Common Laboratory Microbes

By Levi Clancy for Student Reader on

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Optimal temperature of 30°C; strict aerobes, except in presence of nitrate or amino acids, and never fermentative; gram-negative; motile; non-sporulating; and cytochrome oxidase positive. No more than 3µm in size. Some species are capable of dissimilative nitrate reduction (denitrification) -- assimilative nitrate reduction is for nitrogen as a general nutrient, instead of an energy source.

E. Coli

Rod-shaped, gram-negative, motile and diverse.

M. smeg

S. epidermidis

S. salivarius

Gram-positive chains of cocci; requires sucrose to form capsules; ferments glucose.


Soil-dwelling sporulating strict aerobes, many of which secrete antibiotics.