Lab exercise Bacterial culture using differential media As you have been learnin
ID: 192380 • Letter: L
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Lab exercise Bacterial culture using differential media As you have been learning in lecture, microbes have very different metabolisms and, therefore, need very different medias to thrive in s lab setting To accommodate the various metabolism requirements, we have various types of medias to appease microbes and allow us to disoriminate for particular microbes of interest. Differential medias are used to differentiate between microbee; for instance, some plates can be used to discriminate lactose fermenters against these thal do not. Selective Medias typically allow us to select for particular microbes Halophiles require high salt concentrations to thrive, some selective media contain high concentration of salts so that only Halophiles will grow Enriched media have additional nutients in them so that microbes can thrive. Interestingly enough, these media can be a combination of differential, selective, and/or enriched Goals: 1. To determine how different functional media affeet the growth of different Procedure: For today's lab you will be given four different microbes to plate on each of the various medias. You will need to plate all four microbes on each plate (for only a total 4 plates) and record your results. Make sure to answer the following questions as wel 1) Obtain a(n) MacConkey Agar, Blood Agar, Eosin Methylene Blue Agar, and a Mannitol Salt Agar Divide each plate into quadrants-label the other side (MAKE SURE YOU N WHICH MICROBE WAS GROWN WHERE!!!! 2) 3) Inoculate each quadrant with only one microbe so that each quadrant has a unique microbe on it and that you have all 4 microbes on each plate- DO N CROSS CONTAMINATE! 4) Once each plate is properly inoculated, incubate at 37 degrees Celsius for 5) Record what you see and answer the questions on a separate pageExplanation / Answer
A1) Out of all the above mention media, BLOOD AGAR seems to be an enriched media.
A2) The differention media seems to be EOSIN METHYLENE BLUE AGAR as Eosin methylene blue is differential for lactose fermentation.
A3)MacConkey agar is a selective and differential culture medium for bacteria designed to selectively isolate Gram-negative and enteric bacilli and differentiate them based on lactose fermentation.
A4)
There are three types of hemolysis, designated alpha, beta and gamma. Alpha hemolysis is a greenish discoloration that surrounds a bacterial colony growing on the agar. This type of hemolysis represents a partial decomposition of the hemoglobin of the red blood cells. Alpha hemolysis is characteristic of Streptococcus pneumonia and so can be used as a diagnostic feature in the identification of the bacterial strain.
Beta hemolysis represents a complete breakdown of the hemoglobin of the red blood cells in the vicinity of a bacterial colony. There is a clearing of the agar around a colony. Beta hemolysis is characteristic of Streptococcus pyogenes and some strains ofStaphylococcus aureus.
The third type of hemolysis is actually no hemolysis at all. Gamma hemolysis is a lack of hemolysis in the area around a bacterial colony. A blood agar plate displaying gamma hemolysis actually appears brownish. This is a normal reaction of the blood to the growth conditions used (37° C in the presence of carbon dioxide). Gamma hemolysis is a characteristic of Enterococcus faecalis.
A5) The metabolic process that is occuring is fermentation of mannitol. The indicator phenol red, a pH indicator for detecting acid produced by mannitol-fermenting staphylococci, turns colour when fermentation occurs in this type of media.
A6) Yes, it is possible to culture any bacterium, provided you know the optimum conditions and requirements of that bacterium in which it natively grows and is adapted to. there are still some bacterial species that are unculturable due to lack of information about their specific requirements but once they are known, they can be cultured as well.
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