Bioconversion of α-pinene by a novel cold-adapted fungus Chrysosporium pannorum

Abstract

Abstract The psychrotrophic fungus Chrysosporium pannorum A-1 is reported for the first time as a novel biocatalyst for O2-promoted oxidation of α-pinene. GC–MS analysis indicated that the main products of the reaction were compounds of a high commercial value, verbenol (1) and verbenone (2). Exponentially growing cells (days 2–3) were about twice as active as cells in the late stationary phase in terms of the total concentration of products. The highest yields of 1 and 2 were obtained using three-day and two-day-old mycelia and a medium containing 1.5 and 1 % (v/v) of the substrate, respectively. The optimal time for the bioconversion of α-pinene varied from 1 to 3 days, and depended on the kind of product desired. Most of 1 was produced at a relatively high concentration of 360 mg/L after the first six hours of α-pinene bioconversion [with an average yield of 69 mg/(g dry cell L aqueous phase)]. The oxidative activity of C. pannorum was identified across a wide temperature range of 5–25 °C, 10 °C being the optimum for the production of 1 and 20 °C for the production of 2. Sequential addition of the substrate during 3 days of the biotransformation resulted in a significant increase in 1 and 2 up to 722 and 176 mg/L, respectively, and a 2-fold enhancement of product yield as compared to bioconversion with a single supply of α-pinene. The concentration of total conversion products in the culture medium reached 1.33 g/L [which corresponded product yield of 225 mg/(g dry cell L)]. This represents probably the most promising result reported to date for oxidative biotransformation of α-pinene by a wild-type microorganism.