What is the acceptable range for a plate count?
What is the acceptable range for a plate count?
between 25 and 250
“The accepted range for countable colonies on a standard agar plate is between 25 and 250 for most bacteria and Candida albicans. This range was estab- lished in the food industry for counting coliform bacteria in milk.
Why is CFU used in plate counts?
The purpose of plate counting is to estimate the number of cells present based on their ability to give rise to colonies under specific conditions of nutrient medium, temperature and time. This is because the counting of CFU assumes that every colony is separate and founded by a single viable microbial cell.
Why do you use the standard plate count method in microbiology?
Microbiologists use a technique called the ‘standard plate count’ to estimate the population density of bacteria in a broth by plating a small and dilute portion of the sample and counting the number of bacteria colonies. From that number, we can calculate the original cell density in the broth.
How do you do the standard plate count method?
The standard plate count method consists of diluting a sample with sterile saline or phosphate buffer diluent until the bacteria are dilute enough to count accurately. That is, the final plates in the series should have between 30 and 300 colonies.
Is total plate count the same as aerobic plate count?
The APC term stands for aerobic plate count, but again is interchangeable with the others. Other terms used more historically are Standard Plate Count, Mesophilic Count or Total Plate Count these too generally refer to aerobic bacteria able to grow at average temperatures (e.g. 30 to 40°C).
What is standard plate counting?
The Standard Plate Count (SPC) means the colony count of the mesophilic bacteria growing under aerobic condition on standard methods agar (Plate Count Agar), and SPC becomes the representative index indicating the degree of the microbial contamination of the food.
What is an acceptable aerobic plate count?
Counts outside the normal 25-250 range may give erroneous indications of the actual bacterial composition of the sample. Dilution factors may exaggerate low counts (less than 25), and crowded plates (greater than 250) may be difficult to count or may inhibit the growth of some bacteria, resulting in a low count.
Why is standard plate count important?
Standard Plate Count (SPC) is useful to monitor process control and determine sources of contami- nation, but is not a true measure of specific risk pathogens in feed or of overall feed quality.
What does the standard plate count count for?