SMALL SCALE MANIPULATORS: PREY-PREDATORY BACTERIAL POPULATION DYNAMICS IN RECIRCULATING FISH CULTURE SYSTEM

Bdellovibrio and like organisms (BALO`s) are small, Gram-negative predatory bacteria that are obligate predators of other Gram-negative bacteria. They belong to diverse phylogenetic clades and form the monophyletic families Bdellovibrionaceae, Bacteriovoraceae, and Peridibacteraceae in the δ-proteobacteria, and the genus Micavibrio in the α-proteobacteria.

Predation is common in an animal world and much less known in bacterial world where its effect on bacterial populations is not understood. BALO`s may potentially control specific bacterial populations and by that way mediate different processes.

We use an aquaculture zero discharge system (ZDS), to address the effect of environmental changes on the composition and dynamics of BALO populations. This self-regulating and self-recirculating system is composed of several basins where carbon, nitrogen and sulfur transformations take place, forming discrete but connected environments.

BALO`s and prey populations composition and dynamics were obtained from oxic, semi oxic, and anoxic habitats and from suspended and biofilm-associated population over a three-months period. MySeq sequencing showed that bacterial populations were habitat-segregated: oxic populations were similar and significantly different from anoxic populations. BALO`s composition differed between oxic and anoxic locations and showed strong site specification. Absolute and relative BALO population size fluctuated between the habitats and in time.

Their relations to bacterial and environmental parameters are under further analysis.