Effects of kepone on growth and respiration of several estuarine bacteria

The toxicity of Kepone to mixed populations of estuarine microorganisms was determined by standard plate assays on Zobell marine medium containing 0.02, 0.20, and 2.0 mg of Kepone per liter. Under aerobic conditions, Kepone reduced the number of colony-forming units at all concentrations tested, but had no effect on the number of anaerobic microorganisms. Gram-positive organisms were more sensitive to Kepone than were gram-negative organisms. Growth of gram-negative isolates was not inhibited in nutrient broth, but was significantly inhibited in a minimal salts broth. Oxygen uptake by most isolates was reduced 25 to 100% by 20 ppm (20 mg/ml) of Kepone. Oxygen evolution was observed when several gram-positive isolates were exposed to Kepone concentrations of 20 ppm. Pentachlorophenol at concentrations above 28 ppm produced effects similar to those produced by Kepone. Inhibition of electron transport by Kepone was demonstrated by a significant reduction in the specific activities of NADH oxidases and succinooxidase.