Microaerobic and anaerobic metabolism of a Methylocystis parvus strain isolated from a denitrifying bioreactor
Article first published online: 24 AUG 2009
© 2009 Society for Applied Microbiology and Blackwell Publishing Ltd
Environmental Microbiology Reports
Special Issue: Methane Cycle. Editors: Professor J. Colin Murrell and Professor Mike S. M. Jetten
Volume 1, Issue 5, pages 442–449, October 2009
How to Cite
Vecherskaya, M., Dijkema, C., Saad, H. R. and Stams, A. J. M. (2009), Microaerobic and anaerobic metabolism of a Methylocystis parvus strain isolated from a denitrifying bioreactor. Environmental Microbiology Reports, 1: 442–449. doi: 10.1111/j.1758-2229.2009.00069.x
- Issue published online: 8 OCT 2009
- Article first published online: 24 AUG 2009
- Received 23 April, 2009; accepted 8 July, 2009.
An obligate methanotrophic bacterium, strain MTS, was isolated from a methane-fed microaerobic denitrifying bioreactor. 16S rRNA and DNA–DNA hybridization analysis revealed that this organism was most closely related to Methylocystis parvus, a Type II methanotroph, belonging to the α-subclass of the Proteobacteria. The metabolism of the bacterium under microaerobic and anaerobic conditions was studied by 13C-NMR. 13C-labelled poly-β-hydroxybutyrate (PHB) formation occurred in cell suspensions incubated with 13C-labelled methane at low (5–10%) oxygen concentration. Under these conditions low levels of succinate, acetate and 2,3-butanediol were formed and excreted into the culture medium. Intracellular PHB degradation was observed in intact cells under anaerobic conditions in the absence of an exogenous carbon source during a long-term incubation of 90 days. Multiple 13C-labelled β-hydroxybutyrate, butyrate, acetate, acetone, isopropanol, 2,3-butanediol and succinate were identified as products in in vivo13C-NMR spectra and in the spectra of culture medium during the dynamic PHB degradation. The isolated obligate methanotroph clearly shows a fermentative metabolism of PHB under anaerobic conditions. The excreted products may serve as substrates for denitrifying bacteria.