Mixed Cultures of the Phytoplankton Nannochloropsis oculata and the Marine Bacterium Sulfltobacter sp. R03 Inhibit the Growth of Virulent Strains of the Major Fish Pathogen Vibrio anguillarum

摘要

High- and low-virulence serotypes of the fish pathogen Vibrio anguillarum were challenged with a beneficial bacterium {Sulfltobacter sp. R03) in the presence of the phytoplankton Nannochloropsis oculata. The inhibitory activity of Sulfltobacter sp. against these V. anguillarum serotypes were observed in (1)phytoplankton culturing control medium (ESM) and (2) NCF, a filtrate prepared from N. oculata cultured in ESM. The presence of Sulfltobacter sp. in ESM significantly reduced the number of viable cells of allV. anguillarum serotypes tested (02， 03， 04， 09 and 010). In NCF, Sulfltobacter sp. totally eradicated the 02 and 03 serotypes. The viabilities of the low-virulence serotypes 04, 09 and 010 when cultured in NCF in the presence of Sulfltobacter sp. were not significantly different from those cultured in ESM. We conclude, therefore, that phytoplankton cultured in the presence of naturally occurring Sulfltobacter sp. provide an essential tool for inhibiting the growth of the economically significant high-virulence fish pathogen V. anguillarum.