Abstract
Fifty iron-oxidizing bacteria isolated from natural environments were screened for resistance to mercuric ions (Hg2+). Thiobacillus ferrooxidans Funis 2-1, the strain found to show the greatest resistance to Hg2+ among the fifty isolates, gave a cell yield of 7.0 x 107 cells/ml after 8 d cultivation in an Fe2+-medium (pH 2.5) containing 0.7 μM Hg2+. Funis 2-1 volatilized 80% of the total mercury added to the medium over 8 d of cultivation. T. ferrooxidans AP19-3, more sensitive to Hg2+ than Funis 2-1, could not grow in an Fe2+-medium (pH 2.5) containing 0.7 μM Hg2+ even over a 28 d cultivation period. When resting cells of strains Funis 2-1 and AP19-3 were incubated for 3 h in a salt solution containing 0.7 μM Hg2+ (pH 3.0), 14.3% and 7.9% of the total mercury added to the reaction mixtures respectively, were volatilized. The activity of the mercuric reductase from Funis 2-1 was only 2.8 times higher than that of the enzyme from AP19-3. Since the markedly higher mercury resistance of Funis 2-1 compared with that of AP19-3 cannot be explained only by the level of the mercuric reductase activity, the levels of mercury resistance of iron oxidase and cytochrome c oxidase were studied. The 1 μM mercuric ions inhibited the 35% of iron- oxidizing activity from AP19-3. In contrast, the same concentration of Hg2+ did not inhibit the activity of iron oxidase from Funis 2-1. In the case of the cytochrome c oxidases purified from both strains, the 0.2 μM Hg2+ inhibited approximately 40% of cytochrome c oxidizing activity from AP19-3, on the contrary, the activity of the enzyme from Funis 2-1 was activated 1.8- and 1.2-fold, respectively, in the presence of 0.08 and 0.2 μM Hg2+. Since cytochrome c oxidase is one of the most important components of the iron- oxidizing system, these results indicate that both the existence of cytochrome c oxidase resistant to Hg2+ as well as that of mercuric reductase in the cells is responsible for the more rapid growth of Funis 2-1 than that of in an Fe2+-medium containing 0.7 μM Hg2+.
| Original language | English |
|---|---|
| Pages (from-to) | 387-392 |
| Number of pages | 6 |
| Journal | Journal of Bioscience and Bioengineering |
| Volume | 88 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 1999 |
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Keywords
- Iron-oxidizing bacterium
- Mercuric reductase
- Mercury resistance
- Thiobacillus ferrooxidans
ASJC Scopus subject areas
- Biotechnology
- Bioengineering
Cite this
Isolation and some properties of Thiobacillus ferrooxidans strains with differing levels of mercury resistance from natural environments. / Takeuchi, Fumiaki; Iwahori, Kenji; Kamimura, Kazuo; Sugio, Tsuyoshi.
In: Journal of Bioscience and Bioengineering, Vol. 88, No. 4, 1999, p. 387-392.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Isolation and some properties of Thiobacillus ferrooxidans strains with differing levels of mercury resistance from natural environments
AU - Takeuchi, Fumiaki
AU - Iwahori, Kenji
AU - Kamimura, Kazuo
AU - Sugio, Tsuyoshi
PY - 1999
Y1 - 1999
N2 - Fifty iron-oxidizing bacteria isolated from natural environments were screened for resistance to mercuric ions (Hg2+). Thiobacillus ferrooxidans Funis 2-1, the strain found to show the greatest resistance to Hg2+ among the fifty isolates, gave a cell yield of 7.0 x 107 cells/ml after 8 d cultivation in an Fe2+-medium (pH 2.5) containing 0.7 μM Hg2+. Funis 2-1 volatilized 80% of the total mercury added to the medium over 8 d of cultivation. T. ferrooxidans AP19-3, more sensitive to Hg2+ than Funis 2-1, could not grow in an Fe2+-medium (pH 2.5) containing 0.7 μM Hg2+ even over a 28 d cultivation period. When resting cells of strains Funis 2-1 and AP19-3 were incubated for 3 h in a salt solution containing 0.7 μM Hg2+ (pH 3.0), 14.3% and 7.9% of the total mercury added to the reaction mixtures respectively, were volatilized. The activity of the mercuric reductase from Funis 2-1 was only 2.8 times higher than that of the enzyme from AP19-3. Since the markedly higher mercury resistance of Funis 2-1 compared with that of AP19-3 cannot be explained only by the level of the mercuric reductase activity, the levels of mercury resistance of iron oxidase and cytochrome c oxidase were studied. The 1 μM mercuric ions inhibited the 35% of iron- oxidizing activity from AP19-3. In contrast, the same concentration of Hg2+ did not inhibit the activity of iron oxidase from Funis 2-1. In the case of the cytochrome c oxidases purified from both strains, the 0.2 μM Hg2+ inhibited approximately 40% of cytochrome c oxidizing activity from AP19-3, on the contrary, the activity of the enzyme from Funis 2-1 was activated 1.8- and 1.2-fold, respectively, in the presence of 0.08 and 0.2 μM Hg2+. Since cytochrome c oxidase is one of the most important components of the iron- oxidizing system, these results indicate that both the existence of cytochrome c oxidase resistant to Hg2+ as well as that of mercuric reductase in the cells is responsible for the more rapid growth of Funis 2-1 than that of in an Fe2+-medium containing 0.7 μM Hg2+.
AB - Fifty iron-oxidizing bacteria isolated from natural environments were screened for resistance to mercuric ions (Hg2+). Thiobacillus ferrooxidans Funis 2-1, the strain found to show the greatest resistance to Hg2+ among the fifty isolates, gave a cell yield of 7.0 x 107 cells/ml after 8 d cultivation in an Fe2+-medium (pH 2.5) containing 0.7 μM Hg2+. Funis 2-1 volatilized 80% of the total mercury added to the medium over 8 d of cultivation. T. ferrooxidans AP19-3, more sensitive to Hg2+ than Funis 2-1, could not grow in an Fe2+-medium (pH 2.5) containing 0.7 μM Hg2+ even over a 28 d cultivation period. When resting cells of strains Funis 2-1 and AP19-3 were incubated for 3 h in a salt solution containing 0.7 μM Hg2+ (pH 3.0), 14.3% and 7.9% of the total mercury added to the reaction mixtures respectively, were volatilized. The activity of the mercuric reductase from Funis 2-1 was only 2.8 times higher than that of the enzyme from AP19-3. Since the markedly higher mercury resistance of Funis 2-1 compared with that of AP19-3 cannot be explained only by the level of the mercuric reductase activity, the levels of mercury resistance of iron oxidase and cytochrome c oxidase were studied. The 1 μM mercuric ions inhibited the 35% of iron- oxidizing activity from AP19-3. In contrast, the same concentration of Hg2+ did not inhibit the activity of iron oxidase from Funis 2-1. In the case of the cytochrome c oxidases purified from both strains, the 0.2 μM Hg2+ inhibited approximately 40% of cytochrome c oxidizing activity from AP19-3, on the contrary, the activity of the enzyme from Funis 2-1 was activated 1.8- and 1.2-fold, respectively, in the presence of 0.08 and 0.2 μM Hg2+. Since cytochrome c oxidase is one of the most important components of the iron- oxidizing system, these results indicate that both the existence of cytochrome c oxidase resistant to Hg2+ as well as that of mercuric reductase in the cells is responsible for the more rapid growth of Funis 2-1 than that of in an Fe2+-medium containing 0.7 μM Hg2+.
KW - Iron-oxidizing bacterium
KW - Mercuric reductase
KW - Mercury resistance
KW - Thiobacillus ferrooxidans
UR - http://www.scopus.com/inward/record.url?scp=0032695986&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032695986&partnerID=8YFLogxK
U2 - 10.1016/S1389-1723(99)80215-1
DO - 10.1016/S1389-1723(99)80215-1
M3 - Article
VL - 88
SP - 387
EP - 392
JO - Journal of Bioscience and Bioengineering
JF - Journal of Bioscience and Bioengineering
SN - 1389-1723
IS - 4
ER -