抄録
In the culture farm of laver, there are frequent outbreaks of a disease tentatively named, “green spot rotting” (Ryokuhan-byo). Isolation of bacteria was carried out by inoculating a suspension of the diseased frond of Porphyra yezoensis to ZoBELL's 2216 E agar plate. Five strains of the isolates were able to produce the “green spot rotting”-like deterioration, in vitro. The bacteria initiated to invade from the injured part of the frond, collapsing the frond tissue by breaking into single cell or segments of several cells; resulting in turgescence and greening of the liberated cells, and thus macerating the invaded portion. This phenomenon observed in vitro differed from the symptom of the disease occurring naturally, by absence of plasmoptysis from the damaged cells. The bacteria were identified as Pseudomonas sp. (strains N 9, W 1 and W 2) and Vibrio sp. (strains V 7 and Y 1). This experiment supports the supposition that the “green spot rotting” of cultured Porphyra is of bacterial origin.
