Bacteria using methanol were isolated from methanol contaminated soils in Gumi plant complex. The most promising culture was selected based on rapid growth and capacity of PHB accumulation. It was tested that various kinds of precursors such as acids, alcohols, esters, and alkanes could be incorporated in PHB, and certified by gas chromatograph. Only valeric acid could be incorporated in PHB. Selected one was cultivated in various kinds of nutrient limited condition and excess carbon source, because PHB is carbon reserve material. These condition could accelerate accumulation of PHB, and especially nitrogen limitation cause highest product yield(P/X = 0.55). For producing PHB in optimal condition, optimal carbon concentration and pH were selected by Bioscreen C. Optimal methanol concentration was 0.1 to 1.55% (v/v), Ks and Ki in Andrews equation were 0.004, 1.55% respectively. Optimal pH range was 7.0 to 8.0. From above data, fed-batch culture was performed in optimal condition by using D.O.-stat and pH-stat method. Valeric acid was added to 0.2% (v/v) at the begining of stationary phase. Final cell concentration was 45 g/l, P(3HB-co-3HV) was 20.3 g/l, and 3HV fraction in P(3HB-co-3HV) was 4.5%.
