PURPOSE: To obtain the subject microorganism of Pseudomonas sp. AJI-I--I strain belonging to the genus Pseudomonas, having hydrocarbon decomposition capability, actively growing in marine environment by using hydrocarbon as the sole carbon source and capable of decomposing and removing hydrocarbons in seawater.

CONSTITUTION: This microorganism is Pseudomonas sp. AJI-I-I strain (FERM P-13008) belonging to the genus Pseudomonas, capable of decomposing hydrocarbons and actively growing in marine environment using hydrocarbon as the sole carbon source. The microorganism is preferably used for the treatment of seawater polluted with hydrocarbons.