title: Conditions affecting cell surface properties of human intestinal bifidobacteria.
abstract: The cell surface properties of human intestinal bifidobacteria have been characterized for 30 strains isolated from a fecal sample. Strain identification to the species level was obtained by restriction analysis of the amplified 16S rRNA gene and confirmed by DNA/DNA reassociation experiments. The isolates were grouped in four genetically homogeneous clusters whose members belonged to Bifidobacterium bifidum, Bifidobacterium adolescentis, Bifidobacterium longum and Bifidobacterium pseudocatenulatum species. Cell surface properties of Bifidobacterium strains were evaluated by determining the level of hydrophobicity, adhesion to hydrocarbons and contact angle measurements, and their autoaggregation ability. The results showed high and homogeneous level of hydrophobicity in all tested strains when contact angle measurements values were considered. On the contrary, autoaggregation assays and bacterial adhesion to hydrocarbons detected interesting differences in cell surface properties among the tested Bifidobacterium strains. The highest levels of autoaggregation, detected in B. bifidum and B. adolescentis strains, were strictly dependent on the pH of the medium. Moreover, protease treatment experiments suggested that proteins had a key role in the autoaggregating ability of B. bifidum and B. adolescentis strains.
authors.affiliation: Department of Food Science and Microbiology, University of Milan, Via Celoria 2, 20133 Milan, Italy.
authors.forename: Enrica
authors.initials: E
authors.lastname: Canzi
authors.forename: Simone
authors.initials: S
authors.lastname: Guglielmetti
authors.forename: Diego
authors.initials: D
authors.lastname: Mora
authors.forename: Isabella
authors.initials: I
authors.lastname: Tamagnini
authors.forename: Carlo
authors.initials: C
authors.lastname: Parini
mesh_terms: D000328:Adult; D001422:Bacterial Adhesion; D001644:Bifidobacterium / Q000145:classification / Q000302:isolation & purification / Q000502:physiology* / Q000648:ultrastructure; D016172:DNA Fingerprinting; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D006838:Hydrocarbons / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000502:physiology; D009693:Nucleic Acid Hybridization; D010447:Peptide Hydrolases / Q000378:metabolism; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013499:Surface Properties
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D006838:Hydrocarbons; D008565:Membrane Proteins; D012336:RNA, Ribosomal, 16S; D004262:DNA Restriction Enzymes; D010447:Peptide Hydrolases