Insights into ecology, pathogenesis, and biofilm formation of from functional genomics.

SUMMARY is a significant resident of the gastrointestinal tract of most animals, including humans. Although generally non-pathogenic in healthy hosts, this microbe is adept at the exploitation of compromises in host immune functions, resulting in life-threatening opportunistic infections whose treatments are complicated by a high degree of intrinsic and acquired resistance to antimicrobial chemotherapy. Historically, progress in enterococcal research was limited by a lack of experimental models that replicate natural infection pathways and the relevance of studies to the natural biology of the organism.

Arginine impacts aggregation, biofilm formation, and antibiotic susceptibility in .

is a commensal bacterium in the gastrointestinal (GI) tract of humans and other organisms. also causes infections in root canals, wounds, the urinary tract, and on heart valves. metabolizes arginine through the arginine deiminase pathway, which converts arginine to ornithine and releases ATP, ammonia, and CO.

Arginine impacts aggregation, biofilm formation, and antibiotic susceptibility in .

is a commensal bacterium in the gastrointestinal tract (GIT) of humans and other organisms. also causes infections in root canals, wounds, the urinary tract, and on heart valves. metabolizes arginine through the arginine deiminase (ADI) pathway, which converts arginine to ornithine and releases ATP, ammonia, and CO.

Optimized Replication of Arrayed Bacterial Mutant Libraries Increases Access to Biological Resources.

Biological collections, including arrayed libraries of single transposon (Tn) or deletion mutants, greatly accelerate the pace of bacterial genetic research. Despite the importance of these resources, few protocols exist for the replication and distribution of these materials. Here, we describe a protocol for creating multiple replicates of an arrayed bacterial Tn library consisting of approximately 6,800 mutants in 96-well plates (73 plates).

Optimized replication of arrayed bacterial mutant libraries increase access to biological resources.

Unlabelled: Biological collections, including arrayed libraries of single transposon or deletion mutants, greatly accelerate the pace of bacterial genetics research. Despite the importance of these resources, few protocols exist for the replication and distribution of these materials. Here, we describe a protocol for creating multiple replicates of an arrayed bacterial Tn library consisting of approximately 6,800 mutants in 73 × 96-well plates.

Enterococci enhance Clostridioides difficile pathogenesis.

Enteric pathogens are exposed to a dynamic polymicrobial environment in the gastrointestinal tract. This microbial community has been shown to be important during infection, but there are few examples illustrating how microbial interactions can influence the virulence of invading pathogens. Here we show that expansion of a group of antibiotic-resistant, opportunistic pathogens in the gut-the enterococci-enhances the fitness and pathogenesis of Clostridioides difficile.

Structural Differences in Complexes between the Master Regulator PrgX, Peptide Pheromones, and Operator Binding Sites Determine the Induction State for Conjugative Transfer of pCF10.

Pheromone-inducible conjugation in the Enterococcus faecalis pCF10 system is regulated by the PrgX transcription factor through binding interactions at two operator binding sites (XBS1 and XBS2) upstream of the transcription start site of the operon encoding the conjugation machinery. Repression of transcription requires the interaction of a PrgX tetramer with both XBSs via formation of a DNA loop. The ability of PrgX to regulate transcription is modulated by its interaction with two antagonistic regulatory peptides, CF10 (I) and cF10 (C); the former peptide inhibits transcription, while the latter peptide enhances transcription.

The Phosphatase Bph and Peptidyl-Prolyl Isomerase PrsA Are Required for Gelatinase Expression and Activity in Enterococcus faecalis.

Enterococcus faecalis is a common commensal bacterium in the gastrointestinal tract as well as a frequent nosocomial pathogen. The secreted metalloprotease gelatinase (GelE) is an important E. faecalis virulence factor that contributes to numerous cellular activities, such as autolysis, biofilm formation, and biofilm-associated antibiotic resistance.

Dynamics of plasmid-mediated niche invasion, immunity to invasion, and pheromone-inducible conjugation in the murine gastrointestinal tract.

Microbial communities provide protection to their hosts by resisting pathogenic invasion. Microbial residents of a host often exclude subsequent colonizers, but this protection is not well understood. The Enterococcus faecalis plasmid pCF10, whose conjugative transfer functions are induced by a peptide pheromone, efficiently transfers in the intestinal tract of mice.

colonizes and forms persistent biofilm microcolonies on undamaged endothelial surfaces in a rabbit endovascular infection model.

Infectious endocarditis (IE) is an uncommon disease with significant morbidity and mortality. The pathogenesis of IE has historically been described as a cascade of host-specific events beginning with endothelial damage and thrombus formation and followed by bacterial colonization of the nascent thrombus. is a Gram-positive commensal bacterial member of the gastrointestinal tract microbiota in most terrestrial animals and a leading cause of opportunistic biofilm-associated infections, including endocarditis.

Enterococcal Endocarditis: Hiding in Plain Sight.

is a major opportunistic bacterial pathogen of increasing clinical relevance. A substantial body of experimental evidence suggests that early biofilm formation plays a critical role in these infections, as well as in colonization and persistence in the GI tract as a commensal member of the microbiome in most terrestrial animals. Animal models of experimental endocarditis generally involve inducing mechanical valve damage by cardiac catheterization prior to infection, and it has long been presumed that endocarditis vegetation formation resulting from bacterial attachment to the endocardial endothelium requires some pre-existing tissue damage.

Comparative Biofilm Assays Using Enterococcus faecalis OG1RF Identify New Determinants of Biofilm Formation.

Enterococcus faecalis is a common commensal organism and a prolific nosocomial pathogen that causes biofilm-associated infections. Numerous E. faecalis OG1RF genes required for biofilm formation have been identified, but few studies have compared genetic determinants of biofilm formation and biofilm morphology across multiple conditions.

Enterococcal PrgU Provides Additional Regulation of Pheromone-Inducible Conjugative Plasmids.

Efficient horizontal gene transfer of the conjugative plasmid pCF10 from Enterococcus faecalis depends on the expression of its type 4 secretion system (T4SS) genes, controlled by the P promoter. Transcription from the P promoter is tightly regulated, partially to limit cell toxicity caused by overproduction of PrgB, a T4SS adhesin. PrgU plays an important role in regulating this toxicity by decreasing PrgB levels.

Probiotic Affects Enterococcus faecalis Antibiotic Resistance Transfer by Interfering with Pheromone Signaling Cascades.

Enterococcus faecalis, a member of the commensal flora in the human gastrointestinal tract, has become a threatening nosocomial pathogen because it has developed resistance to many known antibiotics. More concerningly, resistance gene-carrying E. faecalis cells may transfer antibiotic resistance to resistance-free E.

Two ABC transport systems carry out peptide uptake in Enterococcus faecalis: Their roles in growth and in uptake of sex pheromones.

Enterococcal pheromone-inducible plasmids encode a predicted OppA-family secreted lipoprotein. In the case of plasmid pCF10, the protein is PrgZ, which enhances the mating response to cCF10 pheromone. OppA proteins generally function with associated OppBCDF ABC transporters to import peptides.

Phage infection and sub-lethal antibiotic exposure mediate Enterococcus faecalis type VII secretion system dependent inhibition of bystander bacteria.

Bacteriophages (phages) are being considered as alternative therapeutics for the treatment of multidrug resistant bacterial infections. Considering phages have narrow host-ranges, it is generally accepted that therapeutic phages will have a marginal impact on non-target bacteria. We have discovered that lytic phage infection induces transcription of type VIIb secretion system (T7SS) genes in the pathobiont Enterococcus faecalis.

Polymer Adhesin Domains in Gram-Positive Cell Surface Proteins.

Surface proteins in Gram-positive bacteria are often involved in biofilm formation, host-cell interactions, and surface attachment. Here we review a protein module found in surface proteins that are often encoded on various mobile genetic elements like conjugative plasmids. This module binds to different types of polymers like DNA, lipoteichoic acid and glucans, and is here termed We analyze all proteins that contain a polymer adhesin domain and classify the proteins into distinct classes based on phylogenetic and protein domain analysis.

Plasmid Acquisition Alters Vancomycin Susceptibility in Clostridioides difficile.

The increasing incidence of primary and recurring Clostridioides difficile infections (CDI), which evade current treatment strategies, reflects the changing biology of C difficile. Here, we describe a putative plasmid-mediated mechanism potentially driving decreased sensitivity of C difficile to vancomycin treatment. We identified a broad host range transferable plasmid in a C difficile strain associated with lack of adequate response to vancomycin treatment.

Enterococcal PrgA Extends Far Outside the Cell and Provides Surface Exclusion to Protect against Unwanted Conjugation.

Horizontal gene transfer between Gram-positive bacteria leads to a rapid spread of virulence factors and antibiotic resistance. This transfer is often facilitated via type 4 secretion systems (T4SS), which frequently are encoded on conjugative plasmids. However, donor cells that already contain a particular conjugative plasmid resist acquisition of a second copy of said plasmid.

Genome-Wide Mutagenesis Identifies Factors Involved in Enterococcus faecalis Vaginal Adherence and Persistence.

is a Gram-positive commensal bacterium native to the gastrointestinal tract and an opportunistic pathogen of increasing clinical concern. also colonizes the female reproductive tract, and reports suggest vaginal colonization increases following antibiotic treatment or in patients with aerobic vaginitis. Currently, little is known about specific factors that promote vaginal colonization and subsequent infection.

Parallel Genomics Uncover Novel Enterococcal-Bacteriophage Interactions.

Bacteriophages (phages) have been proposed as alternative therapeutics for the treatment of multidrug-resistant bacterial infections. However, there are major gaps in our understanding of the molecular events in bacterial cells that control how bacteria respond to phage predation. Using the model organism , we used two distinct genomic approaches, namely, transposon library screening and RNA sequencing, to investigate the interaction of with a virulent phage.

Single-Cell Analysis Reveals that the Enterococcal Sex Pheromone Response Results in Expression of Full-Length Conjugation Operon Transcripts in All Induced Cells.

For high-frequency transfer of pCF10 between cells, induced expression of the pCF10 genes encoding conjugative machinery from the operon is required. This process is initiated by the cCF10 (C) inducer peptide produced by potential recipient cells. The expression timing of an "early" gene just downstream of the inducible promoter, has been studied extensively in single cells.

Gut dysbiosis during antileukemia chemotherapy versus allogeneic hematopoietic cell transplantation.

Background: In the field of malignant hematology, most microbiome studies have focused on recipients of allogeneic hematopoietic cell transplantation (allo-HCT). As a result, this population has remained the primary target for novel microbiota therapeutics. Because the types of insults to the microbiome are similar during hematopoietic cell transplantation and intensive antileukemia therapy, this study evaluated whether the dysbiosis states are similar in the 2 settings.

Enterococcus faecalis Enhances Expression and Activity of the Enterohemorrhagic Escherichia coli Type III Secretion System.

The gut microbiota can significantly impact invading pathogens and the disease they cause; however, many of the mechanisms that dictate commensal-pathogen interactions remain unclear. Enterohemorrhagic (EHEC) is a potentially lethal human intestinal pathogen that uses microbiota-derived molecules as cues to efficiently regulate virulence factor expression. Here, we investigate the interaction between EHEC and , a common human gut commensal, and show that affects both expression and activity of the EHEC type III secretion system (T3SS) via two distinct mechanisms.