bipartite locus to develop a two-step multiplex PCR system to classify strains based on gene content associated with the biosynthesis of the variable side chain structure as well as the rhamnan backbone. Streptococcus thermophilus is present and applied in industrial and artisanal dairy fermentations for the production of various cheeses and yogurt. During these fermentations, S. thermophilus is vulnerable to phage predation, and recent studies have identified the rhamnose-glucose polymer (Rgp) as the definitive receptor for at least one problematic phage species. Detailed analysis of S. thermophilus loci has revealed an unprecedented level of genetic diversity, particularly within the glycosyltransferase-encoding gene content of a given locus. Our study shows that this genetic diversity reflects the biochemical structure(s) of S. thermophilus Rgp. As such, we harnessed the genetic diversity of S. thermophilus loci to develop a two-step multiplex PCR method for the classification of strain collections and, ultimately, the formation of phage-robust rational starter sets.
Topics: Streptococcus thermophilus; Rhamnose; Cell Wall; Polysaccharides; Yogurt
PubMed: 36350137
DOI: 10.1128/aem.01504-22 -
Journal of Molecular Biology Jan 2017Clustered regularly interspaced short palindromic repeat (CRISPR) loci and their flanking CRISPR-associated (cas) genes make up RNA-guided, adaptive immune systems in... (Review)
Review
Clustered regularly interspaced short palindromic repeat (CRISPR) loci and their flanking CRISPR-associated (cas) genes make up RNA-guided, adaptive immune systems in prokaryotes whose effector proteins have become powerful tools for basic research and biotechnology. While the Cas effector proteins are remarkably diverse, they commonly rely on protospacer-adjacent motifs (PAMs) as the first step in target recognition. PAM sequences are known to vary considerably between systems and have proven to be difficult to predict, spurring the need for new tools to rapidly identify and communicate these sequences. Recent advances have also shown that Cas proteins can be engineered to alter PAM recognition, opening new opportunities to develop CRISPR-based tools with enhanced targeting capabilities. In this review, we discuss the properties of the CRISPR PAM and the emerging tools for determining, visualizing, and engineering PAM recognition. We also propose a standard means of orienting the PAM to simplify how its location and sequence are communicated.
Topics: Amino Acid Motifs; CRISPR-Cas Systems; Clustered Regularly Interspaced Short Palindromic Repeats; DNA, Bacterial; Gene Library; Genetic Loci; Plasmids; Protein Engineering; RNA; Staphylococcus epidermidis; Streptococcus thermophilus
PubMed: 27916599
DOI: 10.1016/j.jmb.2016.11.024 -
Biological & Pharmaceutical Bulletin Mar 2021It is well documented that obesity and metabolic syndrome have a deep association with the intestinal immune system of the host animal. Recent studies indicate that some...
It is well documented that obesity and metabolic syndrome have a deep association with the intestinal immune system of the host animal. Recent studies indicate that some selected probiotics can modulate the immune responses of the host animal, thereby altering its lipid metabolism. However, the underlying mechanisms are still not fully understood. This study was conducted to investigate the possibility of probiotics to activate macrophages in the hosts, thus alter the differentiation of pre-adipocytes. In this study, Streptococcus thermophilus MN-ZLW-002 (MN-ZLW-002) was co-cultured with RAW264.7 macrophages, with Lactobacillus rhamnosus GG (LGG) as a control. The conditioned medium (CM) of the co-culture was collected and then added to 3T3-L1 pre-adipocytes. Viable and heat-killed (80 °C, 30 min) MN-ZLW-002 stimulated RAW264.7 cells to produce significant amounts of interleukin (IL)-6 and tumor necrosis factor (TNF)-α and induced intense phosphorylation of P38, p44/42 mitogen-activated protein kinase (MAPK) (extracellular signal-regulated kinase (ERK)) and nuclear factor κB (NF-κB). Cytokine production reduced dramatically when heat-killed MN-ZLW-002 was treated with Ribonuclease. Viable and heat-killed LGG induced less cytokine production and little signaling protein activation. Viable and heat-killed MN-ZLW-002-stimulated RAW264.7-CM notably suppressed pre-adipocytes differentiation. However, viable LGG-stimulated RAW264.7-CM had a weaker effect and heat-killed LGG-stimulated RAW264.7-CM had no effect. These findings suggest that viable and heat-killed (80 °C, 30 min) MN-ZLW-002 may alter its lipid metabolism by regulating its immune response, possibly via the release of cytokine, particularly TNF-α. The RNA of heat-killed MN-ZLW-002 may be a key component in its immune activation effect.
Topics: 3T3-L1 Cells; Adipocytes; Animals; Cell Differentiation; Coculture Techniques; Cytokines; Lipid Metabolism; Macrophage Activation; Mice; Mitogen-Activated Protein Kinases; NF-kappa B; RAW 264.7 Cells; Streptococcus thermophilus
PubMed: 33390424
DOI: 10.1248/bpb.b20-00335 -
Nature Communications Dec 2023Cheese fermentation and flavour formation are the result of complex biochemical reactions driven by the activity of multiple microorganisms. Here, we studied the roles...
Cheese fermentation and flavour formation are the result of complex biochemical reactions driven by the activity of multiple microorganisms. Here, we studied the roles of microbial interactions in flavour formation in a year-long Cheddar cheese making process, using a commercial starter culture containing Streptococcus thermophilus and Lactococcus strains. By using an experimental strategy whereby certain strains were left out from the starter culture, we show that S. thermophilus has a crucial role in boosting Lactococcus growth and shaping flavour compound profile. Controlled milk fermentations with systematic exclusion of single Lactococcus strains, combined with genomics, genome-scale metabolic modelling, and metatranscriptomics, indicated that S. thermophilus proteolytic activity relieves nitrogen limitation for Lactococcus and boosts de novo nucleotide biosynthesis. While S. thermophilus had large contribution to the flavour profile, Lactococcus cremoris also played a role by limiting diacetyl and acetoin formation, which otherwise results in an off-flavour when in excess. This off-flavour control could be attributed to the metabolic re-routing of citrate by L. cremoris from diacetyl and acetoin towards α-ketoglutarate. Further, closely related Lactococcus lactis strains exhibited different interaction patterns with S. thermophilus, highlighting the significance of strain specificity in cheese making. Our results highlight the crucial roles of competitive and cooperative microbial interactions in shaping cheese flavour profile.
Topics: Animals; Cheese; Acetoin; Diacetyl; Lactococcus lactis; Streptococcus thermophilus; Fermentation; Milk; Food Microbiology
PubMed: 38129392
DOI: 10.1038/s41467-023-41059-2 -
Cell Jun 2018
Topics: Bacteriophages; CRISPR-Cas Systems; Escherichia coli; Gene Editing; Haloferax volcanii; Immunity; Streptococcus thermophilus
PubMed: 29906440
DOI: 10.1016/j.cell.2018.05.055 -
Microbial Cell Factories Jun 2020Streptococcus thermophilus is an important food starter and receiving more attention to serve as cell factories for production of high-valued metabolites. However, the...
BACKGROUND
Streptococcus thermophilus is an important food starter and receiving more attention to serve as cell factories for production of high-valued metabolites. However, the low yields of intracellular or extracellular expression of biotechnological and biomedical proteins limit its practical applications.
RESULTS
Here, an enolase EnoM was identified from S. thermophilus CGMCC7.179 with about 94% identities to the surface-located enolases from other Streptococcus spp. strains. The EnoM was used as an anchor to achieve surface display in S. thermophilus using GFP as a reporter. After respectively mixing the GFP-EnoM fusion protein or GFP with S. thermophilus cells in vitro, the relative fluorescence units (RFU) of the S. thermophilus cells with GFP-EnoM was 80-folds higher than that with purified GFP. The sharp decrease in the RFU of sodium dodecyl sulfate (SDS) pretreated cells compared to those of non-pretreated cells demonstrated that the membrane proteins were the binding ligand of EnoM. Furthermore, an engineered β-galactosidase (β-Gal) was also successfully displayed on the cell surface of S. thermophilus CGMCC7.179 and the relative activity of the immobilized β-Gal remained up to 64% after reused 8 times. Finally, we also demonstrated that EnoM could be used as an anchor for surface display in L. casei, L. bulgaricus, L. lactis and Leuconostoc lactis.
CONCLUSION
To our knowledge, EnoM from S. thermophilus was firstly identified as an anchor and successfully achieved surface display in LAB. The EnoM-based surface display system provided a novel strategy for the enzyme immobilization.
Topics: Bacterial Proteins; Membrane Proteins; Phosphopyruvate Hydratase; Streptococcus thermophilus
PubMed: 32552809
DOI: 10.1186/s12934-020-01389-y