Co-immobilised aspartase and transaminase for high-yield synthesis of l-phenylalanine

•One-pot synthesis of l-phenylalanine catalysed by coupling the enzymes aspartase and transaminase.•Enzymes were compatible upon reaction and immobilisation conditions.•Concentration of substrates and enzymes were optimised.•Co-immobilisation of enzymes allowed the synthesis of high concentrations of Phe.