Collagen-Like Proteins (ClpA, ClpB, ClpC, and ClpD) Are Required for Biofilm Formation and Adhesion to Plant Roots by Bacillus amyloliquefaciens FZB42

Abstract

The genes of collagen-like proteins (CLPs) have been identified in a broad range of bacteria, including some human pathogens. They are important for biofilm formation and bacterial adhesion to host cells in some human pathogenic bacteria, including several Bacillus spp. strains. Interestingly, some bacterial CLP-encoding genes (clps) have also been found in non-human pathogenic strains such as B. cereus and B. amyloliquefaciens, which are types of plant-growth promoting rhizobacteria (PGPR). In this study, we investigated a putative cluster of clps in B. amyloliquefaciens strain FZB42 and a collagen-related structural motif containing glycine-X-threonine repeats was found in the genes RBAM_007740, RBAM_007750, RBAM_007760, and RBAM_007770. Interestingly, biofilm formation was disrupted when these genes were inactivated separately. Scanning electron microscopy and hydrophobicity value detection were used to assess the bacterial cell shape morphology and cell surface architecture of clps mutant cells. The results showed that the CLPs appeared to have roles in bacterial autoaggregation, as well as adherence to the surface of abiotic materials and the roots of Arabidopsis thaliana. Thus, we suggest that the CLPs located in the outer layer of the bacterial cell (including the cell wall, outer membrane, flagella, or other associated structures) play important roles in biofilm formation and bacteria-plant interactions. This is the first study to analyze the function of a collagen-like motif-containing protein in a PGPR bacterium. Knocking out each clp gene produced distinctive morphological phenotypes, which demonstrated that each product may play specific roles in biofilm formation. Our in silico analysis suggested that these four tandemly ranked genes might not belong to an operon, but further studies are required at the molecular level to test this hypothesis. These results provide insights into the functions of clps during interactions between bacteria and plants.

Salad dressing spoilage by Bacillus amyloliquefaciens with gas formation

“…amyloliquefaciens is a spore-forming Gram-positive, aerobic, motile rod often found in soil, that belongs to the B. subtilis group and is used in several industrial processes (PRIEST et al, 1987). In addition, it has been described as a plant growth promoting Rhizobacterium, known for its ability to produce a biofilm on root surfaces (ZHAO et al, 2015).…”

dRNA-Seq Reveals Genomewide TSSs and Noncoding RNAs of Plant Beneficial Rhizobacterium Bacillus amyloliquefaciens FZB42

“…subtilis , encodes proteins containing a collagen-related GXT structure motif. This cluster, required for biofilm formation and adhesion to plant roots [ 72 ], was highly expressed in #9h but not in #6h samples ( S8 Fig ). Further, some genes involved in response to oxidative stress (e.g., sodA and tpx ) or adaption to atypical stresses ( cspB , cspC , and cspD ) were also highly induced; these genes may help the rhizobacteria to survive the plant basal defense.…”

Matrix Production, Pigment Synthesis, and Sporulation in a Marine Isolated Strain of Bacillus pumilus

“…These could either be B. pumilus SF214-specific proteins or homologs of proteins characterized in B. subtilis as affecting biofilm synthesis but not analyzed in this study. These include AbrB [ 10 ], RemA-B [ 27 , 28 ], Veg [ 29 ], and SlrA [ 30 ], and also proteins only indirectly related to biofilm, such as collagen-like proteins [ 31 ], components of the RapP-PhrP quorum sensing system [ 32 ], and ribosomal proteins S11 and S21 [ 33 ]. In addition, mutations in genes coding for alpha-phosphoglucomutase [ 23 ], CcpA, glutamate synthase, GltAB, and the aminopeptidase AmpS [ 34 ] have all been shown to have pleiotropic effects and also influence biofilm formation.…”