Characterization of an alginolytic marine bacterium from decaying rishiri-kombu Laminaria japonica var. ochotensis

An alginolytic marine bacterium, H-4, was isolated from decaying thalli of Laminaria japonica var. ochotensis. Strain H-4 is a gram-negative polarly flagellated rod, which oxidatively produces acid from glucose, is oxidase positive and requires seawater for growth. DNA base composition measured from melting point of DNA is 39.8mol%G+C. According to these characteristics, the strain was identified as genus Alteromonas. Alteromonas sp. H-4 resembles A. espejiana but differs in DNA base composition and some properties and could not be identified to any species in the genus Alteromonas.The productivity of extracellular alginate lyase by Alteromonas sp. H-4 increased with seawater concentration and decreased with casitone concentration in the media. Its productivity was observed in a medium without alginate. The bacterium produced a maximum amonut of alginate lyase in liquid media containing 75% seawater, 0.5% casitone, and 0.1% sodium alginate after 96h incubation with shaking at 25°C