Download Jen Trinh.

This is what you’re used to…
…but this is
what can
happen.
Bacterial Colony Growth
In General
•Binary fission
•Increase cell size and mass until the cell can divide
•Doubling period/generations
•Exponential growth
•When there are enough bacteria (quorum), colony behaves
like a multicellular organism
•Normal conditions, normal patterns like on first slide.
Usually nutrients on agar in a petri dish
•But when the colony is stressed…
…cool things can happen.
•Bacteria have sensors and are able to
secrete many different kinds of chemicals
that can deter other bacteria from going
there (areas of high density and/or low food)
or lubricant to facilitate movement on hard
surfaces. Communication methods unclear.
Resemble neural network
•Eshel Ben Jacob: “bacteria are cooperative
beasts that lead complex communal lives
with rapidly evolving social intelligence”
Paenibacillus dendritiformis
•Self-engineering: Two morphotypes
(identities)
•Hard surface response: branching…detect
concentration of chemicals as they go, stop
when they reach places they don’t want to
•Soft surface response: chiral due to flagella
being chiral
B-C
Sources
•http://www.medicalnewstoday.com/articles/24337.php
•http://www.textbookofbacteriology.net/growth.html
•http://polymer.bu.edu/ogaf/html/chp51.htm
•http://star.tau.ac.il/~eshel/papers/Interface.pdf
•http://www.cellsalive.com/ecoli.htm
•http://star.tau.ac.il/~eshel/papers/Bacteria%20harnessing%20complexity.pd
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•Did you know, bacteria contribute about 10% of our genes? Spores can
travel in space!
Branching
Chiral