Boston University biomedical engineers teach bacteri...( BOSTON (05-28-09) -- Biomedical engi...)

BOSTON (05-28-09) -- Biomedical engineers at Boston University have taught bacteria how to count. Professor James J. Collins and colleagues have wired a new sequence of genes that allow the microbes to count discrete events, opening the door for a host of potential applications, which could include drug delivery and sensing environmental hazards.

"This was probably the major application still to be addressed within synthetic biology: Can you count discrete events?" said Collins, who is also a Howard Hughes Medical Institute investigator and a Boston University William Fairfield Warren Distinguished Professor. "And now we've come up with two different designs to do this."

The research is detailed in an article, "Synthetic Gene Networks That Count," that appears in the May 29 issue of Science.

The young but burgeoning field of synthetic biology addresses biological research questions with an engineering approach. Researchers design and build networks of genes, splicing them into bacterial genomes to run specific tasks or manufacture desired molecules a process akin to installing biological computer software. Though the field is rapidly advancing, the gene-based tools available to synthetic biologists remain limited.

Gene networks that give bacteria the ability to count could become powerful devices in the synthetic biology toolkit because they can be coupled to almost any other bacterial function or environmental cue that bacteria can sense, such as presence of a toxin or sunlight. In the future, bacteria might be set to self-destruct after a certain number of cell divisions or after a specified period of time.

"The fundamental application is as a safety mechanism," said Collins. "If you've engineered an organism to be released into the environment as a biosensor, or you've engineered an organism to go into your body to deliver a therapeutic, in many cases you want to ensure after a certain period of time t
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