Beyond genetics: Why do genetically identical bacteria behave differently? - Ka Leo O Hawaii: Opinion

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Beyond genetics: Why do genetically identical bacteria behave differently?

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Posted: Wednesday, January 22, 2014 5:00 am

We are more than just our genes, and it’s no different for bacteria. Genetically identical bacteria behave in dramatically different ways. This phenomenon has been seen in factors such as growth rate, metabolism and resistance to antibiotics.

You know how you have to take all of your antibiotics in regular intervals (e.g., twice a day)? This is because antibiotics work by targeting bacteria at a certain cycle in their lives. Variability in growth rate ensures that it takes longer for some bacteria to become vulnerable to antibiotics. Not surprisingly, this variability has contributed greatly to the success of bacteria.

So if these differences are not caused by genetics, what are they caused by? A recent study conducted by the University of Washington stated that differences in chemical composition could account for extreme differences among bacteria. One of the bacteria in the study, Caulobacter crescentus, produces two daughter cells, which, while genetically identical, are different from each other. One has a tail to swim, while the other has a stalk, which anchors the bacteria to a surface.

This is due to the uneven distribution of chemicals during cell division, where a single bacterium splits into two. Differences in the amounts of important chemicals in individual cells greatly affect the overall appearance and function of the organism. 

These differences may not be limited to bacterial cells. 

“This is another way that cells within a population can diversify,” said Dr. Samuel Miller, the paper’s senior author. “Here we’ve shown it in a bacterium, but it probably is true for all cells, including human cells.”

In an age where genetic sequencing is becoming more commonplace, it is important to remember that our genes do not tell the whole story of who we are. As a human, it is comforting to know that we are more than just a linear sequence of molecules that can be read like a sentence, but rather, a complex network of biological connections that reads more like poetry.