Transformation and Mineralization of Aroclor 1254

Abstract

Aroclor 1254 was transformed by actively growing cells of Acinetobacter P6 to a greater extent than by resting cell suspensions. This was commensurate with the exponential loss of biphenyl-oxidizing activity with whole cells to 5% of the original after 28 hours. Acinetobacter P6 growing on biphenyl was able to transform 34% of Aroclor 1254 (10 ppm). P6 was also grown in co-culture together with three strains that show prospects of transforming metabolites produced by Acinetobacter P6 during co-metabolism of Aroclor. P6, strains HBP1, TCC1, and 4ClBz1 were grown on different combinations of the following substrates: biphenyl, 2,2′-dihydroxybiphenyl, trans-3-chlorocrotonic acid, 4-chlorobenzoic acid, and 10 ppm of Aroclor 1254 spiked with ¹⁴C-Aroclor 1254. In the case of Acinetobacter P6 growing solely on biphenyl, 0.6% of the original radioactivity could be found as ¹⁴C-CO₂. Although up to 45% of the radioactive Aroclor 1254 was transformed in co-cultures of Acinetobacter P6 together with the three additional strains, no more than 2.6% could be recovered as ¹⁴C-CO₂. Degradation of metabolites formed by Acinetobacter P6, rather than the initial oxidation of Aroclor 1254, might be the rate-limiting step in the overall mineralization of these polychlorinated biphenyls.