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The binary toxin BinA and BinB, which is produced in Bacillus sphaericus, is a mosquito-larvicidal crystal protein. It has its maximum activity when both components are present in equimolar ratio[1]. It could kill larvae by forming pores once binA binds to and binB inserts to membrane lipid bilayer, leading to swelling and lysis of the cell[1].

Attempts have been made to produce the binary toxin at a high level in many organisms including Escherichia coli[1]. To obtain a high expression level and a high-potency toxin, one approach is to improving solubility by tagging T7 tag [2] or glutathione S-transferase (GST), between which GST seems to work better. Not only did GST increases the expression level; it also improves the solubility of those proteins[2].

Yeast has also been a good tool for bacterial toxin studies. It can functionally express many bacterial toxins[2]. Since the binary toxin Bin A and Bin B are very specific to insects, we propose that yeast can express this toxin without damaging itself; at the same time, when insects eat the yeast the insect will die. This is why we choose this binary toxin as our “insect killer”.