A bacterium that stereospecifically produces D-p-hydroxyphenylglycine (D-PHPG) from DI~-5-p-hydroxyphenylhydantoin (DL-5-PHPH) was isolated from soil and identified as Agrobacteriurn sp. IP-I 671. The hydantoinase and the N-carbamyl-amino acid amidohydrolase involved in this biotransformation process were both strictly D-stereospecific. Their biosynthesis was found to be inducible by addition of 2-thiouracil to the cultivation media, or to a lesser extent by uracil.The amidohydrolase activity of Agrobacterium sp. was strongly inhibited by ammonium ions co-produced with D-PHPG, whereas the hydantoinase activity under the same conditions was unaffected. Optimum temperature and pH were respectively 55 ° C and 10 for the partially purified hydantoinase, 45°C and 6.75 when resting cells were used. Biotransformations under these slightly acidic conditions allowed to complete conversion of 30 g/1 DL-5-PHPH into 25 g/l of D-PHPG (molar yield 96%) and involved enzymatic racemization of DL-5-PHPH.

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The degradation of Romandolide ([1-(3',3'-dimethyl-1'-cyclohexyl)ethoxycarbonyl] methyl propanoate), a synthetic alicyclic musk, by activated sludge inocula was investigated using both the manometric respirometry test OECD 301F and the CO₂ evolution test. In addition to measuring its biodegradability, key steps of the upper part of the metabolic pathway responsible for Romandolide degradation were identified using extracts at different time points of incubation. Early metabolism of Romandolide yielded ester hydrolysis products, including Cyclademol (1-(3,3-dimethylcyclohexyl)ethanol). The principal metabolites after 31 days were identified as 3,3-dimethyl cyclohexanone and 3,3-dimethyl cyclohexyl acetate. Formation of 3,3-dimethyl cyclohexanone from Cyclademol by sludge was confirmed in subsequent experiments using Cyclademol as a substrate, indicating the involvement of an oxygen insertion reminiscent of a Baeyer-Villiger oxidation. Further mineralization of 3,3-dimethyl cyclohexanone was also confirmed in subsequent studies. Three steps were thus required for complete biodegradation of the alicyclic musk: (1) successive ester hydrolyses leading to the formation of Cyclademol with concomitant degradation of the resulting acids, (2) conversion of Cyclademol into 3,3-dimethyl cyclohexanone, and (3) further mineralization via ring cleavage.

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