الفهرس 
Introduction
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Abstract
This study were conducted to study the ability of microorganisms to bioremediation of chemical pollutants – contaminated water the following experiments were performed.1-Eight textile effluent were collected in sterile collection tubes from the sludge and the wastewater of the ditches at industrial site located in Station Exchange Aldoakhlah and EL-Nasr Company for Textile orchard Each of these areas is located in Al mehalla Alkobra. The samples were transported to the laboratory at 4°C.2-Dilution series were prepared in glass test tubes, each containing 9 ml MSL liquid medium then 100 μl from the third dilution were transferred onto mineral salt agar plates containing crystal violet (50 mg/L) and spread evenly with sterilized glass stick. The plates were sealed in polyethylene bags and incubated at 28 ◦C for 7 days and monitored for appearance of colonies.3-The morphologically distinct bacterial isolates showing clear zones around their colonies due to decolorization of dye were selected for further studies.4-The efficient selected dy-decolorizing bacteria were identified on the basis of several aspects including morphology, biochemical characters and 16S rRNA.5-Experiments were carried out to study the effect of pH and temperature on crystal violet decolorization on MSA containing crystal violet (50 mg/l).6-To detect the effect of nitrogen sources on the efficiency of the seleted microorganisms in decolorization of crystal violet, MSA (containing crystal violet 50 mg/L) was prepared and supplemented with the optimum carbon source, with different concentrations of nitrogen sources such as (NH4)2SO4, ammonium chloride (NH4Cl) (0.5, 1, 1.5 and 2%) and peptone (5g/L), Beef extract (3 g/L) as well as yeast extract (1g/L)7-To determine the effect of incubation period, plates containing MSA supplemented with crystal violet (50 mg/l) were prepared and inoculated with the selected bacterial isolates. the plates were inculated for 3, 5, 7, 9 and 11 days and the clear zones around the bacterial colonies were measured after each incubation period. 8-The isolates were used in decolorization of crystal violet and anther chemical pollutants such as dyes reactive blue 19, disperse red 153 and direct orange 102 in liquid culture. The isolates incubated onto MSA medium supplemented with each dye (50 mg /L) for 7 days.9-The ability of the two selected bacterial isolates to decolorize crystal violet, reactive blue 19, disperse red 153 and direct orange 102 was tested in liquid culture. Each dye was added to liquid medium at concentration of 50 mg /L. The optical density of each dye during decolorization was recorded. The percentage of decolorization of each dye was determined photo metrically using UV–vi spectrophotometer.10-The bioassay of the remaining crystal violet toxicity was performed on the aqueous solutions after 7 days of incubation with the isolates as gram positive bacterium was used as the test organism. The toxicity was determined by recording inhibition zone in growth of Bacillus subtilis comparing to control treatment (untreated). 11-We incubated one of the isolates to bioremediation of pendimethalin The obtained results summarized as follows:1-A total of 19 isolates that have the ability to grow and show the clear zone.2-Among 19 bacterial isolates, two bacterial isolate designated AT 17 and AT 20 exhibited higher crystal violet decolorization (wider clear zone) comparing with the other isolates.3-Bacterial isolates AT 17 and AT 20 showed morphological, cultural, biochemical characteristics and 16S rDNA identical to those known for Pseudomonas sp. and Escherichia sp. respectively.4-Using the two selected bacterial isolates (AT 17 and AT 20) the highest decolorization was achieved at PH 7 and 35 °C.5- The highest crystal violet decolorization by the two selected isolates (AT 17 and AT 20) was achieved when ammonium chloride was used as anitrogen source at concentration of 1.5 g/L.6-Under the optimum growth conditions for the selected bacterial isolates (AT 17 and AT 20) the most suitable incubation period for crystal violet decolorization in mineral salt medium was found to be 7 days.7- Both the selected isolates (AT 17 and AT 20) were found to have the ability to decolorize the tested dyes (reactive blue 19, disperse red 153 and direct orange 102) at concentration of 50 mg/l.8- In aquatic system. Crystal violet exhibited the highest decolorization rate in most cases, while reactive blue 19, disperse red 153 and direct orange 102 were decolorized slower by the both isolates. The general trend of the decolorization for all the tested dyes with P. geniculata (AT 17) was higher than the general trend of the decolorization for all the tested dyes with E. coli (AT 20) under the same conditions. The % of decolorization with the both strains for crystal violet was > reactive blue 19> disperse red 153 > direct orange 102.9- The results showed that the supernatant of crystal violet after 7 days of incubation with P. geniculata (AT 17) had no toxicity against B. subtilis as a test organism.10- The results indicate that P. geniculata (AT 17) was most efficient isolate in pendimethalin dissipation with a half-live of 6 days. One hundred percent of pendimethalin initial concentration was dissipated within 4 weeks by P. geniculata (AT 17). Pendimethalin half-live was 63 days in untreated liquid medium as control treatment.