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Maintenance & Preservation of Bacterial Culture - Coggle Diagram
Maintenance & Preservation of Bacterial Culture
Importance
Maintaining microbial cultures for a long period of time without any genetic change
To stop the microbial growth and reduce minimal rate during storage
To maintain the viability and reduce the toxic by products
Methods involved
Periodic Transfer to Fresh media
transfer bacterial culture to fresh media at specific time interval
medium chosen must be supporting slow growth rate
Could not maintain characteristics of a strain due to emergence of variants & mutants
Refrigeration
cultures maintained at 0 to 4 degree celcius
can be kept for short duration
depletions of nutrients that leads to bacterial death
Lyophilization
removal of water and other solvents thru sublimation
microbes enter dormant stage
they can retain viability for years
Paraffin method
microbes were inoculated at slant with sterilized mineral oil
oil used can prevent dehydration and slow down gas exchange between microbes
Preparing glycerol stock
Methods involved
Inoculating an overnight liquid culture
Add 500microlitre of overnight culture to 500microlitre of 50% glycerol in 2ml screw top tube/ cryovial
Freeze the glycerol stock at -80 degree celcius
To recover bacteria, open the tube, scrape some bacteria using sterile loop and streak on LB agar plate
Advantages
Long term storage & maintain cell viability
Disadvantages
Freezing injuries & Chilling injuries