CONICET | Buscador de Institutos y Recursos Humanos

In this work, a bioprocessing strategy has been developed for the production of polyhydroxybutyrate (PHB) via fermentation of Cupriavidus necator on crude hydrolysates generated from Jerusalem artichoke (JA) tubers. Initially, grounded JA tubers were used as the sole substrate in solid state fermentations (SSF) of Aspergillus awamori that were carried out for the production of crude enzymes including principally inulinases, invertases, proteases, and phosphatases. Different SSF times were evaluated in order to identify the maximum level of enzyme production. Remaining solids from SSF cultures containig crude enzymes were transferred in an aqueous solution of grounded JA tubers for the hydrolysis of major macromolecules (inulin and protein) contained in JA into directly assimilable nutrients (e.g. fructose, glucose, amino acids and peptides). Thismethodology resulted in an inulin to reducing sugar andfructose conversion yield of 0.88 and 0.78 g/g, respectively. This bioprocess could be employed for the production of fructose-based fermentation feedstocks from JA tubers. Batch shake flask fermentations were subsequently carried out with C. necator DSMZ 4058 on JA hydrolysates. In some cases, different amounts of yeast extract were added into the cmplex media in order to acgieve desired nutrient levels. Intracellular PHB contents betwen 15 and 53 % of the total dry weight and total dry weight concentrations between 5 and 10 g/L were commonly attained. Results obtained show that a fructose-based fermentation feedstock can be produced from JA through the proposed bioprocess. In adition, it was demonstrated that this feedstock can sustain cell growth and PHB accumulation by C. necator with a minimum yeast extract supplementation.

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