/ Thesaurus / P Synonyms of purple bacteria Find synonyms for: Noun1. purple bacteria, phototrophic bacteria, phototropic bacteriausage: free-living Gram-negative pink to purplish-brown bacteria containing bacteriochlorophyllWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: winsome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language