Microscope direct counting

Experiment 30
microscope
direct , the purpose requirements1. Clarify the principle of microscope counting.2． Learn how to use a blood cell
to
microorganisms., basic principle the use of blood cell counting boards under the microscope directly counting, is a commonly used microbial counting method. The advantage of this method is that it is intuitive and fast. Place the properly diluted bacterial suspension (or spore suspension) in the counting chamber between the blood cell counting board slide and the cover slide and count under a microscope. Since the volume of the counting chamber is certain ( 0. 1mm2), so the total number of microorganisms per unit volume can be converted to the number of microorganisms observed under the microscope. Because this method is calculated as the sum of living and dead bodies, it is also known as the total bacteria counting method.a blood cell counting board, usually a specially made slide with three platforms made up of four grooves. The intermediate platform is divided into two halves by a short horizontal slot, each side of the platform engraved with a grid, each grid is divided into nine squares, the middle of the large square is the counting room, the count of microorganisms in the counting room. The blood cell count board is constructed as shown in Figure VIII.-1.The scale of thecounting room generally has two specifications, one is a large square divided into 16 Squares, and each Chinese grid is divided into 25 small squares (Figure VIII.-2); But no matter what size of the counting board, the number of small squares in each large square is the same, that is, 16×25 x 400 small squares, as shown in Figure VIII.-2.each large square edge is 1mm long, each large square has an area of 1mm2, and after the cover glass is covered, the height between the slide and the cover glass is 0. 1mm, so the volume of the counting room is 0. 1mm3 。In the count, usually count the total number of bacteria in five Squares, and then find the average of each Chinese grid, multiplied by 16 or 25, to arrive at the total number of bacteria in a large square, and then converted to 1 ml of bacteria in the total number of bacteria.below, take a large square with 25 Chinese grid counting board as an example to calculate: set five Chinese grid in the total number of bacteria A, bacteria dilution multiplies of B, then, the total number of bacteria in a large square in 1 ml , 1cm3 , 1000mm3,, 50000A . B (one)the same, if it is 16 Chinese grid counting board, set the total number of five Chinese grid a', then
three, equipmentwine
yeast
bacteria suspension, blood cell counting board, microscope, cover glass, sterile capillary tube., the operation step 1. Dilutionthe wine-making yeast suspension is properly diluted, if the liquid is not strong, it does not have to be diluted.2． The mirror check the counting room of the counting board before the sample is added. If there is dirt, it needs to be cleaned before it can be counted. 3． Add sample will clean
dyrive
blood cell counting plate covered with a slide, and then with a sterile thin-mouthed dropper will be diluted wine yeast liquid from the edge of the cover glass drop a small drop (not too much), so that the bacteria along the gap by fine penetration into the counting room, the general counting room can be filled with fungus. Be careful not to have bubbles. 4． Microscope Count After 5 minutes of stationary rest, place the blood cell counting plate on the microscope stage, first using a low multiplle to find the location of the counting chamber, and then replaced with a high multiplile mirror to count. If the fluid is found to be too thick or too thin before counting, the dilution must be re-adjusted before counting. General sample dilution requirements of about 5-10 bacteria per small gig is appropriate. Each counting chamber selects 5 middle cells (optional 4 corners and a central grid) to count the bacteria. Bacteria located on the grid are generally only above and on the right line. In the event of yeast germination, when the size of the bud reaches half that of the mother cell, two bacterial counts are made. Counting a sample is calculated from the values in the two counting chambers to calculate the bacteria content of the sample. 5． Wash the blood cell count board After use, rinse the blood cell count board with a water column on the head of the water cage, do not wash it with hard objects, dry itself after washing it or dry it with a hair dryer. A mirror examination to see if there are any residual bacteria or other sediments in each small gig. If not clean, it must be washed repeatedly until it is clean. , the experimental report 1. Results the results in the table below. A represents the total number of bacteria in the five Chinese grids; 2． Question: based on your experiments, what are the main areas of error in counting with blood cell counting boards? How to minimize errors and strive to accurately