Obligate anaerobes which are sensitive to O2 would be found growing A complex me
ID: 194232 • Letter: O
Question
Obligate anaerobes which are sensitive to O2 would be found growing A complex medum is one that has ben completely made in the laboratory and the concentration ofallte nutient s snown. only at the very top of a tube of thioglycolate broth O approximately one-third of the way down the thioglycolate broth. Oonly at the bottom of a tube of thioglycolate broth. 0 throughout a tube of thioglycolate broth. True False Selective medium dffers from difflerential medium bcause A agent is a chemical that inhibits bacteria from reproducing, but does NOT necessarily kill them O selective medium permits growth of more organisms than differential medium xerophilic O bacteriostatic differential medium diferentiates pathogens from nonpathogens while selective medium grows only pathogens selective medium permits growth of a partioular microbial type while differenial medium is used to distinguish behween types of organisms differensial medium contains growth inhibitors while selective medium does not 0 bacteriocidal O bacterio!yicExplanation / Answer
1. Obligate anaerobes which are sensitive to O2 would be found growing only at the bottom of a tube of thioglycolate broth. Since thioglycolate is a differential medium that differentiates organism based on their O2 demand and can establish an oxygen gradient in such a way that the location of growth of an organism in a tube can clearly indicate their oxygen requirement. Through autoclaving, any oxygen that is present initially is minimalized but over time, oxygen slowly diffuses throughout thioglycolate culture from the top when they are inoculated with the microorganism. Now that obligate anaerobes cannot survive in the presence of O2 so they accumulate at the bottom of the tube where O2 concentration is minimal.
2. A complex medium is the one whose exact chemical composition is unknown. Thus above statement in the question regarding complex medium is false. A complex medium includes components such as glucose, yeast extract, agar, water, milk or blood. A complex medium is a good source of growth factor for bacterial pathogen and other fastidious bacteria.
3. Selective medium differs from differential medium because selective medium permits growth of a particular microbial type while the differential medium is used to differentiate between types of organism. Selective media act by inhibiting the growth of organism not meant for study and permitting a particular type by utilizing dyes, alcohol, antimicrobials present in the medium. For an instance EMB(Eosin Methylene Blue) agar contains eosin and methylene blue dyes, inhibits gram-positive organism and is selective for gram-negative. On the contrary, organism growing in differential medium display visible characteristic changes and doesn't inhibit any microorganism. EMB agar is differential when lactose fermenting organism produces a black precipitate on EMB and non-lactose fermentor appear pink.
4. A bacteriostatic agent is a chemical that inhibits bacteria from reproducing but does not necessarily kill them. Once the agent is removed, bacterial growth is no longer inhibited. Bacteriostatic drugs such as sulfonamide, chloramphenicol, tetracycline interfere with DNA replication, protein synthesis or cellular machinery of bacteria.
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