Ice-ice

Abstract: The most common perception of unfavorable environmental factors causing the ice-ice disease in the farmed seaweeds, Kappaphycus and Eucheuma, was demonstrated in this study for the first time using stressful conditions of abiotic factors in a continuous culture system. Light intensity of less than 50 μmol photon m−2 s−1 and salinity of 20% or less induced ice-ice whitening characterized by short segments at midbranches which were similar to those observed in the Philippine seaweed farms, while temperatures of up to 33–35 °C resulted in wide-scale whitening leading to complete damage of the branches. These effects were preceded by slow growth rates from an optimum of 3.7% d−1 to almost −2.0% d−1. Mechanical stress by wound injury did not result to ice-ice whitening similar to the above. Environmental factors observed to trigger ice-ice in the laboratory, although may not necessarily parallel those in the field, may act synergestically to produce similar effects.

Abstract: The occurrence of ice-ice disease in farmedKappaphycus spp. has tremendous implication on thecarrageenan industry in the Philippines. To elucidate the effect of thisdiseaseon the carrageenan quality, the chemical profile of carrageenan extracted fromhealthy and diseased Kappaphycus striatum“sacol” strain, was investigated using 13C and1H NMR, FT-IR and GPC methods of analysis. The native carrageenanextracts were composed predominantly of kappa carrageenan with trace amounts ofiota and 6-O-methylated carrageenan. Structural evidence indicatesdepolymerization of carrageenan from the ice-ice infectedportion of the thallus (whitish and soft part) lowered levels of iota andmethylconstituents. This finding was correlated to its low number average molecularweight (30 kDa) value. Accordingly, appreciable decreases incarrageenan yield, gel strength and viscosity and increase in syneresis indexwere noted. On the other hand, archetype quality of kappa-carrageenan wasobserved from both healthy and uninfected portion of the diseased thalli.

Abstract: Ice-ice disease in cultivated seaweeds is often associated with environmental stress and infection by pathogenic marine bacteria No studies have associated the disease with marine fungi Our study aimed to isolate marine fungi from cultivated Kappaphycus species and assess their ability to induce the disease Kappaphycus alvarezii and K striatum were collected from Calatagan, Batangas, Philippines Following washing with sterile artificial seawater and inoculation into culture media, 18 morphospecies of marine-derived fungi (MDF) were isolated Fungal diversity (Hss24) in infected seaweeds was higher than in healthy specimens K striatum (orange variety) had the highest incidence of MDF with 67 isolates, while K striatum (green variety) had the lowest incidence with only 17 isolates The ability of MDF to produce carrageenolytic and cellulolytic enzymes and utilize algal components was also tested Of the 18 MDF selected, three had carrageenolytic activity and ten had cellulolytic activity Most isolates utilized carrageenan, agar, and cellulose Among the 10 MDF assayed for their ability to induce ice-ice disease, three isolates (Aspergillus ochraceus, A terreus and Phoma sp) induced ice-ice disease symptoms (thallus bleaching) in healthy, non-axenic cultures of K alvarezii

Abstract: Kappaphycus and Eucheuma species have been successfully cultivated in Southeast Asia since the early 1970s. The increasing global demand for carrageenan in processed foods and thereby the need for industrial-scales of biomass to be provided to feed an extraction industry, exceeded wild stock availability and productivity and commercial demands could only be achieved through extensive cultivation of selected carrageenophytes. This unprecedented situation led to the introduction of carrageenophyte species and cultivars around the world; combined production of Eucheuma and Kappaphycus is one of the largest for seaweed biomass in the world.