Flexirubin

Flexirubin is the main pigment in the bacteria genera <a href="/facts/Flexibacter/5724pTXF">Flexibacter</a>, <a href="/facts/Flavobacterium/HujHXh3A">Flavobacterium</a>, <a href="/facts/Chryseobacterium/HSyTWzPI">Chryseobacterium</a>, and <a href="/facts/Cytophaga/C5QKzoTI">Cytophaga</a>. It was isolated for the first time from Flexibacter elegans. Flexirubin is found in these genera, as well as those that produce <a href="/facts/Carotenoid/Jm2eHYwW">carotenoids</a>. The pigment mixture of flexirubin and carotenoids imparts <a href="/facts/Colony_(biology)/b5QfltwY">colonies</a> with an intense yellow-orange color. Structurally, this bacteria pigment is based on a polycarboxylic-<a href="/facts/Chromophore/9RykVkek">chromophore</a> that is linked with a <a href="/facts/Phenol/ACJs5NIU">phenol</a> by an <a href="/facts/Ester/FoUAIIw4">ester</a>, resulting in an <a href="/facts/Alkyl/vmEk8X4v">alkyl</a> side-chain. The first <a href="/facts/Total_synthesis/3GGoqhBm">total synthesis</a> of flexirubin was reported in 1977.
To test for the presence of flexirubin, a cultural strain with a 20% <a href="/facts/Potassium_hydroxide/NBhPBuXc">potassium hydroxide</a> solution is created. A color change from gold to red-brown indicates the presence of flexirubin. Alternatively, the pigment can also be extracted with <a href="/facts/Acetone/cVyJxKqw">acetone</a> and chromatographic methods can be used to ascertain its presence.

Flexirubin open-in-new

Flexirubin