Knock-out of glucose dehydrogenase gene in Gluconacetobacter xylinus for bacterial cellulose production enhancement

Glucose dehydrogenase (GDH) locates in the cytoplasmic membrane of Gluconacetobacter xylinus oxidizes glucose to gluconic acid that decreases the conversion of glucose to bacterial cellulose (BC). In this study, a mutant of G. xylinus was generated by knocking-out the membrane bound GDH gene via homologous recombination of a defect GDH gene. The production of BC by G. xylinus mutant (GDH-KO strain) using glucose as a carbon source was investigated. Without the membrane bound GDH activity, the mutant strain still produces BC and increases glucose utilization efficiency for cellulose biosynthesis. In contrast, the wild-type strain oxidized a large fraction of glucose to gluconic acid that decreased the conversion yield of glucose to BC. Our results showed that the BC production from GDH-KO strain was about 40 and 230% higher than that of wild-type strain in static and shaken culture, respectively.