Link to Pubmed [PMID] – 30833358
J Bacteriol. 2019 Mar 4. pii: JB.00650-18. doi: 10.1128/JB.00650-18. [Epub ahead of print]
Bacteroides thetaiotaomicron is a prominent anaerobe member of the healthy human gut microbiota. While the majority of functional studies on B. thetaiotaomicron addressed its impact on the immune system and the utilization of diet polysaccharide, B. thetaiotaomicron biofilm capacity and its contribution to intestinal colonization are still poorly characterized. We tested the natural adhesion of 34 B. thetaiotaomicron isolates and showed that, although biofilm capacity is widespread among B. thetaiotaomicron strains, this phenotype is masked or repressed in the widely used reference strain VPI 5482. Using transposon mutagenesis followed by a biofilm positive selection procedure we identified VPI 5482 mutants with increased biofilm capacity corresponding to an alteration in the C-terminal region of BT3147, encoded by the BT3148-BT3147 locus, which displays homology with mfa-like typeV pili found in many Bacteroidetes We showed that BT3147 is exposed on B. thetaiotaomicron surface and that BT3147-dependent adhesion also requires BT3148, suggesting that BT3148-BT3147 correspond to the anchor and stalk subunits of a new type V pilus involved in B. thetaiotaomicron adhesion. This study therefore introduces B. thetaiotaomicron as a model to study proteinaceous adhesins and biofilm-related phenotypes in this important intestinal symbiont.IMPORTANCE Although the gut anaerobe Bacteroides thetaiotaomicron is a prominent member of the healthy human gut microbiota, little is known on its capacity adhere to surfaces and form biofilms. Here, we identified that alteration of a surface exposed protein corresponding to a type of pili found in many Bacteroidetes increases B. thetaiotaomicron biofilm formation. This study lays the ground for establishing this bacterium as a model organism for in vitro and in vivo study of biofilm-related phenotypes in gut anaerobes.