초록
Methylobacterium organophilum CZ-2 synthesized polyhydroxyalkanoates (PHAs) under nitrogen limitation with CH<SUB>4</SUB> as carbon source and when either citrate or propionate was added as cosubstrates. The highest PHAs content (y<SUB>PHA</SUB>) in closed flasks was obtained in the CH<SUB>4</SUB>-citrate and CH<SUB>4</SUB>-propionate experiments attaining values of 0.82 and 0.68, respectively. M. organophilum CZ-2 cultivated in bioreactors with citrate and continuous CH<SUB>4</SUB> addition yielded a final PHAs concentration of 143gm<SUP>-3</SUP> containing hydroxybutyrate (HB), hydroxyvalerate (HV) and hydroxyoctanoate (HO), in a 55:35:10 ratio, with, y<SUB>PHA</SUB> of 0.88 and a CH<SUB>4</SUB> elimination capacity (EC) of 20gm<SUP>-3</SUP>h<SUP>-1</SUP>. With propionate, the y<SUB>PHA</SUB> was 0.3 and the EC around 8gm<SUP>-3</SUP>h<SUP>-1</SUP>. From <SUP>1</SUP>H and <SUP>13</SUP>C NMR experiments it was found that the polymer produced with CH<SUB>4</SUB>-citrate contained six different monomers: 3HB, 3HV, 4HV, 4-hydroxyheptanoate (4HH), 3HO and 4HO, showing the great versatility of this PHAs producing bacterium.