Degradation of morpholine, piperidine, and pyrrolidine by mycobacteria: evidences for the involvement of a cytochrome P450

Abstract

Nine bacterial strains that grew on morpholine and pyrrolidine as sole carbon, nitrogen, and energy sources were isolated from three different environments with no known morpholine contamination. One of these strains could also degrade piperidine. These bacteria were identified as Mycobacterium strains. A phylogenetic analysis based on the partial 16S rDNA sequences indicated that the isolated strains clustered within the fast growing group of mycobacteria. When the above-mentioned cyclic amines were used as growth substrates, the synthesis of a soluble cytochrome P450 was induced in all these bacteria. Other laboratory strains, Mycobacterium fortuitum and Mycobacterium smegmatis mc2155, were tested for their abilities to degrade morpholine. Neither of them degraded morpholine but could use pyrrolidine and piperidine. The growth of M. fortuitum and M. smegmatis mc2155 on these compounds involved a soluble cytochrome P450, suggesting that mycobacterial strains are naturally able to use pyrrolidine and have developed a similar enzymatic pathway to metabolize this amine.Key words: mycobacteria, morpholine, piperidine, pyrrolidine, cytochrome P450.