Study On Culture Conditions Of Marine Bacterium Vibrio Agarivorans-1 And Vibrio Agarivorans-2 Producing Agarase And Characteristics Of Agarase

Because of the particularity of the marine environment, marine bacteria have many active substances which other bacteria don’t. They have a broadly development prospect. So far, agar-degrading bacteria mainly from marine bacteria. Studies have shown that agarase degrading bacteria can produce agarase, agarase can make agar polysaccharides degrade into agar oligosaccharides. Agar oligosaccharide has broad application prospects in many fields, because its active function. The enzyme activity of agarase that produced by agarase degrading bacteria is low, so it is necessary to optimize culture conditions of agarase that was produced marine bacteria, and reseach characteristics of agarase.This experiment referred to their single factor experiments results of Culture conditions optimization to do six factors and three levels orthogonal experiment for each of two marine bacteria. The results were determined as follows: the optimal culture conditions of Vibrio agarivorans-1 were 28 ℃, 24 h, pH 7, 50 m L /100 mL fermentation broth,12% inoculum. The optimal culture conditions of Vibrio agarivorans-1 were 28 ℃, 48 h, pH 7.2, 40 mL/100 mL fermentation broth, 10% inoculum.Determination of this two enzyme activity of marine bacteria, Vibrio agarivorans-2 which had the higher enzyme activity was mutated by UV- LiCl, the highly enzyme activity stable strain Vibrio agarivorans-2-32 was isolated. Measured and compared enzyme activity of Vibrio agarivorans-2-32 and Vibrio agarivorans-2.The enzyme activity of Vibrio agarivorans-2-32 was 5.417 U/mL, which was improved by 55.9%.Research the enzyme characteristics: The optimum substrate concentration is 0.20%.The optimum temperature is 40 ℃ and the optimum pH is 7.2.The agarase was stable under 40 ℃ and 6.0-7.0, respectively. The enzyme activity was promoted by Ca²⁺, But inhibited by Fe²⁺, Fe³⁺, Cu²⁺and Zn²⁺.