Genetic diversity of the causative agent of ice-ice disease of the seaweed Kappaphycus alvarezii from Karimunjawa island, Indonesia

Abstract

An essential step in investigating the bacterial role in the occurrence of diseases in Kappaphycus alvarezii is the characterization of bacteria associated with this seaweed. A molecular characterization was conducted on the genetic diversity of the causative agents of ice-ice disease associated with K. alvarezii widely known as the main source of kappa carrageenan. K. alvrezii infected with ice-ice were collected from the Karimunjawa island, North Java Sea, Indonesia. Using Zobell 2216E marine agar medium, nine bacterial species were isolated from the infected seaweed. The molecular characterizations revealed that the isolated bacteria causing ice-ice disease were closely related to the genera of Alteromonas, Bacillus, Pseudomonas, Pseudoalteromonas, Glaciecola, Aurantimonas, and Rhodococcus. In order to identify the symptoms causative organisms, the isolated bacterial species were cultured and were evaluated for their pathogenity. Out of 9 species, only 3 isolates were able to cause the ice-ice symptoms and consisted of Alteromonas macleodii, Pseudoalteromonas issachenkonii and Aurantimonas coralicida. A. macleodii showed the highest pathogenity.