MacConkey Agar

In this video, Biology Professor (Twitter: @DrWhitneyHolden) will describe MacConkey Agar, a bacterial growth medium that is selective for Gram-negative bacteria and differential for enteric bacilli that ferment lactose. It is used to identify bacteria like E. coli, Enterobacter, and Klebsiella from patient samples in a lab setting. The special use for sorbitol-MacConkey agar in isolating the dangerous enterohemorrhagic E. coli O157:H7 is also discussed.

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[@BiologyProfessor]

Cool, happy to help! :)

[@sanaamoha5645]

This was very well explained and informative thank you so much Dr

[@BiologyProfessor]

Thanks :)

[@AeraiRC]

Very simple accurate information.

[@janaan6973]

Thanks so much Professor!

[@hemo2458]

that is very fantastic

[@ramankhatale8285]

Thank you so much. You made it so easy to understand.

[@BiologyProfessor]

I love to hear that. Thank you for telling me! :)

[@ramankhatale8285]

@@BiologyProfessor :)

[@user-xu8pt6uy8h]

Thank you for this great lesson ❤️

[@BiologyProfessor]

You are welcome. Thanks for watching!

[@Garcia....]

Thank you for sharing 👍 to helpful for me.

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Ya this was absolutely fantastic.

[@BiologyProfessor]

Thank you!

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[@blessingchiamaka1542]

Can you make a video like this on CLED AGAR as well please

[@dayanacarrillo3479]

All the MacConkey plates I have ever used are light pink not pale yellow..

[@janiegonzalez5261]

Thank you!

[@prathapagiriharish2687]

Nice explanation 👍

[@biomagnet6664]

Thank you ma'am....

[@biomagnet6664]

I have many doubts in my mind, but you have solved them all...

[@BiologyProfessor]

I’m glad! 😃

[@nooralmoswy7347]

Wow very amazing , thank alot dr💝

[@loveforbioinfo]

So overall, if I have a mixture of bacteria and I n
eed to isolate only the Klebsiella pneumonia, how do I do that? Would MacConkey agar plates with lactose be enough to select and differentiate K. pneumonia from rest of the microbes?

[@BiologyProfessor]

Not necessarily. K. pneumoniae appears as a mucoid lactose fermenter on MacConkey agar, but other types of bacteria could be similar. There may be other media, like the one here, better for definitive identification.
www.ncbi.nlm.nih.gov/pmc/articles/PMC273960/

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I watch your videos that give me information that i need

[@LeGiTBeAsT223]

whats the mechanism for how crystal violet inhibits gram-positive growth? I tried searching for answers but couldn't find much

[@BiologyProfessor]

The CV forms a bulky complex with the peptidoglycan layer, cross-linking a lot of it tightly together and interfering with function. It is explained a bit more here: onlinelibrary.wiley.com/doi/abs/10.1111/j.2042-7158.1967.tb09550.x

[@mustaphamouallif2767]

Hi ! great videos. Thanks. Would you tell me please why we are talking about Fermentation "and not respiration" when we describe the Macconkey utilisation of lactose ? especially because of its occuring in an aerobic enviroment which is the surface of the agar.
Thanks so much in advance for your reply

[@BiologyProfessor]

Many bacteria still use fermentation even in the presence of oxygen, these are called aerotolerant anaerobes and include lactobacilli and streptococci. This type of agar changes color with the production of those fermentation products. en.m.wikipedia.org/wiki/Aerotolerant_anaerobe

[@develstudyworld332]

Good evening ma'am

[@BiologyProfessor]

Hi :)

[@ericklopezmarquez6551]

Awesome video, help my a lot

[@Andrea-yd2ji]

This helped a lot! You’re great! Thanks! :-)

[@mariamroy]

hi! can anyone please tell me if MacConkey Agar is chemically defined or chemically complexed media? from what I have seen, it has defined chemical components and based of that I think its chemically defined. but there are many internet sources which say it is chemically complexed. I would highly appreciate if someone could guide me in this regard,.

[@BiologyProfessor]

I believe it is chemically complex. It is complex or undefined due to the digests of animal tissue, and bile salts in the medium.

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[@BiologyProfessor]

Keto diet ;)

[@pategustavo4392]

Please do a video illustrating the complete chemical mechanism of the Lowry protein assay (room temperature method)

[@BiologyProfessor]

Thanks for the suggestion! I try to do videos that haven't already been done by another channel and it looks like there are several videos on the Lowry method: ruclips.net/user/results?search_query=Lowry+protein
Let me know if you have other suggestions!

[@pategustavo4392]

@@BiologyProfessor the top result was not exclusive to only Lowry method so it got kinda confusing and I am not that smart already

[@abdalkahar22]

can you explain chocolate agar , please ?

[@BiologyProfessor]

I’ve added it to my list. :)

[@abdalkahar22]

Biology Professor Thank you 🙏

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