One hundred random samples of fesiekh, sardine, smoked herring and canned tuna (25 of each) obtained from different localities in Menoufia governorate, Egypt and estimated for their harmful residues including heavy metals (mercury, lead, cadmium & iron). Additionally, trials to control such serious residues by using biological techniques were applied. It was found that the average values of mercury in the investigated samples of fesiekh , sardine, smoked herring and canned tuna were 1.14 ± 0.02, 0.98 ± 0.01, 0.83 ± 0.01and 0.65 ± 0.01mg/kg respectively and in lead they were 0.54 ± 0.01, 0.42 ± 0.01, 0.29 ± 0.01 and 0.23 ± 0.01mg/kg, respectively. The cadmium residues average concentrations in the examined samples of fesiekh , sardine, smoked herring and canned tuna were 0.33 ± 0.01, 0.21 ± 0.01, 0.16 ± 0.01 and 0.09 ± 0.01mg/kg, respectively while, in iron they were 1.71 ± 0.02, 0.65 ± 0.01, 1.06 ± 0.02 and 0.93 ± 0.01mg/kg, respectively.
The effect of L.rhamnosus culture (1x107) on the levels of lead experimentally inoculated to sardine fillets (30 mg/Kg) was decreased to 13.8mg/kg after 8 hours, 7.9 mg/kg after12 hours and 6.5mg/kg after 24 hours by a percentage of reduction 54%,73.7% and 78.3% reduction respectively.