How to Perform Serial Dilutions in Microbiology
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- เผยแพร่เมื่อ 26 ก.ย. 2024
- Dr. Karla Fjeld demonstrates how to perform serial dilutions using Microbiologics lyophilized QC microorganism pellets. Learn more: bit.ly/2Vq8ZMf
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nice to see someone actually using gloves in demonstration. Many videos don't and that is a safety hazard, glad to see you are doing it right and safely
Gloves are dangerious if you use a burner for sterile conditions.
This video was very well done. Thank you for the thorough explanation of everything!
thanks for this video... even though we can't perform this in our lab due to covid but this video was so helpful for students like me(microbiology major)........
I really enjoyed watching this video. Extremely helpful and well taught.
Thank you for the smooth explanation
This was very helpful, thank you
why did you put the first dilution solution into the 10^6 plate? shouldn't be on the 10^1 plate? did anyone noticed that?
Yhaa
Nice!!
But please can I see a sample of a practical report done on Serial dilution?
Thnku sooo much mam ☺
Mam is their any video on sample collection n isolation of thermophiles? ?
Would you please tell us what the optimistic vortex mixer rotation speed is in rpm (round per minute)
Excellent job there
Procedure for antibacterial and antifungal effect of leaf extract from persea Americana mill
I think the dilutions were plated wrong. The higher dilutions should have less colony. But in the 6:01 time of the video, the higher dilution had too numerous colony to count. And the lower dilutions had countable colonies. The way she kept those plates in front of her made this thing wrong. She took the highest dilution numbered plate but put the 1 mL liquid from the lowest dilution tube.
i have a question, why do we do serial dilution? why can't we add a small sample to a large volume of the dilution solution ?
You can do that. It is just important to make sure that you are measuring your small sample volume accurately. As the volume of a measurement decreases (1 µl vs. 1 ml), accuracy of the measurement also decreases. So if you need to dilute from 10^7 to 10^2, you either need to do serial dilutions, or you need to work with a large enough volume to ensure that the dilution is as accurate as possible.
hi, on my view the reason we do serial dilution its because we need to know the amount of bacteria present in the original sample by decreasing their volume
Its a standrad process for dilution gives accurate measurment.Here we add a small sample to a measured volume of the dilution solution. We can't think like mixing a smal drop in an unknown quantity of the dilution solution.
Fantastic explanation mam.thanks.
I was always taught not to keep caps inverted but to asepotcally remove and keep in the hand holding the tube
Thank you for your comment! Aseptically removing the cap and holding in your hand is one technique to minimize contamination during a serial dilution alongside inversion on the bench. If inverting onto a bench, make sure this is sterile or perform the dilution series in a biosafety cabinet or laminar flow hood.
Nice Video. Though I think, 1 mL on one petri dish is very much and would cause condense water in the process of incubation.
Nice explanation. How can I isolate 4 different microbes from a know sample solution using this method?
Do it 4 times. Don't thank me.
please describe the process of making initial stock solution of powdered sample. while dissolving powdered test sample into distilled water, does it get diluted? Also, if 1 gm of powdered sample is dissolved into 10 ml of water, what will be the dilution ratio?
There are many resources online that can help you determine the correct amount of powdered sample to add to create a stock solution. In general, a stock solution is made by weighing out an amount of the solid (powder) and dissolving it in an amount of solvent to get the desired concentration, or Molarity, of the stock solution. Dissolving 1gm of powdered sample into 10ml of water would yield a 1:10 dilution of the powdered sample.
Recently did serial dilutions but I didn't get isolated colonies.There was a lawn type growth on the edges and middle part of the plate.I used to spread 200 ul on the plate.please please guide me.
how come the highest dilution has the greatest amount of growth? is it not supposed to be the reverse?
Thank you ma'am ❤️
Thanks a lot
is there any video on laboratory method of isolation of actinobacteria from waster sample
a question please
Is E test same as dilution test?
Why don't you work in front of a flowhood? Is the lab room that sterile?
is it not necessary to do it inside laminar flow
How do you know how far you need to dilute to get a reasonable amount to count, and how do you know much is growing in the original sample based on the diluted findings?
Sarah - To know how much to dilute your sample in order to get a reasonable number of colonies to count, you must know what your CFU concentration is to begin with and what you want to end up with. If you are using Microbiologics products, it is easy to know what your original CFU concentration is because we tell you. For example, Microbiologics Epower™ E3 product is equal to 1,000 to 9,9999 CFU per pellet. If you are not using a quantitative product, you will need to make a suspension of the microorganisms, measure the concentration using a spectrophotometer or turbidimeter, and then dilute the suspension until you get within countable range.
To calculate the CFU concentration of your original sample, you will need to work backwards. Count the number of colonies on your plate and then multiply this number times the dilution factor.
Check out the Microbiologics Dilutions Guide to learn more: www.microbiologics.com/Microbiologics-Dilutions-Guide
@@Microbiologics thank you very much!
I have a question. Instead of diluting 1ml to 10ml, can we do it from 0.1ml to 1 ml?
yeah you can..but...the reason you dilute 1ml into 9ml to get a total of 10ml is for simple mathematics calculation...your case would be an mathematic nuisance.
what do you do with the tips of the micropipettes? the reuses?
You cannot reuse them, they're no longer sterile. They must be thrown out properly
Thank you
Just i have a qution,,,
What is the liquid you are used to diluttion in a tube.? Is a culturec media or distle water?
Really i need the answer!,,
We used 9.0 mL tubes of 7.2 pH Phosphate Buffer
Nicely done. After incubation you said some plates gave you too numerous to count number of colonies while the last plate gave you countables. When recording the results which should we record?
plates that have the number of colonies within 30-300 based on what I've learned... more than 300 is too numerous too count while less than 30 is too few to count
I have a q. What exactly did you put first in that tube with phosphate buffer? that solid one.
That is the bacteria in dried up form. In this form they can be kept for a long time and they came alive when placed in the buffer
do i need to do this under a laminar flow? and can i only plate the last dilution instead of the whole series?
This is up to the SOP guidelines you follow. At our facility, we do not use a hood when performing dilutions.
What is the amount of innoculum taken?
How to do with L- rod
after transferring and spreading the diluted inoculumn on the agar plate, agar plate should be inverted while incubated ? as the the chance of sample drop off into the lid of the petriplate. kindly guide
After spreading the inoculum on the surface of the agar plate, make sure it has been absorbed into the agar before inverting the agar plates during incubation. The length of time this will take depends on the volume used to inoculate the plate and the depth of the agar. Visually check the agar prior to inverting the plate. If the inoculum has not absorbed into the agar, it can drip onto the lid of the Petridish while inverted.
Inverting the plate prevents condensation kn the lid and dripping water on the colonies
@@Microbiologics ❤
i have a question. If this method is very accuracy, so when should we perform single dilution?
Each dilution is plated on the video as a teaching tool so the viewers will understand what the recovery will be for each dilution. If you do not feel that plating each dilution is necessary, you can adjust your procedure accordingly.
How do you spread 1 mL dilution of homogenate onto each plate? We use pipet 0,1 mL or 0,3 mL.
If using a 1.0 mL inoculum size, we suggest dividing the inoculum onto several agar plates.
Why is soil used?
Is this method used for sterilization. ..?
Can anyone tell me the name of the vibrating machine?
Vortex
Hello.... If found 10 colony from stock solutions than how to calculate cfu/ml... Require any calculations factor?...
Calculating the concentration of your stock solution will depend on how you manipulated the stock solution to get a readable plate. For example, if you removed 1ml from your stock solution, plated it, and counted 10 CFU on this plate, your concentration would be 10 CFU/ml. If you removed 1ml of stock solution, diluted 1:10, plated 1ml, and counted 10 CFU, then you would need to factor in the dilution for your calculation. If you have specific questions based on your protocol, please feel free to reach out to our Technical Support Team at techsupport@microbioloigcs.com.
Technically, 10 colonies is too low to use for CFU/mL. The standard is to use a plate with 30-300 colonies.
Thanks!
What temperature was used to incubate these plates?
Maybe 37°C because E.Coli can be found in human body and doing just fine
This whole process should be done in aseptic condition....since air also does contain microbes....during the transfer of a loop of culture to the plate aerobic microbes also can enter
Yeah, use a flow hood lol
I think the producers are aware of this fact, but recording is more easy this way.
GOOD ONE PLEASE
Woman you are the best 🌹
John Simple your welcome
why do you need to use extra micro-pipette since you the sample is the same
Because concentration of sample is different in every test tube.
thank you. If i pour plates in duplicates, that is, from the 5th and 6th tubes of the dilution, and i take the average of these two, at what power would i report my result, x10^6 0r x10^5?
It is not advisable to determine an average from plates prepared from 2 different dilutions unless both are in your designated ‘countable’ range. This is because counting plates with high counts can lead to inaccuracy. (It is widely accepted that the range for countable colonies on a standard agar plate is between 25 and 250 for most bacteria).
However if both are in your countable range, you would perform the calculation and then determine the mean. For example:
If the 10^5 plate count was 240 CFU, the final count, after multiplying by 100,000 (or 10^5), would be 24,000,000 CFU/ML
If the 10^6 plate count was 28 CFU, the final count, after multiplying by 1,000,000 (or 10^6), would be 28,000,000 CFU/ML
The average of these 2 is 26,000,000 CFU/ML (or 2.6 X 10^7)
Ferfect
thank you
and what bacteria its is?
We used E. coli for this demonstration: www.microbiologics.com/0483E7
okay ,thank you
can you show me how isolate xanthomonas vesicatoria from tomato plant properly?
and what does it mean by 5x10 to pwr 6?
5x10 to the pwr 6 is 5x10^6 or 5,000,000 colony forming units (CFU).
If I get 35 colonies on serial dilution of 10^-6 then how I ll write it??
GAS NEMBOK ?
mam i want learn thing related microbiology and use in biotechnology areas under your guidence can you hier me as a intern?
2:34
you should "vortex" it before you pipette it onto the agar.
its called a SPC
You have whats app
I could not understand anything
You have wats app
So this is why the FDA's sitting on their asses all day...
Iam a medical student I really really hate microbiology subjects may Allah punish all microbs iam just about to die bcz every day our first lecture is microbiology
Same 😭
May God bless you 🙏
i have an examination tomorrow from all the serological reactions and it seems terrifying 😀
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superb