title: Selection of Clostridium spp. in biological sand filters neutralizing synthetic acid mine drainage.
abstract: In this study, three biological sand filter (BSF) were contaminated with a synthetic iron- [1500 mg L⁻¹ Fe(II), 500 mg L⁻¹ Fe(III)] and sulphate-rich (6000 mg L⁻¹ SO₄²⁻) acid mine drainage (AMD) (pH = 2), for 24 days, to assess the remediation capacity and the evolution of autochthonous bacterial communities (monitored by T-RFLP and 16S rRNA gene clone libraries). To stimulate BSF bioremediation involving sulphate-reducing bacteria, a readily degradable carbon source (glucose, 8000 mg L⁻¹) was incorporated into the influent AMD. Complete neutralization and average removal efficiencies of 81.5 (±5.6)%, 95.8 (±1.2)% and 32.8 (±14.0)% for Fe(II), Fe(III) and sulphate were observed, respectively. Our results suggest that microbial iron reduction and sulphate reduction associated with iron precipitation were the main processes contributing to AMD neutralization. The effect of AMD on BSF sediment bacterial communities was highly reproducible. There was a decrease in diversity, and notably a single dominant operational taxonomic unit (OTU), closely related to Clostridium beijerinckii, which represented up to 65% of the total community at the end of the study period.
authors.affiliation: Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Bellville, South Africa; Centre for Microbial Ecology and Genomics (CMEG), Department of Genetics, University of Pretoria, Pretoria, South Africa.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Ramond
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Welz
authors.forename: Marilize
authors.initials: M
authors.lastname: Le Roes-Hill
authors.forename: Marla I
authors.initials: MI
authors.lastname: Tuffin
authors.forename: Stephanie G
authors.initials: SG
authors.lastname: Burton
authors.forename: Don A
authors.initials: DA
authors.lastname: Cowan
mesh_terms: D000143:Acids / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003013:Clostridium / Q000235:genetics / Q000302:isolation & purification*; D005290:Ferric Compounds / Q000378:metabolism; D005296:Ferrous Compounds / Q000378:metabolism; D005374:Filtration; D059013:Microbial Consortia; D008906:Mining; D010084:Oxidation-Reduction; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012822:Silicon Dioxide; D013431:Sulfates / Q000378:metabolism
chemical_list: D000143:Acids; D005290:Ferric Compounds; D005296:Ferrous Compounds; D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D012822:Silicon Dioxide
keywords: bacterial diversity; bioremediation; iron reduction; neutralization; sulphate reduction; unplanted constructed wetland