Free sugars from fruit wastes were evaluated for the production of poly(3-hydroxybutyrate) (PHB) in Paraburkholderia sacchari fed-batch bioreactor fermentations. Different initial sugar concentration, carbon to inorganic phosphorus (C/IP) ratio, IP addition during feeding and volumetric oxygen transfer coefficient (kLa) were evaluated to promote PHB production. The highest intracellular PHB accumulation (66.6%), PHB concentration (108.3 g/L), productivity (3.28 g/(L·h)) and yield (0.33 g/g) were achieved at 40 g/L initial sugars, C/IP 26.5, 202.6 h-1kLa value and 20% IP supplementation in the feeding solution. The effect of different microbial mass harvesting time on PHB properties showed no influence in weight average molecular weight and thermal properties. The harvest time influenced the tensile strength that was reduced from 28.7 MPa at 22 h to 13.3 MPa at 36 h. The elongation at break and Young's modulus were in the range 3.6-14.8% and 830-2000 MPa, respectively.
Keywords: Fermentation optimisation; Fruit waste; Paraburkholderia sacchari; Poly(3-hydroxybutyrate); Thermomechanical properties.
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