| Isophthalonitrile (IPN) is one of the most important pesticide intermediate, and is also used in preparation of plastomer, fiber and curing agent of epoxy resin. It's harmful to animals and human beings, and brought out environment problems. In present research, the degradation bacteria were screened and isolated, and the biological properties were analyzed.After the enrichment and domestication, four strains NJUST1101, NJUST1102, NJUST1103 and NJUST1104 were isolated from the sluge samples could utilize Isophthalonitrile as the sole source of carbon and nitrogen, and NJUST1101 was the advantage bacteria. From the result of the physiological and biochemical experiments, the bacteria were similar to Sporosarcina, Micrococcus, Staphylococcus and Azotobacter respectively.The result showed that degradation rate of IPN by NJUST1101 was much higher than that by NJUST1102, NJUST1103 and NJUST1104. NJUST1101 could degrade IPN observably about 87.2% at the low biomasses. Even of different initial concentration, NJUST1101 could degrade IPN to a low residual concentration (10mg/L). The additional carbon glucose and the additional nitrogen urea and Ammonium sulfate which slowed down the degradation efficiency but not affect the degradation rate of NJUST1101.When original pH was 5.0-9.0, the degradation rate was more than 80% for NJUST1101. At the temperature 25℃, NJUST1101 could degrade 91.32% of IPN. As the result of the orthogonal experiment: 27℃, pH7.0,400mg/L was the best condition for IPN biodegradation by NJUST1101. Analyzed by MS, IPN was degraded to isophthalic acid by nitrilase of NJUST1101.The nitrilase showed the highest activity at the pH6.5 and the temperature at 30℃respectively. The stability of nitrilase to pH7.0-8.0 and to heat below 30℃were good. The crude cell-free samples were purified by Sephadex G-100, and finally got the enzyme band by polyacrylamide gels electrophoresis. According to the mark, the molecular weight of the nitrilase was 76 kD. |
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