Abstract
To produce PHA(polyhydroxyalkanoic acid) from microbr, dozens of microorganism have been screened from sewage sludge. Selected a strain HJ out of 50 strains of PHA producing bacteria has a capability of accumulating large amounts of PHB/HV copolymer when grown in batch culture with a single carbon source (glucose) that was not generally considered as precursor of hydroxyvalerate monomer unit. The strain HJ was identified as the genus Pseudomonas with respect to morphological, cultural, and biochemical characteristics. The optimal temperature and pH for cell growth were $37^{\circ}C$ and 7.0. The optimal medium compositions for cell growth were glucose 1% as a carbon source, (NH4) 2SO4 0.2% as a nitrogen source, K2HPO4 0.3%, and KH2PO4 0.45%. TO investigate she optimal condition for PHA production two-step cultivation method was employed. PHA production was inducted by deficiency of NH4+, SO4-2, Mg+2. Besides carbon source, deficiency of all nutrients stimulated PHA productivity but deficiency of NH4+ stimulated the most HV monomer content. The highest PHA production was C/N molar ratio 95.2. Pseudomonas sp. HJ was also able to pyoduc PHB/HV copolymer when cultivated on alkane, alkanoate, alcohol as carbon sources. The contents of PHA and she proportions of hydroxyvalerate monomer units varied depending on the carbon sources. Especially Pseudomonas sp. HJ was able to incorporate hydroxyvalerate into PHB/HV to level as high as from 49 to 74 mol% when grown in a medium containing hexadecane and propionate. The purified PHA was identified PHB/HV copolymer by HNMR analysis.
하수처리장의 활생오니를 분리원으로 하여 수십종의 PHA 생산균을 분리하였다. 일반적으로 hyd droxyvalerate monomer unit의 전구물질로 알려져 있지않은 glucose로부터 비교적 많은 PHA를 생산 하는 균주를 공시균으로 선정하여 형태학척, 배양적, 생리학적 제 특성을 검토한 결과 Pseudomonas 속으 로 통정되었다. 균체 생육을 위한 최적 배양온도 벚 배양 pH는 각각 $37^{\circ}C$와 7.0이었으며, 최적 탄소원 으로셔 glucose 1 %, 최적 질소원으로서 $(NH_4)_2SO_4$ 0.2%, K1HPO. 0.3%, $KH_2PO_4$ 0.45% 였다. 최적 P PHA 생산조건을 조사하기 위하여 2단계 배양법을 이용하였다 PHA 생산은 배지성분중 $NH_4, O_4$, Mg가 결핍되 였을 때 향상되었고, 그중 $NH_4$, 의 결핍시 PHA 축적률과 HV monomer의 함량이 가장 높았다. C/N molar ratio 95.2에서 PHA 축적률이 가장 높았다. 공시균주 Pseudomonas sp. HJ는 alkane, alkanoic acid, alcohol을 탄소원으로 하여 P PHB/HV를 생산하였다. PHA의 생산량과 HV monomer의 함량은 이용된 기질에 따라 다양하였으며, 특히 hexadecane와 propiOnate를 탄소원으로 하였을 때 PHA중의 HV monomer의 함량이 49~74mol %로 매우 높았다. IH-NMR로셔 공시균으로 부터 분리정제된 PHA의 조성을 분석한 결과 PHB/ H HV copolymer임을 알 수 였였다
