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Cultivation conditions and the diffusion of oxygen into culture media: The rationale for the flask-to-medium ratio in microbiology

Greg A Somerville1* and Richard A Proctor2

Author affiliations

1 School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE 68583-0905, USA

2 Departments of Medicine and Medical Microbiology/Immunology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA

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Citation and License

BMC Microbiology 2013, 13:9  doi:10.1186/1471-2180-13-9

Published: 16 January 2013


Bacterial cultivation requires consideration of three things: The bacterial strain, cultivation medium, and cultivation conditions. Most microbiologists dutifully report their choice of strains and cultivation media in manuscripts; however, these same microbiologists often overlook reporting cultivation conditions. Without this information, it is difficult to determine if cultures were grown aerobically, microaerobically, or anaerobically. To cultivate bacteria aerobically, it is necessary to understand that oxygen does not readily diffuse into culture media; it needs help to get in. Microbiologists can do this by altering the flask-to-medium ratio, rpm of agitation, and/or the concentration of atmospheric oxygen, or by using baffled flasks.

Cultivation conditions; Aeration; Oxygen diffusion