Bioleaching/ Bacterial Leaching

Due to its impressive appearance, Inca masonry, which mostly consists of volcanic, silica containing rock material, has received much attention. A high level of understanding has consequently been reached of the diverse working steps and tools applied. An exception is the reddish mud, “llancac alpa” in the quechua language, and the “gold”, mentioned by early chroniclers as mortar which fitted the stones and later disappeared. Such techniques were related to folklore and not taken seriously. This study tries to understand them and the question was asked: did Inca builders have access to very acid mud? They did, and used the acid mud from their mines, which generated sulphuric acid through bacterial oxidation of pyrite (fools gold). It reaches an acidity of up to pH = 0.5, which is 104 times more acid than humic acid which is known to weather silica containing rocks via silica gel to the clay mineral kaolin. This acid mud allowed dissolving and softening the rock material superficially to a viscoelastic silica gel. The process could be further enhanced more than tenfold by addition of (oxalic acid containing) plant sap, a skill suggested from popular tradition. In special cases moderate heating of crushed pyrite in gaps between chiselled stones generated additional hot sulphuric acid. Where the stone to stone contact transmitted weight, pressure dissolution in the acidic environment removed material, and silica precipitation regenerated material in cracks and pores elsewhere. It is attempted to reconstruct how the Inca builders applied the silica gel technology for shaping stones, for polishing and fitting them. The appearance of shiny and glassy Inca stone junctions and interfaces is explained via solidification of in-situ generated or additionally added silica gel. Modern processes for conservation of stone monuments against environmental deterioration have independently developed similar silica gel based technology.

Key words: Inca masonry; surface treatment; silicate dissolution; acid mine water; bacterial leaching; stone restoration; pyrite

(guilherme.rocha@ug.uchile.cl), Sebastián Zapata (s ebastian.zapata.e@ug.uchile.cl) Ingeniería en Biotecnología Molecular. Curso de Fisicoquímica Macromolecular 2020. Profesor Octavio Monasterio O. RESUMEN El género Acidithiobacillus comprende varias especies de bacterias acidófilas Gram-negativas que prosperan en pH bajo natural y artificial alrededor de una variedad de contextos geo-climáticos. Estas bacterias se aplican en todo el mundo en la industria de la biominería para extraer metales de minerales sulfurados a partir de la obtención energética de la oxidación de hacia la generación de para la disolución de minerales e F 2+ e F 3+ sulfurados. Sin embargo, los mecanismos moleculares de su oxidación férrica siguen siendo indefinidos. Por lo tanto, se consideran un grupo de bacterias biotecnológicamente relevantes, y su identificación y detección en entornos naturales e industriales es de gran preocupación. Su adhesión asociada a minerales, la formación de biopelículas es un paso crítico para la colonización y posterior solubilización de minerales, estructuras de la superficie celular como los pili, que juegan un papel crítico en la autoagregación de células microbianas involucradas en procesos biogeoquímicos. Las proteínas de membrana tienen un rol importante en la cadena de transferencia de electrones de hierro, en la oxidación de azufre, en la formación de biopelículas como también en los procesos catabólicos y anabólicos de la membrana celular. Un análisis bioinformático ha demostrado que el género Acidithiobacillus se divide en cuatro grupos monofiléticos y poseen cuatro vías diferentes para la oxidación de hierro, además de un grupo de genes llamados tce que codifican citocromos responsables por la oxidación del hierro, sin embargo, algunas funciones y estructuras de ciertos tipos de citocromos y su participación en la oxidación de hierro es aún inconclusiva. OBJETIVO El objetivo de este de este trabajo bibliográfico es reunir investigaciones de un periodo de 10 a 20 años respecto a los avances del estudio de la bacteria Acidithiobacillus ferrooxidans , la meta es analizar el estado del arte de esta bacteria como también sus estudios específicos, respectivamente al estudio de genoma, proteínas de membranas y enzimas utilizando diferentes métodos de estudios como modelos bioinformáticos. El interés de estudiar la A. Ferrooxidans es debido a que esta es una bacteria de interés industrial y biotecnológico en el uso de la minería, ya que dentro de sus procesos fisiológicos esta bacteria es capaz de reducir metales oxidados mediante reacciones de oxidorreducción logrando así, que compuestos metálicos que estaban unidos a agentes oxidantes, como oxígeno o azufre, queden disueltos en una solución. Estos al ser disueltos en la solución facilita su extracción debido a que no es necesario pasar por un proceso de fundición, sino que mediante procesos hidrometalúrgicos y de electrólisis se puede obtener el cobre refinado.

The main objective of this project is to Biodeslphurize the coal using of Acidi
Thiobacillus ferroxidans. sulphur removing bacteria and the specific objectives are,to isolate
“Acidi Thiobacillus ferroxidans “from Assam Coal Mine samples. To attempt Bio
desulfurization process of Lignite Coal in Bubble column reactor .To analyse level of
sulphate concentration during biodesulphurization process. To characterize coal samples by
XRD and SEM/EDS for confirming sulphur removal. Sulphur removing bacteria with high
biodesulphurization ability were identified. . This bacterium removed 77% of the sulphur in
bubble coulm reactor. The SEM-EDS and XRD methods identified the mineral matter and
directly quantified the sulphur in the coal matrix. The SEM micrograph was shown high
luminous and less darkness. This indicates the removal of sulphur in biodesulphurized coal.
The EDS results gave the negative value of sulphur, -21.13 wt%. This indicates the absence
of sulphur in the biodesulphurized coal.

The extraction of precious metals, such as nickel (Ni) and cobalt (Co), from a low-grade nickel laterite ore supplied from the Çaldag deposits in Manisa, Turkey has been investigated by employing pure and mixed cultures of mesophilic acidophiles (Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans and Acidithiobacillus thiooxidans). The study examines the effects of parameters such as the pulp density, the amount of externally added elemental sulphur and ferrous iron, and pure and mixed bacterial cultures on the bioleaching of the lateritic ore. The increase in the pulp density adversely influenced the leaching activity of the pure and mixed cultures. Mixed culture (At. ferrooxidans and At. thiooxidans) displayed a better performance than pure cultures on the extraction of nickel and cobalt from the ore. The maximum dissolution of Ni and Co after 40 days was found to be 97% and 95%, respectively, by a bioleaching process that contained 7% (w/v) elemental sulphur, 2.24 g/L of ferrous iron, 1% (w/v) solids and the mixed culture.

Out of 81 isolated bacteria from salt pan of CSIR-CSMCRI's experimental salt farm with salinity range from 10 to 24 Be′, one of the promising bacterial strain identified as Acinetobacter soli showed potassium solubilizing potential of 66-68% (w/w) w.r.t. cell dry weight. It was further optimized with cost effective carbon source for K release in the broth itself which was 10.67% of K (with respect to the K-feldspar present in the broth) utilizing sugarcane baggase hydrolysate with production age of 120 h.

A partir del año 2006,  la  Direcciòn de Desarrollo Urbano y Ecologìa y la Direcciòn de Salud Municipal ha recibido mùltiples informes sobre lixiviados (derrames y efluentes) del relleno sanitario de la ciudad de Chetumal, asì como de potencialmente peligrosas filtraciones de éstos hacia el manto freático, al complejo lagunar y de escurrimientos del Santuario del Manatí Bahìa de Chetumal y  a las redes de agua potable de la ciudad capital de Chetumal.  A encontrar soluciones tecnológicamente factibles de la recolecta y  aprovechamiento integral de estos lixiviados, transformàndolos en productos econòmicamente redituables y cuya producción tenga un impacto social positivo, es que se orienta la presente propuesta.

In a circular economy concept, where more than 300 million tons of mining and quarrying wastes are produced annually, those are valuable resources, supplying metals that are extracted today by other processes, if innovative methods and processes for efficient extraction of these elements are applied. This work aims to assess microbiological and chemical spatial distribution within two tailing basins from a tungsten mine, using a MiSeq approach targeting the 16S rRNA gene, to relate microbial composition and function with chemical variability, thus, providing information to enhance the efficiency of the exploitation of these secondary sources. The tailings sediments core microbiome comprised members of family Anaerolineacea and genera Acinetobacter, Bacillus, Cellulomonas, Pseudomonas, Streptococcus and Rothia, despite marked differences in tailings physicochemical properties. The higher contents of Al and K shaped the community of Basin 1, while AsS -Fe contents were correlated with the microbiome composition of Basin 2. The predicted metabolic functions of the microbiome were rich in genes related to metabolism pathways and environmental information processing pathways. An in-depth understanding of the tailings microbiome and its metabolic capabilities can provide a direction for the management of tailings disposal sites and maximize their potential as secondary resources.