Bioflotation of sulfide minerals with Acidithiobacillus ferrooxidans in relation to copper activation and surface oxidation

2012 ◽  
Vol 58 (9) ◽  
pp. 1073-1083 ◽  
Author(s):  
E.T. Pecina-Treviño ◽  
G.T. Ramos-Escobedo ◽  
P.M. Gallegos-Acevedo ◽  
F.J. López-Saucedo ◽  
E. Orrantia-Borunda
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Elemental Sulfur ◽  
Surface Oxidation ◽  
Surface Characteristics ◽  
Growth Media ◽  
Bacterial Cells ◽  
Sulfur Concentration ◽  
Key Factors ◽  
Culture Cells

Surface oxidation of sulfides and copper (Cu) activation are 2 of the main processes that determine the efficiency of flotation. The present study was developed with the intention to ascertain the role of the phenomena in the biomodification of sulfides by Acidithiobacillus ferrooxidans culture (cells and growth media) and their impact in bioflotation. Surface characteristics of chalcopyrite, sphalerite, and pyrrhotite, alone and in mixtures, after interaction with A. ferrooxidans were evaluated. Chalcopyrite floatability was increased substantially by biomodification, while bacteria depressed pyrrhotite floatability, favoring separation. The results showed that elemental sulfur concentration increased because of the oxidation generated by bacterial cells, the effect is intensified by the Fe(III) left in the culture and by galvanic contact. Acidithiobacillus ferrooxidans culture affects the Cu activation of sphalerite. The implications of elemental sulfur concentration and Cu activation of sphalerite are key factors that must be considered for the future development of sulfide bioflotation processes, since the depressive effect of cells could be counteracted by elemental sulfur generation.

scholarly journals Relationship between Surface Characteristics and Floatability in Representative Sulfide Minerals: Role of Surface Oxidation

2017 ◽  
Vol 58 (7) ◽  
pp. 1069-1075 ◽  
Author(s):  
Gilsang Hong ◽  
Junhyun Choi ◽  
Yosep Han ◽  
Kwang-Suk Yoo ◽  
Kwanho Kim ◽  
...  
Keyword(s):  
Surface Oxidation ◽  
Surface Characteristics ◽  
Sulfide Minerals

Influence of Growth Substrate and Attachment Substratum on EPS and Biofilm Formation by Acidithiobacillus ferrooxidans

2007 ◽  
Vol 20-21 ◽  
pp. 385-385 ◽  
Author(s):  
Kerstin Harneit ◽  
Wolfgang Sand
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Biofilm Formation ◽  
Extracellular Polymeric Substances ◽  
Elemental Sulfur ◽  
Precious Metals ◽  
Solid Substrate ◽  
Specific Substrate ◽  
Growth Substrate ◽  
Culture Cells ◽  
Sessile Cells

Extracellular polymeric substances (EPS) of Acidithiobacillus ferrooxidans and other leaching microorganisms mediate the attachment of cells to pyrite and other minerals. They also play a pivotal role in indirect leaching of base and precious metals via the contact mechanism. The aim of this study is to get more insight on the influence of the growth substrates iron(II) ions, pyrite, chalcopyrite and elemental sulfur on EPS formation, attachment and biofilm formation. The synthesis of EPS by cells of A. ferrooxidans strain A2 is strongely influenced by the growth substrate or attachment substratum of the cells. Cells grown with soluble iron(II) ions generally generate less EPS than cells grown with solid pyrite, chalcopyrite or elemental sulfur. Planktonic cells grown in the presence of solid substrate produce two to four times more EPS than iron(II) ion grown cells. With sessile cells, this factor is further increased to 50 to 240 depending on the specific substrate. The EPS of all the differently grown planktonic and sessile cells of A. ferrooxidans strain A2 contained neutral sugars, fatty acids, uronic acids, proteins and metal ions. The composition of these compounds varied with the growth substrate and type (planktonic or sessile). The attachment behavior of cells of A. ferrooxidans strain A2 also differed with the substrate of the pre-culture. Cells grown on iron(II) ions, pyrite or chalcopyrite attached rapidly to pyrite and chalcopyrite, while attachment to elemental sulfur was poor. On the contrary, sulfur grown cells attached well to elemental sulfur but weakly to pyrite and chalcopyrite. Attachment of EPS-free cells to all substrates was also diminished. Cells of A. ferrooxidans strain A2 cover mineral surfaces with a dense biofilm after a few days of cultivation, as visualized by fluorescence microscopy and AFM. Large amounts of EPS are formed, which eventually cover the cells and the mineral surface. Even after a few weeks of cultivation the biofilm remained monolayered on all substrates.

PTTG has a Dual Role of Promotion-Inhibition in the Development of Pituitary Adenomas

2019 ◽  
Vol 26 (11) ◽  
pp. 800-818
Author(s):  
Zujian Xiong ◽  
Xuejun Li ◽  
Qi Yang
Keyword(s):  
Cell Cycle ◽  
Pituitary Adenoma ◽  
Pituitary Adenomas ◽  
Cell Cycle Progression ◽  
Key Factors ◽  
Cycle Progression ◽  
Sister Chromatids ◽  
Regulation Of Cell Cycle ◽  
Late Stages

Pituitary Tumor Transforming Gene (PTTG) of human is known as a checkpoint gene in the middle and late stages of mitosis, and is also a proto-oncogene that promotes cell cycle progression. In the nucleus, PTTG works as securin in controlling the mid-term segregation of sister chromatids. Overexpression of PTTG, entering the nucleus with the help of PBF in pituitary adenomas, participates in the regulation of cell cycle, interferes with DNA repair, induces genetic instability, transactivates FGF-2 and VEGF and promotes angiogenesis and tumor invasion. Simultaneously, overexpression of PTTG induces tumor cell senescence through the DNA damage pathway, making pituitary adenoma possessing the potential self-limiting ability. To elucidate the mechanism of PTTG in the regulation of pituitary adenomas, we focus on both the positive and negative function of PTTG and find out key factors interacted with PTTG in pituitary adenomas. Furthermore, we discuss other possible mechanisms correlate with PTTG in pituitary adenoma initiation and development and the potential value of PTTG in clinical treatment.

scholarly journals Drought and Salinity in Citriculture: Optimal Practices to Alleviate Salinity and Water Stress

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1283
Author(s):  
Vasileios Ziogas ◽  
Georgia Tanou ◽  
Giasemi Morianou ◽  
Nektarios Kourgialas
Keyword(s):  
Agricultural Sector ◽  
Review Paper ◽  
Cell Metabolism ◽  
High Water ◽  
Crop Productivity ◽  
Fruit Tree ◽  
Key Factors ◽  
Negative Effect

Among the various abiotic stresses, drought is the major factor limiting crop productivity worldwide. Citrus has been recognized as a fruit tree crop group of great importance to the global agricultural sector since there are 140 citrus-producing countries worldwide. The majority of citrus-producing areas are subjected to dry and hot summer weather, limited availability of water resources with parallel low-quality irrigation water due to increased salinity regimes. Citrus trees are generally classified as “salt-intolerant” with high water needs, especially during summer. Water scarcity negatively affects plant growth and impairs cell metabolism, affecting the overall tree growth and the quality of produced fruit. Key factors that overall attempt to sustain and withstand the negative effect of salinity and drought stress are the extensive use of rootstocks in citriculture as well as the appropriate agronomical and irrigation practices applied. This review paper emphasizes and summarizes the crucial role of the above factors in the sustainability of citriculture.

scholarly journals Microbial-Driven Stabilisation of Archaeological Iron Artefacts

2021 ◽  
Vol 2 (2) ◽  
pp. 274-292
Author(s):  
Sarah James ◽  
Edith Joseph
Keyword(s):  
Health And Safety ◽  
Chloride Content ◽  
Key Factors ◽  
Passivation Layers ◽  
Archaeological Iron ◽  
Initial Results ◽  
Sulphur Species ◽  
Partial Success ◽  
Made In

The instability of iron artefacts is rooted in salt contamination during burial and damages associated with exposure to alternative oxygen levels and high relative humidity once excavated. While a combination of chemical and mechanical treatments is utilised to remove the harmful ions (chlorides, sulphur species) and excess bulky corrosion products, these methods can be hazardous for conservation staff’s health, have limited success, or require extensive treatment times. Bio-based treatments provide a potentially greener alternative for removing damaging corrosion and creating biogenic mineral passivation layers, thus remediating concerns over costs, duration, and health and safety. Pseudomonas putida mt-2 (KT2440) is capable of utilising iron under certain conditions and for phosphating mild steel; however, applications have not been made in the cultural heritage sector. To address the potential of using bacteria for conservation purposes, Pseudomonas was assessed for both the bioremediation of salt contaminates and the production of a passivation layer suitable for iron artefacts, with specific conservation concerns in mind. Key factors for optimisation include the role of agitation, chloride content, and oxygen content on bacterial growth and biomineralisation. The initial results indicate a growth preference, not reliance, for NaCl and agitation with partial success of bioconversion of a mineral source.

scholarly journals Targeting Erbin in B cells for therapy of lung metastasis of colorectal cancer

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Tong Shen ◽  
Jing-Lin Liu ◽  
Chu-Yi Wang ◽  
Youlutuziayi Rixiati ◽  
Shi Li ◽  
...  
Keyword(s):  
B Cells ◽  
Lung Metastasis ◽  
Lung Metastases ◽  
Pdz Domain ◽  
Clinical Samples ◽  
Key Factors ◽  
Combined Use ◽  
Iga Production

AbstractThe mechanisms and key factors involved in tumor environments for lung metastasis of CRC are still unclear. Here, using clinical samples from lung metastases of CRC patients, we found that intestinal immune network for IgA production was significantly dysregulated in lung metastases of CRC. Single-cell RNA sequencing discovered a subtype of B cells positive for Erbin, one member of the leucine-rich repeat and PDZ domain (LAP) family, was involved in the lung metastases. Erbin deletion in B cells suppressed lung metastasis of CRC in vivo. And, deletion of Erbin in B cells enhanced the killing effects of CD8+ T cells on tumor cells. Mechanistically, Erbin knockout attenuated TGFβ-mediated suppression of migration of CXCR5+ IgA+ cells and STAT6-mediated PD1 expression. Our study uncovered a key role of Erbin in regulating PD1+ IgA+ B cells in lung metastasis of CRC. Targeting Erbin as well as combined use of neutralizing B cells and antibodies neutralizing PD1 suppresses lung metastasis of CRC in mice, suggesting the potential option for treatment of lung metastasis of CRC.

scholarly journals Spo0A Suppresses sin Locus Expression in Clostridioides difficile

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Babita Adhikari Dhungel ◽  
Revathi Govind
Keyword(s):  
Diarrheal Disease ◽  
Toxin Production ◽  
The United States ◽  
Upstream Region ◽  
Pcr Analysis ◽  
Bacterial Cells ◽  
Master Regulator ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile is the leading cause of nosocomial infection and is the causative agent of antibiotic-associated diarrhea. The severity of the disease is directly associated with toxin production, and spores are responsible for the transmission and persistence of the organism. Previously, we characterized sin locus regulators SinR and SinR′ (we renamed it SinI), where SinR is the regulator of toxin production and sporulation. The SinI regulator acts as its antagonist. In Bacillus subtilis, Spo0A, the master regulator of sporulation, controls SinR by regulating the expression of its antagonist, sinI. However, the role of Spo0A in the expression of sinR and sinI in C. difficile had not yet been reported. In this study, we tested spo0A mutants in three different C. difficile strains, R20291, UK1, and JIR8094, to understand the role of Spo0A in sin locus expression. Western blot analysis revealed that spo0A mutants had increased SinR levels. Quantitative reverse transcription-PCR (qRT-PCR) analysis of its expression further supported these data. By carrying out genetic and biochemical assays, we show that Spo0A can bind to the upstream region of this locus to regulates its expression. This study provides vital information that Spo0A regulates the sin locus, which controls critical pathogenic traits such as sporulation, toxin production, and motility in C. difficile. IMPORTANCE Clostridioides difficile is the leading cause of antibiotic-associated diarrheal disease in the United States. During infection, C. difficile spores germinate, and the vegetative bacterial cells produce toxins that damage host tissue. In C. difficile, the sin locus is known to regulate both sporulation and toxin production. In this study, we show that Spo0A, the master regulator of sporulation, controls sin locus expression. Results from our study suggest that Spo0A directly regulates the expression of this locus by binding to its upstream DNA region. This observation adds new detail to the gene regulatory network that connects sporulation and toxin production in this pathogen.

scholarly journals What Kept the Boat Afloat? Sustainability of Employment in Knowledge-Intensive Sectors Due to Government Measures during COVID-19 Pandemic

2021 ◽  
Vol 13 (15) ◽  
pp. 8441
Author(s):  
Michal Hrivnák ◽  
Peter Moritz ◽  
Marcela Chreneková
Keyword(s):  
Key Factors ◽  
Economic Shocks ◽  
Management Tools ◽  
Employment Retention ◽  
State Compensation ◽  
Business Resilience ◽  
Knowledge Intensive ◽  
Econometric Approach ◽  
The Impact

The COVID-19 pandemic has exposed new aspects of sustainable entrepreneurship and the resilience of SMEs in the conditions of individual countries. This empirical study contributes to entrepreneurship sustainability literature and business resilience literature by estimating the impact of various utilized internal crisis management tools and state compensation measures on retaining the pre-crisis levels of employment after two waves of the pandemic on the conditions of a V4 country. The study adopts an econometric approach towards assessing the influence of key factors of mitigating the problems caused by the pandemic, and the results suggest a crucial role of digitalization, internal policies optimizing variable costs, and utilization of direct governmental supportive measures to compensate for restrictions in force for employment retention in knowledge-intensive SMEs. According to the results, knowledge-intensive SMEs appears to have increased resilience towards economic shocks due to the capability to swiftly change the management of ventures to adapt to a crisis.

scholarly journals Exploring Environmental and Economic Costs and Benefits of a Forest-Based Circular Economy: A Literature Review

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 436
Author(s):  
Dimitra C. Lazaridou ◽  
Anastasios Michailidis ◽  
Marios Trigkas
Keyword(s):  
Cluster Analysis ◽  
Literature Review ◽  
Circular Economy ◽  
Descriptive Analysis ◽  
Forest Sector ◽  
Economic Costs ◽  
Key Factors ◽  
Scientific Publications ◽  
Forest Ecosystem Services

The role of a forest sector in the transition to a circular economy (CE) is critical. Therefore, the purpose of this study is to summarize the main findings of the most important published articles and to provide insights on the interdisciplinary space at the interface of concepts related to a forest-based CE. Moreover, it attempts to assess the challenges raised from adopting the CE in forest sector. Through a systematic literature review, 69 scientific publications were selected and evaluated by two sights: (i) a descriptive analysis and (ii) a cluster analysis of the keywords related to the forest-based CE. The study highlights the need for additional survey on optimizing the interaction between forest ecosystem services and circular economy. Further discussion is also needed about the relations of the key factors associated with the forest-based circular economy, as they emerged from the cluster analysis and the co-occurrence network map.

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