Recombinant Xylanase Production by <i>Komagataella phaffii</i> from Crude Glycerol

Since the demand for sustainable and renewable fuels has increased, the use of side products and especially industrial waste byproducts has become crucial. Therefore, the application of crude glycerol from the biorefinery to Pichia pastoris (Komagataella phaffii) cultivation and recombinant Sugiyamaella lignohabitans xylanase production was investigated as one of its potential further applications. This enzyme cleaves the xylan backbone into xylooligosaccharides (XOs), which are easier to hydrolyze to xylose. High cell-density cultivation (HCDC) with pure glycerol resulted in the xylanase activity of 0.89 U/mL of extracellularly produced enzyme and the productivity of 6.28 U/L/h. The xylanase expression was positively influenced by crude glycerol impurities in all cases. The highest increase in enzyme activity and productivity was achieved when partially purified (1.50 U/mL and 7.34 U/L/h) and even when nonpurified crude glycerol (1.59 U/mL and 9.13 U/L/h) were used. These findings suggest the potential valorization of biodiesel byproduct application for more sustainable biofuel production and its application in biorefineries.