Aerobacter aerogenes and Bacillus subtilis accumulated p,p'-DDT and methoxychlor directly from water. Uptake of both "C-labeled organochlorine insecticides was rapid; 80 to 90% of the 24-h residues were reached within 30 min. Total cellular residues varied linearly with concentrations of DDT and methoxychlor in water ranging from 0.5 to 5.0 Asg/liter. The residue magnification factors from water were between 1,400-to 4,300-fold, but were independent of insecticide concentrations in water. When the insecticide-exposed microbial cells were washed with pesticide-free water, DDT residues were 45% in A. aerogenes and 30% in B. subtilis, whereas the methoxychlor level decreased nearly 75% in both organisms. Subsequent washing did not further reduce the insecticide residue. Autoclave-killed bacteria also rapidly adsorbed DDT and methoxychlor from water and, in some instances, residues were higher than in the living cells. Molecular polarity and lipid solubility appear to influence the retention of the organochlorine insecticides by bacterial cells. we also determined the water content of these bacteria. The values obtained are listed in Table 3. Water samples were extracted twice in a separatory funnel with petroleum ether-diethyl ether (95:5, volV vol) combined, dried over anhydrous sodium sulfate, and carefully evaporated to 1 ml. The emulsifier: fluor was added to the extract, and the sample was counted as previously described. Extraction efficiency from water for both compounds was 99%. Qualitative analyses of the insecticide residues

Aerobacter aerogenes and Bacillus subtilis accumulated p, p ′-DDT and methoxychlor directly from water. Uptake of both 14 C-labeled organochlorine insecticides was rapid; 80 to 90% of the 24-h residues were reached within 30 min. Total cellular residues varied linearly with concentrations of DDT and methoxychlor in water ranging from 0.5 to 5.0 μg/liter. The residue magnification factors from water were between 1,400- to 4,300-fold, but were independent of insecticide concentrations in water. When the insecticide-exposed microbial cells were washed with pesticide-free water, DDT residues were 45% in A. aerogenes and 30% in B. subtilis , whereas the methoxychlor level decreased nearly 75% in both organisms. Subsequent washing did not further reduce the insecticide residue. Autoclave-killed bacteria also rapidly adsorbed DDT and methoxychlor from water and, in some instances, residues were higher than in the living cells. Molecular polarity and lipid solubility appear to influence the retention of the organochlorine insecticides by bacterial cells.