RT Journal Article SR Electronic(1) A1 Rakotoarivonina, Harivony A1 Jubelin, Grégory A1 Hebraud, Michel A1 Gaillard-Martinie, Brigitte A1 Forano, Evelyne A1 Mosoni, PascaleYR 2002 T1 Adhesion to cellulose of the Gram-positive bacterium Ruminococcus albus involves type IV piliThe EMBL accession number for the sequence reported in this paper is AJ416469. JF Microbiology, VO 148 IS 6 SP 1871 OP 1880 DO https://doi.org/10.1099/00221287-148-6-1871 PB Microbiology Society, SN 1465-2080, AB This study was aimed at characterizing a cell-surface 25 kDa glycoprotein (GP25) that was previously shown to be underproduced by a spontaneous adhesion-defective mutant D5 of Ruminococcus albus 20. An antiserum against wild-type strain 20 was adsorbed with the mutant D5 to enrich it in antibodies ‘specific’ to adhesion structures of R. albus 20. The resulting antiserum, called anti-Adh serum, blocked adhesion of R. albus 20 and reacted mainly with GP25 in bacterial and extracellular protein fractions of R. albus 20. The N-terminal sequence of purified GP25 was identical to that of CbpC, a 21 kDa cellulose-binding protein (CBP) of R. albus 8. The nucleotide sequence of the gp25 gene was determined by PCR and genomic walking procedures. The gp25 gene encoded a protein of 165 aa with a calculated molecular mass of 16940 Da that showed 72·9% identity with CbpC and presented homologies with type IV pilins of Gram-negative pathogenic bacteria. Negative-staining electron microscopy revealed fine and flexible pili surrounding R. albus 20 cells while mutant cells were not piliated. In addition, immunoelectron microscopy showed that the anti-Adh serum probing mainly GP25, completely decorated the pili surrounding R. albus 20, thereby showing that GP25 was a major pilus subunit. This study shows for the first time the presence of pili at the surface of R. albus and identifies GP25 as their major protein subunit. Though GP25 was not identified as a CBP, isolated pili were shown to bind cellulose. In conclusion, these pili, which belong to the family of type IV pili, mediate adhesion of R. albus 20 to cellulose., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-148-6-1871