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
During freeze drying, what will happen to the cultures after the removal of water
Cells in a inactive state
Advantages of freeze-drying
- Easy to replicate
- Light and easy to transport
- Less opportunity for changes in characteristics of culture
What glassware does the lyophilized cells are kept?
Borosilicate glass
Examples of freeze dryers
- Typical manifold dryer
- Shelf freeze dryer
- Combination lab dryer
- Console manifold freeze dryer
How small is the borosilicate vial containing the lyophilized culture?
smaller than a pen
What storage temperature is ideal for preservation in agar ?
Ordinary refrigeration (4-10 degree Celsius)
What storage temperature is ideal for cryopreservation?
- 192 degree Celsius
Cryopreservation employs the use of _____ and ______ . Provide also its purpose
liquid nitrogen - to preserve the culture at - 192 degree Celsius, glycerol - to prevent lethal damages to the cells
Commonly used cryoprotectants in cryopreservation (2) provide percent concentrations
Dimethyl sulfoxide (DMSO 5-10%) and glycerol (5-20%)
Purpose of cryoprotectants in cryopreservation (3)
- Aid in preserving cells
- Encourage dehydration
- Minimize solution effects
Properties of good cryoprotectants in cryopreservation (4)
- Non-toxic
- Not biodegradable by the organism to be preserved
- stable and compatible to target microorganism
- readily available
cryoprotectant/s for animal cells with concentration
DMSO (5-10%) or glycerol (5-10%)
cryoprotectant/s for bacteria with concentration
glycerol (5-10%)
cryoprotectant/s for yeast with concentration
glycerol (10%)
cryoprotectant/s for protozoa with concentration
DMSO (5-10%) or glycerol (10-20%)
cryoprotectant/s for plant cells with concentration
DMSO (5-10%) or glycerol (5-10%)
cryoprotectant/s for animal viruses (free) with concentration
none
cryoprotectant/s for animal viruses (infected cells) with concentration
DMSO (7%)
What is the drying temperature
45 degree Celsius
drying preservation method is limited to what type of organisms?
spore and cyst formers (dormant structures)
What structures are being dehydrated during drying preservation?
Vegetative cells and dormant structures
Drying preservation is applicable to ____ organisms especially those who produces _____
soil, endospores
In drying preservation where does the suspension of pure cultures inoculated?
sterile paper disc
aside from paper disc, what else is used in drying preservation method?
porcelain beads
sterile distilled water is more effective in preserving what cultures?
spores or conidia of molds
How does mold spores harvested before preserving in sterile distilled water?
using moistened swab stick
storage temperature for culture preservation in sterile distilled water
room temperature
example of ready-to-use preservation kit for culture preservation methods
“protect” of ThermoFisher Scientific
How do we revive the lyophilized and cryopreserved cultures?
rehydrated of lyophilized cultures and thawing of frozen cultures and inoculated on fresh media
3 ways in checking purity of preserved microorganisms
- Evaluating the cultural characteristics
- Gram staining and microscopy
- performing 16S rRNA gene sequencing
How do we revive the preserved stock from agar, mineral oil and sterile water?
streak for isolation on an appropriate medium
These are organizations that maintain authentic pure culture of microorganism
culture collection centers
Example of institutions with standing name in nomenclature of prokaryotes
- American type culture collection (ATCC)
- National Collection of Type Cultures (NCTC)
- Japan Collection of Microorganisms (JCM)
- Philippine National Collection of Cultures (PNCC)