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.
MCL-PHA의 생산을 위하여 올레익산을 탄소원으로 공급하여, 수도모나스 균주의 고농도배양을 하였다. 영양분의 제한을 주지 않은 배지에서 최적화된 기질 공급전략을 수행하여 173 g/L의 세포 농도를 얻었으나, PHA 농도와 PHA 함량은 32.3 g/L와 18.7 wt%.로 낮았다. PHA의 고농도 생산을 위하여 유가식 배양동안 phosphorus의 제한이 생기도록 $KH_2PO_4$의 농도를 감소시켜 배양을 하였다. $KH_2PO_4$ 의 농도가 4 g/L 일때, 세포의 농도와 PHA 농도, PHA 함량은 38시간 배양으로 각각 141 g/L, 72.6 g/L, 51.4 wt%가 얻어졌고, 그 생산성은 1.91 g PHA/L-h로 높은 값이 얻어졌다.
토양에서 새로이 분리된 Pseudomonas sp. KR-22균주는 올레익산을 탄소원으로 하여 3-hydroxy hexanoic acid, 3-hydroxy octanoic acid, 3-hydroxy decanoic acid, 3-hydroxy dodecanoic acid, and 3-hydroxy-5-cis-tetradecenoic acid 와 같은 여러 종의 MCL-PHA를 생산하였다. 또한, 유가식 배양을 통하여 82 g/L의 세포농도, 28%의 PHA 함량을 41시간의 배양으로 얻을 수 있었고, 이로 인한 생산성은 0.56 g/L-h 였다.
