Cover glass Chamber holding (a) bacteria (b) (c)
Figure 5.14 Ridges that support coverslip To calculate number Coverslip per milliliter of sample: 12 cells×25 large squares×50×103 Number/mm2(3×102) Sample added here.Care must be taken not to allow overflow;space Number/mm3(1.5×104) between coverslip and slide is 0.02 mm Microscopic observation;all mm.Whole grid has 25 large cells are counted in large squares,a total area of 1 mm2 and square(16 small squares): Number/cm3(ml)(1.5 x 107) a total volume of 0.02 mm3. 12 cells.(In practice,several large squares are counted and the numbers averaged.) Direct microscopic counting procedure using the Petroff-Hausser counting chamber
Figure 5.14 Coverslip Ridges that support coverslip To calculate number per milliliter of sample: 12 cells 25 large squares 50 103 Number/mm2 (3 102 ) Number/mm3 (1.5 104 ) Number/cm3 (ml) (1.5 107 ) Sample added here. Care must be taken not to allow overflow; space between coverslip and slide is 0.02 mm ( mm. Whole grid has 25 large squares, a total area of 1 mm2 and a total volume of 0.02 mm3 . Microscopic observation; all cells are counted in large square (16 small squares): 12 cells. (In practice, several large squares are counted and the numbers averaged.) 1 50 Direct microscopic counting procedure using the Petroff-Hausser counting chamber
上泽充通大学 Shanghai Jiao Tong University Limitations of microscopic count Dead cells and living cells are all counted Small cells are difficult to count Need phase contrast microscope Need high cell concentration,106 cells/ml (why?) Precision is difficult to achieve Motile cells must be immobilized before counting No.8 Shanghai Jiao Tong University
No.8 Shanghai Jiao Tong University Limitations of microscopic count Dead cells and living cells are all counted Small cells are difficult to count Need phase contrast microscope Need high cell concentration, 106 cells/ml (why?) Precision is difficult to achieve Motile cells must be immobilized before counting
上泽克通大学 Shanghai Jiao Tong University 5.7.2 Direct Measurements 2: Viable Cell Count活菌记数 No.9 Shanghai Jiao Tong University
No.9 Shanghai Jiao Tong University 5.7.2 Direct Measurements 2: Viable Cell Count 活菌记数
Figure 5.15 Two methods of a viable count(plate count/colony count):spread- plate method and pour-plate method Spread-plate method Surface colonies Incubation Sample is pipetted onto Sample is spread evenly Typical spread-plate surface of agar plate over surface of agar results (0.1 ml or less) using sterile glass spreader Pour-plate method Surface colonies Solidification Subsurface Bun可Bu and incubation colonies Sample is pipetted into Sterile medium is Typical pour-plate sterile plate added and mixed results well with inoculum 活菌记数的两种平板记数法：涂布法与混菌法
Figure 5.15 Sample is pipetted onto surface of agar plate (0.1 ml or less) Sample is spread evenly over surface of agar using sterile glass spreader Typical spread-plate results Surface colonies Surface colonies Subsurface colonies Typical pour-plate results Sample is pipetted into sterile plate Sterile medium is added and mixed well with inoculum Spread-plate method Pour-plate method Incubation Solidification and incubation Two methods of a viable count (plate count/colony count): spreadplate method and pour-plate method 活菌记数的两种平板记数法: 涂布法与混菌法