Bacteria - Study Notes

The culture o use high temp and disinfectants total

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Unformatted text preview: ants Total cell count Number of cells whether living or dead Count cells with haemocytometer Stop bacteria entering the flask with a stopper. Important as bacteria would have been caused reduced growth rate of yeast/killed yeast and competed for space/nutrients Culture is shaken to achieve a uniform distribution of yeast cells/spread out yeast Larger number is taken to avoid anomalies/produce an average Measurement of growth Generation time: time taken for a bacterial population to double Rate of population o = increase in number of yeast cells/time o = number larger - number less/(time larger - time less) Suppose the number of cells in one square are 6 8 9 5 7 The sum of the cells in 5 squares is 35 The mean for one type B square is 7 Therefore 25 squares have 25 x 7 = 175 in 0.1mm3 In 1mm3 there will be 1750 cells or 1,8 x 103 Viable cell count Only living cells since these are the only ones capable of dividing 1cm3 original sample is diluted in 9cm3 distilled H2O Mix 1cm3 from last dilution with 9cm3 distilled H2O - serial dilution 1cm3 of each dilution is put on an agar plate and counted. Number is multiplied by the dilution factor Measurement of growth Number of colonies on the 10-3 dilution plate = 35 Number of viable colonies in 1cm3 of 10-4 dilution of milk o 35 x 1/0.1 = 350 Sample was diluted by 10-3 Number of bacteria in 1cm3 of the or...
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