This is what you’re used to…

1. This is what you’re used to…

2. …but this is what can happen. Bacterial Colony Growth

3. 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…

4. …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”

5. 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

6. B-C

8. 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!

9. Branching

10. Chiral