In order to achieve poly-beta-hydroxybutyric acid (PHB) production using recombinant DNA in various host bacterial cells, the isolation of genes for PHB biosynthesis was attempted. As a result, a 5.2kb DNA fragment containing phbCAB operon of Alcaligenes eutrophus was isolated by colony hybridization using synthetic oligodeoxyribonucleotides as probes. The constructed recmbinant plasmid pSK(+)-phbCAB operon was transferred to Escherichia coli, and the obtained transformant accumulated considerable amount of PHB.