In vitro interactions of Acanthamoeba castellanii Neff and Vibrio harveyi

Free-living amoebae (FLA) are opportunistic protozoa widely distributed in the environment. They are frequently found in water and soil samples, but they have also been reported to be associated with bacterial human pathogens such as Legionella spp. Campylobacter spp or Vibrio cholerae among others. Including within Vibrio spp. V. harveyi (Johnson and Shunk, 1936) is a bioluminescent marine bacteria which has been found swimming freely in tropical marine waters, being part of the stomach and intestine microflora of marine animals, and as both a primary and opportunistic pathogen of marine animals. Our aim was to study the interactions between Vibrio harveyi and Acanthamoeba castellanii Neff. Firstly, in order to analyze changes in it cultivability, V. harveyi was coincubated with A. castellanii Neff axenic culture and with Acanthamoeba Conditioned Medium (ACM) at different temperatures in aerobic conditions. Interestingly, at 4 °C and 18-20 °C bacteria were still cultivable in marine agar, at 28 °C, in aerobic conditions, but there weren't significant differences comparing with the controls. We also noted an enhanced migration of Acanthamoeba toward V. harveyi on non-nutrient agar plates compared to controls with no bacteria.