Farah Amin

Complete degradation of dimethyl phthalate by biochemical cooperation of the Bacillus thuringiensis strain isolated from cotton field soil

Dimethyl phthalate (DMP), a phthalate ester, is widely used in cosmetics, perfumes, and plasticizers. It has been classified as a suspected endocrine disruptor by many countries. The present study describes the biodegradation of DMP by a new aerobic bacterium, isolated from soil samples of a cotton field by an enrichment culture technique utilizing DMP as the sole source of carbon and energy. The isolate was identified as Bacillus thuringiensis based on the morphological and biochemical characteristics as well as gene sequence analysis. Bacillus thuringiensis grows best in a mineral salt medium of pH 7.0 at 30 °C incubation for 48 hours. The effects of temperature, inoculum size, substrate concentration and incubation time on DMP degradation were also studied. Bacillus thuringiensis is able to biodegrade 400 mg L−1 of DMP under aerobic conditions with 99% degradation potential. A combination of GC and GC-MS analysis revealed a complete DMP biodegradation pathway. The results indicate that Bacillus thuringiensis may prove a promising source for DMP bioremediation at a commercial scale.

Utilization of Pleurotus eryngii biosorbent as an environmental bioremedy for the decontamination of trace cadmium(II) ions from water system

In many parts of the world, cadmium metal concentration in drinking water is higher than some international guideline values. To reduce its level below the safety limit, a sustainable and environmental friendly approach is crucial. Thereby, present article introduce an efficient, non-pathogenic and a novel fungal biosorbent Pleurotus eryngii for the removal of Cd(II) ions from aqueous system. The efficiency of P. eryngii were improved and optimized by investigating many significant factors such as; pH, biosorbent dose, initial Cd(II) ion concentration, temperature and contact time. Maximum Cd(II) ions removal (99.9%) was achieved at pH 5.0, biosorbent dosage 0.2 g/10 mL, concentration 20 mg L-1, time 10 min and temperature 50 °C. The isotherm and kinetic models revealed bioremediation of Cd(II) ions as monolayer coverage with biosorption capacity of 1.51 mg g-1 following pseudo second order reaction. Moreover, thermodynamic parameters such as ΔG°, ΔH°, and ΔS° showed that the removal of Cd(II) ions is spontaneous and endothermic in nature. Batch elution process revealed that the complete elution of Cd(II) ions from the biomass were achieved using 0.1 N HNO3 solution. The sorption efficiency decreased from 99.99 to 56.89% as the biomass were recycled up to five times. The efficiency of Cd(II) ions removal from real water samples lies between 85 and 90%. Fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopic (EDS) and atomic force microscopic (AFM) analysis of fungal biomass confirmed that the Cd(II) ions were the most abundant species on the biomass surface after the sorption process.

Accumulation and distribution of lead (Pb) in plant tissues of guar (Cyamopsis tetragonoloba L.) and sesame (Sesamum indicum L.): profitable phytoremediation with biofuel crops

Abstract Contamination of lead indicates one of the major threats to soil system. Phytoremediation technique utilized plants which are able to tolerate and accumulate metals within in their tissues. It has recently been suggested that biofuel plants are more suitable for both utilization and remediation of metal contaminated soil. This study reported Pb phytoremediation potential of Cyamopsis tetragonoloba L. in comparison with Sesamum indicum L. in the framework of a pot-experiment. Plants were subjected to seven Pb concentrations (0, 100, 200, 400, 600, 800 and 1000 mg kg-1 soil) for 12 weeks. Our results demonstrated that both C. tetragonoloba and S. indicum were able to tolerate Pb concentrations up to 1000 mg kg-1 which confirms the plant ability to grow well in higher Pb levels. Significant metal accumulation was observed in root along with reduced biomass for both plants species. Furthermore, both plant species could possibly be used for phytostabilization, with success in marginally polluted soils where their growth would not be impaired and decontamination of Pb could be maintained at satisfying levels. However, bioconcentration factor (BCF), bioaccumulation coefficient (BAC) and translocation factor (TF) values proposed that C. tetragonoloba was more efficient for phytoremediation than S. indicum at higher Pb levels.

Efficient entrapping of toxic Pb(II) ions from aqueous system on a fixed-bed column of fungal biosorbent

Abstract The present research dealt with the successful viability and practicality of Pleurotus eryngii packed bed column for Pb(II) ions biosorption. To achieve the aim of the project, the impact of different parameters including flow rate, initial concentration of Pb(II) ions and bed height were optimized. The column models, i.e.,Thomas and Bed Depth Service Time (BDST) were investigated to assess the column efficiency towards entrapping targeted ion. The adsorption capacity, rate constant and correlation coefficient related to each model for column sorption were also calculated. The adsorption capacity enhanced by increasing the bed height and decreasing initial Pb(II) metal ion concentration along with the flow rate. The maximum Thomas model adsorption (entrapping) capacity was obtained 3.30 mg g−1 for initial concentration of 20 mg L−1 at a constant flow rate of 1 ml min−1, bed height of 3 cm and pH 7. The experimental results implied and affirmed the suitability of the P. eryngii fungal biosorbent for Pb(II) ion biosorption with its nature being favourable, efficient and environment friendly.

Comparative study of Zn-phytoextraction potential in guar (Cyamopsis tetragonoloba L.) and sesame (Sesamum indicum L.): tolerance and accumulation

Abstract Phytoextraction is a plant-based technique for removing heavy metals from polluted soil. The experiment reported in this paper was undertaken to study the Zn phytoextraction potential of Cyamopsis tetragonoloba in comparison with Sesamum indicum in the framework of a pot experiment. Plants were subjected to six Zn concentrations (0, 50, 100, 200, 300, 400 mg kg−1 soil) for 90 days to investigate Zn tolerance and accumulation. Results demonstrated that, at higher Zn levels, root, shoot lengths, biomass and chlorophyll content were all significantly reduced (p < 0.05). A steady increase in Zn accumulation with increasing concentration in soil was observed for all treatments. Both plant species had relatively high Zn tolerance and accumulation capacity, with C. tetragonoloba being more tolerant and having higher Zn accumulation than S. indicum. At 400 mg Zn kg kg−1, accumulation of Zn in C. tetragonoloba was highest in the root (439.33 mg kg−1) followed by stem (436.00 mg kg−1), leaf (40.67 mg kg−1) and pod (11.33 mg kg−1). Considering the rapid growth, high biomass, tolerance, accumulation efficiency, bioconcentration factor (BCF), bioaccumulation coefficient (BAC) and translocation factor (TF) (all greater than 1) established C. tetragonoloba as a potential candidate plant for Zn phytoextraction.