MOLECULAR IDENTIFICATION OF NEW BACTERIUM CAUSING ICE-ICE DISEASES ON SEAWEED Kappaphycus alvarezii  

Marlina Achmad, Alimuddin*, Utut Widyastuti, Sukenda, Enang Harris,  Emma Suryanti
 
 Department of Aquaculture
 Bogor Agriculture University
 Bogor, West Java 16680
 alimuddin@ipb.ac.id
 

Bacteria are suspected to be the cause of ice-ice disease in seaweed Kappaphycus alvarezii. This study was conducted to identify bacteria that induce the onset of ice-ice disease in K.alvarezii. Bacteria were isolated from the thallus of K.alvarezii exhibited ice-ice symptoms of whitening (bleaching) collected from the waters of Bulukumba, South Sulawesi, Indonesia. Identification of bacteria was conducted by biochemical tests and 16S rRNA gene sequence analysis

The results revealed that eight species of bacteria were identified, namely: Shewanella haliotis strain DW01, Vibrio alginolyticus strain ATCC 17749, Stenotrophomonas maltophilia strain IAM 12323, Arthrobacter nicotiannae DSM 20123, Pseudomonas aeruginosa strain SNP0614, Ochrobactrum anthropic strain ATCC 49188, Catenococcus thiocycli strain TG 5-3, dan Bacillus subtilis subsp.spizizenii strain ATCC 6633 (Table 1).      

Furthermore, micropropagules of 2-4 cm in length were soaked in sea water containing 106 cfu/ml bacteria to determine the pathogenicity. Onset of ice-ice symptoms was visually observed every day. The results showed that fastest onset of ice-ice symptoms was by Stenotrophomonas maltophilia (5 hours post challenged), while the slowest was V. alginolyticus (44 hours post challenged). Other bacteria induced ice-ice symptoms at 15-21 hours post challenged. This is the first study reporting Stenotrophomonas maltophilia linked to ice-ice disease in K.alvarezii, and this bacterium might be useful towards generation of ice-ice resistance seaweed (Figure 1).

Based on the observation until seven days that revealed the micropropagules have shown symptoms of bleaching on the morphology and damaged tissue (histology results)      (Figure 2)