Roles of functional amyloids in biofilms

Published on June 29, 2023   48 min

A selection of talks on Microbiology

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Hello. My name is Peter Lipke from the Biology Department at Brooklyn College of the City University of New York. Today I'm going to give a lecture on the roles of functional amyloids in biofilms. I hope at the end of the lecture, you have learned something about biofilms and something about amyloids and the intimate connection between them.
Both amyloids and biofilms are aggregations. Amyloids are well-structured aggregates of proteins at the molecular scale and biofilms are well-structured aggregations of microbes at the cellular scale, therefore we are talking about aggregations with size scales from nanometers to centimeters. Biofilms are communities of aggregated microbes embedded in a matrix and they form at interfaces. They form between solid and liquid interfaces, between liquid and air interfaces and between host and pathogen. Here we see a picture of a biofilm about 5 cm in diameter from Bacillus subtilis, that's the one that's nicely stained pink. Amyloids are structured aggregates of proteins and they usually form insoluble fibers. Here's a picture of some amyloid fibers. They are typically 10-50 nm in diameter. It turns out that these amyloids have essential functions in biofilms. They provide both structure and physical strength, and at the bottom here is a picture of a fungal biofilm. The cells are 2-25 μm in length and this micrograph is stained to show the amyloid structures.
Biofilms are full of amyloids. Here on the left is a scanning electron micrograph of a biofilm of E. coli bacteria. The thin fibers highlighted by the arrowheads are amyloid fibers. On the right is a biofilm from the fungus Candida albicans that's stained with thioflavin T, so amyloid is the only thing that stains and you see these beautiful amyloid sheets around each of the cells in each of the hyphae.