IMMUNOFLUORESCENT DETECTION OF ICE-ICE DISEASE-PROMOTING BACTERIAL STRAIN VIBRIO SP. P11 OF THE FARMED MACROALGA, KAPPAPHYCUS-ALVAREZII (GIGARTINALES, RHODOPHYTA)

A specific immunofluorescent probe consisting of polyclonal antibodies was developed to detect a marine bacterium, Vibrio sp. strain P11, wh ich was found in a previous study to promote the ice-ice disease in th e cultivated red macroalga, Kappaphycus alvarezii. The method involves a combined application of the fluorescent stains, 4',6-diamidino-2-ph enylindole (DAPI) and the P11 PAbs, into a homogenized seaweed sample (<1 g wet wt), which is prediluted to make bacteria countable under an epifluorescence microscope without serious interference from autofluo rescing algal debris. The algal tissue homogenate is then filtered thr ough a 0.2-mu m-pore size Nuclepore membrane filter, serving as a moun ting pad, and viewed using alternating ultraviolet and IB excitation f ilters to detect total and specific bacteria, respectively, on the sam e microscopic field, at the same time. The immunofluorescent probe cou ld be used as a Valuable tool in studying the infection mechanism of t he bacterium in the macroalga In vitro.