Experimental observations of the effects of bacteria on aluminosilicate weathering

Abstract

Other| December 01, 1998 Experimental observations of the effects of bacteria on aluminosilicate weathering W. W. Barker; W. W. Barker University of Wisconsin-Madison, Department of Geology and Geophysics, Madison, WI, United States Search for other works by this author on: GSW Google Scholar S. A. Welch; S. A. Welch Search for other works by this author on: GSW Google Scholar S. Chu; S. Chu Search for other works by this author on: GSW Google Scholar J. F. Banfield J. F. Banfield Search for other works by this author on: GSW Google Scholar Author and Article Information W. W. Barker University of Wisconsin-Madison, Department of Geology and Geophysics, Madison, WI, United States S. A. Welch S. Chu J. F. Banfield Publisher: Mineralogical Society of America First Online: 02 Mar 2017 Online ISSN: 1945-3027 Print ISSN: 0003-004X GeoRef, Copyright 2004, American Geological Institute. American Mineralogist (1998) 83 (11-12_Part_2): 1551–1563. https://doi.org/10.2138/am-1998-11-1243 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation W. W. Barker, S. A. Welch, S. Chu, J. F. Banfield; Experimental observations of the effects of bacteria on aluminosilicate weathering. American Mineralogist 1998;; 83 (11-12_Part_2): 1551–1563. doi: https://doi.org/10.2138/am-1998-11-1243 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Mineral dissolution experiments using batch cultures of soil and groundwater bacteria were monitored with solution chemistry and various microscopic techniques to determine the effects of these organisms on weathering reactions. Several strains of bacteria produced organic and inorganic acids and extracellular polymers in culture, increasing the release of cations from biotite (Si, Fe, Al) and plagioclase feldspar (Si, Al) by up to two orders of magnitude compared to abiotic controls. Microbial colonies on mineral grains were examined by cryo-scanning electron microscopy (cryo-SEM), confocal scanning laser microscopy (CSLM), and epifluorescence microscopy. Bacteria colonized all mineral surfaces, often preferentially along cleavage steps and edges of mineral grains. Low-voltage high-resolution cryo-SEM of high-pressure cryofixed and partially freeze-dried colonized minerals showed many bacteria attached by extracellular polymers of unknown composition. These biofilms covered much larger areas of the mineral surfaces than bacterial cells alone. Mineral surfaces where bacteria and extracellular polymers occurred appeared more extensively etched than surrounding uncolonized surfaces. CSLM was used to observe microbial colonization of biotite and to measure pH in microenvironments surrounding living microcolonies using a ratiometric pH-sensitive fluorescent dye set. A strain of bacteria (B0693 from the U.S. Department of Energy Subsurface Microbial Culture Collection) formed large attached microcolonies, both on the outer (001) surface and within interlayer spaces as narrow as 1 mu m. Solution pH decreased from near neutral at the mineral surface to 3-4 around microcolonies living within confined spaces of interior colonized cleavage planes. However, no evidence of pH microgradients surrounding exterior microcolonies was noted. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.