Predation by Bdellovibrio bacteriovorus significantly reduces viability and alters the microbial community composition of activated sludge flocs and granules.
We recently isolated and characterised a predatory Bdellovibrio bacteriovorus strain from activated sludge (Ulu Pandan Water Reclamation Plant, Singapore), and this strain, B. bacteriovorus UP, was able to prey upon a broad spectrum of bacterial isolates from the activated sludge when grown as planktonic cells or as biofilms. Here, we have tested the effect of Bdellovibrio predation on floccular and granular sludge to determine if the spatial organisation, loosely or tightly aggregated communities, was protective from predation. The effect of predation was assessed using a combination of biomass quantification, cellular activity measurement and microscopic image analysis to determine community viability. Additionally, changes in the microbial communities due to predation by B. bacteriovorus UP were analysed through total RNA sequencing. Predation led to a significant reduction in microbial activity and total biomass for both floccular and granular sludge communities. Predation was also associated with significant changes in the microbial community composition in both communities, with >90% of the community members reduced in relative abundance after 24 h. Of those community members, the dominant organisms, such as Proteobacteria and Bacteroidetes, were the most affected phylotypes. This suggests that predatory bacteria, which display indiscriminant feeding, could significantly shift the species composition and thus, may disturb the operational performance of wastewater treatment systems.
The Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore.
Shugeng
S
Feng
The Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore.|The School of Materials Science and Engineering, Nanyang Technological University, Singapore 637551, Singapore.
Chuan Hao
CH
Tan
The Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore.
Florentin
F
Constancias
The Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore.
Gurjeet S
GS
Kohli
The Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore.
Yehuda
Y
Cohen
The Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore.|The School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore.|The Centre for Marine Bio-Innovation, The School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW 2052, Australia.
Scott A
SA
Rice
D001419:Bacteria; D001501:Bdellovibrio / Q000235:genetics; D000070060:Bdellovibrio bacteriovorus / Q000502:physiology*; D018441:Biofilms; D012722:Sewage / Q000382:microbiology*; D012846:Singapore; D014865:Waste Disposal, Fluid
D012722:Sewage
Bdellovibrio bacteriovorus; activated sludge; floccular sludge; granules; microbial community changes; predation