TY - JOUR
T1 - Microenvironments of pH in biofilms grown on dissolving silicate surfaces
AU - Liermann, Laura J.
AU - Barnes, Amy S.
AU - Kalinowski, Birgitta E.
AU - Zhou, Xiangyang
AU - Brantley, Susan L.
N1 - Funding Information:
The authors thank the following for their contributions to these studies: Tom Rusnak for SEM assistance, Sharon Givens and Don Voigt for hornblende preparation and technical assistance, Jon Chorover and Mingxin Guo for organic acids analyses, and Serguei Lvov for use of lab facilities for microelectrode pH measurements. This manuscript was greatly improved by the comments of Hubert Staudigel and Jeremy Fein. Birgitta E. Kalinowski is grateful to The Swedish Foundation for International Cooperation in Research and Higher Education (STINT) for partial support. The project was funded by NSF grant CHE 9631528 and Liermann is partially funded by NSF DGE-9972759 to S.L. Brantley and the Penn State Biogeochemical Research Initiative for Education (BRIE).
Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2000
Y1 - 2000
N2 - Differences in pH between silicate-biofilm interfaces and bulk medium (△pH = pHinterface - pHbulk) were detectable with commercial microelectrodes in cultures grown in unbuffered medium (ℑ△pH! = 0.27 - 1.08) for an arthrobacter species. but were generally beneath detection (△pH < 0.04) for a streptomyces species. Biofilm half-thicknesses developed by Arthrobacter ranged from 1.2 to 11.5 mm. and were highly variable even for replicates. In buffered medium, neither bacterium produced a measurable △pH across the biofilms grown on silicates. The silicates consisted of polished hornblende, synthetic Fe-rich glass similar to hornblende in bulk composition, and two commercially available float glasses, one low-Fe and one high-Fe. The two species of soil bacteria investigated are both known to accelerate release of Fe from hornblende. For the Arthrobacter, values of !△pH! developed on hornblende crystal or glass substrates were generally larger than those developed on either float glass. Differences in △pH developed on different substrates could not be related simply to relative rates of dissolution of substrates. Differences between the two bacterial species are probably related to differences in (1) rates of growth, (2) production of low-molecular-weight organic acids, (3) physical characteristics of polysaccharide slimes excreted and/or (4) production of siderophores. Although values of !△pH! developed at mineral-water interfaces in natural systems may not be as large as those measured here except for water-saturated systems, it is probable that significant values of △pH (≤pH unit) developed where fast-growing, acid-producing microbes colonize slow-dissolving phases in the presence of unbuffered solutions.
AB - Differences in pH between silicate-biofilm interfaces and bulk medium (△pH = pHinterface - pHbulk) were detectable with commercial microelectrodes in cultures grown in unbuffered medium (ℑ△pH! = 0.27 - 1.08) for an arthrobacter species. but were generally beneath detection (△pH < 0.04) for a streptomyces species. Biofilm half-thicknesses developed by Arthrobacter ranged from 1.2 to 11.5 mm. and were highly variable even for replicates. In buffered medium, neither bacterium produced a measurable △pH across the biofilms grown on silicates. The silicates consisted of polished hornblende, synthetic Fe-rich glass similar to hornblende in bulk composition, and two commercially available float glasses, one low-Fe and one high-Fe. The two species of soil bacteria investigated are both known to accelerate release of Fe from hornblende. For the Arthrobacter, values of !△pH! developed on hornblende crystal or glass substrates were generally larger than those developed on either float glass. Differences in △pH developed on different substrates could not be related simply to relative rates of dissolution of substrates. Differences between the two bacterial species are probably related to differences in (1) rates of growth, (2) production of low-molecular-weight organic acids, (3) physical characteristics of polysaccharide slimes excreted and/or (4) production of siderophores. Although values of !△pH! developed at mineral-water interfaces in natural systems may not be as large as those measured here except for water-saturated systems, it is probable that significant values of △pH (≤pH unit) developed where fast-growing, acid-producing microbes colonize slow-dissolving phases in the presence of unbuffered solutions.
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U2 - 10.1016/S0009-2541(00)00202-3
DO - 10.1016/S0009-2541(00)00202-3
M3 - Article
AN - SCOPUS:0034473778
SN - 0009-2541
VL - 171
SP - 1
EP - 16
JO - Chemical Geology
JF - Chemical Geology
IS - 1-2
ER -