EFFECT OF OXYGEN AND STORAGE-CONDITIONS ON THE METABOLIC-ACTIVITIES OF POLYCHLORINATED-BIPHENYLS DECHLORINATING MICROBIAL GRANULES

The effect of oxygen and storage conditions on the metabolic activitie s, measured by volatile fatty acid (VFA) degradation and methane produ ction, and by the dechlorinating activity of methanogenic polychlorina ted biphenyl (PCB) granules, were studied. Incubation of the granules in air for different periods did not result in significant inhibition in volatile fatty acid degradation and methane production activities. The inhibitory effect of oxygen increased with increased length of exp osure. The overall methanogenic activities, however, recovered after a 10-day incubation period in the absence of oxygen. Oxygen exposure di d not cause any significant effect on the dechlorinating activity of t he granules tested with a PCB mixture, Aroclor 1254. In 6 months, appr oximately 80% [based on the concentration (mu M) of chlorine removed] of the Aroclor 1254 was dechlorinated even by granules exposed to oxyg en for 168 h. Granules stored at room temperature (20 degrees C) appea red to be more active compared to the granules stored at 4 degrees C o r -20 degrees C. Similarly, granules stored with a nutrient mixture, c ontaining methanol, glucose and yeast extract showed higher metabolic activities. Our results demonstrate that the effect of oxy gen exposur e was not significant and was reversible. PCB granules could be stored at room temperature with an auxiliary carbon source in the presence o f PCB without significant loss of activity. These properties make meth anogenic PCB granules suitable candidates for practical use in PCB dec hlorination and biodetoxification.