2013 年 6 巻 2 号 p. 73-80
To describe the predominant bacteria attached to the red alga Gracilariopsis chorda (Holmes) Ohmi collected from the estuary of Katsuura River in Tokushima Prefecture in southwest Japan, the bacterial populations and the floras of the naturally occurring algae, the cultured algae, and those found in the environmental seawater were investigated. The viable counts of the heterotrophic bacteria attached to the naturally occurring algae collected in March and June were 6.5×106 and 1.3×106 cells g-1, respectively. The viable counts of the heterotrophic bacteria attached to the cultured algae in March and June were 5.4×107 and 3.4×107 cells g-1, respectively. The viable bacterial count in the environmental seawater was 1.2×105 cells ml-1. Moraxella sp. was predominant in the environmental seawater. The predominant bacteria attached to the naturally occurring G. chorda collected in March and June were Vibrio sp. and Moraxella sp., respectively. After the continuous culture of algae in a sterile medium, Flavobacterium - Cytophaga sp. was predominant and the percentage of Vibrio sp. decreased. These bacterial flora changes suggest that Flavobacterium - Cytophaga sp. is predominant on the red alga G. chorda.
