Cyanobacterial Extracellular Polymeric Substances for Heavy Metal Removal: A Mini Review

Abstract

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.

Cyanoremediation and phyconanotechnology: cyanobacteria for metal biosorption toward a circular economy

“…Several cyanobacteria genera, such as Anabaena , Cyanobium , Nostoc , Cyanothece , Arthrospira , Microcystis , Synechocystis , and Leptolyngbya , have shown promising results on Cu, Cd, Zn, Cr, Pb, Ni, Co or Hg removal with initial concentration ranging from some mg/L to 150–200 mg/L ( Mota et al, 2016 ; Zinicovscaia et al, 2018 ; Yadav et al, 2021 ; Bloch and Ghosh, 2022 ; Pandey et al, 2022a ). Maximum uptake is typically in the range of 15–80 mg/g dry weight, but some works have presented values even higher than 300 mg/g dry weight ( Cui et al, 2021 ).…”

Cleaner technologies to combat heavy metal toxicity

“…Various biological products such as cyanobacterialexopolysaccharides aid in the absorption of a wide variety of heavy metals. The complex nature of cyanobacterialexopolysaccaharides with the presence of repeating units of different sugars in high concentrations, metallothionein based proteins, pyruvic acid moieties, uronic acids, lipids, and DNA aid in the selection absorption of heavy metals and remediation (Yadav et al, 2021). Novel strategies to develop genetically engineered microbe of E. coli with phytoalexin gene expressed in it and thereby aid in heavy metal bioaccumulation have also been attempted (Bae et al, 2000).…”

Synthetic Biology-Based Approaches for Microalgal Bio-Removal of Heavy Metals From Wastewater Effluents

“…The genetic control of biofilm formation in microorganisms has been studied and several reports on manipulation of biofilm formation in bacteria have been discussed elsewhere (Perni et al, 2013;Benedetti et al, 2016). Mutagenesis studies of cyanobacteria for enhanced EPS production have also been investigated (Pereira et al, 2019;Yadav et al, 2020). However, these remain to be explored in microalgae.…”