For the production of polyhydroxyalkanoates (PHAs) from methanol by Methylobacterium organophilum, the effects of precursors and culture conditions with nutrient limitation were investigated. As precursors for PHAs formation, alcohols, alkanes or acids were used under $NH_4^+$ and $K^+$ limited culture condition. Among various precursors, only valeric acid was effective for the formation of P(3HB-co-3HV) and other PHAs were not produced. With the supplement of valeric acid as a precursor, the production of copolyester of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV), P(3HB-co-3HV) was increased by the limitation of nutrients such as $K^+$, $PO_4^{2-}$, $Mo_2^+$, $NH_4^+$. The maximum production of P(3HB-co-3HV) was achieved to 50% under the $k^+$-deficient condition, whereas the highest fraction of 3HV was obtained as 43 mol% under the DO-limited condition. The feeding of valeric acid in PHA production affected the cell growth, PHA formation and composition of PHA. With two stage fed batch culture under the $K^+$-deficient condition, the effect of ratio of valeric acid/methanol was investigated. With an increase in ratio of valeric acid to methanol, the cell growth and PHA production was decreased, whereas the fraction of 3HV was increased. With the ratio of 1/7.4(g-valeric acid/g-methanol), cell growth, P(3HB-co-3HV) content, and fraction of 3HV was achieved to 9.5 g/l, 41 %, 14.2 mol %, respectively. For the mass production of copolyester of P(3HB-co-3HV) by fed batch culture using DO-stat technique was carried out. Under the $K^+$-deficient culture condition, cell growth was reached to 12.42 g/l with P(3HB-co-3HV) content of 52%.
