Serial Dilutions of a Bacterial Culture

[@glendasworld4125]

You explained WAY WAY better than my professor. Thank you! I understand all of it now!

[@glendasworld4125]

By the way, I’m answering questions like this for my hw. One of the questions is “stefanie and Bradley are lab partners. Using a 10^-2 dilution, Stefanie counts 57 cells in a Petroff-Hauser chamber. Bradley counts 63 cells using the same dilution. What was the average number of cells per mL in the original sample? assuming 25 squares and standard volume.” So I already know how to do answer this kind of question thanks to your video. But I’m not sure how many mL of the dilution they put on the plate or what they mean by “standard volume.” Could you help me with this? It’s for my microbiology class.

[@mrpeanutbutter6094]

Maybes it your prof

[@sam.9602]

Yes he did! My professor tried teaching us without using any units. Talk about confusing :(

[@suya4825]

The best explanation I've found so far on KZbin. Than you very much!

[@infinitecouture13]

I had no idea what my text book was talking about when it came to this topic, but the way you explained it is so simple & easy to comprehend! Thank you so much for making this vid!

[@amailyakter6589]

the best explanation I have ever found!!!! today all sorted about CFU!! May Allah bless you, Mr. lecturer!!! you are the best.

[@mohsenakhavan3500]

Fantastic explanations. I recommend this video to every microbiology students who wants to answer the questions about CFU in the exam. He clearly describe the subject. I couldn't find a word in the literature to thank you.

[@krystaljames6710]

You are an awesome teacher! We really do appreciate you! Keep doing what you do, one day you will be rewarded for it.

[@refresheronce5902]

This is really helpful and makes concept clear on serial dilution. Thank you so much.

[@desmondbaptiste861]

Well thought out video; easy to understand, great content, animations were on point and was an added help. Much appreciated.

[@elanawills2364]

This is the best video explaining serial dilutions. Thank you!!!

[@jeyswam]

Wonderfully explained. I am glad I found this video. Thank you

[@juliahicksfav]

I appreciate the variety of examples. Thank you!!!

[@edwardmaximus5439]

This part in Micro was so confusing to me, thank you so much!

[@MrCompenso]

Very clear and helpful! I'm preparing for an internship in biotech and your videos are making me feel much less nervous about going into a new field. Thank you!

[@ProfGillesBolduc]

That is exciting! The biotech field can be very rewarding . I wish you the best.

[@iMusikkForeva]

You’re a great teacher. Thank you so so much!

[@이동섭-e6m]

강의력이 우리 교수님의 9100만배 인정합니다

[@realtorvalentina]

This has helped me sooo much for my micro test, thank you for taking the time to do this!

[@cocoaxo6126]

Thank GOD for youtube.

[@kristenfarney6786]

This is very helpful, thank you! You are a good teacher!

[@OkohPee]

Man, you are a teacher par excellence. Thank you for the presentation

[@DurgeshKumar-pd1qu]

Very Good Explanation. Most clear explanation with good example 👍👍👌nice and thank you sir

[@csm1276]

This is very useful and great explanation with examples.Thanks Gillis Bolduc.

[@sevdaqurbanova8339]

Thank you for the best explanation!

[@nnabuikeogbonna5565]

Highly explained. Very useful. Thanks so much

[@alexisalexia6880]

Wow,this is the best explanation.

[@thilinijayasinghe3653]

This is great. Thank you million times.

[@anna.sortini]

THANK YOU!!!! It helped me a lot for my micro lab test.

[@taongaphiri6084]

i enjoyed the explanation, its the best I have seen.

[@shamekamir]

THANK YOU!!!!!!!!! You just saved my grade!

[@husnabassal7686]

This video is amazing!! Saved me a lot og time and confusion. Thank you!

[@janniepowerz8893]

He is far better than my lecture, I have understood this very well ,thanks so much

[@ProfGillesBolduc]

It's my pleasure

[@sandisonkosi9835]

I had to subscribe to this what an easy way to make me understand dilutions.

[@tictactoj]

Incredible work, +1

[@aloodenishthescientist1]

Very detailed information clearly explained. Thank you.

[@benjaminnketsiah829]

You are the best keep it it up.I understand now

[@beverleyp.3727]

The best explanation that I've seen yet! Thank you :-)

[@ProfGillesBolduc]

Beverley P. , that’s awesome. Thank you!

[@samritisharma7683]

It is very nicely explained. Thank you.

[@sarifm5688]

You are a life saver sir!

[@bettylou1030]

excellent explanation, thanks for sharing!

[@priscilaesthertalavera2987]

Thank you so much! Perfectly explained

[@janniepowerz8893]

Omg,this is so good ,this man can really explain,I have liked this ,feel so good ,thank indeed,great work ,

[@Beonrightside]

thank you very much . it was very helpful

[@sonyablunt4181]

I'm watching to freshen up for a job interview! THANK YOUUUU

[@ProfGillesBolduc]

You well be great. Let me know if you get the job!

[@hybridone890]

Amazing, best I've found!

[@juanitacruz5237]

Best explanation. Thank you

[@Tes-qe1jc]

That was an amazing and crystal clear explanation of serial dilution of a bacterial culture video on KZbin! Please upload other videos on how to treat #organic #wastes using #Actinomycesbacteria.

[@kundananjinawanzi9561]

Its so so helpful, thank you

[@nvkn2680]

Awesome explanation! Thank you so much!

[@hitkarshkushwaha2434]

Love your lecture!!

[@shashidharnrao]

excellent presentation. very clear.

[@Nik-ps9so]

you are a blessing truly!

[@maksudkerluku7517]

Awesome explanation...thank you, sir !!!

[@hafizibrahim9501]

Thank you!!!

[@naleisasashaderoche295]

This was helpful! Great Video !

[@pritichristian2673]

Thanks. Very useful..

[@priyambadanag6708]

Best explanation ever👍

[@jahmanwritingco2108]

Very simplified...Thank you.

[@napats.8743]

it is so clear. Thank you so much !!

[@kumaylhassan]

There is NO video that explain CFU/ml into LogCFU/ml.. Can AnyBody tell me how to calculate it ?

[@fuugawa741]

Thank you so much, savior!!

[@francismngumi5125]

Good

[@mduplooy6763]

brilliant! THANK YOU.

[@alejandralarasosa7187]

Thank you! I understand it now !

[@originalMP3com247]

This is such a great tutorial

[@kalifasanneh9051]

Thank you very much. Very education . Well explained.

[@princeaju2418]

Thanks for the explanation 👍🏻👍🏻

[@amjadzubair8421]

Smooth simple great educational

[@Michelle-yg2vn]

Very helpful!

[@mahdiah5518]

so so helpful, wish I had found this before sitting my A levels

[@jenniferwarren8643]

This was super helpful. Thank you!

[@mahartanvir2653]

best teacher

[@Ortho1974]

Why delete plate 6 &plate 7? Why not choosing the average result of plate 5-6-7?

[@ashleyfincannon2026]

Thank you!

[@silverdream26]

Thank you so much. Great explanation.

[@firatyildirim2288]

Simple and informative, thank you very much.

[@smitshah8074]

thank you

[@lidyah9862]

Thank you! Best explanation!!!

[@kelebogileclaragumbi4297]

This was helpful thank you

[@gwendolyngreen]

Helpful! Thank you!

[@HK-mq6ys]

Thank you so much, this was very herpful👌

[@iana6659]

Amazing explanation !! I just have one enquiry Why would we have errors if we chose a plate with less than 30 bacterial colonies ?

[@ProfGillesBolduc]

There’s an increase of error because we’re dealing with small numbers. If you have a plate with 10 colonies and a second one with 20 colonies, this isn’t big a difference until you start multiplying and the small error now becomes multiplied.

[@iana6659]

What type of error are you referring to when you mentioned the small error ? I mean error due to what ?

[@ProfGillesBolduc]

It’s all mathematical. There’s less of a difference between 250 CFU and 275 CFU than if your talking about the difference between 5 and 30 CFU. If you count either 250 or 275CFU from a sample diluted 10^6 times than your answer is either 2.5 x10^8 CFU or 2.75 x 10^8 CFU. But if you use data values such as 5 or 30 CFU from a sample that’s similarly diluted 10^6 than your calculated answers would be either 5 x 10^6 or 3 x 10^7 which are more different. Thus there’s a bigger error between to two answers. To make your data more accurate you would average data from triplicate plates with CFU between 30 and 300. This is pretty much standard in most labs. I sometimes hear that scientist will use plates with CFU counts between 20 and 200.

[@vodhiambo]

This is great

[@nanorizkipratama8004]

Thank you Sir

[@corradoblondi9792]

Sometimes the simplest things are the more difficult to get to understand.

[@inammakhabana6540]

thank you so much, this was very helpful

[@MA-jw2qe]

Thank you very much! I would ask, should we always transfer 0.1 ml to the plate? or can I transfer the same volume that was transferred between each tube of dilutions? I hop you get my question

[@ProfGillesBolduc]

You can transfer any volume on a plate. But anything more than 0.1 ml might add too much liquid to the plate and the bacterial colonies may run into each other as they grow. This makes it difficult to count them efficiently. I generally like to use a volume between 0.05 - 0.1 ml.

[@sitinursyahirah6380]

but why for tube 6 only added 2.0ml?

[@ongyj2206]

What if I have 3gram of solid sample, can I add up 7ml of sterile water, then subsequent dilution using 1ml transfer.. The final dilution factor would be like this? 0.7 -> 0.07 -> 0.007 -> 0.0007 -> 0.00007 -> ....

[@ilaila3504]

you are a star thankyou xxxx

[@bankingpreparation4926]

Thank you very much sir.

[@tyrionlannister8]

How did he get 0.1ml when he’s calc. 91 Cfu per ml?

[@pranishsawant9932]

very neatly explained and presented. nice job, but please refrain from saying millilitres as 'mils' rather than as 'ml'. that is all.

[@avyarasikka709]

ok what if two plates have cfu which falls in the range 30 to 300 ? Which cfu to take for calculation ? Do we take average ?

[@ProfGillesBolduc]

Good question. You would use both plates to calculate your answer, then average the two for a better answer.

[@harshdeep7628]

In tube no. 6 it should be 1/6 , bcz 2+4 = 6....rest you explained very well

[@meditationrelaxingpeaceful5632]

Tell me the composition of diluent

[@linkonpaul07]

During the time between 9-10 min for the dilution series, if you add 1 ml in 9.9ml of culture, the factor is 1/10?? or do you mean 0.1 ml in 9.9ml!!! Please let me know, if i am wrong?

[@ProfGillesBolduc]

That is not correct. 1ml (from tube 1) was added to tube 2 (containing 9ml). Tube 2 was mixed a bit and 0.1ml from tube 2 was than added to tube 3 (containing 0.9ml).

[@samwatkins4807]

very helpful!

[@allenlinatoc9177]

Thank you so much

[@anasali2566]

On which base you multiply 91 by 10000... Kindly Sir explained...????

[@anbarulhaque4720]

3.21 cfu/g is my reading .: Then how many colonies are there

[@janniepowerz8893]

But I am confused of why picked five ,why not 7 which had 6 colonies, I request for some clarification please, thanks

[@ProfGillesBolduc]

If you go to 18:41 in the video, plate 5 has 91 CFUs. You want to choose a plate that has between 30 and 300 CFUs to do your calculations. Its shown that numbers out of this range can lead to mathematical errors. To few CFUs can give low final values. To many CFUs, they begin to grow into each other and again lead to errors. Thus, plate 5 has CFUs between 30 and 300. That makes this the plate of choice.

[@janniepowerz8893]

@@ProfGillesBolduc u are such a great teacher, I think I need ur email if u don't mind for some guidance , thanks indeed, I want to know the different between pour playing and spread plate

[@janniepowerz8893]

Even I want to know what technique I can use to different m/o if more than one is found in the same

[@janniepowerz8893]

[phone] my watsup ,pliz I need some help in this ,thanks

[@janniepowerz8893]

So in which incidence would we use plate 7 if we were just looking for the lowest cfus,

[@raneemkhlel2982]

thanks a lot