Isolation and characterization of extracellular halophilic ribonuclease from halotolerant Pseudomonas species

Werasit Kanlayakrit. Faculty of Agro-Industry. Dept. of Biotechnology; Ikeda, Takahiro. Faculty of Agro-Industry. Dept. of Biotechnology; Somporn Tojai. Faculty of Agro-Industry. Dept. of Biotechnology; Mangkorn Rodprapakorn. Faculty of Agro-Industry. Dept. of Biotechnology; Sarote Sirisansaneeyakul. Faculty of Agro-Industry. Dept. of Biotechnology

Isolation and characterization of extracellular halophilic ribonuclease from halotolerant Pseudomonas species

2001

Werasit Kanlayakrit(Kasetsart Univ., Bangkok (Thailand). Faculty of Agro-Industry. Dept. of Biotechnology) | Ikeda, Takahiro(Kasetsart Univ., Bangkok (Thailand). Faculty of Agro-Industry. Dept. of Biotechnology) | Somporn Tojai(Kasetsart Univ., Bangkok (Thailand). Faculty of Agro-Industry. Dept. of Biotechnology) | Mangkorn Rodprapakorn(Kasetsart Univ., Bangkok (Thailand). Faculty of Agro-Industry. Dept. of Biotechnology) | Sarote Sirisansaneeyakul(Kasetsart Univ., Bangkok (Thailand). Faculty of Agro-Industry. Dept. of Biotechnology)

Halotolerant bacterium isolated from Thai fish sauce, obtained in Surathani province, was identified as a Pseudomonas sp. No. 3241. This strain showed halophilic ribonuclease activity. When casamino acid (CA) and yeast extract (YE) were used as the nitrogen source in a mini jar fermenter, a ratio concentration of CA to YE of 15:20 g/l in Sehgal and Gibbons Complex (SGC) medium, without NaCl, gave maximum growth and ribonuclease activity (18.18U/ml). The ribonuclease enzyme was optimal at pH 10.0 and at the temperature of 50 deg C. It had marked halophilic enzyme properties that required an optimal NaCl concentration of 3 M. The ribonuclease was stable between pH 6.0 and 9.0 and at temperatures between 30 and 40 deg C.

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