Oxidation of Lignin-Related Aromatic Alcohols by Cell Suspensions of Methylosinus trichosporium.

Cell suspensions of Methylosinus trichosporium oxidized the aromatic alcohols benzyl alcohol, vanillyl alcohol, and veratryl alcohol to the corresponding aldehydes, and with the exception of vanillyl alcohol, the aldehydes were further oxidized to the corresponding aromatic acids. No other transformation was observed, and the methoxyl moieties attached to the aromatic nucleus remained intact. More than 70% of the alcohol oxidized could be accounted for by aldehyde and/or acid. Investigation of the inhibitor kinetics of EDTA or p-nitrophenylhydrazine (specific for NAD-independent methanol dehydrogenase in methylotrophs) on aromatic alcohol oxidation revealed noncompetitive inhibition in which the V(max) was decreased but the K(m) remained unchanged. The pattern of inhibition of aromatic alcohol oxidation matched that of methanol oxidation, and the K(m) values for all of the substrates were similar (12 to 16 mM). The results indicate that the initial step in the oxidation of aromatic alcohols was similar to that for methanol, and because oxidation was incomplete (i.e., only the corresponding aldehyde or acid was produced), there may be some biotechnological advantages in using whole cells of methylotrophs to facilitate aromatic biotransformations.