Heavy metals from various natural and anthropogenic sources are becoming a chief threat to the aquatic system owing to their toxic and lethal effect. The treatment of such contaminated wastewater is one of the prime concerns in this field. For decades, a huge array of innovative biosorbents is used for heavy metal removal. Though extensive microbes and their biomolecules have been experimented and have showed great potential but most of them have failed to have the substantial breakthrough for the practical application. The present review emphasis on the potential utilization of the cyanobacteria for the heavy metal removal along with the toxic effect imposed by the pollutant. Furthermore, the effect of significant parameters, plausible mechanistic insights of the heavy metal toxicity imposed onto the cyanobacteria is also discussed in detail. The role of extrapolymeric substances and metallothionein secreted by the microbes are also elaborated. The review was evident that the cyanobacterial species have a huge potential towards the heavy metal removal from the aqueous system ranging from very low to very high concentrations.

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Chromium (VI) is a well-known pollutant that is present in industrially polluted soil and water, and has been reported to be mutagenic and carcinogenic. In the present study, we investigated the effective use of Leptolyngbya boryana (cyanobacterium) as an eco-friendly option to overcome Cr (VI) toxicity in tannery effluents. The main objective of this study was to identify the Cr reductase (ChrR) gene and its variability in the context of Cr (VI) stress. Industrial polluted soil samples were collected and processed according to standard protocols for ChrR variation and 16S rDNA gene analysis. Genomic DNA was isolated from the collected samples and the ChrR and 16S rDNA genes were amplified by PCR. Amplified 16S rDNA was sequenced and aligned with known sequences. In the present study, a strong correlation was established between the nucleotide sequences of the ChrR and 16S rDNA genes. The Minimum Inhibitory Concentration (MIC) was determined for Cr (VI), and pure strains of L. boryana were identified and isolated from soil samples. Cr (VI)-stressed conditions and their genetic variability were confirmed by sequencing. In conclusion, the L. boryana strain has been identified an eco-friendly option for overcoming Cr (VI) toxicity in tannery effluents.

Chromium is well known pollutant for its mutagenicity, and carcinogenicity in humans. Excessive uses of chromium in leather tanning industries, stainless-steel production, and wood preservatives have resulted as chromium contamination in soil and water. This investigation indicates the effective use of Leptolyngbya boryana as an eco-friendly option to overcome Chromium (VI) toxicity in tannery effluents. The main objective of this research was to find out ChrR gene and its variability in the context of Cr (VI) stress. This is a novel study in the relation of Leptolyngbya boryana. Industrial polluted soil samples were collected and processed according to the standard protocols for ChrR variation and 16S rRNA gene. DNA was isolated and amplified through PCR. Amplified DNA was sequenced and aligned with the known sequences. In this study a strong co-relation was established in the nucleotide sequences of ChrR and 16S rRNA genes. MIC was determined for Cr (VI) and pure strains of Leptolyngbya boryana were identified and isolated from soil. In the present study presence of ChrR gene variability was recorded in Leptolyngbya boryana which is a cyanobacterium in the soil of tannery effluent under Cr (VI) stressed condition and its gene variability was confirmed by sequencing. We can conclude that Leptolyngbya boryana strain could be eco-friendly option to overcome Chromium (VI) toxicity in tannery effluents.