scholarly journals Cell Wall Glycans Mediate Recognition of the Dairy BacteriumStreptococcus thermophilusby Bacteriophages

2018 ◽  
Vol 84 (23) ◽  
Author(s):  
Paula Szymczak ◽  
Sérgio Raposo Filipe ◽  
Gonçalo Covas ◽  
Finn Kvist Vogensen ◽  
Ana Rute Neves ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Host Recognition ◽  
Structured Illumination ◽  
Sequencing Data ◽  
Structured Illumination Microscopy ◽  
Content Type ◽  
Type Phage

ABSTRACTReceptors on the cell surfaces of bacterial hosts are essential during the infection cycle of bacteriophages. To date, the phage receptors of the industrial relevant dairy starter bacteriumStreptococcus thermophilusremain elusive. Thus, we set out to identify cell surface structures that are involved in host recognition by dairy streptococcal phages. Five industrialS. thermophilusstrains sensitive to different phages (pactype,costype, and the new type 987), were selected to generate spontaneous bacteriophage-insensitive mutants (BIMs). Of these, approximately 50% were deselected as clustered regularly interspaced short palindromic repeat (CRISPR) mutants, while the other pool was further characterized to identify receptor mutants. On the basis of genome sequencing data, phage resistance in putative receptor mutants was attributed to nucleotide changes in genes encoding glycan biosynthetic pathways. Superresolution structured illumination microscopy was used to visualize the interactions betweenS. thermophilusand its phages. The phages were either regularly distributed along the cells or located at division sites of the cells. The cell wall structures mediating the latter type of phage adherence were further analyzed via phenotypic and biochemical assays. Altogether, our data suggested that phage adsorption toS. thermophilusis mediated by glycans associated with the bacterial cell surface. Specifically, thepac-type phage CHPC951 adsorbed to polysaccharides anchored to peptidoglycan, while the 987-type phage CHPC926 recognized exocellular polysaccharides associated with the cell surface.IMPORTANCEStreptococcus thermophilusis widely used in starter cultures for cheese and yoghurt production. During dairy fermentations, infections of bacteria with bacteriophages result in acidification failures and a lower quality of the final products. An understanding of the molecular factors involved in phage-host interactions, in particular, the phage receptors in dairy bacteria, is a crucial step for developing better strategies to prevent phage infections in dairy plants.

scholarly journals Differences in Lactococcal Cell Wall Polysaccharide Structure Are Major Determining Factors in Bacteriophage Sensitivity

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Stuart Ainsworth ◽  
Irina Sadovskaya ◽  
Evguenii Vinogradov ◽  
Pascal Courtin ◽  
Yann Guerardel ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Host Range ◽  
Variable Region ◽  
Cell Surface Receptor ◽  
Host Recognition ◽  
Cell Wall Polysaccharide ◽  
Subtype C ◽  
Content Type ◽  
Type C

ABSTRACTAnalysis of the genetic locus encompassing a cell wall polysaccharide (CWPS) biosynthesis operon of eight strains ofLactococcus lactis, identified as belonging to the same CWPS type C genotype, revealed the presence of a variable region among the strains examined. The results allowed the identification of five subgroups of the C type named subtypes C1to C5. This variable region contains genes encoding glycosyltransferases that display low or no sequence homology between the subgroups. In this study, we purified an acidic polysaccharide from the cell wall ofL. lactis3107 (subtype C2) and confirmed that it is structurally different from the previously established CWPS of subtype C1L. lactisMG1363. The CWPS ofL. lactis3107 is composed of pentasaccharide repeating units linked by phosphodiester bonds with the structure 6-α-Glc-3-β-Galf-3-β-GlcNAc-2-β-Galf-6-α-GlcNAc-1-P. Combinations of genes from the variable region of subtype C2were introduced into a mutant of subtype C1L. lactisNZ9000 deficient in CWPS biosynthesis. The resulting recombinant mutant synthesized a polysaccharide with a composition characteristic of that of subtype C2L. lactis3107 and not wild-type C1L. lactisNZ9000. By challenging the recombinant mutant with various lactococcal phages, we demonstrated that CWPS is the host cell surface receptor of tested bacteriophages of both the P335 and 936 groups and that differences between the CWPS structures play a crucial role in determining phage host range.IMPORTANCEDespite the efforts of nearly 80 years of lactococcal phage research, the precise nature of the cell surface receptors of the P335 and 936 phage group receptors has remained elusive. This work demonstrates the molecular nature of a P335 group receptor while bolstering the evidence of its role in host recognition by phages of the 936 group and at least partially explains why such phages have a very narrow host range. The information generated will be instrumental in understanding the molecular mechanisms of how phages recognize specific saccharidic receptors located on the surface of their bacterial host.

scholarly journals Cell Surface Polysaccharides Represent a Common Strategy for Adsorption among Phages Infecting Lactic Acid Bacteria: Lessons from Dairy Lactococci and Streptococci

mSystems ◽  
2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Jennifer Mahony
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Cell Surface ◽  
Lactococcus Lactis ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Content Type ◽  
Common Strategy ◽  
Surface Polysaccharides

Food fermentations rely on the application of robust bacterial starter cultures, the majority of which are represented by members of the lactic acid bacteria including Lactococcus lactis and Streptococcus thermophilus . Bacteriophage (or phage) proliferation remains one of the most significant threats to the fermentation industry.

scholarly journals Unleashing Natural Competence in Lactococcus lactis by Induction of the Competence Regulator ComX

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Joyce Mulder ◽  
Michiel Wels ◽  
Oscar P. Kuipers ◽  
Michiel Kleerebezem ◽  
Peter A. Bron
Keyword(s):  
Lactococcus Lactis ◽  
Genetic Manipulation ◽  
Bacterial Species ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Natural Competence ◽  
Content Type ◽  
Competence Gene ◽  
Gene Sets ◽  
Novel Traits

ABSTRACT In biotechnological workhorses like Streptococcus thermophilus and Bacillus subtilis, natural competence can be induced, which facilitates genetic manipulation of these microbes. However, in strains of the important dairy starter Lactococcus lactis, natural competence has not been established to date. However, in silico analysis of the complete genome sequences of 43 L. lactis strains revealed complete late competence gene sets in 2 L. lactis subsp. cremoris strains (KW2 and KW10) and at least 10 L. lactis subsp. lactis strains, including the model strain IL1403 and the plant-derived strain KF147. The remainder of the strains, including all dairy isolates, displayed genomic decay in one or more of the late competence genes. Nisin-controlled expression of the competence regulator comX in L. lactis subsp. lactis KF147 resulted in the induction of expression of the canonical competence regulon and elicited a state of natural competence in this strain. In contrast, comX expression in L. lactis NZ9000, which was predicted to encode an incomplete competence gene set, failed to induce natural competence. Moreover, mutagenesis of the comEA-EC operon in strain KF147 abolished the comX-driven natural competence, underlining the involvement of the competence machinery. Finally, introduction of nisin-inducible comX expression into nisRK-harboring derivatives of strains IL1403 and KW2 allowed the induction of natural competence in these strains also, expanding this phenotype to other L. lactis strains of both subspecies. IMPORTANCE Specific bacterial species are able to enter a state of natural competence in which DNA is taken up from the environment, allowing the introduction of novel traits. Strains of the species Lactococcus lactis are very important starter cultures for the fermentation of milk in the cheese production process, where these bacteria contribute to the flavor and texture of the end product. The activation of natural competence in this industrially relevant organism can accelerate research aiming to understand industrially relevant traits of these bacteria and can facilitate engineering strategies to harness the natural biodiversity of the species in optimized starter strains.

scholarly journals Surface Structure Characterization of Aspergillus fumigatus Conidia Mutated in the Melanin Synthesis Pathway and Their Human Cellular Immune Response

2014 ◽  
Vol 82 (8) ◽  
pp. 3141-3153 ◽  
Author(s):  
Jagadeesh Bayry ◽  
Audrey Beaussart ◽  
Yves F. Dufrêne ◽  
Meenu Sharma ◽  
Kushagra Bansal ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Aspergillus Fumigatus ◽  
Surface Defects ◽  
Structure Characterization ◽  
Inert Material ◽  
Cell Wall Polysaccharides ◽  
Melanin Biosynthesis ◽  
Content Type ◽  
Conidial Surface

ABSTRACTInAspergillus fumigatus, the conidial surface contains dihydroxynaphthalene (DHN)-melanin. Six-clustered gene products have been identified that mediate sequential catalysis of DHN-melanin biosynthesis. Melanin thus produced is known to be a virulence factor, protecting the fungus from the host defense mechanisms. In the present study, individual deletion of the genes involved in the initial three steps of melanin biosynthesis resulted in an altered conidial surface with masked surface rodlet layer, leaky cell wall allowing the deposition of proteins on the cell surface and exposing the otherwise-masked cell wall polysaccharides at the surface. Melanin as such was immunologically inert; however, deletion mutant conidia with modified surfaces could activate human dendritic cells and the subsequent cytokine production in contrast to the wild-type conidia. Cell surface defects were rectified in the conidia mutated in downstream melanin biosynthetic pathway, and maximum immune inertness was observed upon synthesis of vermelone onward. These observations suggest that although melanin as such is an immunologically inert material, it confers virulence by facilitating proper formation of theA. fumigatusconidial surface.

scholarly journals Brussowvirus SW13 Requires a Cell Surface-Associated Polysaccharide To Recognize Its Streptococcus thermophilus Host

2022 ◽  
Vol 88 (1) ◽  
Author(s):  
Katherine Lavelle ◽  
Irina Sadovskaya ◽  
Evgeny Vinogradov ◽  
Philip Kelleher ◽  
Gabriele A. Lugli ◽  
...  
Keyword(s):  
Cell Surface ◽  
Product Quality ◽  
Starter Culture ◽  
Streptococcus Thermophilus ◽  
Content Type ◽  
Fermentation Processes ◽  
A Cell ◽  
Dairy Fermentation

Streptococcus thermophilus is an important starter culture bacterium in global dairy fermentation processes, where it is used for the production of various cheeses and yogurt. Bacteriophage predation of the species can result in substandard product quality and, in rare cases, complete fermentation collapse.

Isolation, characterization and utilization of starter cultures for the development of wheyghurt drink

2013 ◽  
Vol 115 (8) ◽  
pp. 1169-1186 ◽  
Author(s):  
Muhammad Saeed ◽  
Faqir Muhammad Anjum ◽  
Moazzam Rafiq Khan ◽  
Muhammad Issa Khan ◽  
Muhammad Nadeem
Keyword(s):  
Starter Culture ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Organoleptic Evaluation ◽  
Content Type ◽  
Overall Acceptability ◽  
Minimum Score ◽  
Good Nutrition ◽  
Sensory Parameters ◽  
And Storage

PurposeWhey products have conventionally been professed as a means of reducing ingredient costs. The authentic benefits of adding whey products are the enhanced worth resulting from flavor, texture and nutritional improvements as well as nutraceutical or health‐enhancing payback. Therefore, the present study aims to isolate and characterize suitable starter cultures for the production of wheyghurt drink.Design/methodology/approachKeeping in view all the benefits of yoghurt technology this study was planned to isolate the starter cultures and optimize the conditions for the production of wheyghurt drink. The starter cultures (Lactobacillus delbruceckii ssp. Bulgaricus and Streptococcus thermophilus) were isolated from the yoghurt and further characterized on the basis of their morphological and biochemical characteristics. The wheyghurt drink prepared from starter cultures with varying starter culture concentrations (1, 1.5, 2 and 2.5 percent) was analyzed for the physicochemical and sensory characteristics to explore the potential of wheyghurt drink.FindingsDuring storage, color, flavor, taste and overall acceptability were affected significantly. But the interaction between treatments and storage was found non‐significant to all the sensory parameters. At zero day maximum score (7.40) for overall acceptability was recorded for T3 and minimum score (5.60) was awarded to T4. After five, ten and 15 days of storage, judges observed a slight decline in overall acceptability in all wheyghurt drink samples. Hence it was concluded that wheyghurt drink sample T3 obtained maximum scores regarding the organoleptic evaluation and remained the best.Practical implicationsThe key to growth is a continuous evaluation and modification of the product to match consumer expectations. Currently there are many apparent benefits that result from incorporating selected whey products into yogurt formulas. The starter cultures for the production of fermented whey products are not presently produced in Pakistan and are imported for industrial use. The use of LAB as starter culture may help to improve the quality and shelf life of the whey products.Originality/valueThe research is useful for food manufacturers in order to develop functional food products for consumers. Understanding consumer needs and preferences is critical to successful product development and enhancing marketing values of a product. Nutritionally improved foods, such as wheyghurt over the conventional counterpart, will be highly successful in the marketplace. Consumers will prefer such kinds of foods because they are more conscious about their health and such foods provide them with what they desire, i.e. health benefits with good nutrition.

Specificity of mycoparasite attachment to the host cell surface

1985 ◽  
Vol 63 (4) ◽  
pp. 772-778 ◽  
Author(s):  
M. S. Manocha
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Lectin Binding ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Host Recognition ◽  
Binding Reaction ◽  
Choanephora Cucurbitarum ◽  
Host Cell Surface ◽  
Germ Tubes

The use of isolated cell wall fragments of Choanephora cucurbitarum (Berk. & Rav.) Thaxter (a host), and of Linderina pennispora Raper and Fennell (a nonhost), has provided not only a convenient method to quantify attachment of the parasite, Piptocephalis virginiana Leadbeater and Mercer, by the artificial inoculation and washing-off procedure, but also an excellent material for investigations on the molecular basis of specificity and host recognition. The parasite germ tubes are attached to the cell wall fragments of the host but not of the nonhost. Attachment was inhibited by the addition of sugars, chitobiose and chitotriose, and by treatment with acid or alkali indicating the involvement of proteins or glycoproteins in recognizing sugar residues at the cell surface. Both host and nonhost showed a positive binding reaction with fluorescent lectins specific for N-acetyl-D-glucosamine oligomer. The cell surface of the nonhost also contains D-galactose and N-acetyl-D-galactosamine residues as lectin binding sites. Sodium dodecyl sulfate – polyacrylamide gel electrophoresis of cell wall extracts of host and nonhost revealed four bands of glycoproteins common to both fungi and two were specific to the host.

scholarly journals Abolishing Cell Wall Glycosylphosphatidylinositol-Anchored Proteins in Candida albicans Enhances Recognition by Host Dectin-1

2015 ◽  
Vol 83 (7) ◽  
pp. 2694-2704 ◽  
Author(s):  
Hui Shen ◽  
Si Min Chen ◽  
Wei Liu ◽  
Fang Zhu ◽  
Li Juan He ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Fungal Infections ◽  
Nuclear Factor Κb ◽  
Mitogen Activated Protein Kinase ◽  
Host Recognition ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Opportunistic Human Pathogen

Fungi can shield surface pathogen-associated molecular patterns (PAMPs) for evading host immune attack. The most common and opportunistic human pathogen,Candida albicans, can shield β-(1 3)-glucan on the cell wall, one of the major PAMPs, to avoid host phagocyte Dectin-1 recognition. The way to interfere in the shielding process for more effective antifungal defense is not well established. In this study, we found that deletion of theC. albicansGPI7gene, which was responsible for adding ethanolaminephosphate to the second mannose in glycosylphosphatidylinositol (GPI) biosynthesis, could block the attachment of most GPI-anchored cell wall proteins (GPI-CWPs) to the cell wall and subsequently unmask the concealed β-(1,3)-glucan. Neutrophils could kill the uncloakedgpi7mutant more efficiently with an augmented respiratory burst. Thegpi7mutant also stimulated Dectin-1-dependent immune responses of macrophages, including activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways and secretion of specific cytokines, such as tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and IL-12p40. Furthermore, thegpi7null mutant could induce an enhanced inflammatory response through promoting significant recruitment of neutrophils and monocytes and could stimulate stronger Th1 and Th17 cell responses to fungal infectionsin vivo. Thesein vivophenotypes also were Dectin-1 dependent. Thus, we assume that GPI-CWPs are involved in the immune mechanism ofC. albicansescaping from host recognition by Dectin-1. Our studies also indicate that the blockage of GPI anchor synthesis is a strategy to inhibitC. albicansevading host recognition.

scholarly journals A Decade ofStreptococcus thermophilusPhage Evolution in an Irish Dairy Plant

2018 ◽  
Vol 84 (10) ◽  
Author(s):  
Katherine Lavelle ◽  
James Murphy ◽  
Brian Fitzgerald ◽  
Gabriele A. Lugli ◽  
Aldert Zomer ◽  
...  
Keyword(s):  
Streptococcus Thermophilus ◽  
Genomic Region ◽  
Host Recognition ◽  
Carbohydrate Binding ◽  
Variable Regions ◽  
Content Type ◽  
Host Interactions ◽  
Binding Domains ◽  
Associated Proteins ◽  
Dairy Plant

ABSTRACTPhages ofStreptococcus thermophiluspresent a major threat to the production of many fermented dairy products. To date, only a few studies have assessed the biodiversity ofS. thermophilusphages in dairy fermentations. In order to develop strategies to limit phage predation in this important industrial environment, it is imperative that such studies are undertaken and that phage-host interactions of this species are better defined. The present study investigated the biodiversity and evolution of phages within an Irish dairy fermentation facility over an 11-year period. This resulted in the isolation of 17 genetically distinct phages, all of which belong to the so-calledcosgroup. The evolution of phages within the factory appears to be influenced by phages from other dairy plants introduced into the factory for whey protein powder production. Modular exchange, primarily within the regions encoding lysogeny and replication functions, was the major observation among the phages isolated between 2006 and 2016. Furthermore, the genotype of the first isolate in 2006 was observed continuously across the following decade, highlighting the ability of these phages to prevail in the factory setting for extended periods of time. The proteins responsible for host recognition were analyzed, and carbohydrate-binding domains (CBDs) were identified in the distal tail (Dit), the baseplate proteins, and the Tail-associated lysin (Tal) variable regions (VR1 and VR2) of many isolates. This supports the notion thatS. thermophilusphages recognize a carbohydrate receptor on the cell surface of their host.IMPORTANCEDairy fermentations are consistently threatened by the presence of bacterial viruses (bacteriophages or phages), which may lead to a reduction in acidification rates or even complete loss of the fermentate. These phages may persist in factories for long periods of time. The objective of the current study was to monitor the progression of phages infecting the dairy bacteriumStreptococcus thermophilusover a period of 11 years in an Irish dairy plant so as to understand how these phages evolve. A focused analysis of the genomic region that encodes host recognition functions highlighted that the associated proteins harbor a variety of carbohydrate-binding domains, which corroborates the notion that phages ofS. thermophilusrecognize carbohydrate receptors at the initial stages of the phage cycle.

scholarly journals Screening for Glycosylphosphatidylinositol-Modified Cell Wall Proteins in Pichia pastoris and Their Recombinant Expression on the Cell Surface

2013 ◽  
Vol 79 (18) ◽  
pp. 5519-5526 ◽  
Author(s):  
Li Zhang ◽  
Shuli Liang ◽  
Xinying Zhou ◽  
Zi Jin ◽  
Fengchun Jiang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Pichia Pastoris ◽  
Cell Surface ◽  
Signal Sequence ◽  
Recombinant Expression ◽  
Cell Wall Proteins ◽  
Heterologous Proteins ◽  
Content Type ◽  
Yeast Cell Surface

ABSTRACTGlycosylphosphatidylinositol (GPI)-anchored glycoproteins have various intrinsic functions in yeasts and different usesin vitro. In the present study, the genome ofPichia pastorisGS115 was screened for potential GPI-modified cell wall proteins. Fifty putative GPI-anchored proteins were selected on the basis of (i) the presence of a C-terminal GPI attachment signal sequence, (ii) the presence of an N-terminal signal sequence for secretion, and (iii) the absence of transmembrane domains in mature protein. The predicted GPI-anchored proteins were fused to an alpha-factor secretion signal as a substitute for their own N-terminal signal peptides and tagged with the chimeric reporters FLAG tag and matureCandida antarcticalipase B (CALB). The expression of fusion proteins on the cell surface ofP. pastorisGS115 was determined by whole-cell flow cytometry and immunoblotting analysis of the cell wall extracts obtained by β-1,3-glucanase digestion. CALB displayed on the cell surface ofP. pastorisGS115 with the predicted GPI-anchored proteins was examined on the basis of potential hydrolysis ofp-nitrophenyl butyrate. Finally, 13 proteins were confirmed to be GPI-modified cell wall proteins inP. pastorisGS115, which can be used to display heterologous proteins on the yeast cell surface.

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