Alteration of iron‐rich lacustrine sediments by dissimilatory iron‐reducing bacteria

Abstract

The reduction of Fe during bacterial anaerobic respiration in sediments and soils not only causes the degradation of organic matter but also results in changes in mineralogy and the redistribution of many nutrients and trace metals. Understanding trace metal patterns in sedimentary rocks and predicting the fate of contaminants in the environment requires a detailed understanding of the mechanisms through which they are redistributed during Fe reduction. In this work, lacustrine sediments from Lake Matano in Indonesia were incubated in a minimal media with the dissimilatory iron reducing (DIR) bacterium Shewanella putrefaciens 200R. These sediments were reductively dissolved at rates slower than pure synthetic goethite despite the presence of an ‘easily reducible’ component, as defined by selective extractions. DIR of the lacustrine sediments resulted in the substrate‐dependent production of abundant quantities of extracellular polymeric substances. Trace elements, including Ni, Co, P, Si, and As, were released from the sediments with progressive Fe reduction while Cr was sequestered. Much of the initial trace metal mobility can be attributed to the rapid reduction of a Mn‐rich oxyhydroxide phase. The production of organo‐Fe(III) reveals that DIR bacteria can generate significant metal complexation capacity. This work demonstrates that DIR induces the release of many elements associated with Fe‐Mn oxyhydroxides, despite secondary mineralization.

Biological modifiers of marine benthic seascapes: Their role as ecosystem engineers

“…They include chemical alteration to pore waters, biomineralisation and precipitation of specific inorganic or organic substances that form microscopically visible entities, larger scale organic and inorganic traces at the sediment surface, and animal burrows deep into the sediment (Schäfer, 1972;Ratcliffe and Fagerstrom, 1980;Bromley, 1996;Crowe et al, 2007;Hausrath et al, 2007;Jenkins et al, 2007;Sivan et al, 2007;Anderson et al, 2011). Microorganisms play a central role in biomineralisation and precipitation to produce new molecules and structures that will then be of use to other organisms.…”

An iron shuttle for deepwater silica in Late Archean and early Paleoproterozoic iron formation

“…Also, how does silica adsorption affect rates and mechanisms of biological iron reduction? Iron-reducing bacteria can access and reduce Fe(III) from a wide array of hydroxide and clay minerals (Lovley et al, 2004;Crowe et al, 2007). When grown on a ferrihydrite substrate containing 1 and 5 mol% silica, Shewanella putrefaciens CN32 exhibited no change in iron reduction rate (Kukkadapu et al, 2004).…”

The Impact of Carbon Tetrachloride on an Anaerobic Methanol-Degrading Microbial Community

“…This accumulation of iron sulphide indicates that iron reduction was a significant process in the Rio column. A number of bacterial species (Lovley et al 2004) such as Shewanella putrefaciens, Geobacter metallireducens, Desulfitobacterium metallireducens (Finneran et al 2002), and even a Clostridium species (Dobbin et al 1999) are known to carry out dissimilatory iron reduction, including ferric iron species present in clay soils (Kostka et al 2002;Crowe et al 2007). Reduced biogenic iron has been demonstrated to be reactive towards chlorinated compounds, particularly carbon tetrachloride (Gerlach et al 2000;McCormick et al 2002;Elsner et al 2004).…”