|Phototrophic Microbial Mats|Stal, L.J.; Bolhuis, H.; Cretoiu, M.S. (2017). Phototrophic Microbial Mats, in: Hallenbeck, P.C. Modern Topics in the Phototrophic Prokaryotes : environmental and applied aspects . pp. 295-321. https://dx.doi.org/10.1007%2F978-3-319-46261-5_9
Microbial mats are structured, small-scale microbial ecosystems, andsimilar as biofilms cover a substratum like a tissue. A general characteristic of amicrobial mat is the steep physicochemical gradients that are the result of the metabolicactivities of the mat microorganisms. Virtually every microbial mat isformed through autotrophic metabolism and through the fixation of atmosphericdinitrogen. Chemoautotrophic organisms fuel these processes in the absence oflight. In illuminated environments photoautotrophic organisms are the drivingforce and these mats are subject of this chapter. In the vast majority of cases, primaryproduction by the oxygenic phototrophic cyanobacteria is the basis of adiverse community that forms a living entity with a macroscopic habitus. Thisentity has its own physiology that is the result of interaction, communication,cooperation, and competition of the individual functional groups of microorganisms.Organic matter is remineralized and in sulfur-dominated environments sulfate-reducing bacteria are responsible for end-oxidation that leads to the productionof sulfide, which is used by anoxygenic photoautotrophic bacteria. Aerobic andanaerobic anoxygenic phototrophic bacteria and proteorhodopsin-containing bacteriaare important as secondary producers and take care of the decomposition oforganic matter in a process that is aided by light.