The Environmental Conditions That Influence the Induction of the Autoinducer-2 Quorum Sensing System in Escherichia coli AB1157 and the Effects of This System on Growth

Escherichia coli strain AB1157 is known to employ the autoinducer-2 (AI-2) quorum sensing system in certain environmental conditions. This system is hypothesized to allow the bacterium to alter its growth rate in response to environmental stimuli such as the nature of the carbon sources available and the pH of the environment. Maximum AI-2 production was expected in acidic, glucose-supplemented media. This maximal level of AI-2 was expected to reduce the growth rate of the test cultures relative to a control situation. The small AI-2 molecule can be quantitatively detected through the use of a Vibrio harveyi reporter strain; this bacterium luminesces at a threshold stimulatory concentration of the autoinducer. The trend observed in the data indicates that maximal autoinducer production may occur when AB1157 is grown in media supplemented with glucose. However, no direct correlation between maximal levels of autoinducer production and alterations in growth pattern were observed. Our results do not conclusively show a relationship between AI-2 production and growth nor can a comparison be made on the effects of glucose versus glycerol metabolism on AI-2 production.