A Novel “Microbial Bait” Technique for Capturing Fe(III)-Reducing Bacteria

B.M. Macaulay, C. Boothman, B.E. van Dongen, J.R. Lloyd

Research output: Contribution to journalArticlepeer-review

Abstract

Microbial reduction of Fe(III) is a key geochemical process in anoxic environments, controlling the degradation of organics and the mobility of metals and radionuclides. To further understand these processes, it is vital to develop a reliable means of capturing Fe(III)-reducing microorganisms from the field for analysis and lab-based investigations. In this study, a novel method of capturing Fe(III)-reducing bacteria using Fe(III)-coated pumice “microbe-baits” was demonstrated. The methodology involved the coating of pumice (approx. diameter 4 to 6 mm) with a bioavailable Fe(III) mineral (akaganeite), and was verified by deployment into a freshwater spring for 2 months. On retrieval, the coated pumice baits were incubated in a series of lab-based microcosms, amended with and without electron donors (lactate and acetate), and incubated at 20℃ for 8 weeks. 16S rRNA gene sequencing using the Illumina MiSeq platform showed that the Fe(III)-coated pumice baits, when incubated in the presence of lactate and acetate, enriched for Deltaproteobacteria (relative abundance of 52% of the sequences detected corresponded to Geobacter species and 24% to Desulfovibrio species). In the absence of added electron donors, Betaproteobacteria were the most abundant class detected, most heavily represented by a close relative to Rhodoferax ferrireducens (15% of species detected), that most likely used organic matter sequestered from the spring waters to support Fe(III) reduction. In addition, TEM-EDS analysis of the Fe(III)-coated pumice slurries amended with electron donors revealed that a biogenic Fe(II) mineral, magnetite, was formed at the end of the incubation period. These results demonstrate that Fe(III)-coated pumice “microbe baits” can potentially help target metal-reducing bacteria for culture-dependent studies, to further our understanding of the nano-scale microbe-mineral interactions in aquifers.
Original languageEnglish
JournalFrontiers in Microbiology
DOIs
Publication statusPublished - 11 Mar 2020

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  • Biochemical and Biophysical Sciences Technology Platform

    Heyes, D. (Senior Technical Specialist), Boothman, C. (Senior Technical Specialist), Cliffe, L. (Technical Specialist), Dunstan, M. (Senior Technical Specialist), Golovanova, M. (Senior Technician), Hoeven, R. (Technical Specialist), Lopez Perez, R. (Senior Technician), Sakuma, M. (Senior Technician), Tait, S. (Senior Technician) & Tilakaratna, V. (Senior Technician)

    FSE Research

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