Influence of Culture Conditions on the Biotransformation of (+)-Limonene by <i>Aspergillus niger</i>

¹Cátedra de Farmacognosia y Productos Naturales, Departamento de Química Orgánica, Facultad de Química, Universidad de la República, Av. Gral. Flores 2124, 11800 Montevideo, Uruguay. Fax: ++598 29244068. E-mail: carlosga@fq.edu.uy

The influence of the cultivation system and of the culture medium on the biotransformation of (+)-limonene by a strain of Aspergillus niger was investigated. Biooxidation products were obtained in all conditions tested. Using a laboratory bioreactor, six terpenes were identified in every medium, predominantly terpineols and carveols, whereas terpinen-4-ol and perillyl alcohol were the only terpenes found when flasks were used for culture. Perillyl alcohol and carveols predominated when the medium was tryptic soy broth (TSB), whereas the formation of terpineols was clearly favoured in malt broth (MB). Thus, there was a marked influence of the culture conditions on the results of the biotransformation. Changes in the conditions led to variations both in the type and relative amount of products obtained.