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Appl. Environ. Microbiol., Mar 1996, 886-891, Vol 62, No. 3
AE Mars, J Houwing, J Dolfing and DB Janssen
Burkholderia (Pseudomonas) cepacia G4 was cultivated in a fed-batch
bioreactor on either toluene or toluene plus trichloroethylene (TCE). The
culture was allowed to reach a constant cell density under conditions in
which the amount of toluene supplied equals the maintenance energy demand
of the culture. Compared with toluene only, the presence of TCE at a
toluene/TCE ratio of 2.3 caused a fourfold increase in the specific
maintenance requirement for toluene from 22 to 94 nmol mg of cells (dry
weight)(sup-1) h(sup-1). During a period of 3 weeks, approximately 65% of
the incoming TCE was stably converted to unidentified products from which
all three chlorine atoms were liberated. When toluene was subsequently
omitted from the culture feed while TCE addition continued, mutants which
were no longer able to grow on toluene or to degrade TCE appeared. These
mutants were also unable to grow on phenol or m- or o-cresol but were still
able to grow on catechol and benzoate. Plasmid analysis showed that the
mutants had lost the plasmid involved in toluene monooxygenase formation
(pTOM). Thus, although strain G4 is much less sensitive to TCE toxicity
than methanotrophs, deleterious effects may still occur, namely, an
increased maintenance energy demand in the presence of toluene and plasmid
loss when no toluene is added.
Copyright © 1996, American Society for Microbiology
Degradation of Toluene and Trichloroethylene by Burkholderia cepacia G4 in Growth-Limited Fed-Batch Culture
Department of Biochemistry, University of Groningen, 9747 AG Groningen, The Netherlands
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