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 are the methods of enumeration of bacteria?
The methods include standard plate counts, turbidimetric measurements, visual comparison of turbidity with a known standard, direct microscopic counts, cell mass determination, and measurement of cellular activity.
How do you count bacteria on a plate?
The primary trick in counting colonies is to count each colony dot once. One approach is to set the Petri dish on a grid background and count the colonies in each grid cell, moving in a methodical pattern through all of the cells. Marking counted colonies on the back of the Petri dish can also be a helpful approach.
Can the standard plate count method be used for the enumeration of specific bacteria?
A Plate Count The plate count method for bacterial enumeration is considered to be the gold standard in microbiology. This method is highly applicable to the enumeration of bacteria from environmental samples.
How is the standard plate count performed?
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.
How do you count your total plate count?
Plate counting method
- Step One: Diluting the sample.
- Step Two: Plating the sample.
- Step 3: Incubating the plates.
- Step 4: Counting the colonies.
- Step 5: Determining how many viable organisms were in the original sample.
Why is standard plate count important?
The standard plate count, sometimes also referred to as the total plate count, is probably the most widely used technique for evaluating microorganisms in foods. The purpose, as its name implies, is to estimate the number of viable microorganism cells in a given sample of food.
How do you calculate total bacterial count?
For example, suppose the plate of the 10^6 dilution yielded a count of 130 colonies. Then, the number of bacteria in 1 ml of the original sample can be calculated as follows: Bacteria/ml = (130) x (10^6) = 1.3 × 10^8 or 130,000,000.
How do you do a standard plate count?
How do you calculate total bacteria count?
Calculate the number of bacteria (CFU) per milliliter or gram of sample by dividing the number of colonies by the dilution factor The number of colonies per ml reported should reflect the precision of the method and should not include more than two significant figures.
How is the enumeration of bacteria done?
The most common procedure for the enumeration of bacteria is the viable plate count. In this method, serial dilutions of a sample containing viable microorganisms are plated onto a suitable growth medium.
How do you count the number of viable bacteria?
There are various techniques/methodologies for the enumeration (counting) of bacteria in a given sample. A viable cell count permits to detect the number of actively dividing cells in a sample. The plate count method is one of the most commonly used procedure as it allows the enumeration of viable cells.
What is the plate count method in microbiology?
The plate count method depends on bacteria forming a colony on a nutrient medium. The colony becomes distinct and is observable to the naked eye, now the number of colonies formed on a plate can be counted.
What are three problems associated with using the standard plate count (SPC)?
Describe three problems associated with using the Standard Plate Count (SPC) method for determining the numbers of bacteria in a sample. 1. Each colony might represent more than one bacterial cell 2. Medium used may affect what type of bacteria is able to grow 3. Number represents only living cells, not the total number of cells