Bacteriological Studies on Diseases of Cultured Laver―III Changes in bacterial population of farm-seawater and laver, especially the detection of bacteria associated with laver-diseases

摘要

An epidemiological survey on the bacteria associated with laver-diseases was carried out with the sea water and laver fronds in Hama culture field, Saga, during the farming of laver. The total heterotrophic bacteria were numerously found in sea water during the growth of laver frond and its harvest, namely from November to December. Chitinoclasters of bacteria were already distributed on laver buds at an early stage of cultivation. Whereas, xylan-decomposing bacteria were detected mainly from late November to January in sea water as well as in laver fronds. In semi-selective isolation of bacteria associated with disease, 26 of 56 strains isolated were positive in the test of inoculation in vitro. Vibrio, causing green rot-like disease, were isolated from some diseased fronds, white rot, and also a healthy frond. Some strains of Agarbacterium and Beneckea were detected and identified. Some chitinoclasters, causing frond reddening, are not yet identified. The strains of Vibrio, Agarbacterium and Beneckea which were associated with laver-diseases were similar or related to the bacteria included in the phenons reported previously.