FIGURE 7.1 Microbial diversity: examples of natural microbial communities. (A) A two-species bacterial biofilm cultivated in the laboratory in which one strain evolves to increase its exploitation of the other. Adapted by permission from Macmillian Publishers Ltd: Nature (Hansen et al., 2007), copyright 2007. (B) A two-strain bacterial aggregate detected on a bean leaf surface (magnification 500×) [Appl Environ Microbiol (2005) 71(9):5484–5493, 10.1128/AEM.71.9.5484–5493.2005. Reproduced with permission from the American Society for Microbiology] (Monier and Lindow, 2005). (C) Stromatolite fossil that is ~2 billion years old. Modern stromatolites consist of multilayered sheets of microorganisms, and are a good example of very diverse, yet spatially structured microbial communities (copyright Merv Feick, http://www.Indiana9Fossils.com). (D) The detection of two of the species present in a bacterial biofilm covering the intestinal mucosae of a self-limiting colitis patient, imaged using triple-color fluorescence in situ hybridization [J Clin Microbiol (2005) 43(7):3380–3389, 10.1128/JCM.43.7. 3380–3389.2005. Reproduced with permission from the American Society for Microbiology] (Swidsinski et al., 2005).
al., 2006; Foster, 2010). Social phenotypes in microbes include not only growth rate regulation (Kreft, 2004), which has the potential to affect the nutrients of surrounding cells, but also the widespread secretion of compounds that either promote or inhibit the growth of neighboring cells (Kerr et al., 2002; Griffin et al., 2004; Xavier et al., 2011).