Microbial Population of Industrial Biooxidation Reactors

Abstract

Microbial population performing biooxidation of flotation concentrate of gold bearing sulfide ore containing pyrite, arsenopyrite, and pyrrhotite was studied using cultural and molecular biological (metagenomics sequencing of V3-V4 fragments of 16S rRNA gene) approaches. The biooxidation of the concentrate was conducted at temperatures from 38 to 42°C. Strains of Acidithiobacillus thiooxidans, Acidiphilium multivorum, Leptospirillum ferriphilum, Sulfobacillus thermotolerans, Ferroplasma acidarmanus, and Ferroplasma acidiphilum were isolated from the samples of the pulp from biooxidation reactors. It was shown that optimum temperatures of isolated strains were from 38 to 40°C. Metagenomic analysis demonstrated predominance of the genera Acidiferrobacter, Acidithiobacillus, Acidiphilum, Leptospirillum, and Ferroplasma. According to results of molecular biological analysis, share of the genus Acidithiobacillus was of 0 to 25%, share of the genus Acidiferrobacter was of 7 to 56%, share of the genus Acidiphilum was of 0.03 to 36%, share of the genus Leptospirillum was of 0.7 to 7%, whereas share of the archaea of the genus Ferroplasma was of 33 to 94%. Thus, it was shown that representatives of the genus Ferroplasma can play significant role in bioleach process. Representatives of the genus Acidiferrobacter were previously detected in acid mine drainages, acid soils as well as in bioleach heaps and reactors, whereas data on predominance of the genus in tank bioleach processes have not been presented in the literature. In the present study, strains of the genus Acidiferrobacter were not isolated despite application of the nutrient media recommended for Acidiferrobacter and their properties were not studied. Nevertheless, results of the present study suggest that representatives of the genus Acidiferrobacter have a great impact on industrial bioleach processes.

Distinct Roles of Acidophiles in Complete Oxidation of High-Sulfur Ferric Leach Product of Zinc Sulfide Concentrate

“…The growth of chemomixotrophic F. acidiphilum was favored by the supernatant of chemolithoautotrophic L. ferriphilum, containing additional sources of the organic carbon (EPS and lysed cells) and vice versa, probably due to detoxification of the medium from organic compounds by mixotrophic F. acidiphilum and extracellular proteins of its "secretome" [58]. The study of the microbial community dynamics in various industrial processes of tank or heap biooxidation showed the dominance of the Ferroplasmaceae family members [59][60][61]. According to the results of our study, F. acidiphilum played a crucial role in the oxidation of sulfide minerals of the leach residue of the zinc concentrate by the mixture of microbial cultures.…”

Unraveling the Central Role of Sulfur-Oxidizing Acidiphilium multivorum LMS in Industrial Bioprocessing of Gold-Bearing Sulfide Concentrates

“…The object of this research was an acidophilic bacterial strain isolated as a predominant sulfur oxidizer from a bioreactor during the processing of the gold-containing sulfidic concentrate at 38 °C [ 15 ]. Biotechnologies for tank biooxidation of sulfidic concentrates using sulfur- and iron-oxidizing acidophilic microorganisms were developed in the 1980s.…”

“…spp., Leptospirillum ( L. ) spp., Sulfobacillus ( Sb. ) spp., Ferroplasma ( F. ) spp., and some other microorganisms [ 15 , 17 , 18 , 19 , 20 , 21 , 22 ]. The Olympiada biooxidation plant is located in the Krasnoyarsk Krai (Siberia, Russia) and has been operated by Polyus Krasnoyarsk JSC since 2001.…”

“…The Olympiada biooxidation plant is located in the Krasnoyarsk Krai (Siberia, Russia) and has been operated by Polyus Krasnoyarsk JSC since 2001. It is one of the largest biooxidation factories in the world that processes from 8 to 9 million tons of gold-bearing ore annually using a high-performance BIONORD® technology developed under the conditions of Extreme North (Siberia, Russia) [ 15 , 20 ]. The average productivity of the Olimpiada plant is 1200–1300 tons of the flotation sulfidic concentrate per day, which allowed the recovery of 30 tons of gold in 2017 [ 20 ].…”

Understanding Stress Response to High-Arsenic Gold-Bearing Sulfide Concentrate in Extremely Metal-Resistant Acidophile Sulfobacillus thermotolerans

“…Sb. thermotolerans is continuously identified as the predominant bacterium in the biomining microbial communities during laboratory-scale and industrial processes of bioleaching/biooxidation of refractory gold ores [ 6 , 11 , 12 , 13 ]. This thermotolerant species possesses a versatile metabolism, which provides for its functioning under fluctuating conditions of natural environments and technological processes (changes in pH and temperature, pulp density, concentrations of heavy metals and metalloids, as well as the availability of energy substrates and oxygen or other electron acceptors to cells) [ 8 , 14 , 15 , 16 ].…”