A comparative study was carried out on the biosynthesis of peroxisomal enzymes in the n-alkane-assimilating yeast Candida tropicalis 1098 and its dicarboxylic acid-producing mutant M2030. The mutant strain showed a drastic decrease in protein levels in acyl-CoA oxidase and 3-ketoacyl-CoA thiolase, constituting the yeast peroxisomal beta-oxidation system, in comparison with those of the wild-type strain. Interestingly, the development of peroxisomes was scarcely observed in the mutant strain.