Metabolic diversity and co-occurrence of multiple Ferrovum species at an acid mine drainage site

Christen L Grettenberger,Jeff R Havig,Trinity L Hamilton

doi:10.1186/s12866-020-01768-w

Christen L Grettenberger, Jeff R Havig + Show 1 more

Open Access

https://doi.org/10.1186/s12866-020-01768-w

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Abstract

BackgroundFerrovum spp. are abundant in acid mine drainage sites globally where they play an important role in biogeochemical cycling. All known taxa in this genus are Fe(II) oxidizers. Thus, co-occurring members of the genus could be competitors within the same environment. However, we found multiple, co-occurring Ferrovum spp. in Cabin Branch, an acid mine drainage site in the Daniel Boone National Forest, KY.ResultsHere we describe the distribution of Ferrovum spp. within the Cabin Branch communities and metagenome assembled genomes (MAGs) of two new Ferrovum spp. In contrast to previous studies, we recovered multiple 16S rRNA gene sequence variants suggesting the commonly used 97% cutoff may not be appropriate to differentiate Ferrovum spp. We also retrieved two nearly-complete Ferrovum spp. genomes from metagenomic data. The genomes of these taxa differ in several key ways relating to nutrient cycling, motility, and chemotaxis.ConclusionsPreviously reported Ferrovum genomes are also diverse with respect to these categories suggesting that the genus Ferrovum contains substantial metabolic diversity. This diversity likely explains how the members of this genus successfully co-occur in Cabin Branch and why Ferrovum spp. are abundant across geochemical gradients.

Highlights

Ferrovum spp. are abundant in acid mine drainage sites globally where they play an important role in biogeochemical cycling
In our previous studies of Cabin Branch, we reported the predominance of a single operational taxonomic unit (OTU; 97% similarity) in our 16S rRNA amplicon data most closely related to F. myxofaciens at this acid mine drainage (AMD) site in the Daniel Boone National Forest in southern Kentucky
Cation concentrations were highest at the emergence and nearby first outflow sites, and lowest at the Rose Pool, including calcium (1.20 to 0.39 mmol/L), magnesium

Summary

Introduction

Ferrovum spp. are abundant in acid mine drainage sites globally where they play an important role in biogeochemical cycling. Betaproteobacteria of the genus Ferrovum play important roles in biogeochemical cycling in AMD environments including carbon fixation and rapid oxidation of iron [4,5,6,7,8,9] and could be of value in bioremediation [10]. High-throughput sequencing and ‘omics techniques have aided in characterizing the metabolic potential of Ferrovum via non-culture-based techniques [15,16,17,18] across these large gradients of Fe and pH. These studies indicate that Ferrovum is a diverse genus composed of six clades (Groups I - VI) of closely related species and strains [18].

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