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Cross-comparison of leaching strains isolated from two different regions: Chambishi and Dexing copper mines.

Ngom B, Liang Y, Liu X - Biomed Res Int (2014)

Bottom Line: Prior to their study in bioleaching, the different strains were characterized and compared at physiological level.The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains.However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms.

View Article: PubMed Central - PubMed

Affiliation: School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, China ; Key Laboratory of Biohydrometallurgy, Ministry of Education, Changsha 410083, China.

ABSTRACT
A cross-comparison of six strains isolated from two different regions, Chambishi copper mine (Zambia, Africa) and Dexing copper mine (China, Asia), was conducted to study the leaching efficiency of low grade copper ores. The strains belong to the three major species often encountered in bioleaching of copper sulfide ores under mesophilic conditions: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferriphilum. Prior to their study in bioleaching, the different strains were characterized and compared at physiological level. The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains. However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms. In addition, microbial community analysis revealed that the different mixed cultures shared almost the same profile, and At. ferrooxidans strains always outcompeted the other strains.

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Influence of initial pH and temperature on cell growth and iron oxidation rates of the Chambishi strains (solid lines) and Dexing strains (long dash lines). Effect of pH on (a) cell growth and (b) iron oxidation rates of the isolates; effect of temperature on (c) cell growth and (d) iron oxidation rates of the different leaching strains.
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Related In: Results  -  Collection


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fig1: Influence of initial pH and temperature on cell growth and iron oxidation rates of the Chambishi strains (solid lines) and Dexing strains (long dash lines). Effect of pH on (a) cell growth and (b) iron oxidation rates of the isolates; effect of temperature on (c) cell growth and (d) iron oxidation rates of the different leaching strains.

Mentions: In terms of energy source, the results revealed that L. ferriphilum strains were only iron-oxidizers and At. thiooxidans strains were only sulfur-oxidizers, while At. ferrooxidans could use both ferrous iron and sulfur. None of them could use organic substrates, but they were differently affected by the presence of carbohydrates, such as glucose, sucrose, yeast extract, peptone, and tryptone soya broth (see Table S1 in Supplementary Material available online at http://dx.doi.org/10.1155/2014/787034). For instance, strains of At. ferrooxidans were inhibited by glucose and sucrose but slightly stimulated by peptone and tryptone soya broth at concentration lower than 0.5 g L−1, while those of L. ferriphilum were inhibited by all these carbon substances. Similar results were reported by Patel et al. [18] who reported that At. ferrooxidans SRDSM2 responded to the addition of 0.5 g L−1 peptone and 1.0 g L−1 tryptone soya broth (TSB) in the ferrous sulfate tryptone soya broth (ITSB) medium with 35.3% and 29.6% increase in iron oxidation rate (IOR) but decrease in the IOR at higher peptone or tryptone soya broth levels [18]. This was more obvious with strain FOX1 (isolated from Chambishi) which scored an increase of IOR of 8.6% against 2.1% for strain YTW (isolated from Dexing) when 0.5 g L−1 TSB was added (see Figure S1 in Supplementary Material). From the obtained results, it is hard to speculate the mechanisms involved in this particular response of At. ferrooxidans strains on peptone and tryptone; however, it might be an interesting future research focus. Nevertheless this result confirms the higher tolerance of At. ferrooxidans species to organic matter and may explain the reason why members of At. ferrooxidans are much easier to grow on agar plate than L. ferriphilum strains [13, 19]. Again, for a given species, strains used the same energy source and responded similarly to the different organic compound; however, there was a slight difference in terms of metabolic activity. Strains isolated from Chambishi were found to have higher growth and iron oxidation rate. For instance, At. ferrooxidans FOX1 (isolated from Chambishi) and At. ferrooxidans YTW (isolated from China) showed an increase in cell density from ~106 to 7.14 × 107 and 5.23 × 107 cells mL−1 (Figures 1(a) and 1(c)) with an iron oxidation rate of 72.6 and 67.1 mg L-1 h−1 (Figures 1(b) and 1(d)) within 5 days in 9K medium containing 4.5% (w/v) of ferrous sulfate, respectively.


Cross-comparison of leaching strains isolated from two different regions: Chambishi and Dexing copper mines.

Ngom B, Liang Y, Liu X - Biomed Res Int (2014)

Influence of initial pH and temperature on cell growth and iron oxidation rates of the Chambishi strains (solid lines) and Dexing strains (long dash lines). Effect of pH on (a) cell growth and (b) iron oxidation rates of the isolates; effect of temperature on (c) cell growth and (d) iron oxidation rates of the different leaching strains.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4248400&req=5

fig1: Influence of initial pH and temperature on cell growth and iron oxidation rates of the Chambishi strains (solid lines) and Dexing strains (long dash lines). Effect of pH on (a) cell growth and (b) iron oxidation rates of the isolates; effect of temperature on (c) cell growth and (d) iron oxidation rates of the different leaching strains.
Mentions: In terms of energy source, the results revealed that L. ferriphilum strains were only iron-oxidizers and At. thiooxidans strains were only sulfur-oxidizers, while At. ferrooxidans could use both ferrous iron and sulfur. None of them could use organic substrates, but they were differently affected by the presence of carbohydrates, such as glucose, sucrose, yeast extract, peptone, and tryptone soya broth (see Table S1 in Supplementary Material available online at http://dx.doi.org/10.1155/2014/787034). For instance, strains of At. ferrooxidans were inhibited by glucose and sucrose but slightly stimulated by peptone and tryptone soya broth at concentration lower than 0.5 g L−1, while those of L. ferriphilum were inhibited by all these carbon substances. Similar results were reported by Patel et al. [18] who reported that At. ferrooxidans SRDSM2 responded to the addition of 0.5 g L−1 peptone and 1.0 g L−1 tryptone soya broth (TSB) in the ferrous sulfate tryptone soya broth (ITSB) medium with 35.3% and 29.6% increase in iron oxidation rate (IOR) but decrease in the IOR at higher peptone or tryptone soya broth levels [18]. This was more obvious with strain FOX1 (isolated from Chambishi) which scored an increase of IOR of 8.6% against 2.1% for strain YTW (isolated from Dexing) when 0.5 g L−1 TSB was added (see Figure S1 in Supplementary Material). From the obtained results, it is hard to speculate the mechanisms involved in this particular response of At. ferrooxidans strains on peptone and tryptone; however, it might be an interesting future research focus. Nevertheless this result confirms the higher tolerance of At. ferrooxidans species to organic matter and may explain the reason why members of At. ferrooxidans are much easier to grow on agar plate than L. ferriphilum strains [13, 19]. Again, for a given species, strains used the same energy source and responded similarly to the different organic compound; however, there was a slight difference in terms of metabolic activity. Strains isolated from Chambishi were found to have higher growth and iron oxidation rate. For instance, At. ferrooxidans FOX1 (isolated from Chambishi) and At. ferrooxidans YTW (isolated from China) showed an increase in cell density from ~106 to 7.14 × 107 and 5.23 × 107 cells mL−1 (Figures 1(a) and 1(c)) with an iron oxidation rate of 72.6 and 67.1 mg L-1 h−1 (Figures 1(b) and 1(d)) within 5 days in 9K medium containing 4.5% (w/v) of ferrous sulfate, respectively.

Bottom Line: Prior to their study in bioleaching, the different strains were characterized and compared at physiological level.The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains.However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms.

View Article: PubMed Central - PubMed

Affiliation: School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, China ; Key Laboratory of Biohydrometallurgy, Ministry of Education, Changsha 410083, China.

ABSTRACT
A cross-comparison of six strains isolated from two different regions, Chambishi copper mine (Zambia, Africa) and Dexing copper mine (China, Asia), was conducted to study the leaching efficiency of low grade copper ores. The strains belong to the three major species often encountered in bioleaching of copper sulfide ores under mesophilic conditions: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferriphilum. Prior to their study in bioleaching, the different strains were characterized and compared at physiological level. The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains. However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms. In addition, microbial community analysis revealed that the different mixed cultures shared almost the same profile, and At. ferrooxidans strains always outcompeted the other strains.

Show MeSH