The production of ethylene by pseudomonas syringae pv. phaseolicola was studied in batch and continuous culture system. This bacterium is a pathogen for Pueraria lobata (Wild) Ohwi (common name, Kudzu) and is considered to be unique in its ability to produce very high level of ethylene. Ethylene was taken from the head space of fermentor using gas sampling bulb and analyzed by a gas chromatography equipped with a flame ionization detector. In order to simplify the assay of ethylene, the predetermined mixture of air and pure oxygen was supplied at low flow rate. From the batch culture, the production pattern of ethylene was found to be growth-associated. Carbon-limited chemostat was executed at the dilution rate of 0.05-0.30hr. $^{-1}$. The effects of different dissolved oxygen concentration on the specific ethylene production rate were investigated to determine a critical dissolved oxygen concentration for ethylence production. From the chemostat culture, dissolved oxygen concentration of 4 mg-$O_2$/L was found to be critical for ethylene production. Below this, a sharp decrease was observed in specific ethylene production rate. On the other hand, ethylene production was inhibited by high dissolved oxygen concentration(above 8 mg-$O_2$/L).
