species (ROS). In order to avoid this situation, the cell starts to produce special kind of protein, enzyme, or any substance which can able to reduce, remove, or transform the Cr(VI). Besides this, microalgae also release electron through photosynthesis and they have a very unique metabolic process compensating the electron for the reduction of Cr(VI) [16, 59].
According to the findings of Nacorda et al., (2010), there is an initial rapid phase of passive extracellular biosorption process [60]. It was carried out following a slower active intracellular bio-absorption. This method is quite similar to the biphasic uptake take place in bacteria, fungi and other microbes. It is also reported that the longer is the incubation time the higher is the amount of Cr(VI) absorbed by Chlorella vulgaris. Another reason behind this bio-absorption may be due to the high storing capacity of the protoplasm.
2.5 Conclusion
Although, chromium is pervasive metal in the environment and Cr(VI) is reported as toxic with several carcinogenic, mutagenic, and a few more hazards, which are affected to behavioral, physiological, biochemical, and immunological aspects. Although bacteria, fungi, and other algal forms are able to convert the hexavalent chromium to trivalent chromium (nontoxic form) but in addition to the common mechanism found in bacteria and all other microbes, the microalgae uses some special mechanism like the residues of flavonoids and the electrons release during photosynthesis for the conversion of hexavalent chromium to trivalent form. Microalgae are potential candidate for the detoxification of Cr(VI), which would be used for the treatment of chromium contaminated water and soil in an eco-friendly manner.
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