Characterization Of A Novel Phenol Hydroxylase In Indoles Biotransformation From A Strain Arthrobacter Sp. W1

Indigo, as one of the oldest dyes, is still used for printing and dyeing worldwide, which is primarily produced by chemical synthesis in modern textile industries. However, researchers have been trying to seek more competitive and greener alternatives for commercial production, which has rejuvenated an interest in the microbial production of indigo. The aim of this study was to investigate the biotransformation of indoles to indigo ids by a novel phenol hydro xylase from Arthrobacter sp. W1. Homo logy modeling and molecular docking were applied to analyze substrate specificity and interactions between indoles and phenol hydro xylase. The color products were identified by HPLC-MS and NMR analysis.This cluster contains six components in the order of KLMNOP, which exhibit relatively low sequence identities (37-72%) with known genes. The optimal expression conditions evaluated by response surface methodology were as follows:seed age7.19h, level1.39%, OD600for inducing0.54, IPTG concentration0.19mmol/L, induction time2.37hand temperature35℃. Under the optimal conditions, the maximal activity of phenol hydro xylase could reach0.6167U/mg. The optimal pH and temperature for phenol hydro xylase was8.0and40℃, respectively.The optimal conditions for biotransformation indole to indigo were OD6002.5, indole concentration200mg/L and the maximal productivity of indigo was92.5mg/L in6h As for indole transformation by strain PH_IND by HPLC-MS and NMR analysis, three color products (indigo, indirubin and2-(7-oxo-1H-indol-6(7H)-ylidene) indolin-3-one) were identified.2-(7-oxo-1H-indol-6(7H)-ylidene) indolin-3-one appeared to be a novel pigment.2-(7-oxo-1H-indol-6(7H)-ylidene) indolin-3-one, is the dimerization of isatin and7-hydroxylindole at the C-2and C-6positions.Molecular docking suggested that indole and all the tested indole derivatives except for3-methylindole were transformed to various substituted indigoid pigments and the predominant color products derived from indoles were identified by spectrum analysis.