EFFECTS OF AROCLOR 1221 ON THE GROWTH OF SOIL BACTERIAOGBONNAYA NWOKORO, OGECHI HANNA EKWEM AND UCHENNA OYEAGUAbstract Seventeen soil bacteria were examined for their ability to tolerate Aroclor 1221. Based on the preliminary screening, two isolates, namely Pseudomonas aeruginosa and Flavobacterium breve, (FC10 and FC14 respectively) with high capacity to tolerate Aroclor 1221 were selected while two other isolates, Micrococcus luteus and Arthrobacter globiformis (FC2 and FC 13 respectively) which showed lowest tolerance to Aroclor 1221 were also selected. All four bacteria were tested for their ability to tolerate 10, 15 and 20 μg/mL Aroclor 1221 in liquid culture. Results show that the growth of all the isolates were concentration dependent. Pseudomonas aeruginosa and Flavobacterium breve were able to grow better in the PCB. In Pseudomonas aeruginosa, the best optimum growth of 0.89 (OD600) was observed when the level of PCB was highest (20μg/mL). Also in Flavobacterium breve, the best optimum growth of 0.85 (OD600) was observed at the highest level of PCB (20μg/mL). These biomass levels were much higher than the control, devoid of PCB. Micrococcus luteus and Arthrobacter globiformis cells treated with Aroclor 1221 at all concentrations caused a decrease in their biomass and the levels produced were significantly lower than the control.
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