Biofilm Formation by a Fimbriae‐Deficient Mutant of Actinobacillus actinomycetemcomitans

Abstract

Actinobacillus actinomycetemcomitans strain 310‐TR produces fimbriae and forms a tight biofilm in broth cultures, without turbid growth. The fimbriae‐deficient mutant 310‐DF, constructed in this study, was grown as a relatively fragile biofilm at the bottom of a culture vessel. Scanning electron microscopy revealed that on glass coverslips, 310‐TR formed tight and spherical microcolonies, while 310‐DF produced looser ones. These findings suggest that fimbriae are not essential for the surface‐adherent growth but are required for enhancing cell‐to‐surface and cell‐to‐cell interactions to stabilize the biofilm. Treatment of the 310‐DF biofilm with either sodium metaperiodate or DNase resulted in significant desorption of cells from glass surfaces, indicating that both carbohydrate residues and DNA molecules present on the cell surface are also involved in the biofilm formation.

FppA, a Novel Pseudomonas aeruginosa Prepilin Peptidase Involved in Assembly of Type IVb Pili

“…In this study, we used functional genomic approaches to further mine the P. aeruginosa genome to identify genes involved in the assembly of cell-surface appendages that could be relevant for bacterial biofilm development. We identified a cluster whose genes encode components previously reported in A. actinomycetemcomitans as being involved in the assembly of Flp pili (17) that support tight adherence and biofilm formation (18).…”

Interactions between the Aggregatibacter actinomycetemcomitans secretin HofQ and host cytokines indicate a link between natural competence and interleukin-8 uptake

“…EMs consist of proteins, extracellular DNA (eDNA) and polysaccharides, such as poly-N-acetylglucosamine (PGA), which is the major polysaccharide in A. actinomycetemcomitans biofilms [9]. However, A. actinomycetemcomitans requires eDNA for cohesive biofilm formation, efficient adhesion to surfaces [10,11], and leukotoxin attachment to the bacterial membrane [12]. …”

Invasion and Survival of Salmonella in the Environment: The Role of Biofilms

“…Enzymatic alteration of EPS is thought to significantly change its physicochemical properties and consequently the entire structure. Some examples of polymeric biofilm matrix constituents include the glucan polysaccharides produced by Streptococcus mutans (Banas and Vickerman, 2003), proteinaceous fimbriae produced by Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis (Kachlany et al, 2001;Lamont et al, 2002); extracellular, doublestranded DNA in biofilms produced by A. actinomycetemcomitans, S. mutans, and Streptococcus intermedius (Inoue et al, 2003;Petersen et al, 2004;Petersen et al, 2005) and a wide variety of proteins, glycoproteins, glycolipids, and enzymes.…”