Publication :

Increasing PHB production with an industrially scalable hardwood hydrolysate as a carbon source

In this study, we report an industrially feasible conversion of wood hydrolysate from a pilot-scale forest biorefinery. The wood hydrolysate was compared to a synthetic hydrolysate with a similar content of carbon sources (glucose, xylose, and acetate). To maximize the PHB concentration, high-cell density cultivations were conducted in bioreactors for 52 h using the bacterium Paraburkholderia sacchari IPT 101 LMG 19450. The conversion of wood hydrolysate yielded a maximum PHB concentration of 34.5 g/L, which is among the highest reported for lignocellulose hydrolysates. In comparison, the use of a synthetic hydrolysate resulted in substantially lower PHB concentration (22.0 g/L). This could be attributed to a higher maximum specific growth rate of 0.36 vs. 0.33 per h for cells grown in wood hydrolysate vs. synthetic hydrolysate. For the wood hydrolysate, the final PHB content per cell mass reached 58 % g/g and a maximum PHB productivity of 0.72 g/(Lh), while the synthetic hydrolysate reached 55 % g/g and 0.46 g/(Lh) respectively. Given the increase in bacterial growth and PHB productivity when using the wood hydrolysate, the chosen lignocellulose conversion process is beneficial for subsequent biotechnological conversion to key bioproducts.