Mechanism controlling the extended lag period associated with vinyl chloride starvation in Nocardioides sp. strain JS614.
The extended lag period associated with vinyl chloride (VC) starvation in VC- and ethene-assimilating Nocardioides sp. strain JS614 was examined. The extended lag periods were variable (3-7 days), only associated with growth on VC or ethene, and were observed in VC- or ethene-grown cultures following 24 h carbon starvation and mid-exponential phase cultures grown on non-alkene carbon sources (e.g. acetate). Alkene monooxygenase (AkMO) and epoxyalkane:coenzyme M transferase (EaCoMT) are the initial enzymes of VC and ethene biodegradation in strain JS614. Reverse-transcription PCR confirmed that the AkMO gene etnC was expressed in response to epoxyethane, a metabolic intermediate of ethene biodegradation. Epoxyethane (0.5 mM) eliminated the extended lag period in both starved and mid-exponential phase cultures, suggesting that epoxyethane accumulation activates AkMO expression in strain JS614. AkMO activity in ethene-grown cultures was not detected after 6.7 h of carbon starvation, while 40% of the initial EaCoMT activity remained after 24 h. Acetate eliminated the extended lag period in starved cultures but not in mid-exponential phase cultures suggesting that acetate reactivates extant AkMO in starved VC- or ethene-grown cultures. The imbalance between AkMO and EaCoMT activities during starvation likely contributes to the extended lag period by delaying epoxide accumulation and subsequent AkMO induction.
Mattes
Timothy E
TE
Department of Civil and Environmental Engineering, 4105 Seamans Center, The University of Iowa, Iowa City, IA 52242, USA. tim-mattes@uiowa.edu
Coleman
Nicholas V
NV
Chuang
Adina S
AS
Rogers
Andrea J
AJ
Spain
Jim C
JC
Gossett
James M
JM
D000222:Adaptation, Physiological; D001673:Biodegradation, Environmental; D005030:Ethylenes / Q000378:metabolism*; D009618:Nocardiaceae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D014752:Vinyl Chloride / Q000378:metabolism*
D005030:Ethylenes; D014752:Vinyl Chloride