Myrosinase overproducing mutants of Aspergillus sp. NR463

• Main Authors: Butrindr B., Niamsup H., Shank L., Rakariyatham N.
• Format: Article
• Language: English
• Published: 2014
• Online Access: http://www.scopus.com/inward/record.url?eid=2-s2.0-33751335584&partnerID=40&md5=a6edd3c7de5b1e3776e60de64ae0632a; http://cmuir.cmu.ac.th/handle/6653943832/6524
• Institution: Chiang Mai University

A myrosinase (thioglucoside glucohydrolase or thioglucosidase, EC 3.2.3.1) producing fungus, Aspergillus sp. NR463, was newly isolated from decayed soil sample obtained in Lamphun province, Thailand and was subjected to mutagenesis and selection for myrosinase production on low cost medium prepared from mustard seed cake (Brassica juncea). Studies of production and stability of the enzyme showed that UV mutagenesis induced myrosinase overproduction. Aspergillus sp. NR463U4 produced myrosinase 2.35 U ml-1 at 36 h of the cultivation. The stability studies revealed that myrosinase from the mutant strains retained activity for 3.5 times longer than wild-type at 30 °C. Analysis of the glucosinolate-degradation products by myrosinase of wild-type and all mutant strains gave similar results showing that allylisothiocyanate was present as a main product while allylcyanide was not detected. Mutant strains consumed glucosinolate in the high concentration (10 mM) and completely degraded in 36 h. Aspergillus sp. NR463U4 maintained constant myrosinase production judging by the production stability comparing with the wild-type for 8 months. High production and prolonged stability of myrosinase demonstrated that this mutant could be a new found candidate for industrial application.