Different Heavy Metals' Toxicities Affect the Growth of Baci
Heavy metals have toxic effects for almost all the living things, but because of different species variety, heavy metal toxicity affects in different ways for different organisms. For example, bacteria as a group are more sensitive to the heavy metal toxicity than fungi, (Rajapaksha et al, 2004). Heavy metal pollution can come from natural source (e.g. silver metal mine), but most of the times, they are caused by human activities. Industrial wastes are the biggest source of heavy metal pollution, (Bae et al, 2000). People need to use heavy metal salts during plating procedure, dyeing, chemical synthesis and other areas. The common heavy metal wastes are silver salts, copper salts, and mercury compounds. This heavy metal can cause a lot of negative effects in living things. First of all, heavy metal can destroy protein structures, and that will make the protein lost its function. Secondly, heavy metal can accumulate in organism's body, and that might cause long-term effects such a
Compare to the zone of inhibition caused by Hg compound, or AgNO3, the zone of inhibition by copper sulfate is smaller with a 5. For the Escherichia coli, Hg causes a 20. 7 diameters of inhibit zone for the Micrococcus luteus grown on the culture, while AgNO3 cause a 12. For the control groups for Bacillus cereus, Escherichia coli, and Micrococcus luteus, it did not show any zones of inhibition, but for the control group for Pseudomonas putida, we got a 10. In fact, bacteria are the good choice. These advantages let us can easily monitor them for even a long term study. This test will let us understand which one in these three metals are the most toxic one, and it also can show us the degree of toxicity for different metals applied. 6 mm diameter large of inhibit area, while AgNO3 creates a 18. I will discuss this result in the discussion section. My hypothesis is different heavy metal have different levels toxicity to the organisms, and different species have different responses to the same heavy metal environment. For the culture with Bacillus cereus inside, we found out a zone of inhibition with diameter 33.
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