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Appl. Environ. Microbiol., Jan 1996, 133-140, Vol 62, No. 1
M Bally and T Egli
Regulation of nitrilotriacetate (NTA) degradation and expression of NTA
monooxygenase (NTA-MO) in the NTA-degrading strain Chelatobacter heintzii
ATCC 29600 in continuous culture at a dilution rate of 0.06 h(sup-1) under
transient growth conditions when the feed was switched between media
containing NTA, glucose, or different mixtures thereof as the sole carbon
and energy sources was investigated. A transition from NTA to glucose was
accompanied by a rapid loss of NTA-MO. A transition from glucose to NTA
resulted in a lag phase of some 25 h until NTA-MO expression started, and
approximately 100 h was needed before a steady state for NTA-MO specific
activity was reached. This transient lag phase was markedly shortened when
mixtures of NTA plus glucose were supplied instead of NTA only; for
example, when a mixture of 90% glucose and 10% NTA was used, induction of
NTA-MO was detected after 30 min. This suggests a strong positive influence
of alternative carbon substrates on the expression of other enzymes under
natural environmental conditions. Regulation of NTA-MO expression and the
fate of NTA-MO were also studied during starvation of both glucose-grown
and NTA-grown cultures. Starvation of NTA-grown cells led to a loss of
NTA-MO protein. No synthesis of NTA-MO (derepression) was observed when
glucose-grown cells were starved.
Copyright © 1996, American Society for Microbiology
Dynamics of Substrate Consumption and Enzyme Synthesis in Chelatobacter heintzii during Growth in Carbon-Limited Continuous Culture with Different Mixtures of Glucose and Nitrilotriacetate
Swiss Federal Institute for Environmental Science and Technology (EAWAG) and Swiss Federal Institute of Technology (ETH), CH-8600 Dubendorf, Switzerland
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