A biodegradation process for the organophosphonate product of Sarin (O-isopropyl methylphosphonofluoridate) hydrolysis, i.e., isopropylmethylphosphonate (IMPA). This process provides a feasible biodegradation demilitarization alternative to Sarin incineration. Public opposition of nerve agent incineration is widespread, and alternative methods are sought to help the U.S. Army meet the 2007 demilitarization deadline imposed by the Chemical Weapons Convention. This process uses a two-step approach to IMPA biodegradation. In the first step, a concentrated IMPA solution is used as the sole nutritional carbon and phosphorus source for microbial cultures. The second step involves diluting the culture and adding an inexpensive carbon source to encourage bacterial phosphate assimilation. The biodegradation typically involves a consortium of microorganisms comprising Methylobacterium radiotolerans GB21, Agrobacterium tumefaciens GB2GA, Klebsiella oxytoca GB2CS, GB272, Aureobacterium sp. GB2 and three bacterial isolates belonging to the same species GB23, GB272, and GB292.