A Search for Fucoidan-Degrading Bacteria in Coastal Sea Environments of Japan

Fucoidan-degrading bacteria were isolated by duplicate elective precultivations accompanying surface inoculation procedure from various samples from coastal sea areas. Fucoidan employed was prepared from a brown seaweed Nemacystus decipiens, and the medium used here consisted of inorganic salts, fucoidan as carbon source, and extract of sea bottom mud. In total 32 isolates were obtained from 396 samples, and sea bottom sand and mud were good sources for isolating. It seemed most likely that the great part of the isolates (28 strains) belonged to the genus Vibrio, but the genus of a few isolates (4 strains) was unknown. The isolates could utilize 41% to 84% of the fucoidan in the medium in a 4-day incubation period at 25°C. Cell extract from a representative isolate of Vibrio sp. conversed about 30% of fucoidan to fucose in exhaustive digestion. On the contrary, no fucoidan-degrading bacteria were found in 213 samples collected from land and freshwater areas.