Biotransformation of l ‐menthol by soil‐borne plant pathogenic fungi ( Rhizoctonia solani )

The biotransformation of l ‐menthol was investigated by using nine isolates of Rhizoctonia solani (AG‐1‐IA Rs24, Joichi‐2, RRG97‐1; AG‐1‐IB TR22, R147, 110.4; AG‐1‐IC F‐1, F‐4 and P‐1) as a biocatalyst. In the cases of Rhizoctonia solani F‐1, F‐4 and P‐1, almost all of the substrate was consumed in 3 days and the major metabolite increased rapidly for the first of 3 days incubation. The structure of the major metabolite was elucidated on the basis of its spectral data. The major metabolite was determined to be (−)‐(1 S ,3 R ,4 S ,6 S )‐6‐hydroxymenthol which indicated that l ‐menthol was hydroxylated at the C‐6 position. From the main component analysis, the nine isolates of Rhizoctonia solani were divided into two groups based on their ability to transform l ‐menthol to (−)‐(1 S ,3 R ,4 S ,6 S )‐6‐hydroxymenthol. This is the first report on the biotransformation of l ‐menthol by Rhizoctonia solani . © 2001 Society of Chemical Industry