Isolation of Bdellovibrio bacteriovorus from a tropical wastewater treatment plant and predation of mixed species biofilms assembled by the native community members

Abstract

It is reported here that a predatory bacterium belonging to the Genus Bdellovibrio, was isolated from activated sludge at the Ulu Pandan Water Reclamation Plant, Singapore. 16S rDNA gene sequencing analysis revealed that this isolate was 99% identical to 'Bdellovibrio bacteriovorus strain Tiberius' and hence is designated as 'Bdellovibrio bacteriovorus UP'. Using a novel approach based on fluorescence in situ hybridization (FISH), a prey cell density-dependent growth pattern of B. bacteriovorus UP was established. B. bacteriovorus UP preyed upon a broad range of bacterial species (60 species) isolated from the activated sludge. Except for Ochrobactrum anthropi, all Gram-negative species were sensitive to predation by B. bacteriovorus UP irrespective of the mode of growth (planktonic or biofilm). Similarly, the predation-sensitive species were not protected by the predation-resistant species, O. anthropi, as determined in multiple dual-species planktonic and biofilm consortia. Given the broad prey spectrum, B. bacteriovorus UP may impact functional community members, which are largely members of the Proteobacteria. Thus, these results provide an important insight to the role of predatory bacteria in shaping of community structure and function in both natural and engineered ecosystems.

Biotechnological Potential of Bdellovibrio and Like Organisms and Their Secreted Enzymes

“…Floccular activated sludge has a function in the degradation of organic matter as well as the removal of nitrogen and phosphorus. Feng et al (2016Feng et al ( , 2017 demonstrated that these biofilms do not protect sensitive species from BALOs predation, with BALOs being able to penetrate and/or degrade the biofilm for access to its prey. Thus, the vast majority of Gram-negative bacteria within the sludge are sensitive to BALOs, irrespective of if they are planktonic or in biofilm.…”

“…This, in turn, led to a reduction of the preyassociated recombinant plasmid, limiting the chances for HGT. Predatory bacteria thrive in environments with high prey density, hence are naturally occurring in WWTPs (El-Shanshoury et al, 2016;Feng et al, 2016;Yu et al, 2017). Not only do they kill the prey, but they also completely degrade its DNA (Matin and Rittenberg, 1972;Rosson and Rittenberg, 1979), consequently reducing the pool of ARGs in the environment.…”

Revisiting Antibiotic Resistance Spreading in Wastewater Treatment Plants – Bacteriophages as a Much Neglected Potential Transmission Vehicle

“…More experimental approaches have been conducted to possibly modulate the WWTP microbiome, rather than specifically address the amounts of bacteria within the plant. Of those approaches, addition of bacteriophages to target specific bacteria ( Withey et al, 2005 ), as well as addition of predatory bacteria targeting Gram-negative bacteria specifically ( Feng et al, 2016 ), has been postulated. While both approaches offer a unique ability to modulate the microbiome, and remove planktonic as well as biofilm bacteria, their impact in spreading of antibiotic resistance has not been studied; neither has the stress they impose upon bacteria.…”

Predation strategies of the bacterium Bdellovibrio bacteriovorus result in overexploitation and bottlenecks

“…Bdellovibrio and like organisms have a wide prey range (Stolp & Starr 1963;Jurkevitch et al 2000;Dashiff et al 2011;Feng et al 2016).…”