Polymers containing nitrophenyl groups were isolated when P. oleovorans was grown with 5-(2＇,4＇-dinitrophenyl)valerie acid (DNPVA). Growth experiments were carried out containing variable ratios of this and nonanoic acid (NA). These revealed a loss of the 2＇-nitro group as the experiment proceeded. The bacteria produced polymeric materials with 1.2%-6.9% of repeating units containing 4＇-nitro and/or 2＇,4＇-nitrophenyl rings, depending on the DNPVA:NA molar ratio and total concentration of these carbon sources, according to NMR analysis. The polymeric material isolated from approximately 15% dry cell weight when using a 7:3 DNPVA:NA molar ratio at 10 mM total concentration was a yellow, elastic substance. Thermal analysis indicated the presence of two T-g values, T-g,T-1 = -35.95 degrees C and T-g,T-2 = 28.74 degrees C, and one T-m value of 56.42 degrees C. These data suggest the presence of two polymers, one which contains nitrophenyl rings and the other being the copolymer of nonanoic acid.