Kind Discrimination and Competitive Exclusion Mediated by Contact-Dependent Growth Inhibition Systems Shape Biofilm Community Structure
نویسندگان
چکیده
Contact-Dependent Growth Inhibition (CDI) is a phenomenon in which bacteria use the toxic C-terminus of a large exoprotein (called BcpA in Burkholderia species) to inhibit the growth of neighboring bacteria upon cell-cell contact. CDI systems are present in a wide range of Gram-negative proteobacteria and a hallmark feature is polymorphism amongst the exoprotein C-termini (BcpA-CT in Burkholderia) and amongst the small immunity proteins (BcpI) that protect against CDI in an allele-specific manner. In addition to CDI, the BcpAIOB proteins of Burkholderia thailandensis mediate biofilm formation, and they do so independent of BcpA-mediated interbacterial competition, suggesting a cooperative role for CDI system proteins in this process. CDI has previously only been demonstrated between CDI+ and CDI- bacteria, leaving the roles of CDI system-mediated interbacterial competition and of CDI system diversity in nature unknown. We constructed B. thailandensis strains that differed only in the BcpA-CT and BcpI proteins they produced. When co-cultured on agar, these strains each participated in CDI and the outcome of the competition depended on both CDI system efficiency and relative bacterial numbers initially. Strains also participated in CDI during biofilm development, resulting in pillar structures that were composed of only a single BcpA-CT/BcpI type. Moreover, a strain producing BcpA-CT/BcpI proteins of one type was prevented from joining a pre-established biofilm community composed of bacteria producing BcpA-CT/BcpI proteins of a different type, unless it also produced the BcpI protein of the established strain. Bacteria can therefore use CDI systems for kind recognition and competitive exclusion of 'non-self' bacteria from a pre-established biofilm. Our data indicate that CDI systems function in both cooperative and competitive behaviors to build microbial communities that are composed of only bacteria that are related via their CDI system alleles.
منابع مشابه
Functional Characterization of Pseudomonas Contact Dependent Growth Inhibition (CDI) Systems
Contact-dependent inhibition (CDI) toxins, delivered into the cytoplasm of target bacterial cells, confer to host strain a significant competitive advantage. Upon cell contact, the toxic C-terminal region of surface-exposed CdiA protein (CdiA-CT) inhibits the growth of CDI- bacteria. CDI+ cells express a specific immunity protein, CdiI, which protects from autoinhibition by blocking the activit...
متن کاملMechanisms of biofilm resistance to antimicrobial agents.
Biofilms are communities of microorganisms attached to a surface. It has become clear that biofilm-grown cells express properties distinct from planktonic cells, one of which is an increased resistance to antimicrobial agents. Recent work has indicated that slow growth and/or induction of an rpoS-mediated stress response could contribute to biocide resistance. The physical and/or chemical struc...
متن کاملEffect of Isolated Specific Lytic Phage against Growth and Biofilm Inhibition of Streptococcus mutans and Streptococcus sanguinis Isolated from Decayed Dental Plaque
Background and purpose: Despite advances in oral health and dental industry, tooth decay remains one of the most common oral diseases. One of the new methods to combat dental plaque, which is the main cause of caries, is using specific lytic bacteriophage. This study aimed to investigate the effect of isolated specific lytic phage against growth and biofilm inhibition of Streptococcus mutans an...
متن کاملEvaluation of the Effect of Zinc Oxide Nanoparticles on the Inhibition of Biofilm formation of standard Pathogenic Bacteria and Comparison with Drug Resistant Isolates
Introduction: Traditional medicines cannot adequately reach the target tissues, due to their large size; therefore, the attention of researchers has been drawn to the use of nanomedicines. In fact, the use of biological active compounds loaded on the surface of nanoparticles can be effective the in the promotion of their antimicrobial activity. In the earlier studies, it was demonstrated that b...
متن کاملInhibition of Aspergillus fumigatus and Its Biofilm by Pseudomonas aeruginosa Is Dependent on the Source, Phenotype and Growth Conditions of the Bacterium
Aspergillus fumigatus (Af) and Pseudomonas aeruginosa (Pa) are leading fungal and bacterial pathogens, respectively, in many clinical situations. Relevant to this, their interface and co-existence has been studied. In some experiments in vitro, Pa products have been defined that are inhibitory to Af. In some clinical situations, both can be biofilm producers, and biofilm could alter their physi...
متن کامل