Effect of some abiotic stresses on the biotransformation of α-pinene by a psychrotrophic Chrysosporium pannorum

• Abiotic stress factors may improve the yield of terpene biotransformation.
• The bioconversion activity increased after pre-incubation of the psychrotrophic fungus with dioxane.
• Some organic solvents create changes in the ratio of the bioconversion products.
• Dioxane, chloroform and ethanol and thermal stress at 50 °C caused predominance of trans-pinocarveol over trans-verbenol.

Biotransformation of hydrophobic terpenes is limited by their toxicity and low bioavailability to biocatalyst cells. The metabolic activity of microorganisms, which is strongly dependent on environmental parameters, may also be affected by stressful conditions. The influence of pre-incubation of the fungus Chrysosporium pannorum in different stress conditions (organic solvents, medium pH and temperatures) on its activity in the oxidative bioconversion of α-pinene to verbenone and verbenol was examined. The total bioconversion activity increased over 2-fold after 15-min pre-treatment with 1.4-dioxane as an abiotic stress factor. Also, the change of the medium pH from the optimal 5.6 to 2.0 and 10 for 1 h before biotransformation enhanced product yield nearly 1.5-fold. Moreover, the use of dioxane, chloroform and ethanol and thermal stress at 50 °C caused changes in the oxidation product profile (predominance of trans-pinocarveol over trans-verbenol). A maximum increase in the yield of verbenol was observed when the biocatalyst was subjected to 15-min dioxane stress before 24-h biotransformation of 1% (v/v) pinene. The significance of the data presented is that abiotic stresses may improve the bioconversion activity or create changes in the proportion of the main biotransformation products.

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