A novel method for characterisation of microbial growth kinetics on volatile organic compounds

A novel method for the determination of microbial growth kinetics on hydrop hobic volatile organic compounds (VOC) has been developed. A stirred tank r eactor was operated as a fed-batch system to which the VOC was continuously fed via the gas phase, assuring a constant VOC concentration in the minera l medium. A flow of air was saturated with the VOC, and then mixed with a f urther flow of air, to obtain a predetermined VOC concentration. Thus, diff erent VOC concentration; in the mineral medium could be obtained by alterin g the VOC concentration in the feed gas. The growth kinetics of Xanthobacte r autotrophicus GJ10 on 1,2-dichloroethane (DCE) and of Pseudomonas sp. str ain JS150 on MonoChloroBenzene (MCB) were assessed using this method. The g rowth of strain JS150 than 160 mg l(-1) and the results were fitted using a piecewise function. The growth kinetics of strain GJ10 were described by t he Luong model where maximum growth rate mu(max) = 0.12 h(-1) substrate sat uration constant K-S = 7.8 mg l(-1) and maximum substrate concentration S-m (above which growth is completely inhibited) = 1080 mg l(-1). Varying nitr ogen and oxygen hows enabled the effect of oxygen concentration on the grow th kinetics of Pseudomonas JS150 to be determined.