Immobilized aculeacin A acylase from Actinoplanes utahensis: characterization of a novel biocatalyst

Aculeacin A acylase from Actinoplanes utahensis (AuAAC), an amidohydrolase able to catalyze the acyl moieties of antifungal echinocandin antibiotics, has been also described to efficiently hydrolyze penicillin V and natural aliphatic penicillins to yield 6-aminopenicillanic acid (6-APA). Hence, taking into account its potential use in the synthesis of beta-lactam antibiotics as well as antifungal echinocandins, the recombinant enzyme was covalently immobilized onto several epoxy-activated supports in order to obtain a robust biocatalyst to be used in industrial bioreactors. The best biocatalyst was obtained by attaching the enzyme on Sepabeads EC-EP5 where immobilized AuAAC was homogeneously distributed over the surface of this support as shown by confocal scanning microscopy. The obtained biocatalyst showed a specific enzymatic activity of 35.2 IU/g wet carrier in the hydrolysis of penicillin V at pH 8.0 and 45 degrees C. Temperature-activity profile of immobilized AuAAC at pH 8.0 showed that the highest activity for the hydrolysis of penicillin V was achieved at 75 degrees C, whereas pH-activity profile at 40 degrees C indicated the highest activity for the hydrolysis of penicillin V was achieved at pH 8.5. The immobilized enzyme was highly thermostable since it suffered no loss of activity at 65 degrees C and pH 8.0 during 360 min, and it could be recycled for at least 30 consecutive batch reactions at pH 8.0 and 45 degrees C without loss of catalytic activity. Substrate specificity of the derivative also showed its ability to efficiently hydrolyze other natural aliphatic penicillins such as penicillins K, F and dihydroF besides its own substrate aculeacin A. Such interesting properties of this immobilized biocatalyst could allow its exploitation in industrial preparation of beta-lactam antibiotics and echinocandins.