Thursday, 18 December 2014

Second last lecture!

Microbial growth topic continued.

Here are some definitions:
Culture medium: A nutrient material prepared for the growth of microorganisms in a laboratory.
Inoculum: Microbes that are introduced into a culture medium to initiate growth. 
Culture: The microbes that grow and multiply in on or culture medium.
Sterile: No living organisms. 

And the most interesting part, we have some calculation here! Hehe I've been missing mathematics so much.
The formula is to calculate number of generations and generation time.

Number of generation = log num of cells(end) - log num of cells (beginning)
0.301

Generation time = 60min (hours)
                                num of gen



This is Bacterial Growth Curve.
Lag phase: adapt to environment.
Log phase: adapted--start to replicate--use up nutrient--enzyme produced--end product produced.
Stationary phase: maximum sustainability due to deficiency of nutrient--start to reduce growth.
 Death phase: no nutrient left--die

To calculate number of bacteria in direct microscopic count:

Number of bacteria=  number of cells counted
                                    volume of area counted

And on control of microbial growth topic, the frequently used terms are:

Sterilization- removal of a microbial life
Commercial sterilization- killing C. botulinum endospores
Disinfection- Destruction of pathogens
Antisepsis- destruction of pathogens from living tissue
Degerming- removal of microbes from a limited area
Sanitization- lower microbial counts on eating utensils
Biocide/germicide- kills microbes
Bacteriostasis- inhibiting, not killing, microbes

Ok that's all for now.

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