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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