Although microbial life abounds on earth and has done so for billions of years, particularly the prokaryotic microbes defied an evolutionarily perspective until the 1980s. Archaea (formerly known as archaebacteria) were hardly known about then and many bacteria studied were human, animal or plant pathogens. Microbiologists studied bacteria by isolating them in pure culture on agar media (incubated under specific conditions of temperature, pressure and atmosphere) and defined their taxonomy by determining aspects of their phenotype (e.g. sole carbon sources for growth, acid production) and their genotype (e.g. mol% G+C of the genome).
How did the field of microbial ecology evolve? Development of methods exploring the 16S rRNA and its gene was crucial. PCR using “universal” 16S rRNA gene primers with DNA isolated from complex microbial communities, cloning and sequence analysis lead to the understanding that microbial diversity was tremendously greater than imagined and that bacterial taxonomy based on phenotype was flawed. Metagenomics was born and several complex microbial communities were subjected to this procedure. This led to some comprehension of resident microorganisms and genes in the community, to development of methods linking community structure with function and to discovery of organisms with novel metabolic pathways. Other “omics” and “meta” fields were spawned to address microbial community function. Microbial ecology is a field in evolution and the talk will highlight some of the procedures and findings that allows it to inform us about critical aspects of life on earth.