Energy coupling and respiration inNitrosomonas europaea |
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Authors: | Jan William Drozd |
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Institution: | (1) Woodstock Laboratory, Shell Research Ltd., Sittingbourne Research Centre, ME9 8AG Sittingbourne, Kent, UK |
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Abstract: | Intact cells ofNitrosomonas europaea grown in an ammonium salts medium will oxidise ammonium ions, hydroxylamine and ascorbate-TMPD; there is no oxidation of carbon monoxide, methane or methanol. TheK
m
value for ammonia oxidation is highly pH dependent with a minimum value of 0.5 mM above pH 8.0. This suggests that free ammonia is the species crossing the cytoplasmic membrane(s). The measurement of respiration driven proton translocation indicates that there is probably only one proton translocating loop (loop 3) association with hydroxylamine oxidation. The oxidation of endogenous substrates is sometimes associated with more than one proton-translocating loop. These results indicate that during growth hydroxylamine oxidation is probably associated with a maximum P/O ratio of 1.Abbreviations H+/O ratio
g equiv. H+ translocated/g atom O consumed |
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Keywords: | Nitrosomonas europaea Autotrophic bacteria Energy coupling Proton translocation Chemiosmotic hypothesis Ammonia oxidation |
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