1. The Effect of Caffeine on Growth of Pseudomonas fluorescens Author: Eric Huffman Samy Behairy

2. In the Mix P. fluorescens, a common bacteria found in soil and water, that also has a versatile metabolism. 2% nutrient broth is used for optimum growth in solution. Caffeine a stimulant to humans, is used as a defense mechanism against insects and fungi.

3. Hypothesis Given the research on caffeine production by plants and from scholarly articles, it is hypothesized that caffeine will act as a antibacterial agent on the growth of P. fluorescens. Given high mutation rates of bacteria, in 2% Nutrient broth, it is hypothesized that P. fluorescens can mutate to resist increasing levels of caffeine concentrations.

4. What and How? What is the concentration of NB to support optimal growth of P. fluorescens? What is the effect of caffeine in various concentrations on the growth of the bacteria with optimal NB concentration? How resistant can we make overnight cultures of P. fluorescens to those caffeine concentrations in the shortest amount of time?

8. Conclusion Both hypothesis were proven, with limitations. Caffeine had an antibacterial effect on P. fluorescens, decreasing growth as caffeine percentage increased. Inoculated to increasing percentages of caffeine in overnight cultures, P. fluorescens showed increased resistance with negative feedback at levels inoculated above 1% caffeine overnight cultures. Future research can study the effects of higher concentration of caffeine where sample size is not a limitation (difficulty maintaining proportions) Why do resistant cultures take longer for the initial growth burst (Lag Phase)?

9. Sources Pictures in order. http://web.mst.edu/~microbio/BIO221_2009/images _2009/Pseudomonas-1.jpg http://web.mst.edu/~microbio/BIO221_2009/images _2009/Pseudomonas-1.jpg http://www.caffeine.com/2762115755_162d5e3423_ o.png http://www.caffeine.com/2762115755_162d5e3423_ o.png http://7bigspoons.com/wp- content/uploads/2011/06/bacteria-living-on- caffeine-only.png http://7bigspoons.com/wp- content/uploads/2011/06/bacteria-living-on- caffeine-only.png