The Dehalogenase Complement of a Soil Pseudomonad Grown in Closed and Open Cultures on Haloalkanoic Acids

Abstract

Pseudomonas sp. strain E4 was grown in continuous-flow culture with either monochloroacetate (MCA) or 2-monochloropropionate (2MCPA) as the growth-limiting substrate. In contrast to previous observations made for this organism grown in closed culture on 2MCPA, a third dehalogenase was detected under certain growth conditions, as well as dehalogenases I and II. The response of Pseudomonas sp. strain E4, in terms of its enzyme complement, varied depending on the organism’s growth rate and the nature of the growth-limiting substrate. With MCA as the growth-limiting substrate, dehalogenases II and III were only detected in slowly growing organisms. With 2MCPA as growth-limiting substrate, the responses were more variable and complex. The overall dehalogenase activities also depended on the growth rate and substrate limitation, with higher dehalogenation rates found in organisms growing slowly with MCA limitation compared with 2MCPA limitation. In fast growing organisms the relative rates of dehalogenation were reversed for the two limitations.