IGEM

A model on the process of Cu²⁺ elimination by “Copper Terminator”.

Pathogen detection is one major topic related to the access to health care, the failing of which leads to serious consequences. Pseudomonas aeruginosa and Staphylococcus aureusare two problematic pathogenic Gram-negative bacteria causing various diseases. Fast and sensitive detection of them is required for rapidly administered and appropriate antibiotic treatment in serious medical conditions.

The copper contamination.

Today, from a spoon to a skyscraper, the uses of copper is extending everywhere. For meeting the increasing demand of copper in the world, the massive copper ores are mined every year [Figure 2.1.1].

And most copper is mined as copper sulfides such as chalcopyrite.Those type of mines are more likely to produce acid mine drainage (AMD) which refers to the outflow of acidic water from metal mines or coal mines [Fig 2.1.2].

The specific process of generating AMD includes three chemical reactions:

The oxidization of pyrite which is iron-sulfide is primary contributor to AMD, the major process is:

2FeS₂(s) + 7O₂(g) + 2H₂O(l) = 2Fe²⁺(aq) + 4SO₄²⁻(aq) + 4H⁺(aq)

The ferrous iron (II) generated from oxidization of pyrite is oxidized to ferric iron(III).

4Fe²⁺ (aq) + O₂ (g) + 4H⁺ (aq) = 4Fe³⁺(aq) + 2H₂O(l)

And another process happens simultaneously with oxidization of pyrite and need to be catalyzed by microbes.

FeS₂ (s) + 14Fe³⁺ (aq) + 8H₂O(l) = 15Fe²⁺ (aq) + 2 SO₄²⁻ (aq) + 16H⁺ (aq)

Those reactions jointly lower the PH of water and produce soluble ferric iron(III),and finally the acid mine drainage emerges [Figure 2.1.3].

Associating with water and air, the metal mines where the ore is sulfide mineral or comprises pyrite can easily produce the highly acidic effusion. Usually the predominant metal ion isn’t iron but copper, zinc. The most common ore mined is chalcopyrite which is a copper-iron-sulfide and occurs with a range of other sulfides. Thus, copper mines are primary crime of AMD.

Copper tolerance of E.coli.

Massive mining and extensive using of copper results in serious contamination to environment, and then copper contamination threaten the balance of the whole ecosystem. Even the low concentration of copper is toxic to the organism (look at our algae experiment). But there is an exception, Escherichia coli ,which has several sophisticated and powerful systems to maintain the copper homeostasis so it can survive in skyhigh concentration(look at our MIC(minimum inhibitory concentration, MIC)experiment).Basing on this characteristic of E.col, we start to design an bio-machine to solve the problem of copper contamination effectively.

Refrences:

[1] Rensing, C., & Grass, G. (2003). Escherichia coli mechanisms of copper homeostasis in a changing environment. FEMS microbiology reviews,27(2‐3), 197-213.

All Pictures come from Wikipedia.