No abstract

No abstract

CO +)O + AH. CO. + H,O A (2) NH3 4-OA + AH-NHOH + H.O + A (3) T'he immediate source of reductant (AH.) can be reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] in methanotr-ophs, but in ammonia oxidizeirs it may be a cytochroome c (25. 157). All of the above oxidations are pparently catalyzed by monooxygenase enzymes: methane monooxygenase in methanotrophs and ammonia monooxygenase in ammonia oxidizei-s (25, 61). Only CH4 can support growth in the former organisms. and only NH. can support growth in the latter (39. 79. 80, 139). In both methanotrophs and ammonia oxidizers, there are reports that CH,OH is metabolized to CO, and cell C (25, 79, 164). While the pathway of CH,OH oxidation is well characterized in methanotrophs, in ammonia oxidizers it remains incompletely understood (148, 149). In addition, during the production of NO. from NH4' by both methanotrophs and ammonia oxidizers, small amounts of N,O are evolved (174, 177, 178). Although there is evidence that, in certain environments, methanotrophs and armmonia oxidizers may carry out oxidation of the growth substrate of the other as well as CO, few, if any, attempts have been made to measure directly the 68

No abstract

For personal use only.