Tolerance of Nitrobacter to toxicity of hydrocarbon fuels

The effects of four hydrocarbon fuels (jet fuel, kerosene, gasoline and diesel oil) on the nitrite utilization and logarithmic rate of growth of Nitrobacter were investigated. Nitrite utilization was determined by coupling of diazotised sulfanilic acid with naphthylamine hydrochloride. Nitrite utilization increased with increase in exposure period to the fuels. Low fuel concentrations proved stimulatory while high concentrations were inhibitory to the nitrification process. The percent-log survival of Nitrobacter decreased with increase in exposure time and concentration of the fuels. Nitrobacter sensitivity to hydrocarbon fuels decreased in the order, kerosene > jet fuel = gasoline > diesel oil.