Document Type

Article

Publication Date

1-2018

Keywords

Algae, Bioassay, Biogenic weathering, Biotite, Chelation, Cyanophyte, Epilithic, Iron minerals

Abstract

A sandstone outcrop exposed to freshwater seepage supports a diverse assemblage of photosynthetic microbes. Dominant taxa are two cyanophytes (Oscillatoria sp., Rivularia sp.) and a unicellular green alga (Palmellococcus sp.). Less abundant taxa include a filamentous green alga, Microspora, and the desmid Cosmarium. Biologic activity is evidenced by measured levels of chlorophyll and lipids. Bioassay methods confirm the ability of these microbes to dissolve and metabolize Fe from ferruginous minerals. Chromatographic analysis reveals citric acid as the likely chelating agent; this low molecular weight organic acid is detectable in interstitial fluid in the sandstone, measured as 0.0756 mg/mL. Bioassays using a model organism, Synechoccus elongates strain UTEX 650, show that Fe availability varies among different ferruginous minerals. In decreasing order of Fe availability: magnetite > limonite > biotite > siderite > hematite. Biotite was selected for detailed study because it is the most abundant iron-bearing mineral in the sandstone. SEM images support the microbiologic evidence, showing weathering of biotite compared to relatively undamaged grains of other silicate minerals.

Link to full text article: http://www.mdpi.com/2076-2607/6/1/8/htm

Publication Title

Microorganisms

Volume

6

Issue

1

First Page

8

Required Publisher's Statement

doi:10.3390/microorganisms6010008

Link to full text article: http://www.mdpi.com/2076-2607/6/1/8/htm

Language

English

Format

application/pdf

Included in

Geology Commons

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