Measurement & Motility of Microorganisms

Hi and welcome to my blog. so our last practical class we did the experiment of measurement of microorganisms and the examination of microorganisms using hanging drop and wet mount. The hanging drop technique is a well-established method for examining living, unstained, very small organisms. The traditional procedure employs a glass slide with a circular concavity in the centre into which a drop of fluid, containing the 'microorganisms', hangs from a coverslip. Meanwhile for In a wet mount, the specimen is placed in a drop of water or other liquid held between the slide and the cover slip by surface tension. This method is commonly used, for example, to view microscopic organisms that grow in pond water or other liquid media, especially when studying their movement and behavior.

preparation of hanging-drop

Preparing wet mount

Meanwhile for the practical of measurement of microorganisms, we need ocular micrometer and stage micrometer. first we need to find the calibration factor. Then next we can measure the size of microorganisms, find its average and multiply with calibration factor so we can get the size of microorganisms. 

A Stage Micrometer is simply a microscope slide with a finely divided scale marked on the surface. The scale is of a known true length and is used for calibration of optical systems with eyepiece graticule patterns. To achieve the calibrated measurement of the sample, multiply the measured value of the sample by the labeled magnification of the objective lens divided by the actual magnification ratio. An ocular micrometer is a glass disk with ruled scale on the surface which is etched in chromium.An ocular micrometer is a glass disk that fits in a microscope eyepiece that has a ruled scale, which is used to measure the size of magnified objects. The physical length of the marks on the scale depends on the degree of magnification. To calibrate a microscope we must Start with the lowest power objective on the microscope. The scale on the stage micrometer is aligned with the scale of the eyepiece graticule and then a reading is taken from the scales. These readings are then used to calculate the calibration factor for the objective lens in use.