Strain P14 of facultative methylotrophic bacteria that synthetisizes poly-beta-hydroxybutyrate has been isolated. The cells are gram-negative motile rods with a polar flagellum. They do not form spores or capsules, but do have a caretenoid pigment. Predominant in the fatty acid composition of the cells is cis-vaccenic acid (cis 18:1: omega 7)--72%. In the phospholipid composition phosphatidylcholine predominates (45%), along with phosphatidylenthanoloamine (27%) and phosphatidylglycerol (17%). The main biquinone is Q-10; other ubiquinones (Q-8, Q-9, Q-11) are present in minor quantities. The cells accomplish the icl-variant of serine pathway. The GC content of DNA (Tm) is 65 mole%. A high level DNA-DNA homology with representatives of the genus Methylobacterium was observed. The strain has been identified as Methylobacterium extorquens strain P14.