Abstract: In the present study, biodegradation of organophosphorus compounds (OP’s) using various bacteria strains isolated from specified contaminated area along Marriute Lake in Alexandria was investigated. Wild bacteria were isolated from the collected water and sediment samples from different lake locations. Six strains of isolated bacteria were identified as Escherichia coli (E. coli) type using morphological and biochemical characteristics. The efficiency of the isolated strains either E. coli or non-E. coli for paraoxon biodetoxification were evaluated. The biodegradation activities of the E. coli type isolated from sediment samples were found to be superior to those isolated from water samples. However, non-E. coli type of isolated strains from water samples demonstrated an increase in the activity percentages than those of same type strains isolated from sediment samples. Generally, paraoxon biodegradation by E. coli isolated strains was higher than those of non-E. coli isolated strains.