Adsorption of cadmium to Bacillus subtilis bacterial cell walls: a pH-dependent X-ray absorption fine structure spectroscopy study

Boyanov, Maxim I.; Kelly, Shelly D.; Kemner, Kenneth M.; Bunker, Bruce A.; Fein, Jeremy B.; Fowle, David A.

doi:10.1016/s0016-7037(02)01343-1

Cited by 217 publications

(165 citation statements)

References 54 publications

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“…It has been reported that cadmium ion adsorb preferentially onto phosphate groups of the B. subtilis cell walls at pH values lower than 4.5, and that the contribution of carboxylate groups increases as pH increases (Boyanov et al 2003). In the present study, the contribution of phosphate groups to the adsorption of rare earth ions would be high because the adsorption activity was studied at pH 3.…”

Section: Discussionmentioning

confidence: 68%

Adsorption of rare earth ions onto the cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis

Moriwaki

Koide

Yoshikawa

et al. 2012

Appl Microbiol Biotechnol

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Section: Discussionmentioning

confidence: 68%

Adsorption of rare earth ions onto the cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis

Moriwaki

Koide

Yoshikawa

et al. 2012

Appl Microbiol Biotechnol

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“…However, it must be borne in mind that functional groups can only be reliably identified by other methods, such as X-ray spectroscopy analysis. X-ray adsorption spectroscopy experiments conducted by Boyanov and colleagues (9) suggested that Cd 2ϩ adsorption onto Bacillus subtilis at a pH of 3.4 is predominated by phosphoryl ligands, whereas carboxylic ligands are the dominant binding sites in the pH range of 5.0 to 7.8.…”

Section: Discussionmentioning

confidence: 99%

Cadmium Ion Biosorption by the Thermophilic Bacteria Geobacillus stearothermophilus and G. thermocatenulatus

Hetzer

Daughney

Morgan

2006

Appl Environ Microbiol

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This study reports surface complexation models (SCMs) for quantifying metal ion adsorption by thermophilic microorganisms. In initial cadmium ion toxicity tests, members of the genus Geobacillus displayed the highest tolerance to CdCl 2 (as high as 400 to 3,200 M). The thermophilic, gram-positive bacteria Geobacillus stearothermophilus and G. thermocatenulatus were selected for further electrophoretic mobility, potentiometric titration, and Cd 2؉ adsorption experiments to characterize Cd 2؉ complexation by functional groups within and on the cell wall. Distinct one-site SCMs described the extent of cadmium ion adsorption by both studied Geobacillus sp. strains over a range of pH values and metal/bacteria concentration ratios. The results indicate that a functional group with a deprotonation constant pK value of approximately 3.8 accounts for 66% and 80% of all titratable sites for G. thermocatenulatus and G. stearothermophilus, respectively, and is dominant in Cd 2؉ adsorption reactions. The results suggest a different type of functional group may be involved in cadmium biosorption for both thermophilic strains investigated here, compared to previous reports for mesophilic bacteria.Various metal compounds can be either essential or toxic for living organisms, depending on the form and concentration. In important physiological catalytic reactions, many enzymes require metal ions as central atoms. In order to generate energy, several microorganisms depend on metal compounds that act as final electron acceptors during anaerobic respiration and as electron donors in chemolithotrophic metabolism. In contrast, nonessential metal ions, in particular, and metal ions (both nonessential and essential) at high concentrations, in general, harm the living cell by potentially displacing essential metal ions (in enzymes), competing with structurally related nonmetals in cell reactions and blocking functional groups in biomolecules (29). Therefore, organisms have developed several metal homeostasis and detoxification strategies, including an active efflux system, changes in ion permeability, adsorption, and intra-and extracellular complexation, biotransformation, and compartmentation (10,21,27,31,36).Adsorption of metals by cell wall components is one of the more important interaction mechanisms, and it has been the subject of many studies (for review, see references 3, 15, 20, 34, 35, and 40). Several recent investigations have used surface complexation models (SCMs) to describe the extent of metal adsorption by bacteria as important physical, chemical, and biological parameters are independently varied (5,8,14,16,19,23,43). These SCMs are based upon a set of molecular-scale thermodynamic reactions, each describing adsorption of a particular dissolved chemical species to a particular type of cell wall functional group using a single stability constant, K. Some previous investigations indicate that different bacterial species display similar types of reactive surface functional groups (e.g., carboxyl, phosphoryl, hydroxyl, or ...

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“…Since surface 168 waters exposed to the atmosphere have a pH of approximately 5.6 due to the dissolution of 169 carbon dioxide into the water, we chose to work at pH 5.5 to make our results relevant to 170 environmental and geochemical systems. Metal adsorption on bacterial cell surfaces have been 171 previously conducted at similar pH conditions (Boyanov et al, 2003; Claessens and Van 172 Cappellen, 2007;Wei et al, 2011). In addition, we conducted experiments at pH 5.5 to exclude 173 potential effects of insoluble Hg-hydroxide formation which are highly favorable at alkaline pH 174 conditions.…”

mentioning

confidence: 99%

Stoichiometry of mercury-thiol complexes on bacterial cell envelopes

Mishra

Shoenfelt

et al. 2017

Chemical Geology

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30We have examined the speciation of Hg(II) complexed with intact cell suspensions (10 13 31 cells L -1 ) of Bacillus subtilis, a common gram-positive soil bacterium, Shewanella oneidensis 32 MR-1, a facultative gram-negative aquatic organism, and Geobacter sulfurreducens, a gram-33 negative anaerobic bacterium capable of Hg-methylation at Hg(II) loadings spanning four orders 34 of magnitude (120 nM to 350 µM) at pH 5.5 (±0.2). The coordination environments of Hg on 35 bacterial cells were analyzed using synchrotron based X-ray Absorption Near Edge Structure 36 (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy at the Hg LIII 37 edge. The abundance of thiols on intact cells was determined by a fluorescence-spectroscopy 38 based method using a soluble bromobimane, monobromo(trimethylammonio)bimane (qBBr) to 39 block thiol sites, and potentiometric titrations of biomass with and without qBBr treatment. The 40 chemical forms of S on intact bacterial cells were determined using S k-edge XANES 41 spectroscopy. 42Hg(II) was found to complex entirely with cell bound thiols at low Hg:biomass ratios. 43 For Bacillus subtilis and Shewanella oneidensis MR-1 cells, the Hg-S stoichiometry changed 44 from Hg-S3 to Hg-S2 and Hg-S (where 'S' represents a thiol site such as is present on cysteine) 45 progressively as the Hg(II) loading increased on the cells. However, Geobacter sulfurreducens 46 did not form Hg-S3 complexes. Because the abundance of thiol was highest for Geobacter 47 sulfurreducens (75 µM/g wet weight) followed by Shewanella oneidensis MR-1 (50 µM/g wet 48 weight) and Bacillus subtilis (25 µM/g wet weight), the inability of Hg(II) to form Hg-S3 49 complexes on Geobacter sulfurreducens suggests that the density and reactivity of S-amino acid 50 containing cell membrane proteins on Geobacter sulfurreducens are different from those of 51Bacillus subtilis and Shewanella oneidensis MR-1. Upon saturation of the high affinity thiol sites 52 at higher Hg:biomass ratios, Hg(II) was found to form a chelate with -hydroxy carboxylate 53anion. The stoichiometry of cell envelope bound Hg-thiol complexes and the associated 54 abundance of thiols on the cell envelopes provide important insights for understanding the 55 differences in the rate and extent of uptake and redox transformations of Hg in the environment. Introduction 66Mercury is a common contaminant found in many terrestrial and aquatic systems, and its 67 bioaccumulation in organisms, including humans, is a major environmental concern (Mergler et 68 al, 2007). The solubility, speciation, toxicity and the ultimate fate of Hg within aquatic 69 ecosystems is dependent on a large number of chemical and biological variables (Morel et al., 70 1998;Barkay and Schaefer, 2001). In aquatic systems, Hg solubility is high under oxygen-rich 71 acidic conditions but it is significantly inhibited under anoxic sulfide-rich waters (Martell and 72 Smith, 1974). The Hg-sulfide complexes are among the strongest complexes of all known Hg 73 i...

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Adsorption of cadmium to Bacillus subtilis bacterial cell walls: a pH-dependent X-ray absorption fine structure spectroscopy study

Cited by 217 publications

References 54 publications

Adsorption of rare earth ions onto the cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis

Adsorption of rare earth ions onto the cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis

Cadmium Ion Biosorption by the Thermophilic Bacteria Geobacillus stearothermophilus and G. thermocatenulatus

Stoichiometry of mercury-thiol complexes on bacterial cell envelopes

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