Comparison of the degradation patterns of polychlorinated biphenyl congeners in Aroclors byPseudomonasstrain LB400 after growth on various carbon sources

Abstract

Resting cells of Pseudomonas strain LB400, grown on biphenyl, transformed 80, 50, and 17% of Aroclor 1242, 1254, and 1260, respectively. Resting cells grown on glucose or glycerol also transformed these polychlorinated biphenyl (PCB) mixtures to the extent of 60, 35, and 9% for Aroclors 1242, 1254, and 1260, respectively. Time courses of the transformation of the separated individual congeners in the Aroclors were plotted and used to determine the transformation rate constants (k). By analysis of the rate constants, it was concluded that the order of degradation of the different congeners in an Aroclor were similar regardless of the growth substrate. In general, k values for the conversion of a particular congener were lower for cells grown on glucose or glycerol compared with cells grown on biphenyl. Generally, k values for the transformation of the same congener in different Aroclors were not the same: rate constants had highest values for the congener in Aroclor 1242 and lowest values in Aroclor 1260. The data allowed congeners to be grouped according to their relative rates of degradation. The ratio of k values for transformation of individual congeners in Aroclors by cells grown on biphenyl and glucose were not constant.Key words: Pseudomonas strain LB400, polychlorinated biphenyls, Aroclors, transformation, resting cells.