OCCASIONAL PATHOGENIC BACTERIA PROMOTING ICE-ICE DISEASE IN THE CARRAGEENAN-PRODUCING RED ALGAE KAPPAPHYCUS-ALVAREZII AND EUCHEUMA-DENTICULATUM (SOLIERIACEAE, GIGARTINALES, RHODOPHYTA)

The bacterial isolates from normal and diseased branches of Kappaphycu s alvarezii and Eucheuma denticulatum in the Philippines were examined for possible role in the development of the ice-ice disease. The numb ers of bacteria on and in ice-iced branches were 10-100 times greater than those from normal, healthy ones. Grampositive bacteria predominat ed in almost all branch sources, but with an increasing proportion of agar-lysing bacteria in branches suffering from the ice-ice disease. T hese agar-lysing bacteria were composed of yellow and non-pigmented, s preading colonies identified to the Cytophaga-Flavobacterium complex a nd the Vibrio group. Among isolates which mainly appeared on ice-iced branches, two strains, designated as P11 (Vibrio sp.) and P25 (Cytopha ge sp.), which showed pathogenic activity, were obtained. These strain s caused early ice-ice whitening of K. alvarezii especially when subje cting branches to environmental stress, such as reduced salinity and l ight intensity, suggesting that these bacteria were occasionally patho genic. This paper offers new evidence of bacterial role in the develop ment of so-called ice-ice disease among farmed species of Kappaphycus.