High Manganese Tolerance and Biooxidation Ability of Serratia marcescens Isolated from Manganese Mine Water in Minas Gerais, Brazil

Abstract

Manganese is an important metal for the maintenance of several biological functions, but it can be toxic in high concentrations. One of the main forms of human exposure to metals, such as manganese (Mn), is the consumption of solar salt contaminated. Mn-tolerant bacteria could be used to decrease the concentration of this metal from contaminated sites through safer environmental-friendly alternative technology in the future. Therefore, this study was undertaken to isolate and identify Mn resistant bacteria from water samples collected from a Mn mine in the Iron Quadrangle region (Minas Gerais, Brazil). Two bacterial isolates were identified as Serratia marcescens based on morphological, biochemical, 16S rDNA gene sequencing and phylogeny analysis. Maximum resistance of the selected isolates against increasing concentrations of Mn(II), up to 1200 mg L-1 was determined in solid media. A batch assay was developed to analyze and quantify the Mn removal capacities of the isolates. Biological Mn removal capacities of over 55% were detected for both isolates. Whereas that mechanism like biosorption, precipitation and oxidation could be explaining the Mn removal, we seek to give an insight into some of the molecular mechanisms adopted by S. marcescens isolates. For this purpose, the following approaches were adopted: leucoberbelin blue I assay, Mn(II) oxidation by cell-free filtrate and electron microscopy and energy-dispersive X-ray spectroscopy analyses. Overall, these results indicate that S. marcescens promotes Mn removal in an indirect mechanism by the formation of Mn oxides precipitates around the cells, which should be further explored for potential biotechnological applications for water recycling both in hydrometallurgical and mineral processing operations.

Biosorption Characteristics of Mn (II) by Bacillus cereus Strain HM-5 Isolated from Soil Contaminated by Manganese Ore

“…Bacillus sp. SG-1, Pseudomonas putida strains MnB1 and GB-1, and Leptothrix discophora strains SS-1 and SP-6 are examples of bacteria that have been extensively studied [50]. Bacillus sp.…”

Alterations in the proteomic composition of Serratia marcescens in response to manganese (II)

“…The analysis allowed us a better physiological understanding of the tolerance and oxidation of Mn by the LG1 strain of this species. Serratia species isolated from different environments exhibit the ability to remove heavy metals and radioactive elements, both by enzymatic pathways and indirect mechanisms such as biosorption [8, 13, 17–21]. As expected, the Mn (II) - resistant LG1 strain showed a good Mn (II) removal rate even during the short period of growth observed, and was able to produce oxidized species of Mn, confirming its potential for bio-oxidation of this heavy metal.…”

“…Serratia marcescens strains can tolerate and remove high concentrations of Mn (II) [8]. However, its proteomic profile in response to this metal remains to be elucidated.…”

Impact of Different Trace Elements on the Growth and Proteome of Two Strains of Granulicella, Class “Acidobacteriia”

“…WH15 and 5B5 only showed tolerance to Mn, exhibiting growth at the concentration of 40 mM Mn, which is higher than typically observed for most bacterial strains. For instance, a resistant Serratia marcescens strain, isolated from Mn mine waters in Brazil, could grow on a maximum concentration of 6 mM Mn (Barboza et al, 2017). Mn tolerance can vary widely in microorganisms, with a minimal inhibitory concentration ranging from 0.1 to 228.9 mM Mn in certain marine bacterial strains (Gillard et al, 2019).…”