الفهرس 
INTRODUCTION AND AIM OF THE WORKOnly 14 pages are availabe for public view
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Abstract
Five samples from different environmental sites including two soil samples from TRENCO around coal and paraffin oil tank, one liquid sample from discharge of Egyptian Company for Starch, Yeast and Cleaners, one soil sample around Al-Oroba for Trade and Paper Industry, and one liquid drainage sample from a Pesticide Company were collected to study detoxification of organophosphorus pesticides. Four nonspecialized samples were isolated non selectively and selectively on two levels of CPF (100 and 500 ppm) in presence and absence of glucose and the fifth specialized sample was isolated selectively only on 100 ppm of CPF in presence of G. They were assayed for their degradation capabilities for 50 and 100 ppm of Paraoxon and CPF.
The most efficient selective isolates for CPF degradation were pesticide drainage isolate followed by oil isolate. These efficient isolates were assessed for their degradation efficiencies for MP and Malathion. They could not degrade them may be due to nonspecialty, since they were isolated selectively on 100 ppm of CPF. The most two efficient isolates were streaked individually, purified and their individual isolates (one from oil and three from pesticide drainage spots) were assessed for their degradation efficiencies for CPF. Two individual isolates (DI*100Gb and DI*100Gc) from pesticide drainage spot scored the highest degradation efficiency followed by individual isolate (OI*100Ga) from oil spot ending with (DI*100Ga) from pesticide drainage spot. Enhancement of individual isolates from pesticide drainage spot through biostimulation (in presence of glucose, sucrose, sodium citrate or CPF) and starvation (deprivation for 80 days from any source of carbon) was done. Two starved individual isolates from pesticide drainage spot (DI*100Gb and DI*100Gc) achieved the highest degradation efficiency.
Immobilization of the most efficient isolates, starved individual isolates, on sodium alginate and formation of biobeads like shape was done to detoxify CPF from water. Biobead numbers (5, 10 and 15) were examined for CPF degradation. As the number of biobeads increase the degradation efficiency increase and 10 biobeads per 10 ml buffer was the most optimum conditions. Stability test of the immobilized individual isolates was tested on CPF degradation after 0, 10, 20 and 30 days of their preparation. Results reported that these immobilized starved individual isolates were stable with time and only 9, 11% from their degradation efficiency were lost after 30 days.
Toxicity experiments were carried out using Culex pipiens treated with serial concentrations of CPF, drawing concentration mortality curve and LC5, LC50 & LC95 were determined. The effect of various treatments: CPF alone (C+ve), CPF after treated with enhanced starved isolates (DI*100Gb and DI*100Gc) and CPF after treated with nonenhanced isolates (DI*100Gb and DI*100Gc) on the mortality percent of Culex pipiens after 24 hr was examined. Results illustrated that mortality of the 3rd instar larval stage of mosquito Culex pipiens decrease when CPF was treated with both the enhanced and nonenhanced bacterial isolates. Also, enhanced bacterial isolates achieved less remaining CPF concentrations and less mortality compared tononenhanced ones and this confirms the better degradation effect of enhanced (starved) than nonenhanced ones.
The degradation efficiency of CPF can be predicted from the following modeling equation obtained by Minitab version 17. This model contains two factors: firstly, isolates: two isolates (Immobilized starved isolates (DI*100Gb and DI*100Gc) from pesticide drainage spot), secondly, incubation time: five levels (1/6, 1, 2, 4, and 7 days). The most effective factor is incubation time (day 4 followed by day 7, day 2) followed by the factor of isolates (isolate DI*100Gb followed by isolate DI*100Gc) ending with incubation time (day 1 followed by day 1/6).
Degradation (%) = 46.371 + 0.029 Immobilized starved isolate DI*100Gb – 0.029 Immobilized starved isolate DI*100Gc – 31.37 (day 1/6) – 22.37 (day 1) + 11.29 (day 2) + 28.81 (day 4) + 13.64 (day 7).
Biochemical identification for the most efficient enhanced isolates showed that DI*100Gb is Citrobacter freundii and DI*100Gc is Serratia marcescens.
5.2. CONCLUSION
Degradation efficiency of consortium of selective isolates scored better degradation capabilities than their purified individual isolates.
Individual isolates of specialized spots achieved better degradation efficiency than nonspecialized ones.
Immobilization of isolates gave better stability with time.
Starvation as an enhancement tool gave better degradation efficiency results.
The enhanced isolates achieved better detoxification results than nonenhanced ones using Culex pipiens.
5.3. RECOMMENDATION
Further studies should be done on the molecular level of the two starved individual isolates to examine the starvation effect on the modification of genes responsible for OP(s) biodegradation.
It is recommended to use starvation as an enhancement tool for microorganisms.
Immobilization is recommended for industrial purposes as it adds microbial stability with time.
Further studied should be done on ascale other than Culex pipiens to examine if the obtained efficient isolates are environmentally benign or not.
Biochemical (represented in AChE determination) and molecular studies are recommended on Culex pipiens to show the effect of OP(s) treatment.