FIG 4.

Bright-field micrograph of an anammox biofilm surface protein construct (amino acids 1354 to 1439) in an aqueous solution of 20 mM Tris (pH 7.5)–125 mM NaCl–2 mM DTT, 4°C, with (A) and without (B) polyethylene glycol at 100 μM), showing that liquid droplet formation in the Tris solution is induced by PEG. (C) Photograph of solution of an anammox biofilm surface protein construct (amino acids 1254 to 1338) in a 4-mm glass tube in the absence (left) and presence (right) of 20% (wt/vol) PEG, showing increased turbidity following PEG addition (C). (D and E) Bright-field (D) and epifluorescence (E) micrographs of isolated anammox biofilm surface protein (0.6 μM) in an aqueous solution of 20 mM Tris (pH 7.5)–125 mM NaCl–2 mM DTT, 4°C, labeled with protein-specific Alexa Fluor 647 dye (Thermo Fisher). This shows that the liquid droplets formed in the Tris solution are proteinaceous.