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.pdf

•Did you know, bacteria contribute about 10% of our genes? Spores can travel in space!

Branching

Chiral