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

Journal Article · Mon Sep 01 04:00:00 EDT 2003 · Geochim. Cosmochim. Acta

DOI:https://doi.org/10.1016/S0016-7037(02)01343-1· OSTI ID:961472

Boyanov, M I; Kelly, S D; Kemner, K M; Bunker, B A; Fein, J B; Fowle, D A

The local atomic environment of Cd bound to the cell wall of the gram-positive bacterium Bacillus subtilis was determined by X-ray absorption fine structure (XAFS) spectroscopy. Samples were prepared at six pH values in the range 3.4 to 7.8, and the bacterial functional groups responsible for the adsorption were identified under each condition. Under the experimental Cd and bacterial concentrations, the spectroscopy results indicate that Cd binds predominantly to phosphoryl ligands below pH 4.4, whereas at higher pH, adsorption to carboxyl groups becomes increasingly important. At pH 7.8, we observe the activation of an additional binding site, which we tentatively ascribe to a phosphoryl site with smaller Cd-P distance than the one that is active at lower pH conditions. XAFS spectra of several cadmium acetate, phosphate, and perchlorate solutions were measured and used as standards for fingerprinting, as well as to assess the ability of FEFF8 and FEFFIT to model carboxyl, phosphoryl, and hydration environments, respectively. The results of this XAFS study in general corroborate existing surface complexation models; however, some binding mechanism details could only be detected with the XAFS technique.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; OUS; NSF
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 961472
• Report Number(s): ANL/ER/JA-48129
• Journal Information: Geochim. Cosmochim. Acta, Journal Name: Geochim. Cosmochim. Acta Journal Issue: 18 ; Sep. 2003 Vol. 67; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
ABSORPTION SPECTROSCOPY
ADSORPTION
BACILLUS SUBTILIS
CADMIUM
CELL WALL
DISTANCE
ENVIRONMENT
FINE STRUCTURE
HYDRATION
LIGANDS
PERCHLORATES
PH VALUE
RANGE
SOLUTIONS
SPECTRA
SPECTROSCOPY
SURFACES
X-RAY SPECTROSCOPY