Arezoo Dadrasnia

Biosurfactant Production by Bacillus salmalaya for Lubricating Oil Solubilization and Biodegradation

This study investigated the capability of a biosurfactant produced by a novel strain of Bacillus salmalaya to enhance the biodegradation rates and bioavailability of organic contaminants. The biosurfactant produced by cultured strain 139SI showed high physicochemical properties and surface activity in the selected medium. The biosurfactant exhibited a high emulsification index and a positive result in the drop collapse test, with the results demonstrating the wetting activity of the biosurfactant and its potential to produce surface-active molecules. Strain 139SI can significantly reduce the surface tension (ST) from 70.5 to 27 mN/m, with a critical micelle concentration of 0.4%. Moreover, lubricating oil at 2% (v/v) was degraded on Day 20 (71.5). Furthermore, the biosurfactant demonstrated high stability at different ranges of salinity, pH, and temperature. Overall, the results indicated the potential use of B. salmalaya 139SI in environmental remediation processes.

Organic wastes to enhance phyto-treatment of diesel-contaminated soil.

Toxic inorganic and organic chemicals are major contributors to environmental contamination and pose major health risks to human population. In this work, Dracaena reflexa and Podocarpus polystachyus were investigated for their potential to remove hydrocarbons from 2.5% and 1% diesel fuel-contaminated soil amended individually with 5% organic wastes (tea leaf, soy cake and potato skin) for a period of 270 days. Loss of 90% and 99% oil was recorded in soil contaminated with 2.5% and 1% oil with soy cake amendment, respectively, compared with 52% and 62% in unamended soil with D. reflexa at the end of 270 days. Similarly, 84% and 91% oil loss was recorded for P. polystachyus amended with organic wastes in 2.5% and 1% oil, respectively. Diesel fuel disappeared more rapidly in the soil amendment with SC than in other organic waste supplementation. It was evident that plants did not accumulate hydrocarbon from the soil, while the number of hydrocarbon-utilizing bacteria was high in the rhizosphere, thus suggesting that the mechanism of the oil degradation was rhizodegradation. The kinetic model result indicated a high rate of degradation in soil amendment with SC at 1% with D. reflexa compared with other treatments. Thus, a positive relationship was observed between diesel hydrocarbon degradation with plant biomass production. Dracaena reflexa with organic wastes amendment has a greater potential of restoring hydrocarbon-contaminated soil compared to P. polystachyus plant.

Biotechnological Potential of Bacillus salmalaya 139SI: A Novel Strain for Remediating Water Polluted with Crude Oil Waste

Environmental contamination by petroleum hydrocarbons, mainly crude oil waste from refineries, is becoming prevalent worldwide. This study investigates the bioremediation of water contaminated with crude oil waste. Bacillus salamalaya 139SI, a bacterium isolated from a private farm soil in the Kuala Selangor in Malaysia, was found to be a potential degrader of crude oil waste. When a microbial population of 108 CFU ml-1 was used, the 139SI strain degraded 79% and 88% of the total petroleum hydrocarbons after 42 days of incubation in mineral salt media containing 2% and 1% of crude oil waste, respectively, under optimum conditions. In the uninoculated medium containing 1% crude oil waste, 6% was degraded. Relative to the control, the degradation was significantly greater when a bacteria count of 99 × 108 CFU ml-1 was added to the treatments polluted with 1% oil. Thus, this isolated strain is useful for enhancing the biotreatment of oil in wastewater.

Biosorption Potential of Bacillus salmalaya Strain 139SI for Removal of Cr(VI) from Aqueous Solution

The present study investigated the biosorption capacity of live and dead cells of a novel Bacillus strain for chromium. The optimum biosorption condition was evaluated in various analytical parameters, including initial concentration of chromium, pH, and contact time. The Langmuir isotherm model showed an enhanced fit to the equilibrium data. Live and dead biomasses followed the monolayer biosorption of the active surface sites. The maximum biosorption capacity was 20.35 mg/g at 25 °C, with pH 3 and contact time of 50 min. Strain 139SI was an excellent host to the hexavalent chromium. The biosorption kinetics of chromium in the dead and live cells of Bacillus salmalaya (B. salmalaya) 139SI followed the pseudo second-order mechanism. Scanning electron microscopy and fourier transform infrared indicated significant influence of the dead cells on the biosorption of chromium based on cell morphological changes. Approximately 92% and 70% desorption efficiencies were achieved using dead and live cells, respectively. These findings demonstrated the high sorption capacity of dead biomasses of B. salmalaya 139SI in the biosorption process. Thermodynamic evaluation (ΔG0, ΔH0, and ΔS0) indicated that the mechanism of Cr(VI) adsorption is endothermic; that is, chemisorption. Results indicated that chromium accumulation occurred in the cell wall of B. salmalaya 139SI rather than intracellular accumulation.

Diesel Fuel Degradation from Contaminated Soil by Dracaena reflexa Using Organic Waste Supplementation

At global level, crude oil productions are estimated to be more than twelve million metric tons annually and about 1.7 to 8.8 million metric tons of oil are released into the aquatic environment and soil respectively per annum1). About 90 % of this emission is directly related to human activities including deliberate illegal waste disposal. Fuel oil may enter the water or soil environment as a result of spillages during transportation and by leakages from the storage facilities or pipelines. The more volatile components of fuel oils (low molecular weight alkanes) can be degraded in both water and soil and could get evaporated from there and enter into the atmosphere where they will from contaminants. Remediation of petroleum-contaminated systems can be achieved by physical, chemical or biological methods. However, the unattended negative consequences of physical and chemical approaches are currently directing greater attention to the use of the biological alternatives. An alternative method to remediate soil polluted by organic compounds is phytoremediation, where plants have been able to reduce organic contaminant by principally providing an optimal environment for microbial proliferation in the root zone (rhizosphere)2),3). These degradative processes are influenced not only by rhizosphere microorganisms, but also by the unique properties of the host plant4). Plant exudates and sloughed tissue may enhance the degradation of the complex compounds due to increased bioavailability of the contaminants and the interaction among microbes, nutrients and contaminants5). This often leads to enhanced breakdown of organic contaminants in vegetated soil area, compared to its opposite scenario. If plants can be successfully established on polluted soils, then the plant-microbial interaction in the rhizosphere may provide an effective method for enhancing microbial degradation of complex organic contaminants. Many studies have shown that microbial population increased in soil contaminated with hydrocarbons6)~8). Aprill and Sims (1990) reported the effect of prairie grasses on the biodegradation of four PAHs and reported that the disappearance of PAHs was greater for all the vegetated soils compared to unvegetated soil9). By growing plants on diesel oil contaminated soil, optimal conditions are required for the microbial degradation of the contaminant to be enhanced. It has been estimated that more than 300 species of plants naturally absorb toxic materials from the environment10) (Adam and Duncan, 2002; Cunningham et al., 1996). Very little work has been carried out in identifying contaminated sites in Malaysia13). Contaminated land can 236 Journal of the Japan Petroleum Institute, 56, (4), 236-243 (2013)

Bio-Enrichment of Waste Crude Oil Polluted Soil: Amended with Bacillus 139SI and Organic Waste

Biodegradation of waste crude oil contaminated soil amended by Bacillus 139SI and used tea leaf amendments was investigated to determine the rate of hydrocarbon remediation. Previously, Bacillus 139SI was isolated from an agricultural soil in the Serdang agricultural center, Malaysia. Within 60 days, 14% oil loss was recorded in unamended polluted autoclaved soil, while waste crude oil disappeared more rapidly in the soil amendment with both strain and organic waste, recorded above 89%. Utilizing bacteria counts were significantly higher in all amended treatments comparing to control soil. Dehydrogenase activity in soil was markedly enhanced by the application of amendments. Waste crude oil composition monitored by GC/FID indicated complete degradation of n-C9–C25. First-order kinetic model revealed that organic waste and strain were the best of treatments, with biodegradation rate constant of 0.17day-1and half life of 4 days. The results showed there is potential for tea leaf and Bacillus 139SI to enhance biodegradation of waste crude oil contaminated soil.

Remediation of Contaminated Sites

Oil pollution in the environment is now being taken seriously by the oil industries and as such, these companies are always looking for cost-effective methods of dealing with this pollution. The global environment is under great stress due to urbanization and industrialization as well as population pressure on the limited natural resources. The problems are compounded by drastic changes that have been taking place in the lifestyle and habits of people. The environmental problems are diverse and sometimes specific with reference to time and space. The nature and the magnitude of the problems are ever changing, bringing new challenges and creating a constant need for developing newer and more appropriate technologies.

Remediation of Oil Contaminated Media Using Organic Material Supplementation

With the fact that anthropogenic activities are inevitable, especially with the continuous use of fossil fuels and other sources of hydrocarbons, environmental pollution appears to be a recurring issue. However, nascent science and technologies try to identify and apply varied options that can remedy polluted sites, which include oil spill situations. The present review elucidates the remediation options on the event of oil spill/contamination with emphasis on the adoption of biological treatment (supplement addition and phytoremediation), and overview on the potential relevance of remediation via advances in nanotechnology. The associated negativities and cost tend to outweigh the advantages of both methods when sustainability is considered.

Prevalence, characterization and antibiotic resistance of Pasteurella multocida isolated from bovine respiratory infection

The objectives of this study were to determine the prevalence, characterization and antibiotic resistance of Pasteurella multocida isolated from calves with respiratory infection in Iran. P. multocida was detected in 141/169 bovine respiratory infection cases on Iranian dairy and beef farms. P. multocida were grouped into serogroups A (126/141), D (12/141), and B (3/141). Of the P.  multocida isolates, all harboured the psl, ompH, oma87, fimA, ptfA, nanB, and nanH genes, 139/141 had hsf-2, and 115/141 pfhA, and tadD. The isolates were most frequently resistant to penicillin G (43/141 resistant isolates; 30.5%) and streptomycin (31/141; 22%).

Biostimulation and Monitoring of Diesel Fuel Polluted Soil Amended With Biowaste

A lab-scale experiment was set up to investigate the efficiency of addition 5% (w/w) individually of three different organic solid waste amendments to enhance the rate of degradation at 5% and 15% diesel oil in polluted soil during 18 weeks. A total of 81% and 42% oil loss was recorded in soil amended with soycake at 5% and 15% oil pollution, respectively. The measured δ13C signature of CO2 evolved from amending contaminated soil varied between –24 and –28‰. First-order kinetic model demonstrated that soycake had the highest rate of biodegradation of 0.114 days−1 at 5% oil pollution. The results clearly indicate that those treatments amended with organic wastes had the best efficiency on the biodegradation of soil contaminated with diesel fuel.