Aryl carboxylic acid reduction and further reactions with GABA and glucose promoted by whole cells of Xylaria arbuscula

• Screening of whole cell biotransformation of p-substituted benzoic acids by endophytic fungus Xylaria arbuscula.
• Aryl carboxylic acid reduction to alcohol, GABA incorporation and glycosylation.
• Bioreduction activity is dependent on substituents with respect to carboxylic acid in benzene ring.

Xylaria arbuscula was collected from a “Cypress” tree, Cupressus lusitanica. The whole cells of this endophytic fungus were used in screening for microbial bioreduction of aryl acids. Different p-substituted benzoic acids were evaluated. However, only p-bromobenzoic acid, p-chlorobenzoic acid and p-nitrobenzoic acid were converted to their corresponding alcohols. Aryl acid metabolism of X. arbuscula included GABA incorporation and glycosylation when the substrates were p-bromobenzoic and p-chlorobenzoic acids were also observed. The substrates p-hydroxybenzoic and p-aminobenzoic acids were not transformed. These results could suggest that electron-withdrawing groups at para orientation activate the substrate for reduction.

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