Effects of glycerol concentrations on the bioproduction of PGHX by HX1126.

PGHX is a polymer of β (1-3)-galactose which posses the gel-forming property. As previously reported in the flask culture experiment, the crude PGHX (24.9 g/L, 48.2% in yield) with the maximum gel strength of 957 g/cm can be generated. However, PGHX produced in the stirred bioreactor had no gel-forming property when using the same medium. Hence, the effects of different glycerol concentrations on both the yield and the gel-forming property of PGHX were investigated and the reason for gel-forming property losing was explored. We proposed a new strategy for the production of PGHX with enhanced gel formation in the stirred bioreactor by mediating both the concentration of carbon source and the duration of fermentation. As a result, we managed to obtain the crude PGHX (22 g/L, 42.4% in yield) with the maximum gel strength of 438 g/cm at 56 h in the bioreactor. This strategy would help the enhancement of PGHX yield in the industrial production.