in this video we'll talk about the microbial culture media we'll focus on the frequently used culture media in medical laboratories microbes need nutrients to grow just like any other organism and we'll classify the microbial culture media on basis of different criterias we can classify them on basis of their chemical composition there would be different classes like simple media defined media or even complex media there could be classification which is based on the physical nature of the media like whether it is solid or liquid there could be classification on basis of their function such as supportive media enriched selective or differential media in this video we'll talk about some popular media that are frequently used and which are of interest for medical pathologists so first we'll talk about simple or basal media here these kind of media are used routinely in labs and they are generally used to grow non-fastidious bacteria like esterasia coli enterobacter and pseudomonas originosa so they have very simple composition they need to have a carbon source a nitrogen source and some salts so generally they have beef extract or yeast extract which can serve as nitrogen source peptone and also they have salts such as sodium chloride sometimes they have solidifying agent such as agar if we are talking about a solid media so these kind of media is used to primarily isolate microbes from patient sample or let's say from other sources example of these media includes nutrient broth nutrient agar peptone water etc now the defined media or synthetic media are slightly different from the simple media both these media need to have carbon and nitrogen sources but the difference between these two media is in defined media all these sources are really defined for example in simple media beef extract or yeast extract are kind of like undefined source of nitrogen but in case of defined media all these proportions has to be exact let's talk about enriched media as the name suggests there are additional nutrients which are added in this media such as blood serum egg yolk etc so enriched media is kind of like a basal media that means the minimal requirement for growth that means carbon source nitrogen source salts etc along with that some goodies are added to this particular media since several goodies are added to this media these are useful to grow nutritionally demanding bacteria or nutritionally exacting bacteria such as fastidious organisms now example of such media are blood eager chocolate egg blood egger is preferred uh prepared by adding of five to ten percent of sheep blood to the minimal media and this is appropriate for the growth of staphylococcus pneumonia or many other organisms now chocolate agar is one version of the blood agar where the plate is slightly heated and the blood cells are lysed among others hemophilus influenzae can grow in this particular media next let's talk about selective media so in selective media we designed this kind of media to suppress the growth of one category of microorganism while allowing the growth of other category selective media is agar based media and generally individual colonies can be isolated from this particular selective media manitoba salt agar salt milk agar etc are used for recovery of specific organisms such as staphylococcus aureus so manitoba salt agar has been used to isolate staphylococcus aureus and cephalococcus aureus colonies can ferment manitol and thereby they have this characteristic yellow colour in these colonies more examples involve mcconkey auger which is selective as well as differential culture media so it is designed to isolate gram negative and enteric bacteria and differentiate them from differentiate based on like lactose fermentation property so in a mcconciagger all the lactose fermenters would produce a pink colored colony such as klebsiella enterobacter etc whereas the lactose non-fermenters such as salmonella shigella would produce a yellow colony so based on color they can be differentiated campylobacter agar is another aggro for uh selection so it's another selective media so campylobacter agar is dedicated for isolation of campylobacter jejuni which is found from the rectal or the fecal swab it has a cocktail of antibiotics such as vancomycin polymix in b all of these would allow the growth of only campylobacter and reduce or inhibit the growth of other bacteria in that plane now let's talk about another differential media and this media is known as differential indicator media or chromogenic media so these media are designed in such a way that different bacteria can be recognized based on their colony colors so obviously chromogenic substrates are used upon metabolism bacteria produce different colors so in simple words different bacterial colony on the different in in that same plate would have different colors and based on that we can discriminate them so a simple example was uh manitoba salt agar because manitoba fermentation leads to a yellow colored colony and this is very characteristic of staphylococcus aureus also you can think of the example of mcconkey agar where lactose fermenter versus lactose non-fermenters can be discriminated based on their colony colors also we can talk about saboroids agar which is used for isolation of fungi such as candida albiguns and these are frequently used in the medical laboratories to isolate fungus not bacteria so it's another kind of selective media now we can classify media on based on their chemical nature some media which are frequently used they are solid media generally they are in a plate and agar is added into this media there are other medias which are liquid media which don't have um agar in that so they don't solidify so robertson's cooked meat is one kind of like example so where it is used for cultivation of aerobic or anaerobic microorganism so let's say the benefit of liquid media is you have some patient sample but the amount of the patient sample is very less so you have a small swab you can dip it inside a liquid culture media and then allow it to grow for a while and then from this particular liquid culture media you can inoculate in a plate in a solid plate and then it would allow the growth and isolation of specific bacteria from that plate now from an industrial perspective liquid culture systems are really important because in industry we can grow thousands of liter of bacterial culture to get various products such as think about the antibiotic industry they need to grow bacteria in bulk in order to extract antibiotics from them also think about a particular industry which involves production of insulin or other kind of recombinant proteins there then you need to produce huge amount of biomass from there they can extract that particular product so from an industrial point of view liquid culture is really important so overall we learned the most important type of bacterial culture media used in lab if you 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