The Role of FLO11 in Saccharomyces cerevisiae Colonization of The Role of FLO11 in Saccharomyces cerevisiae Colonization of the Lepidopteran Gastrointestinal Tract the Lepidopteran Gastrointestinal Tract

Effects of Hexuronic Acids on the Expression of Genes for Structural Flagellar Proteins and Regulators of Biofilm Formation in Escherichia coli K-12 MG1655

The data obtained allows suggesting that SsrS and CsrC small RNAs played an important role in regulation of the cell switching to formation of biofilms, and hexuronates can be used as modeling agents in clinical practice.

The role of HIL1 in strain-level adhesion and immune recognition in Debaryomyces hansenii

ABSTRACT Strains of food-derived microbes can become facultative pathogens in susceptible human hosts. Surprisingly, we previously isolated Debaryomyces hansenii, a yeast common in fermented foods, from Crohn disease (CD) ulcers, raising questions about its strain-specific traits that influence host interactions. Here, we further developed the genetic tractability of D. hansenii and identified a single adhesin, Hil1, as a major determinant of colony morphology, biofilm formation, and immune targeting in CD patients. We used Agrobacterium tumefaciens-mediated transformation to perform a forward genetic screen in a food-derived reference strain. We isolated mutants that converted from a wrinkled, biofilm-forming phenotype to a smooth, non-adherent phenotype characteristic of CD patient isolates. Mapping of multiple insertion sites showed a disrupted subtelomeric Hyr/Iff-like adhesin gene, herein referred to as HIL1. CRISPR-Cas9-mediated deletion of HIL1 recapitulated the mutant phenotype, demonstrating that HIL1 was necessary for biofilm formation and high cell-surface hydrophobicity phenotypes. To contextualize these findings, we performed comparative genomics on a D. hansenii strain collection to assess allelic variation in the number of HIL1 tandem repeats. Longer alleles in food strains correlated with increased biofilm formation, while CD-isolated strains contained shorter HIL1 alleles and reduced binding to surfaces. Serology profiling showed that HIL1 was a direct antigenic target of circulating immunoglobulin G (IgG) in CD patients. Together, these results suggest Hil1 is a key, strain-variable adhesin shaping fungal surface properties and host immune recognition. This work establishes D. hansenii as a genetically tractable system and shows how adhesin polymorphisms may influence fungal behavior in food and disease contexts. IMPORTANCE Debaryomyces hansenii is a yeast that is common in food and is generally recognized as safe for human consumption, though recently it has been identified within diseased regions of the intestine in Crohn disease patients. A current need is to determine the genetic and phenotypic differences between safe food isolates and isolates from human Crohn disease patient ulcers. Here, we used a loss-of-function genetic screen and identified HIL1, an adhesin that we found mediates cellular adhesion in many food strains but not in patient strains. We identified circulating HIL1-reactive antibodies in patients with Crohn disease, indicating that food strains can be a target of host immune responses through Hil1. Debaryomyces hansenii is a yeast that is common in food and is generally recognized as safe for human consumption, though recently it has been identified within diseased regions of the intestine in Crohn disease patients. A current need is to determine the genetic and phenotypic differences between safe food isolates and isolates from human Crohn disease patient ulcers. Here, we used a loss-of-function genetic screen and identified HIL1, an adhesin that we found mediates cellular adhesion in many food strains but not in patient strains. We identified circulating HIL1-reactive antibodies in patients with Crohn disease, indicating that food strains can be a target of host immune responses through Hil1.

Identification of a conserved GNAT-family lysine acetyltransferase in Streptococcus gordonii involved in biofilm formation and oral colonization

It is demonstrated that SGO_2031, but not SGO_2030, seems to contribute to biofilm formation by modulating the abundance of extracellular polysaccharides within the biofilm matrix, and proposed naming this enzyme Streptococcal Lysine Acetyltransferase A (SktA) after Streptococcus gordonii.

Strain-specific thermotolerance, UV-C tolerance, and biofilm formation on clinically relevant plastic substrates in the emerging opportunistic pathogen Rhodotorula mucilaginosa

Genomic characterization and biological activities of cell-free supernatant from Lactiplantibacillus pentosus CROT01 against clarithromycin-resistant Helicobacter pylori

Helicobacter pylori is a major gastric pathogen associated with chronic gastritis, peptic ulcers, and gastric cancer, while increasing antibiotic resistance has reduced the effectiveness of standard eradication therapies. This study investigated the antibacterial, antibiofilm, anti-inflammatory, probiotic-related, and genomic properties of cell-free supernatant (LCFS) derived from Lactiplantibacillus pentosus CROT01 against H. pylori. LCFS exhibited inhibitory activity against all tested H. pylori strains, including the clarithromycin-resistant strain ATCC 700684, with inhibition zones ranging from 10.67 ± 0.58 to 17.33 ± 1.53 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) ranged from 12.5–50 mg/mL and 25–50 mg/mL, respectively. LCFS significantly inhibited biofilm formation and eradicated established H. pylori biofilms. Scanning electron microscopy revealed marked morphological alterations in treated cells, including membrane disruption, deformation, and cellular shrinkage. Anti-inflammatory activity was demonstrated through suppression of nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 cells. In addition, L. pentosus CROT01 exhibited tolerance to acidic pH and pancreatin, high cell surface hydrophobicity, and moderate adhesion ability toward Caco-2 cells. Whole-genome sequencing identified several bacteriocin-associated genes, including plantaricin E, plantaricin F, pediocin, enterolysin A, and bovicin-related peptides, whereas no virulence-associated or acquired antimicrobial resistance genes were detected. Thus, these findings suggest that LCFS derived from L. pentosus CROT01 possesses promising anti-H. pylori activity and may represent a potential postbiotic-based strategy against antibiotic-resistant H. pylori infection.

Identification of Bacillus megaterium as a Probiotic and Its Action to Control Biofilms of Foodborne Pathogens

Bacillus megaterium isolated from coffee fermentation demonstrated potential probiotic properties against Bacillus cereus ATCC 11778, Escherichia coli ATCC 8739, and Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311 through the production of active compounds, including δ-valerolactam and ε-caprolactam. This is the first report on its potential utility in producing active compounds, forming protective biofilms, or blocking cell adhesion and aggregation of foodborne pathogenic bacteria on material mimicking the intestinal mucosa. The quorum-sensing signal molecule N-butanoyl-L-homoserine lactone, an auto-inducer for biofilm formation, was detected in the crude culture supernatant, supporting its capability for biofilm formation. Characterization assays showed B. megaterium to tolerate up to 6% bile salt and to survive at pH 1.5. In addition, it demonstrated negative hemolytic activity and sensitivity to antibiotics at the level. It also produced various bioactive compounds that function with therapeutic properties. Therefore, B. megaterium has potential to be used as a human and animal probiotic in the future.