ABSTRACT
Periodontal diseases are multifactorial infections elicited by a complex of primarily gram-negative bacteria that interact with host tissues and lead to the destruction of the periodontal structures. Bdellovibrio bacteriovorus is a gram-negative bacterium that preys upon other gram-negative bacteria. It was previously shown that B. bacteriovorus has an ability to attack and remove surface-attached bacteria or biofilms. In this study, we examined the host specificity of B. bacteriovorus strain 109J and its ability to prey on oral pathogens associated with periodontitis, including; Aggregatibacter actinomycetemcomitans, Eikenella corrodens, Fusobacterium nucleatum, Prevotella intermedia, Porphyromonas gingivalis and Tannerella forsythia. We further demonstrated that B. bacteriovorus 109J has an ability to remove biofilms of Ei. corrodens as well as biofilms composed of A. actinomycetemcomitans. Bdellovibrio bacteriovorus was able to remove A. actinomycetemcomitans biofilms developed on hydroxyapatite surfaces and in the presence of saliva, as well as to detach metabolically inactive biofilms. Experiments aimed at enhancing the biofilm removal aptitude of B. bacteriovorus with the aid of extracellular-polymeric-substance-degrading enzymes demonstrated that proteinase-K inhibits predation. However, treating A. actinomycetemcomitans biofilms with DspB, a poly-N-acetylglucosamine (PGA) -hydrolysing enzyme, increased biofilm removal. Increased biofilm removal was also recorded when A. actinomycetemcomitans PGA-defective mutants were used as host cells, suggesting that PGA degradation could enhance the removal of A. actinomycetemcomitans biofilm by B. bacteriovorus.
Subject(s)
Antibiosis/physiology , Bdellovibrio/physiology , Gram-Negative Bacteria/physiology , Periodontitis/microbiology , Acetylglucosamine/antagonists & inhibitors , Aggregatibacter actinomycetemcomitans/physiology , Bacterial Adhesion/physiology , Bacteriological Techniques , Bacteroides/physiology , Bdellovibrio/drug effects , Biocompatible Materials/chemistry , Biofilms , Deoxyribonucleases/pharmacology , Durapatite/chemistry , Eikenella corrodens/physiology , Endopeptidase K/pharmacology , Enzyme Inhibitors/pharmacology , Fusobacterium nucleatum/physiology , Humans , Microscopy, Electron, Scanning , Porphyromonas gingivalis/physiology , Prevotella intermedia/physiology , Saliva/microbiology , Surface PropertiesABSTRACT
AIMS: The focus of this study was to evaluate the potential use of the predatory bacteria Bdellovibrio bacteriovorus and Micavibrio aeruginosavorus to control the pathogens associated with human infection. METHODS AND RESULTS: By coculturing B. bacteriovorus 109J and M. aeruginosavorus ARL-13 with selected pathogens, we have demonstrated that predatory bacteria are able to attack bacteria from the genus Acinetobacter, Aeromonas, Bordetella, Burkholderia, Citrobacter, Enterobacter, Escherichia, Klebsiella, Listonella, Morganella, Proteus, Pseudomonas, Salmonella, Serratia, Shigella, Vibrio and Yersinia. Predation was measured in single and multispecies microbial cultures as well as on monolayer and multilayer preformed biofilms. Additional experiments aimed at assessing the optimal predation characteristics of M. aeruginosavorus demonstrated that the predator is able to prey at temperatures of 25-37°C but is unable to prey under oxygen-limiting conditions. In addition, an increase in M. aeruginosavorus ARL-13 prey range was also observed. CONCLUSIONS: Bdellovibrio bacteriovorus and M. aeruginosavorus have an ability to prey and reduce many of the multidrug-resistant pathogens associated with human infection. SIGNIFICANCE AND IMPACT OF THE STUDY: Infectious complications caused by micro-organisms that have become resistant to drug therapy are an increasing problem in medicine, with more infections becoming difficult to treat using traditional antimicrobial agents. The work presented here highlights the potential use of predatory bacteria as a biological-based agent for eradicating multidrug-resistant bacteria, with the hope of paving the way for future studies in animal models.
