Susceptibility of Biofilms to Bdellovibrio bacteriovorus Attack

Abstract

Biofilms are communities of microorganisms attached to a surface, and the growth of these surface attached communities is thought to provide microorganisms with protection against a range of biotic and abiotic agents. The capability of the gram-negative predatory bacterium Bdellovibrio bacteriovorus to control and reduce an existing Escherichia coli biofilm was evaluated in a static assay. A reduction in biofilm biomass was observed as early as 3 h after exposure to the predator, and an 87% reduction in crystal violet staining corresponding to a 4-log reduction in biofilm cell viability was seen after a 24-h exposure period. We observed that an initial titer of Bdellovibrio as low as 10 2 PFU/well or an exposure to the predator as short as 30 min is sufficient to reduce a preformed biofilm. The ability of B. bacteriovorus to reduce an existing biofilm was confirmed by scanning electron microscopy. The reduction in biofilm biomass obtained after the first 24 h of exposure to the predator remained unchanged even after longer exposure periods and reinoculation of the samples with fresh Bdellovibrio; however, no genetically stable resistant population of the host bacteria could be detected. Our data suggest that growth in a biofilm does not prevent predation by Bdellovibrio but allows a level of survival from attack greater than that observed for planktonic cells. In flow cell experiments B. bacteriovorus was able to decrease the biomass of both E. coli and Pseudomonas fluorescens biofilms as determined by phase-contrast and epifluorescence microscopy.

Cell-cycle progress in obligate predatory bacteria is dependent upon sequential sensing of prey recognition and prey quality cues

“…Strikingly, a different gene-expression profile was obtained in AP cells incubated with prey extract without ghosts: bd0108 and pilA were not silenced, and groES1 and ftsZ, both strongly enhanced in the GP (40,56), were specifically induced. The other GP marker genes (pcnB, dgcB, rpoD, and rpoH) as well as the bdelloplast formation genes (bd0816 and bd3459) and merRNA responded similarly as when incubated with the ghost preparation.…”

“…In effect, this scheme represents a prudent betting strategy. In contrast to the successful recognition of the carefully produced prey ghosts, in nature B. bacteriovorus, an effective predator of biofilms (56,60), encounters prey remains from which the first cue is hypothesized to be easily lost, as observed with prey lysate and perforated envelopes (Results).…”

Predation Efficacy of <i>Bdellovibrio bacteriovorus</i> on Multidrug-Resistant Clinical Pathogens and Their Corresponding Biofilms

“…Nevertheless, previous research showed that the thick polysaccharide capsule is not difficult for Bdellovibrio to penetrate (23), making it easier for B. bacteriovorus to access and efficiently disperse biofilms. It is reported that B. bacteriovorus is able to access biofilms as thick as 30 m (24). To further visualize biofilm predation after treatment with B. bacteriovorus, biofilms predeveloped on coverslips were exposed to B. bacteriovorus or a predator-free control and then analyzed by SEM (Fig.…”

Bacterial predator–prey dynamics in microscale patchy landscapes

“…Previous work has shown that while B. bacteriovorus can predate an E. coli biofilm, a significant fraction of the biofilm often remains [39], in contrast to predation on planktonic E. coli cultures where only a minute fraction of the population survives due to phenotypic resistance. In the microhabitats under investigation here, part of the prey population grows as a surface-associated biofilm (see electronic supplementary material, movies S1, S4, and S5).…”