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Name: Mason
Status: student
Grade: 6-8
Location: LA
Country: USA
Date: Winter 2012-2913
Question:
How much does bacteria weigh?


Replies:
There are many different kinds of bacteria of varying sizes, so one can only obtain an estimate. To estimate the general order of magnitude (to within about 10 times the actual amount), you could make the following assumptions: the volume of many bacteria is approximately 1 cubic micrometer. If you assume that most of a bacteria is composed of water, assuming the bacterial density to be 1 g/ml (at 4 degrees Celsius), one can estimate that a single bacterium has a mass of about 1 X 10 ^-12 grams, or 1 picogram. This is only a rough estimate - a specific bacterium can be larger or smaller than the estimate, and the density of a bacterium is almost certainly higher than that of pure water.

For a sense of how small a picogram is, you would have to gather 150 million million bacteria in order to have approximately the same mass as a baseball.

Dr. Shimon Unterman

Hi Mason,

Thanks for the question. Since there are many types of bacteria, each bacteria will have its own weight. I estimate that a bacteria weighs about 10 nanograms or 0.00000001 g. This value is only a crude estimate.

I hope this helps. Please let me know if you have any more questions. Thanks Jeff

It depends on which bacteria. The estimates range from 6.25 x 10^-10 the heaviest to 3 x 10^-16.

(reference is http://hypertextbook.com/facts/2003/LouisSiu.shtml)

Stephen R. Dunn Ass't Professor of Medicine (ret.) Dept. Medicine/ Div. Nephrology & Cancer Genomics Kimmel Cancer Center Thomas Jefferson University


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