How can you....?

Question

How can you measure bacteria?

I'm not sure that a microscope will work...

Eh, whatever...

Answer 1

Prepare it for electron microscopy.
Measure the magnification factor with a standard lines provided by the EM company.

Answer 2

Depends what you mean by "measure"...

If you want to know how many there are, then you can measure the OD (optical density) in a spectrophotometer - basically the "cloudiness" of the bacterial suspension. The more bacteria there are, the cloudier the suspension will be, and the less light will make it through the solution.
Another method is to perform terminal dilutions on agar plates from your suspension. You take your suspension, and spread 1ml on an agar plate. Dilute your suspension 1/10, and spread 1 ml of that on another plate. Dilute *that* 1/10, and repeat. Eventually, you'll get a plate where only 1 or 2 colonies grow: so you know that *that* dilution had 1 or 2 bacteria in 1 ml of the suspension. So, for example, if you had to dilute 5 times to get that 1 bacterium per ml, then you can work backwards to figure out that your original suspension had ~100,000 bacteria/ml.

If you mean physically measure the bacterial cell length, etc. - then you'll need to use an electron microscope. Light microscopes generally cannot give you sufficient resolution to properly measure individual bacterial cells, so SEM or TEM are the way to go for this.

Answer 3

Yup, microscope. Many microscopes have a ruler in the field of view (which can be made because you know how many times your optics are magnifying what you are looking at). As for the technicalities of how the manufacturer of the microscope puts the little ruler in the field of view...hmm... Engineers are very smart :)

Or a more complicated way if you didn't have the little ruler...I'm just guessing...you could use a microscope to count how many bacterial cells you had in a solution of bacteria and measure out, say 10 million of them. Compact them using a centrifuge so that there is no liquid between them. The volume this occupies will be the volume of 10 million bacteria. (You could estimate volume by weighing the bacteria, since they are mostly water and we know the density of water.) Then, back at your microscope, estimate the shape of your bacteria. (for example, a cylinder that is 20 times longer than it is wide). You know the volume of one bacterium, so a little geometry, and - boom - a rough estimate of dimensions.

Answer 4

Measuring instruments for microscopes can be obtained. For microscopic measuring, the instruments are glass slides that are etched with lines. The lines are certain divisions of a millimeter and with the tools you can measure/count bacteria.

Answer 5

Under microscope using a graticule and stage micrometer

Answer 6

With a microscope.

Answer 7

You can use a spectrophotometer to measure the optical density (OD) of the suspension.

Answer 8

With a tiny measuring tape!! LOL