Enumeration methods ppt
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Enumeration methods are used to count microorganisms in samples to identify spoilage organisms in food. The two main techniques discussed are viable counts using the spread plate method and total counts using the pour plate method, both involving serial dilution and incubation on nutrient media. Understanding microbial presence helps prevent food spoilage by enabling environmental changes that inhibit spoilage organisms.
Enumeration methods ppt
- 1. ENUMERATION METHODS Malathi Meenakshinathan I M.Sc., Microbiology (2017-2019) Tirupur Kumaran College For Women,Tirupur TamilNadu.
- 2. Enumeration • Enumeration is counting of microorganisms present in a sample. • This is done to know the intense of presence of the spoilers in the spoiled food. • To detect which type of organism is responsible for the spoilage. • Mostly this is done two important methods. Viable count Total count
- 3. Types of enumeration: Viable count •Spread plate method Total count •Pour plate method
- 4. Viable count • A viable cell count allows one to identify the number of actively growing or dividing cells in a sample. • The plate count method or spread plate method relies on bacteria growing a colony on a nutrient medium. • Number of colonies can be counted. • Plate count agar is used for general count • MacConkey agar is used for Gram negative organisms.
- 5. Direct viable count: A direct viable count method involves a standard plate count, in which repeated dilutions of a sample. • The sample is serially diluted as (1:10,1:100,1:1000 etc,) in sterile distilled water and cultivated on nutrient agar for bacteria. • Potato dextrose agar or sabouraud’s dextrose agar is used or fungal identification.
- 6. Dilution Series: dilution 9ml broth 1/10 1ml 1/100 1ml 1/1,000 1ml 1/10,000 1ml 1/100,000 1ml
- 8. Dilution Series: Colony counts 1/100,000 1/100 1/1,0001/10 1/10,000
- 12. Total count The initial analysis is done by mixing serial dilution of sample in liquid nutrient agar which is then poured into bottles. The bottles are then sealed and laid on their sides to produce a slopping agar surface. The colonies are then counted by eye.The total number of colonies are said as Total Viable Count.
- 13. Pour plate method • The same procedure is done for this till serial dilution. • The serially diluted sample is then mixed with the molten nutrient agar. • Then poured onto the sterile petridish. • Incubated under appropriate temperature amd the colonies where counted.
- 14. Conclusion • The enumeration of these spoiled food samples are important to encounter the type of microbe is causing the spoilage. • And hence this is used to prevent the same type of spoilage. • This can be avoided by making the environmental changes which inhibits the organism which is responsible for the spoilage.