Colony counting method on petri dish
(1) First calculate the average number of colonies at the same dilution. If one of the petri dishes has large sheet-like lawns, it should not be used. Instead, a petri dish without sheet-like lawns should be used as the average number of colonies for the dilution. If the size of the sheet-like lawn is less than half of the petri dish, and the remaining half of the colonies are evenly distributed, you can multiply this half of the number of colonies by 2 to represent the number of colonies in the full petri dish, and then calculate the dilution The average number of colonies.
(2) First select the average colony number between 30-300, when only one dilution of the average colony number meets this range, then the average colony number multiplied by the dilution factor is the total number of bacteria in the water sample.
(3) If there are two dilutions with an average colony count between 30 and 300, it is determined by the ratio of the total number of colonies between the two. If the ratio is less than 2, the average of the two should be used; if it is greater than 2, the smaller total number of colonies should be used.
(4) If the average number of colonies for all dilutions is greater than 300, the average number of colonies with the highest dilution should be multiplied by the dilution factor.
(5) If the average number of colonies for all dilutions is less than 30, the average colony number with the lowest dilution should be multiplied by the dilution factor.
(6) If the average colony count of all dilutions is not between 30-300, multiply the average colony count of the nearest 300 or 30 by the dilution factor.
Culture Petri Dish,Petri Dish 90mm Sterile,Plastic Petri Dish
Post time: Dec-15-2021