title: Organoheterotrophic Bacterial Abundance Associates with Zinc Removal in Lignocellulose-Based Sulfate-Reducing Systems.
abstract: Syntrophic relationships between fermentative and sulfate-reducing bacteria are essential to lignocellulose-based systems applied to the passive remediation of mining-influenced waters. In this study, seven pilot-scale sulfate-reducing bioreactor columns containing varying ratios of alfalfa hay, pine woodchips, and sawdust were analyzed over ∼500 days to investigate the influence of substrate composition on zinc removal and microbial community structure. Columns amended with >10% alfalfa removed significantly more sulfate and zinc than did wood-based columns. Enumeration of sulfate reducers by functional signatures (dsrA) and their putative identification from 16S rRNA genes did not reveal significant correlations with zinc removal, suggesting limitations in this directed approach. In contrast, a strong indicator of zinc removal was discerned in comparing the relative abundance of core microorganisms shared by all reactors (>80% of total community), many of which had little direct involvement in metal or sulfate respiration. The relative abundance of Desulfosporosinus, the dominant putative sulfate reducer within these reactors, correlated to representatives of this core microbiome. A subset of these clades, including Treponema, Weissella, and Anaerolinea, was associated with alfalfa and zinc removal, and the inverse was found for a second subset whose abundance was associated with wood-based columns, including Ruminococcus, Dysgonomonas, and Azospira. The construction of a putative metabolic flowchart delineated syntrophic interactions supporting sulfate reduction and suggests that the production of and competition for secondary fermentation byproducts, such as lactate scavenging, influence bacterial community composition and reactor efficacy.
authors.affiliation: Department of Civil and Environmental Engineering, Colorado School of Mines , 1500 Illinois Street, Golden, Colorado 80401, United States.
authors.forename: Dina M
authors.initials: DM
authors.lastname: Drennan
authors.affiliation: Department of Civil and Environmental Engineering, Colorado School of Mines , 1500 Illinois Street, Golden, Colorado 80401, United States.
authors.forename: Robert
authors.initials: R
authors.lastname: Almstrand
authors.affiliation: Freeport McMoRan Inc. 1600 Hanley Blvd., Oro Valley, Arizona 85737, United States.
authors.forename: Ilsu
authors.initials: I
authors.lastname: Lee
authors.affiliation: Department of Civil and Environmental Engineering, Colorado School of Mines , 1500 Illinois Street, Golden, Colorado 80401, United States.
authors.forename: Lee
authors.initials: L
authors.lastname: Landkamer
authors.affiliation: Department of Civil and Environmental Engineering, Colorado School of Mines , 1500 Illinois Street, Golden, Colorado 80401, United States.
authors.forename: Linda
authors.initials: L
authors.lastname: Figueroa
authors.affiliation: Department of Civil and Environmental Engineering, Colorado School of Mines , 1500 Illinois Street, Golden, Colorado 80401, United States.
authors.forename: Jonathan O
authors.initials: JO
authors.lastname: Sharp
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D003901:Desulfovibrio / Q000378:metabolism*; D008031:Lignin / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D013431:Sulfates / Q000737:chemistry / Q000378:metabolism; D015032:Zinc / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D013431:Sulfates; C036909:lignocellulose; D008031:Lignin; D015032:Zinc