Prof. Jose' Onuchic to give Tenneco Lecture

October 11, 2010

In nature, bacteria are living in large colonies whose numbers may reach up to 100 times the amount of people on Earth. New research shows how under life alarming conditions the bacteria in a colony communicate via chemical messages and how each bacterium performs a sophisticated decision process by using a specialized network of genes and proteins. This complex network enables the bacteria to perform complex calculations in order to assess the pros and cons of the different choices guided by the  new principles of game theory.

Many bacteria respond to extreme stresses, such as starvation, poisons and damage to DNA by creating spores, dormant versions that are highly resistant to threats. The spores wait and germinate if and when the stress is removed.  This process involves more than 500 genes, and takes about 10 hours in studied bacteria - Bacillus subtilis. Sporulation ends with the death of the mother cell after a copy of the DNA is stored within the spore. The mother cell then breaks open and its DNA and left over proteins are released to the environment. The bacteria on the road towards sporulation have the option to decide to change their fate and escape into a different state called competence.

This is where game theory enters. Bacteria game theory is far more advanced than the well-known case of the Prisoner Dilemma. The classic prisoner's dilemma is a situation where two prisoners are given an offer - if the first prisoner does not admit to a crime, while the second does, the first will be given a 6 year sentence and the second will only receive a 2 year sentence. If they both admit to the crime - they will both get 4 years.  However, if neither admits to the crime, they will both be released. The “Prisoner's dilemma” here is more complex; each bacterium must decide whether to become a spore (cooperate) or escape into competence (take advantage of the others) with a limited time to decide while the clock is ticking.