Lecture 4: Culture Preservation and Maintenance_1 Flashcards
Goal of culture preservation (2)
- Retain viability and functionality of the stock culture for a long period of time
- Maintain purity and trait of being “true-to-type”
_____ means to maintain the live form or viability of the organism
Viability
______ is maintaining the normal characteristics or phenotypes of the organisms
Functionality
Importance of culture preservation (4)
- ensures the availability, supply and functionality of microbial strains for future studies
- as reference for standardized assays and tests
- for taxonomic purposes
- as valuable stock for biotechnological applications
Important principles for preservation and maintenance of stock cultures (3)
- Reduction in the temp of growth of the organism
- Dehydration or desiccation of the medium of growth
- Limitation of nutrients to the organism
Important things to remember in culture preservation (7)
- Zero tolerance to contaminants
- Number of replicates
- Competent personnel
- Knowledge about the culture
- Proper labeling for containers
- Proper protective gear/clothing
- Proper and secure inventory
Considerations of periodic transfer to fresh media (3)
- Time interval pf transfers
- Proper medium
- Proper storage temperature
Name the 7 culture preservation methods
- Storage in distilled water
- Drying
- Lyophilization
- Periodic transfer to fresh media
- Cryopreservation
- Overlaying cultures with mineral oil
- Ready to use preservation kit
Aerobic organisms are usually inoculated in
Agar slants and petri plates
Anaerobic organisms are usually inoculated in
Agar stabs
Advantages of periodic transfer to fresh media (2)
- Easy to prepare
- Does not require expensive equipment
Disadvantages pf periodic transfer to fresh media (3)
- Risk of spontaneous mutation
- Prone to contamination
- Requires larger space to maintain several cultures
The aim of overlaying cultures in mineral oil (2)
- Limit the availability of O2
- Reduce the rate of dehydration of medium
overlaying cultures in mineral oil is most effective to _______ bacteria
Aerobic
Advantages of overlaying cultures in mineral oil (3)
- Cheap and readily available
- Easy to prepare
- Working culture can be directly obtained from mineral oil stock
Disadvantages of overlaying cultures in mineral oil (2)
- Requires larger space to maintain several cultures
- Viability of microorganisms varies with species
Microorganisms which can degrade mineral oil (3)
- Pseudomonas putida
- Rhodococcus erythropolis
- Bacillus thermoleovorans
Freeze drying (lyophilization) employs _____ of ice or other frozen solvents from the material through the process of ______ and the removal of bound water molecules through the process of ____
removal, sublimation, desorption
Examples of cryoprotective agents (lyoprotectants)
Skim milk, glycerol etc
The efficacy period of maintaining the cultures subjected to freeze drying
>20 years
Is considered as one of the most effective method in culture preservations
Freeze drying