K-066. Isolation and Characterization of Telephthalate and Isophthalate Utilizing Bacteria from Compost

Y. Kishi, H. Takeda, K. Ohgi;
Hoshi Univ., Tokyo, JAPAN.

Background: Telephthalate (TPA) and Isophthalate (IPA) are known to be degraded via 2-pyrone-4,6-dicarboxylic acid (PDC). PDC is utilized as material of biodegradable polymer. Less microbial species have been reported to utilize IPA as the sole carbon source than that of TPA. The metabolic pathway and enzymes involved in the IPA degradation has not been studied or reported so far. In this study, we isolated, identified and characterized the bacteria which utilizes both TPA and IPA as the sole carbon and energy source from compost. The expression of enzyme which estimated to be involved in degradation of TPA or IPA were examined. Methods: In order to test the expression of TPA and IPA degrading enzymes, resting cell assay was carried out as follows; each cell which cultivated in 0.2× LB medium or W medium with 10 mM TPA or IPA, was washed with Tris-HCl buffer and resuspended in Tris-HCl buffer with final concentration to give an OD600 =1.0. Each suspension was incubated with shaking at 37ºC for 120 min with 1 mM TPA or 1 mM IPA. The remaining concentrations of TPA or IPA in reaction mixture were analized by HPLC. Results and Conclusion: The bacteria isolated from compost named Rhodococcus sp. HAL1. The strain was able to grow up to a temperature of 42ºC and couldn’t grow at 20ºC. The optimum growth temperature was 37ºC. Resting cell assay showed that 1mM TPA were mostly decreased within 90 min by resting cell which cultivated in W medium with TPA. This result suggested that the expression of enzyme which estimated to be involved in degradation of TPA was induced by TPA, but not by IPA in HAL1. While the experiment was performed in the same condition except IPA, the expression enzyme which estimated to be involved in degradation of IPA was induced by IPA , but not by TPA.