Course Meeting Times

Lectures: 1 session / week, 2 hours / session


At least one of the following courses:

7.03 (Genetics)
7.08 (Molecular Biology)

Course Description

Bacteria survive in almost all environments on Earth, including some considered extremely harsh. From the steaming hot springs of Yellowstone to the frozen tundra of the arctic to the barren deserts of Chile, microbes have been found thriving. Their tenacity to survive in such extreme and varied conditions allows them to play fundamental roles in global nutrient cycling. Microbes also cause a wide range of human diseases and can survive inhospitable conditions found in the human body.

In this course, we will examine the molecular systems that bacteria use to adapt to changes in their environment. What types of signal transduction pathways do bacteria use to monitor their surroundings? How do they activate the appropriate cellular response? Model systems such as Escherichia coli and Bacillus subtilis have been the tools for discovering many key concepts, and most of the course will address how these organisms execute their responses to changes in the environment. We will consider stresses commonly encountered, such as starvation, oxidative stress and heat shock, and also discuss how the adaptive responses affect the evolution of the bacteria. We will also examine how different signals integrate into signal transduction pathways to determine whether the bacteria will deal with one specific stress or enter a more general dormant state and "batten down the hatches" until conditions improve.

Throughout the course, we will refer to the clinical and industrial applications of the stress responses in medically and environmentally relevant organisms. We will gain an appreciation of the power of bacterial genetics and how our detailed understanding of the microbial stress response is key to our ability to control bacteria in the wild and in disease.


The objectives of this course are:

  1. Be able to read and critique the primary scientific literature.
  2. Understand the signaling pathways microbes use to monitor their environment and the corresponding strategies they enact to survive in different conditions.
  3. Understand the molecular techniques commonly used in microbiology.
  4. Be able to design novel experiments with the proper controls to test new hypotheses.


Each week, students will read the assigned papers carefully and participate actively in the group discussion. Students are expected to come to class with an understanding of all the figures and tables in the papers. To help guide the discussion, students will submit two questions about each paper to the instructor before the class; the questions can be about background information, techniques, figures or tables, or conclusions.


This course is graded pass/fail. Grading will depend on student attendance, participation in class discussions and completion of two assignments.


Introduction to the general stress response and sporulation (3 sessions)
1 Introduction  
2 The general stress response and sporulation  
3 Evolution of the general stress response and sporulation  
Mechanisms of sensing stresses (3 sessions)
4 Protein-protein interactions: Two-component systems  
5 sRNAs: Regulating translation mRNA of RpoS (the general stress response activator)  
6 Small molecules: The stringent response  
7 Field trip to the Laub laboratory Written Assignments due
Mechanisms of mitigating stresses (4 sessions)
8 Pumping out toxins: Antibiotics  
9 Scavenging toxins: Reactive oxidative species  
10 Promoting tolerance: Extreme heat and cold  
11 Final oral presentations  
12 Repair calls: Single-stranded DNA damage