Mosses and lichen growing symbiotically on concrete surfaces: How do they got there and why can they live there?

How can anything survive and grow on concrete? What are the nutrients that could support the growth of plants on concrete? By forming the energy and carbon source at the base of the food chain, cyanobacteria form the basis for the establishment of a more complex niche where fungus can use the organic compounds produced by cyanobacteria as food for growth. This is the keystone species concept in ecology, where a specific species helps lay the foundations (in this case, nutrients, or coax a habitat from non-habitable to habitable) for other species to thrive at the same ecological niche. Cyanobacteria is the pillar of oxygen requiring life on Earth, and led to the establishment of land-based ecosystems by being able to photosynthesize and convert carbon dioxide into complex molecules and release oxygen as a byproduct in the process. Known as symbiosis, the complex exchange of metabolites and other as yet unknown functions between fungus and cyanobacteria is a good example for students to understand mutually beneficial interactions between species at the cell cluster level. Naturally, different levels of biological organization and complexity will have differing impact on how symbiosis is articulated in practice, whether it is exchange of metabolites, byproducts as nutrients, energy or shelter. Green slimy material on concrete drains in urban Singapore arose my curiosity on how beautiful they are, and how tenacious life is, and led to a rapid capture of photographs of what is probably mosses and lichen (cyanobacteria and fungus symbiont). The photographs are embedded within the appended PDF file together with a short write-up that highlights important and interesting research questions on how life could possibly start on inorganic materials many eons ago. Questions which I have no answers to, but which are fundamental to our understanding of how life first evolved on Earth. Educators are free to use the photographs to tell the important concept of symbiosis between organisms, keystone species as laying the bedrock of an ecosystem, as well as introduce the shape and form of such symbiotic community in an urban environment. What I saw is likely to be mats of mosses growing on lichen in a drain, but my conjecture cannot be verified without standard microbiology technique of sampling, cultivation, pure culture and identification through 16S rRNA gene sequencing, whole genome sequencing, or the increasingly useful and reliable mass spectrometry enabled microbe identification. The last point is crucial: what you see in microbes’ identities need to be verified through understanding their genetic repertoire at 16S rRNA.