Highlight—Microbial Mat Morphology—Nature or Nurture?

Microbial mat descriptions and classifications in modern peritidal systems focused on morphological descriptions, leaving the origins to be debated among beer-drinking geologists. To understand the roles of microbial communities and environmental conditions in the genesis and morphology of tidal flat microbialites, Trembath-Reichert and others applied optical microscopy and gene sequencing methods to study the microbial composition of mats from a tidal algal marsh in Caicos, B.W.I. Microscopy results are consistent with an interpretation that Cyanobacteria colonizing the initial mat surface are responsible its structure.  Although genetic data show the same relative abundances of the same Cyanobacteria in both “flat” and “biscuit” type mats, gene sequencing reveals that total diversity and community composition is significantly greater in the biscuit mat morphotype. These results suggest that mat morphology reflects time-integrated microbial response to various environmental factors, and in which the community diversity increases with time after environmental disturbance.  Morphology is not a consistent signature of component microorganisms. [Ed. Note: The importance of Genes cannot be understated.]

Gene sequencing-based analysis of microbial mat morphotypes: Caicos Platform, British West Indies by Elizabeth Trembath-Reichert, Lewis M. Ward, Sarah P. Slotznick, Steven L. Bachtel, Charles Kerans, John P. Grotzinger, and Woodward W. Fischer