QVprep Microbiology Lessons

Microbial Classification



Mycoplasmatales: Because Mycoplasma species lack a cell wall, the Mycoplasmatales, which include Mycoplasma species and are aligned with the Phylum Firmicute (G+), stain Gram negative. During the Gram stain, if crystal violet was attracted to the cell membrane of Mycoplasma, decolorizing would remove this; thus, the counterstain would leave these cells looking as if they were Gram negative.

Phylum Proteobacteria: Within the Domain Bacteria is the Phylum Proteobacteria. This phylum consists of Gram-negative bacteria. Phylum Proteobacteria is the largest taxonomic group of bacteria. Classes of Proteobacteria include alpha, beta, gamma, delta, and epsilon proteobacteria.

Salmonella enterica : The current classification scheme that the CDC has sanctioned for Salmonella identification includes two distinct species, which comprises numerous serotypes. Genetic evidence suggests that the many species that once characterized the genus Salmonella are merely strains of one species, i.e. Salmonella enterica with a lesser amount comprising the species S. bongori.

Binomial system for naming microorganisms: In the binomial system for naming microorganisms, the first part of the name is the genus and the second part is the specific epithet. These two together constitute the species name. When writing scientific names, the genus is capitalized and the specific epithet is lower case. Also the name is either italicized (most common) or underlined, as in Escherichia coli.