Predation Response of Vibrio fischeri Biofilms to Bacterivorus Protists

Abstract

Vibrio fischeri proliferates in a sessile, stable community known as a biofilm, which is one alternative survival strategy of its life cycle. Although this survival strategy provides adequate protection from abiotic factors, marine biofilms are still susceptible to grazing by bacteria-consuming protozoa. Subsequently, grazing pressure can be controlled by certain defense mechanisms that confer higher biofilm antipredator fitness. In the present work, we hypothesized that V. fischeri exhibits an antipredator fitness behavior while forming biofilms. Different predators representing commonly found species in aquatic populations were examined, including the flagellates Rhynchomonas nasuta and Neobodo designis (early biofilm feeders) and the ciliate Tetrahymena pyriformis (late biofilm grazer). V. fischeri biofilms included isolates from both seawater and squid hosts (Euprymna and Sepiola species). Our results demonstrate inhibition of predation by biofilms, specifically, isolates from seawater. Additionally, antiprotozoan behavior was observed to be higher in late biofilms, particularly toward the ciliate T. pyriformis; however, inhibitory effects were found to be widespread among all isolates tested. These results provide an alternative explanation for the adaptive advantage and persistence of V. fischeri biofilms and provide an important contribution to the understanding of defensive mechanisms that exist in the out-of-host environment.

Ecological Diversification of Vibrio fischeri Serially Passaged for 500 Generations in Novel Squid Host Euprymna tasmanica

“…Biofilm formation is positively correlated in many host-associated vibrios with colonization potential, immunity avoidance, and eukaryotic cell attachment in hosts [57–59]. Biofilms are known to increase bacterial survival against environmental stress [58–61]. …”

Eukaryotic microbes, principally fungi and labyrinthulomycetes, dominate biomass on bathypelagic marine snow

“…Non-parasitic species of this group of flagellates are known to feed well on bacteria attached to particles (Artolozaga et al, 2000;Boenigk and Arndt, 2002) and in biofilms (Chavez-Dozal et al, 2013). Members of this group (Bodo sp., Neobodo designis) do not feed well on freely-suspended cells but prefer to feed on attached prokaryotes (Caron, 1987;Bochdansky and Clouse, 2015).…”

Coping with multiple enemies: pairwise interactions do not predict evolutionary change in complex multitrophic communities

“…The strength of predator defence evolution of B. subtilis from each treatment was assessed through biofilm formation, which is frequently used as a proxy of bacterial defence strategy based on bacterial cell aggregates that cannot be consumed by protists because they are too large or attached to surfaces (Böhme et al 2009, Chavez-Dozal et al 2012, Friman et al 2015. To this end, evolved and ancestral Bacillus bacteria were grown in 96-well plates containing 200 ml of microcosm medium at 22°C with the addition of approximately 10 washed P. caudatum cells.…”

“…To this end, evolved and ancestral Bacillus bacteria were grown in 96-well plates containing 200 ml of microcosm medium at 22°C with the addition of approximately 10 washed P. caudatum cells. After 24 h, P. caudatum cell number was counted and biofilm measured (Böhme et al 2009, Chavez-Dozal et al 2012, Friman et al 2015, as follows. The liquid medium was first decanted and all unattached cells removed through a water rinse.…”