QVprep Microbiology Lessons

Microbial Classification



Actinobacteria: Members of the Phylum Actinobacteria are Gram positive bacteria with a high G+C content.

Classification of Microbes - Three-Domain System for the classification of organisms: In the late 1970’s, Carl Woese developed the Three-Domain System for the classification of organisms. The three domain system consists of two prokaryotic domains (Archaea and Bacteria) and a single domain that encompasses all eukaryotes (Eukarya). Prokaryotes are divided into two distinct domains (Archaea and Bacteria) based on the differences in molecules of rRNA.

Family level (taxon) of classification of bacteria: The Enterobacteriaciae are gram-negative bacteria that include Escherichia coli and Salmonella species In accordance with the five Kingdom classification system, Enterobacteriaciae is the family level (taxon) of classification of bacteria.

Gram positive bacteria: The gram positive bacteria are divided mainly into the Actinobacteria and the Firmicutes. Actinobacteria consists of organisms with DNA that is high G+C. Firmicutes consists of microbes with low G+C genomes. Clotridiales include Clostridium species are orders of the Phylum Firmicute are endospore formers. This Order also includes the giant bacterium Epulopiscium.