Lake pigment rich red color. They were very often used by Titian and other Venetian artists of the 16th century to depict fine draperies and fabrics. Indigo and rose madder are now produced more cheaply from synthetic sources, although some use of natural products persists, especially among artisans. The food and cosmetics industries have shown renewed interest in cochineal as a source of natural red dye. Lake pigment A lake pigment is a pigment made by precipitating a dye with an inert binder, or "mordant", usually a metallic salt. Unlike vermilion, ultramarine, and other pigments made from ground minerals, lake pigments are
Photosynthetic pigment other groups of bacteria use the bacteriochlorophyll pigments (similar to the chlorophylls) for photosynthesis. Unlike the cyanobacteria, these bacteria do not produce oxygen; they typically use hydrogen sulfide rather than water as the electron donor. Recently, a very different pigment has been found in some marine γ-proteobacteria: proteorhodopsin. It is similar to and probably originated from bacteriorhodopsin (see below: under Archaea). Bacterial chlorophyll b has been isolated from Rhodopseudomonas spp. but its structure is not yet known to us. Halobacteria use the pigment bacteriorhodopsin which acts directly as a proton pump when exposed to light. Photosynthetic pigment A photosynthetic pigment