Biology subjects

BECHON, N.

Publications and source records attributed to BECHON, N..

3 recordsLinked to original sources

bioRxiv2024

Identification of V. parvula and S. gordonii adhesins mediating co-aggregation and its impact on physiology and mixed biofilm structure

The dental plaque is a polymicrobial community where biofilm formation and co-aggregation, the ability to bind to other bacteria, play a major role in the construction of an organized consortium. One of its prominent members is the anaerobic diderm Veillonella parvula, considered as a bridging species, which growth depends on lactate produced by oral Streptococci. Understanding how V. parvula co-aggregates and the impact of aggregation has long been hampered due to the lack of appropriate genetic tools. Here we studied co-aggregation of the naturally competent strain V. parvula SKV38 with various oral bacteria and its effect on cell physiology. We show that V. parvula requires different trimeric autotransporters of the type V secretion system to adhere to oral Streptococci and Actinomyces. In addition, we describe a novel adhesin of Streptococcus gordonii, VisA (SGO_2004), as the protein responsible for co-aggregation with V. parvula. Finally, we show that co-aggregation does not impact cell-cell communication, which is mainly driven by environmental sensing, but plays an important role in the architecture and species distribution within the biofilm.

microbiology↗

bioRxiv2021

Bacteroides thetaiotaomicron uses a widespread extracellular DNase to promote bile-dependent biofilm formation

Bacteroides thetaiotaomicron is a gut symbiont that inhabits the mucus layer and adheres to and metabolizes food particles, contributing to gut physiology and maturation. Whereas adhesion and biofilm formation could be key features for B. thetaiotaomicron stress resistance and gut colonization, little is known about the determinants of B. thetaiotaomicron biofilm formation. We previously showed that the B. thetaiotaomicron reference strain VPI-5482 is a poor in vitro biofilm former. Here we demonstrated that bile, a gut-relevant environmental cue, triggers the formation of biofilm in many B. thetaiotaomicron isolates and common gut Bacteroidales species. We identified the genetic determinants of this bile-dependent biofilm formation and showed that it involves the production of the DNase BT3563, degrading extracellular DNA, in biofilms formed in the presence of bile. Our study therefore identifies a physiologically relevant condition inducing B. thetaiotaomicron biofilm and shows that, in contrast to the biofilm-promoting role played by bacterial eDNA scaffold in Firmicutes and Proteobacteria models, degradation of eDNA by BT3563 DNAse and its widespread homologs is required to achieve B. thetaiotaomicron bile-dependent biofilm formation.

microbiology↗

bioRxiv2020

Capsular polysaccharides cross-regulation modulates Bacteroides thetaiotaomicron biofilm formation

Bacteroides thetaiotaomicron is one of the most abundant gut symbiont species, whose contribution to host health through its ability to degrade diet polysaccharides and mature the immune system is under untense scrutiny. By contrast, adhesion and biofilm formation, which are potentially involved in gut colonization, microbiota structure and stability, have hardly been investigated in this intestinal bacterium. To uncover B. thetaiotaomicron biofilm-related functions, we performed a transposon mutagenesis in the poor biofilm-forming reference strain VPI 5482 and showed that capsule 4, one of the eight B. thetaiotaomicron capsules, hinders biofilm formation. We then showed that the production of capsules 1, 2, 3, 5 and 6 also inhibits biofilm formation and that decreased capsulation of the population correlated with increased biofilm formation, suggesting that capsules could be masking adhesive surface structures. We also showed that, by contrast, capsule 8 displayed intrinsic adhesive properties. Finally, we demonstrated that BT2934, the wzx homolog of B. thetaiotaomicron glycosylation locus, competes with capsule production and therefore impacts its adhesion capacity. This study identified regulation of capsular polysaccharides as a major determinant of B. thetaiotaomicron biofilm formation, providing new insights into how modulation of different B. thetaiotaomicron surface structures affect in vitro biofilm formation.

microbiology↗