DEGRADATION OF HOMOVANILLATE BY A STRAIN OF VARIOVORAX-PARADOXUS VIA RING HYDROXYLATION

A newly isolated strain of Variovorax paradoxus could grow on homovani llate and several monohydroxylated phenylacetic acids. During growth o n homovanillate, the organism formed separate NAD(P)H-dependent hydrox ylases with activity towards 4-hydroxyphenylacetic acid and homovanill ate. Homovanillate hydroxylase catalysed a typical monooxygenase react ion and had little activity towards 4-hydroxyphenylacetic acid. GC-MS and TLC analysis suggested that homovanillate was 1-hydroxylated to yi eld a dihydroxymonomethoxyphenylacetic acid which served as a substrat e for homogentisate 1,2-dioxygenase. Methanol, but not formaldehyde, w as released either during ring-cleavage or subsequent metabolism of th e ring-cleavage product.