Microbial transformation of β-sitosterol: accumulation of 3-(5α-hydroxy-7aβ-methyl-1-oxo-3aαH-hexahydroindan-4α-yl)propionic acid and the X-ray structural identification of its δ-lactone

Abstract

β-Sitosterol is degraded by a mutant of Nocardia sp. M29 to 3-(5α-hydroxy-7aβ-methyl-1-oxo-3aαH-hexahydroindan-4α-yl)propionic acid (VI), the δ-lactone of which (VII) was identified by X-ray structural analysis. The ratio of the acid to its lactone is found to be dependant on the pH of the medium and is not the result of enzymatic interaction. The characteristics of the β-sitosterol degradation are discussed.