BIMO Class of 1960s Scholar Seminar

Friday, September 26, 2014 at 1:10pm

Thompson Biology

Dianne Newman, PhD., CalTech

Why changing color matters to Pseudomonas aeruginosa

One of the defining attributes of Pseudomonas aeruginosa is its striking blue-green color.  While microbiologists and clinicians have long used color to identify the organism, why it is colored in the first place—and why its color changes with aeration—is a question that not many have considered.  We now know that phenazines, a class of redox-active pigments, are responsible not only for the blue-green color of P. aeruginosa in the presence of oxygen, but also for different colors displayed by other Pseudomonas species.  Phenazines came to be known as "secondary metabolites", molecules produced at late stages of microbial growth in laboratory cultures whose function was thought to be to protect Pseudomonas species from competitors.  While the antibiotic activity of phenazines has been elegantly shown in a variety of contexts, labeling phenazines as “secondary metabolites” suggests that they are not essential to the growth or survival of their producers.  I will discuss a variety of important physiological functions phenazines play for P. aeruginosa under anoxic conditions that transcend their antibiotic activity, including controlling carbon flux through central metabolic pathways, redox homeostasis, iron acquisition, survival in multicellular communities, and cell-cell signaling including the implications of these findings for treating cystic fibrosis infections.

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Biology, Chemistry, Biochemistry & Molecular Biology

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