Development of fed-batch culture for the production of Medium-chain-length polyhydroxyalkanoate by pseudomonas

Abstract

High cell density fed-batch cultures of Pseudomonas putida were carried out for the production of medium-chain-length polyhydroxyalkanoates (PHAs) using oleic acid as a carbon source. By employing an optimal feeding strategy without the limitation of any nutrient, high cell concentration of 173 g/L was achieved, but the PHA concentration and PHA content were only 32.3 g/L and 18.7 wt%. To increase the PHA concentration and PHA content, phosphorus limitation was applied during the fed-bath culture by reducing the initial $KH_2PO_4$ concentration. When the initial $KH_2PO_4$ concentration was reduced to 4 g/L, cell concentration, PHA concentration and PHA content obtained in 38 h were 141 g/L, 72.6 g/L and 51.4 wt%, respectively, resulting in a high productivity of 1.91 g PHA/L-h. Newly screened Pseudomonas sp. KR-22 from soil sample produced MCL-PHA mainly composed of 3-hydroxy hexanoic acid, 3-hydroxy octanoic acid, 3- hydroxy decanoic acid, 3-hydroxy dodecanoic acid, and 3-hydroxy-5-cis-tetradecenoic acid. By fed-batch culture, 82 g/L of DCW and 28% of PHA content was obtained in 41 h. This resulted in a productivity of 0.56 g/L-h.