Abstract: This invention pertains to substantially purified cultures of a gram-negative, aerobic, filamentous bacterium with cells ranging in length from 20-200 .mu.m, that accumulates intracellular poly-.beta.-hydroxybutyrate in intracellular granules, and that degrades chlorinated aliphatic compounds such as trichloroethylene and dichloroethylene, as well as phenol and other substituted benzenes. The invention includes the representative strain A-1, which has been deposited at the American Type Culture Collection under the accession number 55581. Also included are methods for using the new bacterium for bioremediation of contaminated environmental sites.