Enzymatic and Microbial Biosynthesis of Novel Violacein Glycosides with Enhanced Water Solubility and Improved Anti-nematode Activity

Abstract

Violacein, a microbial metabolite with multiple applications, was produced in Escherichia coli, and glycodiversified using purified Bacillus glycosyltransferase (YjiC) enzyme with glucose, galactose, and N-acetylglucosamine, to generate five novel O-glycoside derivatives. One of the glucose-conjugated derivatives, violacein 5′-O-glucoside, was produced from engineered E. coli harboring entire violacein biosynthetic gene cluster (VioABCDE) and a glycosyltransferase gene (yjiC) in tryptophan supplemented TB medium. Violacein 5′-O-glucoside gained anti-nematodal activity against pine wood nematode Bursaphelenchus xylophilus, a causative agent of pine wilt disease. Moreover, the conjugation of sugar moieties in violacein enhanced water solubility. Violacein 5′-O-diglucoside was completely retained in water fraction, while its aglycone parent molecule was completely insoluble in water.