الفهرس 
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Abstract
The aims of this study is to evaluate both of the heavy metals concentrations, the pollution indices and bio- chemical properties in soil samples collected from soil irrigated with polluted drainage water from No.5drains and Zefta Drain in El-Mahlla El-Kobra area . In addition to study integration effect of arsenic resistant strains of (Rhizobim nepotum) and (Glutamicibacter halophytocola) bacteria and synthesized Nano-MgO on maize growth in soil contaminated with arsenic concentrations in pot experiments. These can be achieved by the following: 1- Evaluating the heavy metals concentrations of V, Co, Cr, As and Cd in soil samples from soil irrigated with polluted drainage water from drains No.5 and Zefta drain in El-Mahlla El-Kobra area. 2- Evaluating the pollution indices and bio- chemical properties of collected soil samples contaminated with heavy metals. 3- Arsenic-resistant bacteria isolation and purification from contaminated soil with arsenic. 4- Indecation of the most potent bacterial isolates biochemical identification and identified phylogenetically (16S ribosomal RNA (16S rRNA) sequence analysis). 5- Assessment the ability of bacterial isolates to biosorption of arsenic from cultures. 6- Screening of effective arsenic resistant bacterial isolates for their beneficial attributes (In Vitro). 7- Studying of effective of arsenic tolerant strains of (Rhizobim nepotum) and (Glutamicibacter halophytocola) bacteria and synthesized Nano-MgO on maize growth (Zea Mays L.) in soil contaminated with arsenic concentrations in pot experiment. In order to achieve the objectives of this study, twenty surface soil samples (0- 20) had been taken from soil irrigated with polluted drainage water from No.5drains and Zefta Drain for a period of more than 10 years to evaluate the heavy metals concentration in the studied area. The enrichment culture used to isolate the arsenicresistant bacteria by the three-way plate streak method to select and purify the colonies. Evaluation studies were carried out to select the isolates most resistant to different levels of arsenic (100, 200, 300, 400 and 500 mg L-1) and to examine their efficiency in producing different growth regulators, and then genetic identification using sequencing analysis of ribosomal RNA (16S rRNA). To study the effect of two bacterial isolates in bioremediation of As in contaminated soil, two pot experiments has been conducted in Soil and Water department, Faculty of Agriculture, Tanta University, Egypt. ABSTRACT The first experiment: was designed in the form of split plot design, where the main plots were the concentrations of Arsenic (0 ppm – 50 ppm – 100 ppm – 300 ppm) and the sub plots were four treatments, which are (Arsenic - Arsenic + (R. nepotum) - Arsenic + (G. halophytocola) – Arsenic + MgO-NPs) The second experiment: was designed in factorial experiment in the form of complete randomized block design, which are Arsenic 300 ppm used as control and their mixture with ((R. nepotum), (G. halophytocola) and MgO-NPs) The obtained results could be summarized as follows: 1- All sites from which soil samples were taken exceeded the concentration of heavy metals for the permissible limit. The pollution indices (CD, MCD, PLI, Pn, PER) confirmed that they were contaminated with high to very high levels of contamination. 2- The biological activity in the studied soil samples from El-Mahlla El-Kobra area was affected by heavy metal pollution, where a significant correlation was found between the soil contamination degree and the total count of microbes, microbial biomass carbon, and soil organic matter. 3- Twenty-two bacterial isolates were obtained from a total of 20 soil samples using nutrient broth or agar medium enriched with high concentrations (0-500 ppm), and the results showed that two of them were more tolerant to arsenic. 4- The bacterial isolate (N13) produced the highest amounts of indole acetic acid, gibberellic acid, soluble phosphate, and siderophores among all the tested bacterial isolates. 5- Two arsenic-resistant bacterial isolates, R. nepotum and G. halophytocola, were identified by biochemical identification using a VITEK 2 compact system and molecular identification by 16S ribosomal RNA (16S rRNA) sequence analysis. 6- The addition of R. nepotum and G. halophytocola alone or with Nano-MgO improved the biological activity and increased the growth parameters of maize plants grown in highly polluted soil (300 mg/kg). 7- The use of G. halophytocola individually reduced plant content of As under conditions of high levels of contamination compared to Nano-MgO and R. nepotum, and thus we recommend their use for arsenic-contaminated soil treatment. The result recommended the use of R. nepotum, G. halophytocola, alone or in ABSTRACT combination with Nano-MgO for bioremediation of highly arsenic-contaminated soils and for improving some soil properties and increasing growth parameters of maize plants.