Host specificity and action mechanism of algicidal Saprospira.

Research Project

Project/Area Number	04660230
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Fisheries chemistry
Research Institution	Kagoshima University
Principal Investigator	SAKATA Taizo Faculty of Fisheries, Accociate Professor, 水産学部, 助教授 (10041724)
Project Period (FY)	1992 – 1993
Project Status	Completed (Fiscal Year 1993)
Budget Amount *help	¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1992: ¥1,500,000 (Direct Cost: ¥1,500,000)
Keywords	Algicidal bacteria / Algicidal / Saprospira / Plaque / Diatom / Cellular fatty acids / 硅藻 / アミノ酸
Research Abstract	The aim of this study is to isolate marine algicidal microorganisms and to clarify the mechanism of algicidal action by the microorganisms. The outline of the results obtained in this study is as follows ; (1) Four kinds of microorganisms including Amoeba, Labyrinthula, Saprospira and Vitreoscilla, which form plaques on double layr agar plates containing diatom cells (Chaetoceros ceratosporum), were isolated from sea water in Kagoshima Bay and Kuruma-prawn culture ponds. (2) Saprospira isolates was classified as 3 species in terms of cellular morphology, physiological properties, growth response and fatty acid composition of whole cell lipids. (3) Saprospira strains formed plaque on double layr agar plates, but on addition of amino acids or organic acids to basal medium, plaque formation, colony formation or no growth of bacteria occurred depending on the kind of amino acids or organic acid added. (4) Saprospira strains were algicidally effective on some diatoms such as Skeletonema sp.besides Chaetoceros sp. (5) Although the addition of bacterial cells of Saprospira strains caused decrease in turbidity of algal culture, the supernatant of mixed culture of algae and bacteria did not inhibit the growth of diatoms. These results suggest that algicidal activity of Saprospira spp.is attributed to macromolecules distributed in surface layr of bacterial cells, which act on algal cell wall as there is direct contact between bacterial cells and host algal cells.