Xylonic acid production by recombinant Komagataella phaffii strains engineered with newly identified xylose dehydrogenases

Abstract

Microbial production of xylonic acid can be achieved via xylose oxidation catalyzed by the xylose dehydrogenase enzyme. In the present study, 11 putative xylose dehydrogenases (XDH) from bacterial and fungi were identified through in silico analysis using the sequences of the two XDH previously described. Among them, 6 genes were successfully cloned and expressed in Komagataella phaffii (Pichia pastoris) as demonstrated by the ability of the strains to produce xylonic acid. The best strain was capable of producing up to 37.1 ± 1.9 and 11.7 ± 1.6 g/L of xylonic acid with yields of 0.96 ± 0.02 and 0.40 ± 0.06 g/g in mineral medium and sugarcane bagasse hydrolysate, respectively. The results presented here demonstrated the functionality of 6 newly identified xylose dehydrogenases, increasing the number of XDH described. In addition, the efficiency of K. phaffii as a xylonic acid producer is showed for the first time.