Terrance J. Beveridge

Formation of fine-grained metal and silicate precipitates on a bacterial surface (Bacillus subtilis)

Abstract The ability of the Gram-positive bacterium B. subtilis to bind and nucleate precipitates from silicate anions has been studied over 24 weeks in the presence of Fe and A1 at concentrations close to those levels in soils, and at slightly acid (5.5) and basic (8.0) pH. In all cases formation of silicate crystallites (quasi-crystalline precipitates) on the bacterial surfaces was observed. Bacterially-mediated minerals were more diverse in composition and morphology, less crystalline, smaller and (sometimes) more abundant than those that were abiotically formed. Fe pretreatment of the bacterial cells enhanced the binding of silicate at pH 8.0. Walls which were not pretreated with Fe, bound silicate more favourably at acid values. When heavy metals (Pb, Cd, Zn, Cr, Ni, Cu) were added to the mixture at pH 4.5, silicate retention was greatly favoured, giving greater retention of either Si or metals than was seen in abiotic controls. Experiments with only heavy metals showed a high affinity of the bacterial walls for the metals, even at low temperatures (4°C). It is postulated that a cationic bridging mechanism is involved in the binding of silicate anions by bacterial cell walls.

V. Functions of S‐layers

Although S-layers are being increasingly identified on Bacteria and Archaea, it is enigmatic that in most cases S-layer function continues to elude us. In a few instances, S-layers have been shown to be virulence factors on pathogens (e.g. Campylobacter fetus ssp. fetus and Aeromonas salmonicida), protective against Bdellovibrio, a depository for surface-exposed enzymes (e.g. Bacillus stearothermophilus), shape-determining agents (e.g. Thermoproteus tenax) and nucleation factors for fine-grain mineral development (e.g. Synechococcus GL 24). Yet, for the vast majority of S-layered bacteria, the natural function of these crystalline arrays continues to be evasive. The following review up-dates the functional basis of S-layers and describes such diverse topics as the effect of S-layers on the Gram stain, bacteriophage adsorption in lactobacilli, phagocytosis by human polymorphonuclear leukocytes, the adhesion of a high-molecular-mass amylase, outer membrane porosity, and the secretion of extracellular enzymes of Thermoanaerobacterium. In addition, the functional aspect of calcium on the Caulobacter S-layer is explained.

The in vitro formation of placer gold by bacteria

A laboratory simulation was developed to provide mechanistic information about placer (nugget) gold development in the natural environment. To initiate the simulation, ionic gold was immobilized to a high capacity by Bacillus subtilis 168 (116.2 μg/mg dry weight bacteria) as fine-grained intracellular colloids (5–50 nm). During the low-temperature diagenesis experiment (60°C), the release of organics due to bacterial autolysis coincided with the in vitro formation of hexagonal-octahedral gold crystals (20 μm). This octahedral gold was observed to aggregate, forming fine-grained placer gold (50 μm). In addition to achieving a fundamental understanding into secondary gold deposition, a significant economic benefit could be realized by employing this environmentally safe procedure to concentrate widely dispersed gold in placer deposits to facilitate mining by conventional methodologies.

The occurrence of sulfur and phosphorus within bacterially derived crystalline and pseudocrystalline octahedral gold formed in vitro

Abstract A temperature study (4°C, room temperature, 60°C and 90°C) employing a bacterial in vitro model (Southam and Beveridge, 1994) revealed a role for S and P in octahedral An formation. Ionic Au immobilized by Bacillus subtilis 168 was first precipitated as colloidal Au. During diagenesis, these colloids were transformed into spherical pseudocrystalline gold particles composed of 74.56 ± 2.60 at% Au, 8.56 ± 1.71 at% S, and 13.94 ± 1.48 at% P. These minerals then aggregated as roughly shaped noncrystalline octahedral Au which was subsequently transformed into crystalline octahedral Au containing 85.37 ± 0.16 at% Au (the maximum detected[, 0.77 ± 1.33 at% S, and 10.27 ± 0.88 at% P. The strong P signals (13.39 ± 2.01 average at%[ obtained from the Au minerals examined by energy-dispersive X-ray spectroscopy suggest that organic phosphate compounds also play a role in the in vitro development of octahedral Au, possibly as bacteria-Au-complexing agents. Increasing the time to 4 weeks at room temperature or the temperature to either 60°C or 90°C enhanced formation of the crystalline octahedral gold. This crystalline octahedral Au generated an electron diffraction pattern consistent with synthetic Au.

Formation of Green Rust and Immobilization of Nickel in Response to Bacterial Reduction of Hydrous Ferric Oxide

This investigation documents the formation of Green Rust (GR) and immobilization of Ni 2+ in response to bacterial reduction of hydrous ferric oxide (HFO). In the absence of Ni 2+ , 79% of the total Fe(III) present as HFO was reduced; at 10 -3 and 10 -4 M Ni 2+ , 36% of the total Fe(III) was reduced, whereas 45 to 50% of the total Fe(III) was reduced at 10 -5 M Ni 2+ . The inhibitory effect of 10 -3 and 10 -4 M Ni 2+ on Fe(III)-reduction corresponded to a 50% decrease in number of viable cells relative to the Ni 2+ -free condition, and a 25% decrease at 10 -5 M Ni 2+ . A prominent GR peak at d = 10.9 nm was evident in X-ray diffraction patterns of postreduction residual solids from the cultures. Minor peaks arising for vivianite and magnetite were also present. In samples prepared for scanning electron microscopy, thin hexagonal plates of GR were easily distinguished as a solid phase transformation product of HFO. Small hexagonal sheets and fragments of larger GR plates were also observed in transmission ...This investigation documents the formation of Green Rust (GR) and immobilization of Ni 2+ in response to bacterial reduction of hydrous ferric oxide (HFO). In the absence of Ni 2+ , 79% of the total Fe(III) present as HFO was reduced; at 10 -3 and 10 -4 M Ni 2+ , 36% of the total Fe(III) was reduced, whereas 45 to 50% of the total Fe(III) was reduced at 10 -5 M Ni 2+ . The inhibitory effect of 10 -3 and 10 -4 M Ni 2+ on Fe(III)-reduction corresponded to a 50% decrease in number of viable cells relative to the Ni 2+ -free condition, and a 25% decrease at 10 -5 M Ni 2+ . A prominent GR peak at d = 10.9 nm was evident in X-ray diffraction patterns of postreduction residual solids from the cultures. Minor peaks arising for vivianite and magnetite were also present. In samples prepared for scanning electron microscopy, thin hexagonal plates of GR were easily distinguished as a solid phase transformation product of HFO. Small hexagonal sheets and fragments of larger GR plates were also observed in transmission electron microscopy whole mounts together with bacteria that were mineralized by surface precipitates of microcrystalline magnetite. Energy dispersive spectroscopy (EDS) confirmed that GR contained Fe and P, as well as Ni in those samples taken from the Ni 2+ -amended experiments. EDS detected neither P nor Ni in the magnetite precipitates associated with the bacterial cells. Dissolved Ni2 + concentrations decreased in an exponential fashion with respect to time in all experimental systems, corresponding to an overall first-order rate constant k of -0.030 day -1 . At the same time, a strong linear relationship (r 2 = 0.99) between the dissolved and solid phase Ni 2+ /Fe 2+ ratios over the entire period of the Fe(III)reduction experiments provided evidence that the solid-phase partitioning of Ni 2+ in GR extended from equilibrium solid-solution behavior.

Advances in bacterial paracrystalline surface layers

Introduction: A Perspective on SLayer Research (R.G.E. Murray). Structural Analysis of SLayers: SLayers Found on Clinical Isolates (K. Lounatmaa et al.). SLayers of Agricultural and Environmental Importance: Predation on Bacteria Possessing SLayers (S.F. Koval). Chemistry and Molecular Biology of SLayers: Glycoprotein Nature of Select Bacterial SLayers (P. Messner et al.). SLayer Glycoproteins from Moderately and Extremely Halophilic Archaeobacteria (M. Sumper). Applications for SLayers: Molecular Nanotechnology with SLayers (S. Pum, U.B. Sleytr). Stable Liposomes Formed from Archaeal Ether Lipids (C.G. Choquet et al.). Poster Presentations: Linker Mutagenesis of the Caulobacter crescentus SLayer Protein (W.H. Bingle et al.). Summary Statements: Summary Statements (T.J. Beveridge et al.). 28 additional articles. Index.

Redox-reactive membrane vesicles produced by Shewanella.

This manuscript is dedicated to our friend, mentor, and coauthor Dr Terry Beveridge, who devoted his scientific career to advancing fundamental aspects of microbial ultrastructure using innovative electron microscopic approaches. During his graduate studies with Professor Robert Murray, Terry provided some of the first glimpses and structural evaluations of the regular surface arrays (S-layers) of Gram-negative bacteria (Beveridge & Murray, 1974, 1975, 1976a). Beginning with his early electron microscopic assessments of metal binding by cell walls from Gram-positive bacteria (Beveridge & Murray, 1976b, 1980) and continuing with more than 30 years of pioneering research on microbe-mineral interactions (Hoyle & Beveridge, 1983, 1984; Ferris et al., 1986; Gorby et al., 1988; Beveridge, 1989; Mullen et al., 1989; Urrutia Mera et al., 1992; Mera & Beveridge, 1993; Brown et al., 1994; Konhauser et al., 1994; Beveridge et al., 1997; Newman et al., 1997; Lower et al., 2001; Glasauer et al., 2002; Baesman et al., 2007), Terry helped to shape the developing field of biogeochemistry. Terry and his associates are also widely regarded for their research defining the structure and function of outer membrane vesicles from Gram-negative bacteria that facilitate processes ranging from the delivery of pathogenic enzymes to the possible exchange of genetic information. The current report represents the confluence of two of Terrys thematic research streams by demonstrating that membrane vesicles produced by dissimilatory metal-reducing bacteria from the genus Shewanella catalyze the enzymatic transformation and precipitation of heavy metals and radionuclides. Under low-shear conditions, membrane vesicles are commonly tethered to intact cells by electrically conductive filaments known as bacterial nanowires. The functional role of membrane vesicles and associated nanowires is not known, but the potential for mineralized vesicles that morphologically resemble nanofossils to serve as palaeontological indicators of early life on Earth and as biosignatures of life on other planets is recognized.

Modern freshwater microbialites from Kelly Lake, British Columbia, Canada

Small stromatolites and thrombolites occur in Kelly Lake, British Columbia, Canada. Thrombolites appear as welllithified, irregular calcite crusts on hard submerged surfaces, whereas poorly mineralized stromatolites exist on the thrombolite crusts as small laminated hemispherical domes 1.0 to 2.0 cm in diameter and height. Microscopic examination of the thrombolitic crusts reveal the presence of many coccoid and fewer small filamentous cyanobacteria. In contrast, large filamentous cyanobacteria are predominant in the stromatolitic domes. The inorganic carbon and elemental content of the two different microbialites are similar; however, the stromatolites contain more organic carbon (0.5% dry wt) than the thrombolites (0.2% dry wt). This implies that the production rate of organic matter in the stromatolites is higher, relative to the calcification rate, than in the thrombolites. Stable carbon isotope analyses show that the calcite precipitated within the microbialites is enriched in 13C compared to the dissolved inorganic carbon (DIC) source. The enrichments are the result of photosynthetic 12C fractionation by the respective microbial communities. Calcite precipitated within the stromatolites is even more enriched in 13C than that within the thrombolites, corresponding to an enhanced productivity level for the filamentous cyanobacteria in the stromatolites. These data indicate that the degree of mineralization, isotopic fractionation, and morphogenesis of modern microbialites are controlled to a large extent by relative rates of microbial growth and calcification.

A Tactile Response in Staphylococcus aureus

It is well established that bacteria are able to respond to temporal gradients (e.g., by chemotaxis). However, it is widely held that prokaryotes are too small to sense spatial gradients. This contradicts the common observation that the vast majority of bacteria live on the surface of a solid substrate (e.g., as a biofilm). Herein we report direct experimental evidence that the nonmotile bacterium Staphylococcus aureus possesses a tactile response, or primitive sense of touch, that allows it to respond to spatial gradients. Attached cells recognize their substrate interface and localize adhesins toward that region. Braille-like avidity maps reflect a cells biochemical sensory response and reveal ultrastructural regions defined by the actual binding activity of specific proteins.

Frequency and structure of spinae on Chlorobium spp.

Several Chlorobium species have been observed to possess spinae. Spinae are non-prosthecate, helically wound, rigid structures that extend from the outer bacterial cell surface into the external environment. Spinae length was variable within and between Chlorobium species. Spinae width was fairly consistent within species but varied between species (39.4 ± 2.6 nm to 82.6 ± 8.0 nm). The number of spinae per cell varied. The spinae did not penetrate the bacterial cell envelope and were randomly located on the cell surface. Spinae were not geographically restricted. The observation of spinae on pure cultures of Chlorobium spp. maintained for 25–30 years suggests that spinae may be of significant use to the cell.