URL: http://eemj.eu/index.php/EEMJ/article/view/3554

URL: https://www.mdpi.com/2075-163X/9/2/69

DOI: https://doi.org/10.3390/min9020069

Description: Bioleaching of metal sulfides is an interfacial process where adhesion and subsequent biofilm formation are considered to be crucial for this process. In this study, adhesion and biofilm formation by several acidophiles (Acidithiobacillus, Leptospirillum and Sulfobacillus) isolated from different biotopes with sulfide ores in Armenia were studied. Results showed that: (1) these bacteria adhere to pyrite surfaces to various extents. A correlation between pyrite biooxidation and adhesion of S. thermosulfidooxidans 6, L. ferriphilum CC, L. ferrooxidans ZC on pyrite surfaces is shown. It is supposed that bioleaching of pyrite by S. thermosulfidooxidans 6, L. ferriphilum CC, L. ferrooxidans ZC occurs by means of indirect leaching: by ferric iron of bacterial origin; (2) cells of At. ferrooxidans 61, L. ferrooxidans ZC and St. thermosulfidooxidans 6 form a monolayer biofilm on pyrite surfaces. The coverage of pyrite surfaces varies among these species. The order of the biofilm coverage is: L. ferrooxidans ZC ≥ At. ferrooxidans 61 > St. thermosulfidooxidans 6; (3) the extracellular polymeric substances (EPS) analysis indicates that the tested strains produce EPS, if grown either on soluble ferrous iron or solid pyrite. EPS are mainly composed of proteins and carbohydrates. Cells excrete higher amounts of capsular EPS than of colloidal EPS. In addition, cells grown on pyrite produce more EPS than ones grown on ferrous iron.
Keywords: adhesion; biofilm; extracellular polymeric substances (EPS); atomic force microscopy (AFM); epifluorescence microscopy (EFM)

Description: In the paper kinetics of ferrous iron oxidation by isolated Leptospirillum
ferriphilum CC was studied in conical flasks on rotary shaker. The effect of initial
ferrous iron concentration on bacterial growth and substrate oxidation was studied in the
concentration range of 50-400 mM FeSO4 x7H2O. The highest specific growth (0.41-
0.48 h1) and Fe2+ oxidation rates (6.0-6.2 mM/l h) were detected at ferrous ion
concentrations of 100-200 mM. At higher concentrations, the growth of bacteria and
Fe2+ oxidation suppression was observed, reaching maximum values at 400 mM Fe2+
.
The maximum specific growth rate (µmax) of bacteria and half saturation constant (Ks)
determined using Monod equation were 6.2mM /h, and 0.83h-1, respectively. It was
shown that Fe2+ oxidation competitively inhibited by Fe3+ and the inhibition constant
(Ki) was 61.95 mM. The comparison of kinetic parameters obtained for L. ferriphilum
with other bacteria indicates the high potential of L.ferriphilum CC in leaching processes
of ores and concentrates for biogenic regeneration of concentrated ferric iron.

Description: The treatment of low-grade ores which is considered as an important source of non-ferrous
and precious metals requires the development of high-efficient technologies for metal extraction
ensuring low impact on environment. The goal of the present work was to study the possibilities of
application of biohydrometallurgical approach for the processing of Kajaran low-grade coppermolybdenum ore. Sulfide and oxidized ore samples containing 0.63 and 0.77 % of copper, 1.81
and 1.55 % of iron and 0.14 and 0.023 % of molybdenum, respectively were used. The
experiments were carried out in 250 ml flasks under shaking conditions as well as glass columns.
Indigenous and adapted bacterial consortia “Kajaran” and “Kavart” were used for bioleaching of
ore samples. The influence of particle size (PS), pulp density (PD), adaptation of culture on the
process of copper extraction was studied

URL: https://www.mdpi.com/2075-4701/11/3/425

DOI: https://doi.org/10.3390/met11030425

Description: The aim of this study is to investigate the potential of newly isolated strain Leptospirillum (L.) ferriphilum CC for bioleaching of pyrite and chalcopyrite in pure or mixed culture with other iron- and/or sulfur-oxidizing bacteria. In this paper, kinetics of ferrous iron (Fe2+) oxidation by newly isolated strain Leptospirillum (L.) ferriphilum CC was studied. The effect of initial Fe2+ in the concentration range of 50–400 mM on bacterial growth and iron oxidation was studied. It was shown that microbial Fe2+ oxidation was competitively inhibited by Fe3+. The influence of copper, zinc, nickel and cobalt ions on the oxidation of Fe2+ by L. ferriphilum CC was also studied. Minimal inhibitory concentrations (MIC) for each metal ion were determined. The toxicity of the ions was found to be as follows: Co > Zn > Ni > Cu. The comparison of iron oxidation kinetic parameters of L. ferriphilum CC with other strains of L. ferriphilum indicates the high potential of strain L. ferriphilum CC for biogenic regeneration of concentrated ferric iron (Fe3+) in bioleaching processes of ores and ore concentrates. Bioleaching tests indicated that the newly isolated L. ferriphilum CC can be a prospective strain for the bioleaching of sulfide minerals in pure culture or in association with other iron- and/or sulfur-oxidizing bacteria.
Keywords: leptospirillum ferriphilum; iron-oxidizing kinetics; specific grow rate; saturation constant; tolerance to metal ions

URL: https://www.tandfonline.com/doi/full/10.1080/01490451.2022.2060385

DOI: https://doi.org/10.1080/01490451.2022.2060385

Description: The treatment of porphyry copper ores which are considered an important source of non-ferrous
and precious metals requires the development of high-efficient technologies for metal extraction
ensuring a low impact on the environment. The goal of the present work was to study the feasibility of a biohydrometallurgical approach for the processing of Kajaran porphyry coppermolybdenum ore as no attempt was done previously for microbiological processing of the
mentioned ore. Sulfide and oxide ore samples used for bioleaching tests contained 0.63 and
0.77% copper, 1.81 and 1.55% iron, and 0.14 and 0.023% molybdenum, respectively. The experiments were carried out in 250 ml flasks under shaking conditions. Indigenous and adapted bacterial consortia ‘Kashen’ and ‘Kavart’ were used for bioleaching of ore samples. The objectives of the
study were to investigate the influence of particle size (PS), pulp density (PD), and adaptation of
the bacterial cultures to the process of copper extraction. The composition of feed material and
leaching residues from bioleaching experiments were characterized by geochemical, mineralogical,
and particle analyses. As a result, nearly complete bioleaching of the sulfide and oxide ores could
be achieved after the optimization of the experiments. The particle analyses showed an enhanced
liberation of chalcopyrite particles out of the intergrown ore under bioleaching conditions
compared to the abiotic controls and hence an improved Cu solubilization under bioleaching conditions.

URL: https://www.mdpi.com/2075-163X/13/2/243

DOI: https://doi.org/10.3390/min13020243

Description: A strain of Leptospirillum sp. CC previously isolated from Akhtala polymetallic ore (Armenia) was studied. The main morphological and physiological characteristics of CC were revealed. The optimal growth temperature was 40 °C and optimal pH 1.5. A phylogenetic analysis based on 16S rRNA gene sequences (GenBank ID OM272948) showed that isolate CC was clustered with L. ferriphilum and possessed 99.8% sequence similarity with the strain L. ferriphilum OL12-2 (KF356024). The molar fraction of DNA (G + C) of the isolate was 58.5%. Bioleaching experiment indicates that L. ferriphilum CC can oxidize Fe(II) efficiently, and after 17 days, 44.1% of copper and 91.4% of iron are extracted from chalcopyrite and pyrite, respectively. The efficiency of L. ferriphilum CC in pyrite oxidation increases 1.7 times when co-cultivated with At. ferrooxidans ZnC. However, the highest activity in pyrite oxidation shows the association of L.ferriphilum CC with heterotrophic Acidocella sp. RBA bacteria. It was shown that bioleaching of copper and iron from chalcopyrite by association of L. ferriphilum CC, At. ferrooxidans ZnC, and At. albertensis SO-2 in comparison with pure culture L. ferriphilum CC for 21 days increased about 1.2 and 1.4–1.6 times, respectively.

Description: Материалы 5-ого Всероссийский симпозиум с международным участием"
Автотрофные микрорганизмы"-М.,МАКС

ISBN 978-5-317-051419

Description: Международной научно-практической конференции «Микробное
биоразнообразие: актуальные проблемы и решения», посвященной 25-летию
Независимости Республики Казахстан, Астана, 2016

Description: Международной научно-практической
конференции «Микробное биоразнообразие: актуальные проблемы и решения»,
посвященной 25-летию Независимости Республики Казахстан, Астана, 2016

Description: Book of Abstracts, IV International Scientific
Conference of Young Researches, Biotechnology: Science and Practice, September 28-30,
2017, Yerevan, Armenia,

Description: Book of Abstracts, IV International Scientific Conference of Young Researches,
Biotechnology: Science and Practice, September 28-30, 2017, Yerevan, Armenia

Description: 23rd International Biohydrometallurgy Symposium, IBS 2019 Fukuoka, Japan, 20-23 October
ISBN 978-9939-1-1010-3

Description: Book of Abstracts. International Conference “MICROBES: Biology & Application”
October 9-11, 2019, Yerevan, Armenia
ISBN 978-9939-1-1010-3

Description: Book of Abstracts.
International Conference “MICROBES: Biology & Application”, October 9-11, 2019,
Yerevan, Armenia, ISBN 978-9939-1-1010-3.

Description: FEMS Online Conference on Microbiology//, 28-31 October 2020, Belgrade, Serbia., Electronic
Abstract Book

URL: http://biotechnology-spib2021.com

Description: International Scientific and Practical Conference
“Biotechnology: Science and Practice, Innovation and Business” dedicated to the 10th
Anniversary of the SPC “Armbiotechnology” NAS RA, October 20-22, 2021, Yerevan,
Armenia, Articles Part II, ISBN 978-9939-1-1354-8.

Description: 24th International Biohydrometallurgy Symposium (IBS)
2022 | Perth, Australia & online | 20-23 November 2022

Description: Low-grade copper ores are nowadays a primary source
of Cu and remain one of the main targets for the world
mineral industry. The objective of this work was to study
the recovery of copper from low-grade sulfide and oxide
ore samples of Kajaran Mine in Armenia. It was shown that
the extent of copper extraction depends on pulp density and
the ratio of sulfide and oxide ore samples in the pulp. The
optimal ratio of sulfide and oxide ores in the pulp was
revealed ensuring enhanced copper extraction.