الفهرس 
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Abstract
Population growth, rapid industrialization and urbanization have led to the spread of enormous amounts of pollutants all around. The ultimate goal of environmental scientists across the globe is to achieve environmental sustainability using efficient, eco-friendly and economically viable technologies. Environmental pollution resulting from petroleum hydrocarbons has increased, resulting in an urgent need for remediation. Petroleum hydrocarbons are one of the most alarming pollutants due to their high toxicity to human and environmental health. Petroleum hydrocarbon-degrading bacteria are ubiquitous in nature and can utilize these compounds as sources of carbon and energy. Bacteria displaying such capabilities are often exploited for the bioremediation of petroleum oil-contaminated environments. Recently, microbial remediation technology has developed rapidly and achieved major gains.
Current study aimed to emerge environment friendly clean up technology which entails the application of crude oil bacterial biodegradation process by combination with nanoparticles for the detoxification of pollutants. This methodology possesses a huge potential for large scale environmental cleanup with reduced cost and minimum generation of harmful byproducts. Nanomaterials have received much attention from scientists and researchers in different sectors of environmental sciences attributed to their unique physico-chemical properties. In this study we developed a novel method could be utilized in application of nanoparticles and natural oil-degrading bacteria for oil remediation in marine and non-marine systems. In the present study, we
use a combination of NPs and oil- degrading bacteria for enhanced oil removal at the laboratory scale.
Twenty four oil contaminated soil and water samples were collected from Ras Sedr oil field which is managed by the general petroleum company (GPC), Southern Sinai, Egypt in October 2017. Two hundred and sixty-five isolates exhibited growth onto the basal mineral medium (BMS) supplemented with crude oil (0.2 % v/v). All isolates were screened for lipolytic activity. 175 isolates exhibited lipolytic activity. The most promising isolates were identified by 16S rRNA genes sequencing and were submitted to GenBank as Bacillus thuringiensis S1 (MN180699), Pseudomonas aeruginosa S2 (MN180700) and Psychrobacter faecalis S3 (MN180701). In this study, the maximum crude oil biodegradation was achieved at 8, 4 and 6 gm/l oil concentrations for B. thuringiensis (MN180699), P. aureginosa (MN180700) and P. faecalis (MN180701), respectively. The temperature ranged between 20 and 37ºC showed maximum crude oil biodegradation. The bacterial isolates showed optimal biodegradation activities at different initial pH values which were 7, 5 and 11 for B. thuringiensis (MN180699), P. aureginosa (MN180700) and P. faecalis (MN180701), respectively.
The results demonstrated that the biodegradation percentage increased with increasing the incubation time and reached its maximum after 21 days of incubation. In This study, the optimum rotation speed was 200 rpm for oil biodegradation by B. thuringiensis (MN180699) and P. aureginosa (MN180700), while 300 rpm was optimum for P. faecalis (MN180701). In the current study, Total petroleum hydrocarbon was estimated by representative GC chromatograms of hydrocarbons extracted from crude oil BMS-medium at zero time (as a control) and GC-spectra of crude oil degraded by B. thuringiensis (MN180699), P. aeruginosa (MN180700) and P. faecalis
(MN180701), Fe2O3, ZnO NPs and combination of NPs with the selected strains showed different and significant pattern.
The saturated hydrocarbons are distributed covering the range of n-C12 to n-C40 as shown in the control chromatogram. GC-spectra of crude oil degraded by the tested three strains showed different patterns of crude oil, whereas standard carbons were completely disappeared by the action of the three isolates. GC-spectra of crude oil degraded by B. thuringiensis (MN180699) indicated that the distance of the range from C12 to C40 was considerably disappeared in comparing with the reference chromatogram. Furthermore, there was a significant decrease or completely disappearance in peak height for all aliphatic/aromatic hydrocarbons by the action of tested strains.
The saturated hydrocarbons are distributed covering the range of n-C17 to n-C40 as shown with Fe2O3 NPs and ZnO NPs chromatogram. There was a significant decrease or completely disappearance in peaks height for all aliphatic/aromatic hydrocarbons by the action of tested strains when adding to NPs. All standard carbons from C19 to C40 disappear completely as shown with B. thuringiensis (MN180699) and P. faecalis (MN180701) when added to ZnO NPs. New isomers appear with all selected isolates chromatogram when added to Fe2O3 NPs. However, there were significant differences in peaks height of C17 & C18 fingerprints in all patterns in comparing with NPs chromatogram.
The biodegradation percentage of Bacillus thuringiensis (MN180699), was 81.12%, 87.47 % for Pseudomonas aeruginosa (MN180700) and 80.28% for Psychrobacter faecalis (MN180701) after 21 days.
Iron oxide nanoparticles (Fe2O3 NPs) and zinc oxide nanoparticles (ZnO NPs) were synthesized and examined for the crude oil biodegradation with
70.62 and 72.23% degradation, respectively after 3 days. The combination of Fe2O3 NPs and biodegradation species achieved 97.62, 97.23, and 97.89%, while with ZnO NPs were 96.27, 95.81, and 96.35% biodegradation percentage after 3 days for B. thuringiensis (MN180699), P. aureginosa (MN180700) and P. faecalis (MN180701), respectively.
The crude oil biodegradation percentage reaches 96.35% after 3days using ZnO NPs and approximately 98% after 3 days using Fe2O3 NPs in combination with the selected bacterial isolates. The novel combination method of bacterial species with NPs approves the ability to degrade up to 98% of crude oil.
The data confirmed that adding NPs to the bacterial isolates showed high crude oil degrading percentage than NPs alone or bacteria isolates alone. Adding NPs accelerate the process of the biodegradation from 3 weeks to 3 days in higher percentage.
The crude oil bioremediation, using oil-degrading bacteria, removed 80-87% after 21 days. Moreover, NPs alone could remove approximately 72% of alkanes chain (C12-C17) after only 3 days of incubation. The combination of NPs and oil-degrading bacterial strains significantly removed oil within a shorter time. The crude oil biodegradation percentage reaches 96.35% and 98% after only 3 days using the selected bacterial strains in combination with ZnO and Fe2O3 NPs, respectively. That indicates the acceleration of the oil-degrading bacteria process using NPs, which meets the increasing need for quick solutions in treating this type of pollution.