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Team:NYMU-Taipei/Project
From 2013.igem.org
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Overall project
In hope of protecting the eco-system, food supply and agricultural economy, the goal of our project is to solve the Colony Collapse Disorder (CCD), a severe disease that causes bees to dramatically decline or disappear. Since the culprit of CCD is a microsporidian called Nosema ceranae, we created Bee. coli to strengthen bees’ immune system and further wipe N. ceranae out.
The dormant stage of N. ceranae is a long-lived spore which is small enough to be ingested by bees through food or water. When N. ceranae travels to the bees’ midgut, it will germinate a polar filament to reach the epithelial cells. Midgut cells are then dominated by N. ceranae and thus bee’s ability to gain nutrition is decreased. In addition, some spores will come out in feces, leading to feces-oral or oral-oral infection in the beehive. N. ceranae is fatal to bees; however, so far there has been no efficient way to stop this pathogen. This year, we endow Bee. coli with multiple functions to resist the invasion of N. ceranae, hoping to cure CCD and prevent colonial infection.
Bee. coli’s functions are designed to work sequentially. Before N. ceranae approaches the midgut cells, Bee. coli will secrete mannosidase to inhibit N. ceranae from growing a polar filament. The epithelial cells will secrete reactive oxygen species (ROS) once being attacked by N. ceranae. ROS will activate promoters containing OxyR binding site in Bee. coli, serving as a signal of N. ceranae invasion, eventually resulting in Bee. coli producing substances such as defensin and abaecin to kill N. ceranae while still being safe to bees and Bee. coli itself. Moreover, if the methods above unfortunately fail, Bee. coli will secrete ethanol to kill the single bee, that is to say, to sacrifice few infected bees in order to protect the healthy bees.
Concerning safety, Bee. coli is designed to commit suicide if it escapes from midgut. Once Bee. coli senses that the pH of the environment is different from that of the midgut, Bee. coli will produce a lysis protein and kill itself. Last but not least, to make Bee. coli more practical for survival, we chose to use E. coli K-12 MG1655, a bacteria naturally occurring in honeybees' gut. We then use encapsulation to transport Bee. coli into the bee’s midgut. The beekeepers can add the Bee. coli capsules into sugar-water which are then consumed by bees. That way, Bee. coli can come into reality and solve the CCD problem.
