Scanning Electron Microscope Study of Bacteria on Mineral Surfaces

1976 ◽  
Vol 34 ◽  
pp. 130-131
Author(s):  
V.K. Berry
Keyword(s):  
Oxidation Reaction ◽  
Electron Microscope Study ◽  
Elemental Sulfur ◽  
Thiobacillus Ferrooxidans ◽  
Physical Contact ◽  
Metal Sulfides ◽  
Low Grade ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
Scanning Electron Microscope Study

There are two strains of bacteria viz. Thiobacillus thiooxidansand Thiobacillus ferrooxidanswidely mentioned to play an important role in the leaching process of low-grade ores. Another strain used in this study is a thermophile and is designated Caldariella .These microorganisms are acidophilic chemosynthetic aerobic autotrophs and are capable of oxidizing many metal sulfides and elemental sulfur to sulfates and Fe2+ to Fe3+. The necessity of physical contact or attachment by bacteria to mineral surfaces during oxidation reaction has not been fairly established so far. Temple and Koehler reported that during oxidation of marcasite T. thiooxidanswere found concentrated on mineral surface. Schaeffer, et al. demonstrated that physical contact or attachment is essential for oxidation of sulfur.

Observations of Selective Attachment of Bacteria on Low-Grade Ore: Evidence for Direct-Contact Bacterial Leaching of Sulfide Minerals

1976 ◽  
Vol 34 ◽  
pp. 132-133
Author(s):  
V.K. Berry ◽  
L.E. Murr
Keyword(s):  
Direct Contact ◽  
Sulfide Mineral ◽  
Sulfide Minerals ◽  
Physical Contact ◽  
Metal Sulfides ◽  
Low Grade ◽  
Bacterial Leaching ◽  
Indirect Contact ◽  
Chalcopyrite Ore ◽  
Contact Mechanism

The mechanism of bacterial leaching of sulfide minerals is not fully understood. There are two obvious mechanisms which have been proposed by Silverman and Ehrlich involving either indirect contact where Fe2+ ions oxidize metal sulfides while being reduced to Fe3+, or direct (physical) contact between the bacteria and the sulfide mineral under aerobic conditions. While the direct contact mechanism has been suggested by observations of bacterial acceleration of the oxidation rate of iron-free sulfides such as molybdenite (M0S2), chalcocite (Cu2S), and covellite (CuS)2-4, similar results have been demonstrated with pyrite (FeS2)5, but not with iron-containing sulfides such as bornite (Cu5FeS4) or chalcopyrite (CuFeS2). Recent work by Murr and Berry on the attachment of bacteria to low-grade chalcopyrite ore has, however, shown that bacteria seem to attach preferentially to the chalcopyrite phases; lending support to the direct contact mechanism.

A Scanning Electron Microscope Study of Isolated Guard Cells

1973 ◽  
Vol 31 ◽  
pp. 454-455 ◽  
Author(s):  
P. Dayanandan ◽  
P. B. Kaufman
Keyword(s):  
Electron Microscope ◽  
Electron Microscope Study ◽  
Three Dimensional ◽  
Guard Cells ◽  
Scanning Electron Microscope Study ◽  
Psilotum Nudum ◽  
Subsidiary Cells ◽  
Welwitschia Mirabilis ◽  
Cycas Revoluta ◽  
Scanning Electron

A three dimensional appreciation of the guard cell morphology coupled with ultrastjuctural studies should lead to a better understanding of their still obscure dynamics of movement. We have found the SEM of great value not only in studies of the surface details of stomata but also in resolving the structures and relationships that exist between the guard and subsidiary cells. We now report the isolation and SEM studies of guard cells from nine genera of plants.Guard cells were isolated from the following plants: Psilotum nudum, four species of Equisetum, Cycas revoluta, Ceratozamia sp., Pinus sylvestris, Ephedra cochuma, Welwitschia mirabilis, Euphorbia tirucalli and Allium cepa.

Scanning Electron Microscope Study of Root Canal Filling (First Report)

1987 ◽  
Vol 41 (6) ◽  
pp. 1238-1243
Author(s):  
Yohichiroh Soh ◽  
Junroh Tahara ◽  
Takashi Hayashikawa ◽  
Masatoshi Hitaka ◽  
Kohzoh Kubota ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Root Canal ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Root Canal Filling ◽  
Scanning Electron Microscope Study ◽  
First Report ◽  
Scanning Electron

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

2020 ◽  
Vol 8 (3) ◽  
pp. 386 ◽  
Author(s):  
Maxim Muravyov ◽  
Anna Panyushkina
Keyword(s):  
Microbial Community ◽  
Zinc Sulfide ◽  
Elemental Sulfur ◽  
Waste Product ◽  
Sulfur Oxidation ◽  
Low Grade ◽  
Sulfide Concentrates ◽  
Sulfide Concentrate ◽  
Elemental Sulfur Oxidation ◽  
Ferric Leaching

A two-step process, which involved ferric leaching with biologically generated solution and subsequent biooxidation with the microbial community, has been previously proposed for the processing of low-grade zinc sulfide concentrates. In this study, we carried out the process of complete biological oxidation of the product of ferric leaching of the zinc concentrate, which contained 9% of sphalerite, 5% of chalcopyrite, and 29.7% of elemental sulfur. After 21 days of biooxidation at 40 °C, sphalerite and chalcopyrite oxidation reached 99 and 69%, respectively, while the level of elemental sulfur oxidation was 97%. The biooxidation residue could be considered a waste product that is inert under aerobic conditions. The results of this study showed that zinc sulfide concentrate processing using a two-step treatment is efficient and promising. The microbial community, which developed during biooxidation, was dominated by Acidithiobacillus caldus, Leptospirillum ferriphilum, Ferroplasma acidiphilum, Sulfobacillus thermotolerans, S. thermosulfidooxidans, and Cuniculiplasma sp. At the same time, F. acidiphilum and A. caldus played crucial roles in the oxidation of sulfide minerals and elemental sulfur, respectively. The addition of L. ferriphilum to A. caldus during biooxidation of the ferric leach product proved to inhibit elemental sulfur oxidation.

Sign in / Sign up

Export Citation Format

Share Document