Production of Fermentation Feedstock from Jerusalem Artichoke Tubers and its Potential for Polyhydroxybutyrate Synthesis

Abstract

A conceptual bioprocessing strategy has been developed for the production of a generic fermentation feedstock from Jerusalem artichoke (JA) tubers. Ground JA tubers were used as substrate in solid state fermentations (SSF) of Aspergillus awamori aiming at the simultaneous production of crude enzymes (e.g. inulinase, invertase, protease) that could be employed in the hydrolysis of JA meal macromolecules. After 48 h SSF, remaining solids that contained the crude enzymes were transferred to an aqueous solution of ground JA tubers for the hydrolysis of major macromolecules (inulin and protein) into assimilable nutrients (e.g. fructose, glucose, amino acids and peptides). Conversions of up to 70 % (w/w) inulin to fructose and glucose, among the highest reported in the literature, were achieved. This bioprocess could be employed for the production of fructose- and glucose-based fermentation media from JA tubers. Crude JA hydrolysates were tested as fermentation media for PHB production in shake flask fermentation resulting in intracellular PHB content up to 51.9 % and PHB concentrations up to 4 g L−1.