Browsing by Author "Diab, Ali"

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Biodegradation of Polycyclic Aromatic Hydrocarbons (PAHs) in the Rhizosphere Soil of Cyperus conglomeratus, an Egyptian Wild Desert Plant
(Nature and Science, 2010) Diab, Ali; Sandouka, Maram
Phytoremediation is a promising technology for the clean-up of petroleum hydrocarbon-polluted soil, especially in the developing countries. In the present study, the rhizosphere soil of Cyperus conglomeratus (a wild Egyptian desert plan) was collected and studied for the removal of PAH compounds from the polluted desert soil. The rhizosphere soil of this plant was rich in total bacteria and oil-degraders. The rhizosphere soil was able after 180 days to reduce total PAHs from 2329.0 to 576.3 mgkg-1 soil (i.e. 75.2% loss), this is in contrast to 45.2% reduction value for the non-rhizosphere soil. The rhizosphere soil significantly enhanced the biodegradation of the 16 PAH individuals (48.4-98.5%) as compared to the non-rhizosphere soil (23.1-94.4). The 2-ringed and the 3-ringed PAHs were highly degraded in the rhizosphere soil (98% and 93.1% respectively) as compared to the other PAH groups. Eight carcinogenic PAHs were resolved among the 16 PAH individuals. The sum of the 8 PAHs decreased in the rhizosphere soil from 1204.5 to 390.9 mgk-1 soil, i.e. a reduction of 67.7%, while in the non-rhizosphere soil the reduction value was 41.0%. Collectively, the 5-ringed carcinogenic PAHs were more degraded in the rhizosphere soil (87.8%) than the 4-ringed carcinogenic PAHs (59.2%). Both groups were weakly degraded in the non-rhizosphere soil (34.7% and 30.6% respectively). A particular notable distinction of the rhizosphere soil of Cyperus conglomeratus plant is the greater efficiency to degrade the carcinogenic PAHs especially benzo(a)pyrene, (90.3%), chrysene (86.9%), benzo(a)flouranthene (84.1%) and indeno (1,2,3-c,d) pyrene (82.2%). The present study clearly demonstrates at the first time in Egypt, a successful bioremediation strategy of PAH-contaminated soil by using the rhizosphere effect of the native desert plant Cyperus conglomeratus.
Effect of Phytogenic Biosurfactant on the Microbial Community and on the Bioremediation of Highly Oil-Polluted Desert Soil
(J. Am. Sci, 2012) Diab, Ali; Sandouka, Maram
The effect of a phytogenic surfactant on the microbial community and on the biodegradation of crude oil in a highy polluted desert soil (8%) were investigated. The addition of this biosurfactant increased total heterotrophie bacteria (THB) to reach the range of 4.3 – 20.3 CFUx108g dried soil, with increased factor of 7.18 – 10.38. Oil-degraders were in the range of 2.48-30.2 CFUx107 in presence of the biosurfactant, this in a range of 27.2-143.8 increased factor Higher percentages of 5.7-17.6% of the oil degraders were recorded in presence of biosurfactant. In presence of biosurfactant the biodegradation rate of the oil increased to reach 23.8-30.0% after 90 days, this is in contrast to 3.8-10% in the absence of this biosurfactant. The maximum biodegradation of the saturates and the aromatic fraction were 92.8% and 41.8% respectively in presence of the biosurfactant. Based on these results it is advisable to use this cost-effective phytogenic surfactant for cleaning the highly oil-polluted sites especially in the absence of NP fertilizer
Production and Characterization of Biosurfactants Produced by Bacillus spp and Pseudomonas spp Isolated from the Rhizosphere Soil of an Egyptian Salt Marsh Plant
(Nature and Science, 2013) Diab, Ali; Gamal El Din, Shereen
Seventeen bacterial strains were isolated from the rhizosphere soil of an Egyptian salt marsh plant and screened for biosurfactant production. 76.5 % of the bacterial strains were found to produce biosurfactants, they were identified as Bacillus spp (4 strains) and Pseudomonas spp (9 strains), of which P. aeruginosa was represented by 6 strains. From the preliminary experiment, (Bacillus SH 20, SH 26 and Pseudomonas aeruginosa SH 29, SH 30) were the most active biosurfactant producers. The four main active biosurfactant producers were selected and studied. The results showed that P. aeruginosa SH 29 represents a good candidate for the production of the biosurfactants when grown on both nutrient broth (NB) and inorganic salt media (ISM) supplemented with waste frying oil. On the other hand Bacillus spp (SH 20 and SH26) were active biosurfactant producers when grown on molasses. Waste frying oil and molasses represent good, cheap and easily available substrates which have the advantage of reducing the production cost and help economic production of biosurfactants. The results of using different vegetable oils varied with the variation of media and bacterial strains. Olive oil was promising followed by sunflower oil and soybean oil. All of the four bacterial strains were able to emulsify the studied hydrocarbon oils and vegetable oils but with different E24 values. Bacillus spp SH 20, SH 26 produced the highest E24 values for petroleum oil (84.4 ± 5.2 and 75.0 ± 5.6 % respectively). This was followed by P. aeruginosa SH 30 (66.7 ± 3.8 %) and P. aeruginosa SH 29 (62.0 ± 3.4 %). The results also showed that the produced biosurfactants in the present study were stable at 0-121 °C, pH 1-14 values and at different concentrations of NaCl. An attempt was made to isolate the biosurfactant produced by P. aeruginosa SH 29 when grown in waste frying oil (2% w/v). The production yield of this crude product was estimated as 2.8 g/L. This crude material was selected and kept for further purification and studies. Accordingly, the four bacterial strains may be useful in petroleum industry (e.g petroleum recovery, cleaning of oil storage tanks and recovery of oil from oily sludge) and they may help in bioremediation of oil contaminated sites. [Ali Diab and Shereen Gamal El Din. Production and Characterization of Biosurfactants Produced by Bacillus spp and Pseudomonas spp Isolated from the Rhizosphere Soil of an Egyptian Salt Marsh Plant. Nat Sci 2013;11(5):103-112]. (ISSN: 1545-0740). http://www.sciencepub.net.
Serratia marcescens P25, A New Strain Isolated From The Phycoplane of the Red Marine Alga Punctaria sp Produced Potent Biosurfactant Used for Enhancing the Bioremediation of Spent Motor Oil-Polluted Soil
(International Journal of Science and Research, 2015) Diab, Ali; Ageez, Amr; Gardoh, Iman
Samples of marine algae were collected from a coastal area at Abokir, Alexandria, and identified as: Punactraia sp (brown alga), Colpomenia sp (brown alga), Jania sp (red alga) and Ulva sp (green alga). 25 bacterial strains were isolated and purified from the phycoplane of Punctaria sp and were screened for the production of biosurfactants using cheap substrate (waste frying oil). The production of biosurfactants was tested by the plug agar and the ODA method. 60% and 80% of the tested strains were biosurfactant producers when the plug agar and the ODA method respectively used. Five red pigmented strains were very active biosurfactant producers (158-167.6 Cm2 ODA) were selected and studied for their emulsification activity and their stability at wide range of temperature (0-121°C), pH values (2-12) and salinity (5-25% NaCl-W/V). The selected five bacterial strains were identified as members of Serratia marcescens. Strain P25 was characterized by producing a biosurfactant of more stability at wide range of temperature, pH and salinity, this is in addition to its ability to produce high emulsion activity against spent motor oil. The produced emulsion was stable at 7-30 days. The above characters give this Serratia marcescens P25 strain a potential application in petroleum industry such as cleaning oil storage tanks, recovery of oil from oily sludge, microbial enhanced oil recovery (MEOR),washing oil- contaminated soil and enhancing the bioremediation of hydrocarbon- contaminated sites. The cell free culture broth (supernatant) containing the biosurfactant that was produced by strain P25 was sterilized and applied for the bioremediation of spent motor oil- contaminated soil. The result show that the addition of the sterilized supernatant alone increased the biodegradation of the oil to 65.0±5.2%. Addition of NP fertilizer alone failed to increase the biodegradation more than 46.0±2.0%, while in the presence of a mixture of biosurfactant and NP (BRNP) the biodegradation increased to 60.0±5.0%. Statistically, no significant difference between the result in presence of BR in the presence of BRNP (P>0.05). It can be concluded that the promising factor in the biodegradation of spent motor oil is the addition of BR alone or in combination with NP.