Document Type

Research Paper


A consortium is a close physical association between microbial cells of different lineage (Liu et al. 2013). The phototrophic consortium is an aggregation of two different lineages of bacteria: one large motile bacterium surrounded by many smaller photosynthetic bacteria. They live in freshwater lakes around the world with varying degrees of morphological differences. Bacteria are historically accepted as a ubiquitous species, meaning that if the environment permits them to live there, they will. This hypothesis was first introduced by Beijerinck and Becking in the early 1900s to describe the distribution of microorganisms, with the official mantra being, “everything is everywhere, but the environment selects” (Becking 1934, 15). Although this has proven true with common pathogenic bacteria such as E. coli and Salmonella, studies suggest that conditions do not always permit this hypothesis to hold true. With the similarities in environment that the phototrophic consortia inhabit, and the striking parallels between the evolved interspecific interactions, it would make sense that they are all descendants of one symbiotic partnership, and have diverged morphologically over time within a region. However, the morphological differences that have been found to exist between the geographic distributions of bacteria may indicate separately evolved symbiotic relationships. I believe that the increased fitness—greater ability to survive and divide—provided by the consortium of the two bacterial genera was enough to drive the same symbiotic evolution across separate geographic locations.



Subjects - Topical (LCSH)

Bacteria--Evolution; Bacteria--Geographical distribution


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