Microbial metabolism of chlorosalicylates: effect of prolonged subcultivation on constructed strains |
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Authors: | Miguel Angel Rubio Karl-Heinrich Engesser Hans-Joachim Knackmuss |
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Affiliation: | (1) Abt. für Gewässerreinigungstechnik, Technische Universität Hamburg-Harburg, D-2100 Hamburg 90, Germany;(2) Gesamthochschule Wuppertal, Lehrstuhl für Chemische Mikrobiologie der Bergischen Universität, D-5600 Wuppertal 1, Germany;(3) Institut für Mikrobiologie der Universität Stuttgart, D-7000 Stuttgart 1, Germany |
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Abstract: | The hybrid strain Pseudomonas sp. WR4016 was subcultivated with increasing concentrations of 5-chlorosalicylate (510 mM) as sole carbon source over a period of 9 months. At intervals of approximately 3 months derivative strains WR4017, WR4018 and WR4019 were isolated which exhibited higher growth rates and increased substrate tolerance. Comparative analysis of the turnover rates of the key enzymes in chlorosalicylate degradation showed that the adaptation process did not result from structural modifications of these proteins. Instead, balanced over-production of the salicylate hydroxylase and catechol 1,2-dioxygenase prevented the accumulation of toxic chlorocatechols and accounted for the reduction of the doubling times with 4- or 5-chlorosalicylate. A comparative analysis of a genetically engineered chlorosalicylate degrader PL300-1 showed similar regulatory patterns as the most advanced isolate WR4019 from the adaptation series. |
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Keywords: | Balanced regulations Higher growth rates Cloned strain PL300-1 Pseudomonas |
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