The present invention provides an economical and efficient method for the elimination and biodegradation of soil and groundwater containing polar organic solvents, especially acetone. The bioremediation methods of the present invention comprise contacting the bacteria Xanthomonas maltophilia or Bacillus thuringiensis with the contaminated medium under appropriate conditions. In addition, the present invention provides for a composition of matter useful in the bioremediation of a medium, e.g., groundwater or soil contaminated with polar organic compounds, such as acetone.