Chemotaxing E. coli do not count single molecules.

Area of Science:

• Microbiology
• Biophysics
• Systems Biology

Background:

• Organisms require sensory-motor behaviors for survival.
• Previous research indicated that bacterial movement speed is limited by information acquisition.
• The precision of chemical sensing is theoretically limited by molecule arrival stochasticity.

Purpose of the Study:

• To investigate the factors limiting sensory accuracy in Escherichia coli chemosensing.
• To determine if the physical limit of molecule arrival stochasticity constrains bacterial chemosensing.
• To quantify the information encoded by E. coli's signaling pathway during chemotaxis.

Main Methods:

• Derivation of the physical limit for behaviorally-relevant information in chemical sensing.
• Quantitative experiments measuring information encoding in E. coli's signaling pathway.
• Application of information theory to analyze chemosensing performance.

Main Results:

• E. coli encodes significantly less information than an ideal sensor limited by shot noise.
• Bacterial chemosensing is not constrained by the fundamental limit of particle arrival noise.
• A two-orders-of-magnitude difference was observed between theoretical limits and E. coli's information encoding.

Conclusions:

• The sensory fidelity of E. coli is limited by factors other than particle arrival noise.
• Bacterial chemosensing accuracy is constrained by internal signaling pathway limitations.
• Further research is needed to identify the specific constraints on E. coli's sensory accuracy.