Abstract
The enzymatic properties of the bacteriolytic activity was examined on the homogenates of skin mucus in yellowtail Seriola quinqueradiata. The activity was determined by the tubidimetric method using both lyophilized cells of Micrococcus lysodeikticus and Pasteurella piscicida as the substrates.
The skin mucus showed high bacteriolytic activity against both cells in distilled water or in low molar buffer. The activity against Micrococcus lysodeikticus was maximal at pH 8.0, 30°C and that against Pasteurella piscicida was maximal at pH 8.0, 50°C. Furthermore, the skin mucus after absorption to chitin hardly showed bacteriolytic activity against Micrococcus lysodeikticus but that against Pasteurella piscicida remained. The bacteriolytic activity of the skin mucus against both cells were completely inhibited by ρ-chloromercuribenzoic acid sodium salt (ρ-CMB), and that against Pasteurella piscicida was 40% inhibited by phenylmethylsulfonyl fluoride (PMSF). Ethylenediaminetetraacetic acid (EDTA) increased the activity against Pasteurella piscicida.
From the above-mentioned properties, it was suggested that plural bacteriolytic substances existed in the skin mucus of yellowtail.
