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Appl. Environ. Microbiol., 12 1996, 4318-4322, Vol 62, No. 12
C Zipper, K Nickel, W Angst and HP Kohler
Sphingomonas herbicidovorans MH (previously designated Flavobacterium sp.
strain MH) was able to utilize the chiral herbicide (RS)-2-(4-
chloro-2-methylphenoxy)propionic acid (mecoprop) as the sole carbon and
energy source. When strain MH was offered racemic mecoprop as the growth
substrate, it could degrade both the (R) and the (S) enantiomer to
completion, as shown by biomass formation, substrate consumption, and
stoichiometric chloride release. However, the (S) enantiomer disappeared
much faster from the culture medium than the (R) enantiomer. These results
suggest the involvement of specific enzymes for the degradation of each
enantiomer. This view was substantiated by the fact that resting cells of
strain MH grown on (S)-mecoprop were able to degrade the (S) but not the
(R) enantiomer of mecoprop. Accordingly, resting cells of strain MH grown
on (R)-mecoprop preferentially metabolized the (R) enantiomer.
Nevertheless, such cells could transform (S)-mecoprop at low rates. Oxygen
uptake rates with resting cells confirmed the above view, as oxygen
consumption was strongly dependent on the growth substrate. Cells grown on
(R)-mecoprop showed oxygen uptake rates more than two times higher upon
incubation with the (R) than upon incubation with the (S) enantiomer and
vice versa.
Copyright © 1996, American Society for Microbiology
Complete microbial degradation of both enantiomers of the chiral herbicide mecoprop [(RS)-2-(4-chloro-2-methylphenoxy)propionic acid] in an enantioselective manner by Sphingomonas herbicidovorans sp. nov
Swiss Federal Institute for Environmental Science and Technology (EAWAG), Dubendorf, Switzerland.
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