How do you do a standard plate count?
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.
What are some other methods of isolating bacteria on a plate?
There are two main ways to isolate organisms.
- Streaking for isolation on an agar plate.
- The pour plate method.
What is the principle of spread plate method?
The main principle behind this Spread Plate technique is that as the Petri dish rotated, at some stage, single cells will be deposited with the bent glass rod on to the agar surface, these cells will be separated from each other by a distance sufficient to allow the colonies that develop to be free from each other.
What is plating for isolation?
This technique typically is used to separate microorganisms contained within a small sample volume, which is spread over the surface of an agar plate, resulting in the formation of discrete colonies distributed evenly across the agar surface when the appropriate concentration of cells is plated.
Why standard plate count method is used?
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.
What does standard plate count indicate?
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 isolation method?
Isolation method: In this method all the reactants are taken in very large excess except one and the order of the reaction is determined by the first method. The concentrations of the substances taken in excess are considered to be constant.
What are the three most common isolation methods?
The three most common isolation methods include cotton roll isolation, rubber dam, and: dry angles.
What is a CFU count?
CFU stands for Colony Forming Units. What this means is the number of alive and active microorganisms in one serving of a probiotic dietary supplement. These are typically measured in CFUs per gram or per milliliter. A colony refers to the individual colonies of bacteria, yeast or mold growing together.
What is spread plating?
Spread plate technique is the method of isolation and enumeration of microorganisms in a mixed culture and distributing it evenly. The technique makes it easier to quantify bacteria in a solution.
What is the purpose of spread plating and streak plating in isolating cultures?
Colony streaking leads to to the isolation of individual colonies, which are a group of microbes that came from one single progenitor mircrobe. Spread plates allow for the even spreading of bacteria onto a petri dish; allowing for the isolation of individual colonies, for counting or further experiments.
How is the spread plate culture technique used?
PRINCIPLE OF SPREAD PLATE CULTURE TECHNIQUE. The spread plate culture method is one of the commonly used culture technique for the isolation of microorganisms, especially the bacteria, in the laboratory. In this technique, a serially diluted specimen containing 2 or more bacteria or microbe
How are bacteria isolated from a spread plate?
A successful spread plate will have a countable number of isolated bacterial colonies evenly distributed on the plate. Spread plate culture technique is among the most widely used culture technique for isolating the bacteria.
How to calculate colony formation in a spread plate?
Count the number of colonies using a magnifying device. Once you count the colonies, multiply by the appropriate dilution factor to determine the colony-forming units (CFU) present per ml in the original sample. CFU/ml = (no. of colonies x dilution factor) / volume of culture plate
How big of a volume can be spread on a spread plate?
Volume no greater than 0.1 ml can be spread on the nutrient agar plate because it would not soak well and may result in colonies to coalesce as they form. http://www.expertsmind.com/questions/explain-advantages-and-disadvantages-of-spread-plate-method-30175983.aspx