Fermentative production of ribavirin by overexpressing purine nucleoside phosphorylase in Bacillus

Yuechao Ma, Shuyao Yang, Li Li

Abstract

Ribavirin, a well-known broad spectrum antiviral agent, has been produced successfully by chemical or enzymatic method. However, the complex synthetic route and expansive material cost limit its large-scale production. In this work, we report a novel fermentative method for ribavirin production by engineered nucleoside producing strain. Two kinds of purine nucleoside phosphorylase (PNPase), i.e. high-molecular-mass PNPase (deoD) and low-molecular-mass PNPase (pupG) were intracellularly or extracellularly overexpressed in different nucleoside (adenosine, inosine, and guanosine) producing strains to accumulate ribavirin. The highest titer of 13.8 ± 0.9 g/L ribavirin was obtained by extracellularly overexpressed PNPase in the guanosine producing strain B. amyloliquefaciens TA208-LS. To further increase the ribavirin yield, the adding time of fermentative precursor 2H-1,2,4-triazole-3-carboxamide (TCA) and fermentation temperature were investigated. Under the optimal condition, a titer of 19.1 g/L ribavirin was obtained after 60 h fermentation in 7.5 L fermenter. This fermentation strategy provides a novel approach for industrial ribavirin production.