For the 2017 IGEM, Team AshesiGhana is working on a bio-mining project. The objective of our project is to develop an organism capable of liberating gold from the refractory ore. We aim to provide not only an alternative, non-toxic approach for small scale mining, but also deliver an easy and fast bio-detection and quantification method of ore in the mining industry of our country. The availability of such a biosensor will allow routine monitoring of the ore before a mining endeavor is undertaken thus preventing the destruction of the environment. The project will engineer the typical environmental organism Acidithiobacillus ferroxidans with a FRET probe.
This new organism will primarily be capable of sensing and quantifying the amount of gold in the ore. This will be accomplished by using a two-part probe, a donor part which is made up of gold binding protein (golB) attached to a green fluorescent protein (nowGFP). The second part of the acceptor is also made up of a binding protein and a red fluorescent protein (mRuby2). In the presence of a high amount of free gold, the two parts would be in close proximity and energy transfer can take place and the red protein would be excited giving off a fluorescent signal. Using calibration experiments, we can relate the amount of fluorescence to the amount of gold present,liberated by the organism from the ore.
As Acidithiobacillus ferroxidans is a difficult organism to grow in large quantities, we will engineer a strain of E coli to produce two of the main oxidizing enzymes for iron and sulphite which will liberate the gold from the ore. The organism will also be engineered with protective enzymes against the low pH, which is one of the bi-products of the gold liberation reaction, and metal toxicity. The same FRET biosensor part can be added to the E coli strain for the quantification of gold. This new organism can easily be grown in large batches and so can be used to extract gold from refractory ore without the need of any toxic treatment thus providing a safe alternative for small scale mining.