Directed Evolution: Engineering Biocatalysts, Spring 2008

Abstract:: Enzymes, nature's catalysts, are remarkable biomolecules capable of extraordinary specificity and selectivity. Directed evolution has been used to produce enzymes with many unique properties, including altered substrate specificity, thermal stability, organic solvent resistance, and enantioselectivity--selectivity of one stereoisomer over another. The technique of directed evolution comprises two essential steps: mutagenesis of the gene encoding the enzyme to produce a library of variants, and selection of a particular variant based on its desirable catalytic properties. In this course we will examine what kinds of enzymes are worth evolving and the strategies used for library generation and enzyme selection. We will focus on those enzymes that are used in the synthesis of drugs and in biotechnological applications. This course is one of many Advanced Undergraduate Seminars offered by the Biology Department at MIT. These seminars are tailored for students with an interest in using primary research literature to discuss and learn about current biological research in a highly interactive setting. Many instructors of the Advanced Undergraduate Seminars are postdoctoral scientists with a strong interest in teaching.

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Isolating Multiple Strains of Escherichia coli for Coliphage Isolation, Phage-typing, and Mutant Recovery

Abstract:: Recovery of Escherichia coli from a rectal swab begins a series of procedures combining mastery of technique with productive experiments. After isolating his/her own E. coli strain, each student recovers a unique coliphage from raw sewage and determines its host range, thereby revealing the genetic individuality of each bacterial and viral isolate. Colonies of virus-resistant mutants can often be recovered in regions where sensitive bacteria have been destroyed. After antibiotic sensitivity testing of E. coli isolates, a variety of antibiotic resistant mutants can be recovered, thus yielding genetically marked strains for future bacterial genetics experiments.

Abstract:: In this course, we will discuss the microbial physiology and genetics of stress responses in aquatic ecosystems, astrobiology, bacterial pathogenesis and other environments. We will learn about classical and novel methods utilized by researchers to uncover bacterial mechanisms induced under both general and environment-specific stresses. Finally, we will compare and contrast models for bacterial stress responses to gain an understanding of distinct mechanisms of survival and of why there are differences among bacterial genera.