Effect of lead on metallothionein concentration in lead-resistant bacteria Bacillus cereus isolated from industrial effluent

Abstract

Metallothioneins (MTs) are cysteine-rich metal-binding proteins found in a wide variety of organisms including bacteria, fungi as well as all eukaryotic plant and animal species. MTs bind essential and nonessential heavy metals. MTs production was evaluated by a simple spectrophotometry methodology. The study elucidated that the metallothionein concentration in Bacillus cereus treated with different concentrations of lead increased with increasing lead concentration. The protein samples from B.cereus treated with different concentrations of lead were isolated and electrophoresed on SDS-PAGE and 2-D gels. The study of gels revealed that a thick protein band appeared around 14.3KD in case of B. cereus treated with lead unlike the control samples.

Lead (Pb) bioaccumulation; genera Bacillus isolate S1 and SS19 as a case study

“…Therefore almost all the protein bands are expressed on lead exposure which also found in normal circumstances without PbCl2 presence (except on isolates S1 that found protein bands with molecular weight 127 kDa). Bacteria expressed a number of stress proteins as a survival mechanism on stressed condition [9,16]. Protein which occurred on the conditions of exposure to PbCl2 had allegedly as one mechanism of bacterial resistance to metallic lead.…”

“…Protein with lower molecular weight about 14 kDa protein belongs to the group of metallotionein, which was responsible for the resistance mechanism of the organism towards heavy metals (Cd, Ag, Pb, Cu, and Hg) [9]. Protein with a molecular weight of 28 and 55 kDa was detected in the expression of mold biomass that exposure with lead (Pb) are identified as superoxide dismutase containing Fe and Zn (FeZnSOD) [24].…”

“…Biosorption was a mechanism that involves the role of EPS (exopolysaccaryde) on the cell walls of bacteria that also acted as a chelator of heavy metals on bacterial cell surface. Bacterial cells were abundant with the sides containing the negative charge located on the wall of his cell, such as phosphoryl (PO43-), carboxyl (COO-), sulfhydryl or the thiol (-SH) and the hydroxyl (-OH), so metal ion interactions with the negative charge that form ligand might be occurred [9,16].…”

“…Some of adaptations response were proteins and enzymes formation, or modify the biomolecules conformation as well as protection from heavy metal toxicity [9]. Bacteria as one of microorganisms performed gene expression through adaptation response in form of protein.…”

“…Bacillus was bacteria that abundant in nature relatively, it can be isolated from various habitats even environment which contaminated lead (Pb) [4,7,8,9,10,11]. Bacteria which able to life in habitats or the environment polluted lead (Pb) called lead (Pb) resistant bacteria.…”