Neutrophilic Microbial Community with High Rate of Elemental Sulfur Oxidation

Abstract

Using molecular genetic methods, 10 species wereidentified in the community of neutrophilic microorganisms isolated from thebioreactor during the process of biooxidation of gold-arsenicpyrrhotite-bearing sulfide ore flotation concentrate. The microbial communitywas composed of chemolithotrophs oxidizing elemental sulfur and its reducedcompounds and chemoorganotrophs. The predominant S0-oxidizingchemolithotrophic strain and 3 strains of chemoorganotrophs were isolated inpure cultures. Phylogenetic identification of the pure cultures revealed thechemolithotrophic microorganism to belong to Thermithiobacillus tepidarius,while organotrophic microorganisms were identified as Parapedobacter sp.,Nocardioides nitrophenolicus, and Nocardioides sp. Themorphological and physiological characteristics of Thermithiobacillustepidarius and Nocardioides nitrophenolicus, the culturespredominant in the community of neutrophilic microorganisms, were studied.Active growth of T. tepidarius occurs within a temperature range of38–48°C at the optimal pH value of 7.0–7.5. The maximal specific growth rate ofT. tepidarius on sulfur and on solid residue which remains after theprocess of bioleaching/biooxidation of sulfide ore flotation concentrate (biooxidationresidue) was 0.13 and 0.135 h-1, respectively. The average maximalrate of S0 oxidation in the biooxidation residue was 0.107 g S0oxidizedper g S0initial h-1. The ability of Nocardioidesnitrophenolicus to destruct thiocyanate was shown.

Toward Sustainable Solution for Biooxidation of Waste and Refractory Materials Using Neutrophilic and Alkaliphilic Microorganisms—A Review

“…Parapedobacter species grow between pH 6.0 and 9.0, 15–45 °C, and up to 0.86 M Na + . Their ability to oxidize reduced sulfur compounds is unknown; however, it was observed in the neutrophilic community where it was isolated from the sulfide flotation concentrate bioreactor and the oxidation of the biocake. , …”

“…Thermithiobacillus tepidarius (formerly known as Thiobacillus tepidarius ) is a moderate thermophile, obligate aerobe that utilizes the oxidation of sulphide, sulfur, thiosulfate, tri-, tetra-, hexa-, and hepta-thionate for growth . Growth was observed from 35 to 52 °C (optimum at 43 °C) and pH 5.5–8.0 (optimum at pH 7.0–7.5). − Furthermore, it fixes carbon dioxide via the CBB cycle, and the salinity requirements are not known.…”

“…84 A species in the genus Nocardioides was observed in elemental sulfur oxidation tests. 76 The bacterium was associated with a neutrophilic community isolated from a gold−arsenic pyrrhotite-bearing sulfide ore flotation concentrate bioreactor operating at pH 7.5 and 38 °C to oxidize elemental sulfur. Belyi et al 73 used these microorganisms and tested their oxidation capabilities on elemental sulfur and antimony sulfide.…”

“…68 Their ability to oxidize reduced sulfur compounds is unknown; however, it was observed in the neutrophilic community where it was isolated from the sulfide flotation concentrate bioreactor and the oxidation of the biocake. 11,76 Rhodobacter Species. The Rhodobacter genus consists of mesophilic bacteria that are facultative photoheterotrophs and halophiles, isolated from marine environments, estuarine, and freshwater ponds.…”

Biodegradation of Thiocyanate and Cyanide in CIL Leaching Waste’s Liquid Phase

“…However, all of them are either expensive or produce not less environmentally hazardous compounds, and they are not effective enough to destruct thiocyanates. In this regard biological methods of cyanides and thiocyanates destruction in gold recovery plants tailings are attractive [1,2]. In this paper data are presented from laboratory researches (conducted in 2,2 m 3 tanks) on cyanides and thiocyanates biological degradation in Olimpiada gold recovery plant tailings.…”