Growth kinetics of EDTA biodegradation by Burkholderia cepacia

A pure culture of an EDTA-degrading strain was isolated from the Taiwan environment. It was identified as Burkholderia cepacia, an aerobic bacterium, elliptically shaped with a length of 5–15 m. The degradation assay showed that the degradation efficiency of Fe-EDTA by B. cepacia was approximately 91%. Evaluation of kinetic parameters showed that Fe-EDTA degradation followed substrate inhibition kinetics. This is evident from the decrease in specific growth rate with an increase in the initial substrate concentration greater than 500 mg/l. To estimate the kinetic parameters – _max, K_S and K_I, five substrate–inhibition models were used. From the results of non-linear regression, the value of _max ranged from 0.150 to 0.206 d^–1, K_S from 74 to 87 mg/l, and K_I from 890 to 2289 mg/l. The five models were found to underestimate the maximum specific growth rate by 1.5–3.7. Therefore, predictions based on these models would result in lower predicted value than those from the experimental kinetic data.