Physical and chemical effects of extracellular polymers (EPS) on Zn adsorption to Bacillus licheniformis S-86

Enthalpies of proton adsorption onto Bacillus licheniformis at 25, 37, 50, and 75°C

“…Specific investigation of the identity of site L 3 for a different strain of B. licheniformis found unclear results. Tourney et al (2009) performed XAS measurement of Zn adsorption onto B. licheniformis S-86 and could not definitively identify a Zn-P complex. The authors determined that a phosphoryl influence was the most likely source of deviation from a pure Zn-C signal representing adsorption onto a carboxyl site.…”

“…Information regarding reactive site identity can also be inferred from this data. Spectroscopic techniques provide a more direct probe of reactive site identity and coordination environments than does surface complexation modeling; however, data interpretation does not always lead to clear results (Beech et al, 1999;Kelly et al, 2002;Boyanov et al, 2003;Omoike and Chorover, 2004;Guine et al, 2006;Tourney et al, 2009). Microscopic techniques offer unique information on cell structure and mechanical properties Beveridge, 2005, 2007;Vadillo-Rodriguez et al, 2008).…”

The effect of ionic strength on the electrophoretic mobility and protonation constants of an EPS-producing bacterial strain

“…The reproducibility between the titrations conducted at different biomass concentrations is poorer than for the EPS-free cells. This has been attributed to variations in the degree of cell aggregation, which are more pronounced in the native cells [8] (discussed further in Section 4.2). There appears to be a trend towards greater buffering capacity as ionic strength decreases.…”

“…In this case, it is thought that the production of EPS by the cells encourages aggregation in solution, particularly at high biomass concentrations. The evidence for and implications of this behaviour are discussed in Tourney et al [8]. Generally, cell aggregation in suspension may lead to an overall slight underestimate in the surface site concentrations for the native cells, depending on the extent to which the cell aggregates are proton-permeable.…”

“…Much of the recent work has focussed on accurately constraining the adsorption mechanisms, by means of both macroscopic batch experiments and spectroscopic analysis [1][2][3][4][5][6][7][8][9][10]. Since bacteria develop surface charge owing to the presence of proton-active surface functional groups, it is intuitive to assume that surface complexation modelling of macroscopic adsorption data would require characterisation of the electrostatic interactions between the cell surface and the electrolyte in which the adsorption reaction is taking place.…”