ABSTRACT
A possible aerobic degradation mechanism for polyacrylate (PA) was examined with acrylic oligomer-utilizing bacteria (Microbacterium sp., Xanthomonas maltophilia, and Acinetobacter sp.), using a model compound (1,3,5-pentane tricarboxylic acid, PTCA). Acyl-coenzyme A synthetase activities were detected with dialyzed cell-free extracts of PTCA-utilizing bacteria toward PTCA, PA 500, and PA 1000. This result suggested that PA is activated by coenzyme A and metabolized via PA-coenzyme A. Metabolic products formed from PTCA were detected in culture filtrates and reaction mixtures of washed cells. Fraction A was detected as a main metabolite by high-performance liquid chromatogra phy. A small amount of fraction B was concomitant with fraction A. Also, another fraction, C, was detected. These intermediate metabolites were characterized by LC-MS as 1,3,5-( 1-or 2-pentene)tricarboxylic acid for fractions A and B and as l,3,5-(2-oxopentane)tricarboxylic acid for fraction C. Fraction A was metabolized far faster than fraction B. Fraction B was thought to be an artifact formed from fraction A under alkaline conditions. Thus PTCA and also PA seemed to be metabolized by the mechanism similar to /?-oxidation of fatty acids. The degradation of PTCA by washed cells was slower than that by growing cells and was inhibited by 5 mM NaN3. This suggests that the metabolism is linked to a respiratory chain of bacteria.
