Abstract
Pseudomonas aeruginosa RW9 is a promising candidate for the bioremediation of chromium hexavalent (Cr(VI)) pollution, as it resists a high concentration of up to 60 mg/L of Cr(VI). Leaving cells exposed to Cr(VI) has large bioreduction potential, implying its capacity to extract the ions from the contaminated medium. In this study, the tolerance for and distribution of Cr(VI) were investigated to identify the cells’ adaptation and removal strategies. Micro-characterization analysis was conducted to assess the effect of Cr(VI) on the cells. The cells’ elongation was observed at higher Cr(VI) concentrations, signifying their adaptation to DNA damage caused by Cr(VI) toxicity. Cr(VI) distribution analysis showed that the strain developed a complex mechanism to adapt to Cr(VI), based on surface-bound (0.46 mg/L), intracellularly accumulated (1.24 mg/L) and extracellular sequestration (6.74 mg/L), which accounted for 85% of the removal efficiency. The extracellular sequestration might be attributable to the production of metabolites, in accordance with the fourier-transform infrared spectroscopy (FTIR) spectra and orcinol analysis that confirmed the presence of a glycolipid biosurfactant, rhamnolipid. Remarkably, the rhamnolipid was slightly induced in the presence of Cr(VI). From the data obtained, it was confirmed that this local strain is well equipped to survive high doses of Cr(VI) and has great potential for application in Cr(VI) bioremediation.
Highlights
Heavy metal pollution has been a great concern around the globe
For inoculum preparation in the Cr(VI) bioremediation experiment, a single colony of the 24 h incubated strain was cultured into 50 mL of nutrient broth (NB) and placed in a shaking incubator at
It was found that P. aeruginosa RW 9 can grow well and tolerate
Summary
Heavy metal pollution has been a great concern around the globe. The compounds often exist as elements that possess the non-degradability characteristic and persist in the environment over time [1]. Various remediation tools have been developed to remediate the pollutants Conventional methods such as physical adsorption [2], coagulation [3] and membrane filtration [4] are among the commonly used techniques to treat metals from industrial effluent. Pre-treatments need to be applied to the wastewater prior to subjection to a membrane filtration system, which causes the technique to become financially inefficient [5]. These drawbacks have caused researchers to shift to the development of microbial remediation as a potential alternative to conventional techniques [7]
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