hat is the purpose of trying to get single colonles on the culture platés? What
ID: 141862 • Letter: H
Question
hat is the purpose of trying to get single colonles on the culture platés? What is a colony Why is there a difference in the temperatures used to incubate the different cultures? What temperatures are used for the different cultures? Why is it ideal to provide continuous shaking for the suspension culture? Why do we flame the mouths of glass tubes and other equipment, and why do we work next to a turned on bunsen burner even when we're not flaming equipment? Why do you use the elaborate zigzag pattern when streaking a plate? After 1 or 2 days have passed, return to lab, and look for your class section's culture tubes (your instructor will have set them out on a bench somewhere). Compare your MM294 tube to your LB only tube (you may want to gently thwack both tubes a couple of times with your finger to stir up any cells in the bottom of the tubes). Does your LB only sterile culture tube look completely clear relative to your E. coli tube, which should be cloudy? If so, congratulations, you've successfully practiced sterile technique and inoculation! If not, try to remember what you did in lab. If the LB tube is cloudy, what step do you think was most likely the one at which a bacterial cell got into the LB media, and if the MM294 E.coli tube is clear, what do you think could have killed your E. coli or stopped them from growing? (The answer will be different for each person).
Explanation / Answer
We generally incubate cultures in different temperatures to get the desired growth of the particular strain.
- Through this procedure we can understand the best adapted temperatures for the specific organisms as different bacteria can grow in different temperatures.
- Through this method we can eliminate unwanted bacteria and can get only the growth of the desired organism.For example, pathogenic bacteria grow faster at 370C rather than any other residential microbial flora.
- There is a need to know about the optimal growth temperature of a newly discovered bacteria which can be determined and studied by incubating the plates in different temperatures.
- To identify the specific strain. For example, Enterococcus faecalis can grow at 450C which is the characteristics of this particular organism.
- At the point of bacterial survival temperature bacteria releases stress response proteins which are short term survival proteins and with this method the proteins can be studied.
The different temperatures are -
1. 600C and more than that - Hyperthermophiles.
2. Optimum growth between 450C and 1220C - Thermophiles.
3. Between 200C and 450C - Mesophiles ( most pathogens can grow in this temperatures).
4. 00C - Psychrotrophs.
5. - 150C and 100C and lower than that - Psychrophiles.
Continous shaking of suspension culture gives enough aeration for the growth of the organisms and the nutrients will distribute equally in the suspension. This is more useful to purify the plasmid and the method also helpful to separate away the waste products from the suspension.
The procedure generates convection currents which actually forces out the air from the glass tubes. So the airborne contaminants cannot enter into the tube.
When we work under bunsen burner we maintain aseptic sterile environment throughout the work bench which is necessary to prevent airborne contaminants.
The zigzag pattern of streaking helps in diluting the number of organisms and reduce the density. So it is easy to isolate individual pure colonies from a mixed culture.
LB only tube may got contaminated while preparing the broth.
The bacteria may lost the plasmid and the degradation of unstable antitoxin becomes faster which can kill the organism by programmed cell death.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.