『Abstract
　This study used batch reactors to characterize the rates and mechanisms of elemental release during the interaction of a single bacterial species (Burkholderia fungorum) with Columbia River Flood Basalt at T = 28℃ for 36 days. we primarily examined the release of Ca, Mg, P, Si, and Sr under a variety of biotic and abiotic conditions with the aim of evaluating how actively metabolizing bacteria might influence basalt weathering on the continents. Four days after inoculating P-limited reactors (those lacking P in the growth medium), the concentration of viable planktonic cells increased from 〜10⁴ 10 ⁸ CFU (Colony Forming Units)/mL, pH decreased from 〜7 to 4, and glucose decreased from 〜1200 to 0μmol/L. Mass-balance and acid-base equilibria calculations suggest that the lowered pH resulted from either respired CO2, organic acids released during biomass synthesis, or H⁺ extrusion during NH4⁺ uptake. Between days 4 and 36, cell numbers remained constant at 〜10⁸ CFU/mL and pH increased to 〜5. Purely abiotic control reactors as well as control reactors containing inert cells (〜10⁸ CFU/mL) showed constant glucose concentrations, thus confirming the absence of biological activity in these experiments. The pH of all control reactors remained near-neutral, except for one experiment where the pH was initially adjusted to 4 but rapidly rose to 7 within 2 days. Over the entire 36 day period, P-limited reactors containing viable bacteria yielded the highest Ca, Mg, Si, and Sr release rates. Release rates inversely correlate with pH, indicating that proton-promoted dissolution was the dominant reaction mechanism. Both biotic and abiotic P-limited reactors displayed low P concentrations. Chemical analyses of bacteria collected at the end of the experiments, combined with mass-balances between the biological and fluid phases, demonstrate that the absence of dissolved P in the biotic reactors resulted from microbial P uptake. The only P source in the basalt is a small amount of apatite (〜1.2％), which occurs as needles within feldspar grains and glass. We therefore conclude that B. fungorum utilized apatite as a P source for biomass synthesis, which stimulated elemental release from coexisting mineral phases via pH lowering. The results of this study suggest that actively metabolizing bacteria have the potential to influence elemental release from basalt in continental settings』

1. Introduction
2. Materials and methods
　2.1. Characterization and preparation of basalt samples
　2.2. Growth media
　2.3. Model microorganism
　2.4. Culture preparation
　2.5. Batch experiments
　2.6. Collection and preparation of cell biomass for chemical analyses
　2.7. Chemical analyses
3. Results and discussion
　3.1. Basalt mineralogy and geochemistry
　3.2. Glucose consumption, bacterial growth, and pH trends
　3.3. Source of acidity
　3.4. Dissolved elemental concentrations
　3.5. Elemental release rates
　3.6. Elemental uptake by bacteria
4. Conclusions and implications
Acknowledgments
References