Mucilaginibacter sp. Strain Metal(loid) and Antibiotic Resistance Isolated from Estuarine Soil Contaminated Mine Tailing from the Fundão Dam

Abstract

In 2015 a mine dam with Mn-Fe-rich tailings collapsed releasing million tons of sediments over an estuary, in the Southwest of Brazil. The tailings have a high concentration of metals that contaminated soil until the present day. The high contaminant concentrations possibly caused a selection for microorganisms able to strive in such harsh conditions. Here, we isolated metal(loid) and anti-biotic resistance bacteria from the contaminated estuarine soil. After 16S rDNA sequencing to identify the strains, we selected the Mucilaginibacter sp. strain for a whole-genome sequence due to the bioprospective potential of the genus and the high resistance profile. We obtained a complete genome and a genome-guided characterization. Our finding suggests that the 21p strain is possibly a new species of the genus. The species presented genes for resistance for metals (i.e., As, Zn, Co, Cd, and Mn) beyond resistance and cross-resistance for antibiotics (i.e., quinolone, aminoglycoside, β-lactamase, sulphonamide, tetracycline). The Mucilaginibacter sp. 21p description as new species should be further explored, as their extracellular polymeric substances and the potential of this strain as bioremediation and as a growth promoter in high met-al(loid) contaminated soil.

Keywords: Bacteroidetes; EPS; SAMARCO disaster; genomic island; heavy metal.

Figure 1

Image of the Rio Doce estuary indicating the locations of sampling sites (S). Coordinate System. GCS WGS 1984 Datum: WGS 1984.

Figure 2

Phylogenetic positioning of the isolate Mucilaginibacter sp. 21p (highlighted in bold) based on the maximum likelihood phylogenomic tree based on 120 single-copy conserved amino acid sequences. GenBank Assembly accession code in parentheses. Percentages of bootstraps values above 50% are presented. Bar: 0.1 substitutions per position.

Figure 3

(A) Circular visualization of the genomes from Mucilaginibacter sp. 21p and the three closest strains according to the phylogenomic tree. Genomes are represented in each radial layer with the black bars representing clusters of genes. Environmental resistance genes present among clustered gene calls are indicated; (B) Circular visualization of the genomic island of Mucilaginibacter sp. 21p, GC content, and some resistance genes distributed in the genome.