Cometabolism of methyl tertiary butyl ether and gaseous n-alkanes by Pseudomonas mendocina KR-1 grown on C5 to C8 n-alkanes.
Pseudomonas mendocina KR-1 grew well on toluene, n-alkanes (C5 to C8), and 1 degrees alcohols (C2 to C8) but not on other aromatics, gaseous n-alkanes (C1 to C4), isoalkanes (C4 to C6), 2 degrees alcohols (C3 to C8), methyl tertiary butyl ether (MTBE), or tertiary butyl alcohol (TBA). Cells grown under carbon-limited conditions on n-alkanes in the presence of MTBE (42 micromoles) oxidized up to 94% of the added MTBE to TBA. Less than 3% of the added MTBE was oxidized to TBA when cells were grown on either 1 degrees alcohols, toluene, or dextrose in the presence of MTBE. Concentrated n-pentane-grown cells oxidized MTBE to TBA without a lag phase and without generating tertiary butyl formate (TBF) as an intermediate. Neither TBF nor TBA was consumed by n-pentane-grown cells, while formaldehyde, the expected C1 product of MTBE dealkylation, was rapidly consumed. Similar Ks values for MTBE were observed for cells grown on C5 to C8 n-alkanes (12.95 +/- 2.04 mM), suggesting that the same enzyme oxidizes MTBE in cells grown on each n-alkane. All growth-supporting n-alkanes (C5 to C8) inhibited MTBE oxidation by resting n-pentane-grown cells. Propane (Ki = 53 micromoles) and n-butane (Ki = 16 micromoles) also inhibited MTBE oxidation, and both gases were also consumed by cells during growth on n-pentane. Cultures grown on C5 to C8 n-alkanes also exhibited up to twofold-higher levels of growth in the presence of propane or n-butane, whereas no growth stimulation was observed with methane, ethane, MTBE, TBA, or formaldehyde. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism.
Smith
Christy A
CA
Department of Microbiology, North Carolina State University, Raleigh, North Carolina 27695, USA.
O'Reilly
Kirk T
KT
Hyman
Michael R
MR
D000473:Alkanes / Q000378:metabolism*; D003470:Culture Media; D007700:Kinetics; D008738:Methyl Ethers / Q000378:metabolism*; D010084:Oxidation-Reduction; D044203:Pseudomonas mendocina / Q000254:growth & development / Q000378:metabolism*; D013997:Time Factors
D000473:Alkanes; D003470:Culture Media; D008738:Methyl Ethers; C043243:methyl tert-butyl ether