FIG. 6.1 A metabolic classification of organisms. Organisms can be classified according to their energy and carbon sources.

Photo sources: (clockwise from top-left) Dr. Tony Brain/Science Source; ScienceFoto.DE/Dr. Andre Kemp/Getty Images; Copyright 1997 Microbial Diversity, Rolf Schauder; Martin Oeggerli/Science Source; DNY59/iStockphoto; David J. Patterson; EM image by Manfred Rohde, Helmholtz Centre for Infection Research, Braunschweig, Germany; Anna Omelchenko/Dreamstime.com.