GENOMIC ANALYSES OF NOVEL IRON-OXIDIZING THIOMONAS ISOLATES FROM ACID MINE DRAINAGE
Date
2019-05
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Publisher
University of Delaware
Abstract
Certain acid mine drainage (AMD)-derived microorganisms can sequester and detoxify metals, which could be useful for bioremediation if we can determine the mechanisms and controls. Here we describe the isolation, physiological characterization, and genomic analysis of two new species, Thiomonas ferrovorans FB-6 and Thiomonas metallidurans FB-Cd, isolated from Fe-rich AMD sediment in Ronneburg, Germany. While Thiomonas spp. are known as mixotrophic sulfur-oxidizers and As-oxidizers, the FB strains could oxidize Fe, which would allow them to efficiently remove Fe and other metals via co-precipitation. However, Thiomonas Fe oxidation physiology and mechanisms are not well-established. Therefore, we conducted a genomic analysis to investigate their genetic mechanisms of Fe oxidation, other metal transformations, and additional adaptations, comparing the two FB strains with 12 other isolates. The FB strains fall within a relatively novel group of Thiomonas (Group II), which includes the one other strain (b6) with evidence of Fe oxidation. Most Thiomonas isolates, including the FB strains, have the putative iron oxidation gene cyc2, but only the FB strains possess the putative Fe oxidase genes mtoAB. The FB strain genomes contain the highest numbers of strain-specific gene clusters, greatly increasing the known Thiomonas genetic potential. Our results reveal that the FB strains are two distinct novel species of Thiomonas, with the genetic potential for bioremediation of AMD via iron oxidation.
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Keywords
Iron-oxidizing, Thiomonas isolates, Acid mine drainage