Biosafety is the ethical obligation of a bioengineer. Throughout our project design we have tried to be as mindful as possible regarding identifying strategies for robust biosafety. Since our project is closely related to a consumable sugar, we have devised a three-tier fail-safe mechanism after taking into consideration the various use cases of our chassis.
Level 1: Kill Switch
We intend to introduce our strain of bacteria into the sugarcane matrix to synthesise anti-invertase. Considering the close proximity of the system to both agricultural environments and human consumables, it is indispensable that our bacteria include a lethality mechanism. We propose to use a modified type II ccdA-ccdB toxin-antitoxin system as our kill switch that is activated upon exposure to atmospheric concentrations of oxygen. A change in the oxygen concentration in the environment results in a sharp increase in the amount of the toxin protein being synthesised which disturbs the already established equilibrium between the toxin and antitoxin, effectively killing the cell, and thus preventing any contamination by stray microbes. More information about the design of the kill switch can be found here and a study of its dynamics here.
Level 2: Auxotropic Regulation
There are several amino acids that have been detected in sugarcane including, pipecolic acid and hydroxypipecolic acid. Increasing the supply of nitrogen increases markedly the amides asparagine and glutamine and less markedly the basic amino‐acids lysine, histidine, arginine and tryptophan. The neutral and acidic amino‐acids tend to increase and then decrease in level with increasing nitrogen supply. An auxotroph of tryptophan would
Level 3: Sugar Manufacturing Process
Need better quality image of the industy process
During the sugar manufacturing process the cane juice is heated at the evaporation station to temperatures greater than 100°C for upto eught hours. Furthermore, sulphur dioxide is passed through the solution at the clarifying stage along with a change in pH. We have designed experiments to mimic these industrial conditions on a lab scale. More details about the same can be found here. The bacteria would not be able to handle the stress of these conditions and hence the manufacturing process would act as a third failsafe.