scholarly journals Potential Role of Thiobacillus caldus in Arsenopyrite Bioleaching

1999 ◽  
Vol 65 (1) ◽  
pp. 36-40 ◽  
Author(s):  
Mark Dopson ◽  
E. Börje Lindström
Keyword(s):  
Mixed Culture ◽  
Pure Culture ◽  
Potential Role ◽  
Mixotrophic Growth ◽  
Moderately Thermophilic ◽  
Surface Active Agents ◽  
Pure Cultures ◽  
Surface Active ◽  
Leaching Efficiency

ABSTRACT We investigated the potential role of the three strains ofThiobacillus caldus (KU, BC13, and C-SH12) in arsenopyrite leaching in combination with a moderately thermophilic iron oxidizer,Sulfobacillus thermosulfidooxidans. Pure cultures ofT. caldus and S. thermosulfidooxidans were used as well as defined mixed cultures. By measuring released iron, tetrathionate, and sulfur concentrations, we found that the presence ofT. caldus KU and BC13 in the defined mixed culture lowered the concentration of sulfur, and levels of tetrathionate were comparable to or lower than those in the presence of S. thermosulfidooxidans. This suggests that T. caldusgrows on the sulfur compounds that build up during leaching, increasing the arsenopyrite-leaching efficiency. This result was similar to leaching arsenopyrite with a pure culture of S. thermosulfidooxidans in the presence of yeast extract. Therefore, three possible roles of T. caldus in the leaching environment can be hypothesized: to remove the buildup of solid sulfur that can cause an inhibitory layer on the surface of the mineral, to aid heterotrophic and mixotrophic growth by the release of organic chemicals, and to solubilize solid sulfur by the production of surface-active agents. The results showed that T. caldus KU was the most efficient at leaching arsenopyrite under the conditions tested, followed by BC13, and finally C-SH12.

scholarly journals Enhanced Removal of a Pesticides Mixture by Single Cultures and Consortia of Free and ImmobilizedStreptomycesStrains

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
María S. Fuentes ◽  
Gabriela E. Briceño ◽  
Juliana M. Saez ◽  
Claudia S. Benimeli ◽  
María C. Diez ◽  
...  
Keyword(s):  
Mixed Culture ◽  
Pure Culture ◽  
Immobilized Cells ◽  
Mixed Cultures ◽  
Ex Situ ◽  
Antagonistic Effects ◽  
Pure Cultures

Pesticides are normally used to control specific pests and to increase the productivity in crops; as a result, soils are contaminated with mixtures of pesticides. In this work, the ability ofStreptomycesstrains (either as pure or mixed cultures) to remove pentachlorophenol and chlorpyrifos was studied. The antagonism among the strains and their tolerance to the toxic mixture was evaluated. Results revealed that the strains did not have any antagonistic effects and showed tolerance against the pesticides mixture. In fact, the growth of mixed cultures was significantly higher than in pure cultures. Moreover, a pure culture (Streptomycessp. A5) and a quadruple culture had the highest pentachlorophenol removal percentages (10.6% and 10.1%, resp.), whileStreptomycessp. M7 presented the best chlorpyrifos removal (99.2%). Mixed culture of allStreptomycesspp. when assayed either as free or immobilized cells showed chlorpyrifos removal percentages of 40.17% and 71.05%, respectively, and for pentachlorophenol 5.24% and 14.72%, respectively, suggesting better removal of both pesticides by using immobilized cells. These results reveal that environments contaminated with mixtures of xenobiotics could be successfully cleaned up by using either free or immobilized cultures ofStreptomyces, throughin situorex situremediation techniques.

scholarly journals Pyrite Biooxidation by Acidophilic Archaea AcidiplasmaSp. MBA-1 Under Varied Conditions

2022 ◽  
Author(s):  
Aleksandr Bulaev
Keyword(s):  
Potential Role ◽  
Sulfide Mineral ◽  
High Rate ◽  
Mineral Nutrient ◽  
Acidophilic Microorganisms ◽  
Moderately Thermophilic ◽  
Operational Temperature ◽  
Low Levels ◽  
Acidophilic Archaea

The goal of this research was to study pyrite (FeS2 ) bioleaching by a strain of the genus Acidiplasma under different conditions (temperature, pH) to evaluate the potential role of Acidiplasma representatives in biooxidation of this sulfide mineral. To compare the role of Acidiplasma archaea in pyrite biooxidation with other acidophilic microorganisms, the experiments were also performed with representatives of othergroups of microorganisms predominant in biohydrometallurgical processes.Pure and mixed cultures of moderately thermophilic acidophilic microorganisms, including strains Acidithiobacillus caldus MBC-1, Sulfobacillusthermosulfidooxidans VKMV 1269T and Acidiplasmasp. MBA-1, were used. The experiments were carried out in flasks with 100 mL of mineral nutrient medium supplemented with 0.02% yeast extract and 1 g of pyrite on a rotary shaker for 20 days. Bioleaching was performed at 45, 55, and 60∘С. The results demonstrated that the representatives of the genus Acidiplasmaprovided a comparatively higher rate of pyrite bioleaching at high temperatures (55 and 60∘C) and low pH of the medium (1.0). Thus, according to the results, strains of thegenus Acidiplasma may provide a high rate of pyrite bioleaching at low levels ofpH. Therefore, the results suggest that archaea of the genus Acidiplasma may be promising microorganisms to improve bioleaching processes with an increase in the operational temperature, which is usually maintained at 40–45∘C in industrial-scale reactors. Keywords: biomining, bioleaching, acidophilic microorganisms, sulfide minerals, pyrite

scholarly journals Effects of Pure and Mixed Autochthonous Torulaspora delbrueckii and Saccharomyces cerevisiae on Fermentation and Volatile Compounds of Narince Wines

Foods ◽  
2018 ◽  
Vol 7 (9) ◽  
pp. 147 ◽  
Author(s):  
Ebru Arslan ◽  
Zeynep Çelik ◽  
Turgut Cabaroğlu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Volatile Compounds ◽  
Mixed Culture ◽  
Volatile Acid ◽  
Wine Aroma ◽  
Mixed Culture Fermentation ◽  
Black Sea Region ◽  
Torulaspora Delbrueckii ◽  
Pure Cultures

The cultivar of Narince is a native white grape variety of Vitis vinifera, grown in Tokat city, the Mid-Black Sea Region of Anatolia. In this study, the effects of pure and mixed autochthonous Torulaspora delbrueckii-214 and Saccharomyces cerevisiae-1088 cultures on the fermentation behavior and aroma compounds of Narince wines were investigated. Volatile compounds formed in wines were extracted using a liquid–liquid extraction method and determined by GC-MS-FID. Narince grape must was fermented in duplicate, under the following three conditions. Two pure cultures of T. delbrueckii-214 and S. cerevisiae-1088 and a mixture of T. delbrueckii-214 and S. cerevisiae-1088 (1:1). The presence of the non-Saccharomyces T. delbrueckii-214 yeast slowed down the fermentation and produced a lower level of ethanol and a higher levels of glycerol and volatile acid. Only the pure culture of T. delbrueckii-214 was unable to finish fermentation. On the other hand, mixed culture fermentation improved the aroma intensity and complexity of wine due to increased levels of higher alcohols and esters. According to sensory analysis, wine fermented with mixed culture was the most preferred wine followed by wine inoculated with pure S. cerevisiae-1088. This study confirms the role of T. delbrueckii in wine aroma and the potential of non-Saccharomyces use in winemaking.

The Role of Surface Active Agents in Sulfonation of Double Bonds

2014 ◽  
Vol 51 (4) ◽  
pp. 352-355
Author(s):  
Dariush Farkhani ◽  
Ali Asghar Khalili ◽  
Ali Mehdizadeh
Keyword(s):  
Double Bonds ◽  
Surface Active Agents ◽  
Surface Active

scholarly journals Technical sheet of influence of Freeze-Dried Yeast Starter Cultures on Volatile Compounds of Tchapalo, a Traditional Sorghum Beer from Côte d’Ivoire

2017 ◽  
Vol 6 (3) ◽  
pp. 913-918
Author(s):  
COULIBALY Wahauwouélé Hermann ◽  
BOUATENIN Koffi Maizan Jean-Paul ◽  
KOUAME Kohi Alfred ◽  
RIGOU Peggy
Keyword(s):  
Volatile Compounds ◽  
Mixed Culture ◽  
Pure Culture ◽  
Empirical Process ◽  
Starter Cultures ◽  
Higher Alcohols ◽  
Higher Alcohol ◽  
Freeze Dried ◽  
Pure Cultures ◽  
Microbiological Stability

The production of the Ivorian sorghum beer known as tchapalo remains more or less an empirical process. The use of starter cultures was therefore suggested as the appropriate approach to alleviate the problems of variations inorganoleptic quality and microbiological stability. In this study, we evaluated the capacity of S. cerevisiae and C. tropicalis to produce sorghum beer as freeze-dried starter in mixed or pure cultures. Beers produced with mixed freeze-dried cultures of S. cerevisiae F12-7 and C. tropicalis C0-7 showed residual sugars and ethanol contents similar to beers obtained with S. cerevisiae F12-7 pure culture, but the total sum of organic acids analyzed was the highest with the mixed culture (15.71 g/L). Higher alcohols were quantitatively the largest group of volatile compounds detected in beers. Among these compounds, 2-phenyl ethanol, a higher alcohol that plays an important role in beer flavor, was highly produced with the mixed culture (10174.8 µg/L) than with the pure culture (8749.9 µg/L).

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