A. Antibiotics, such as gentamicin, are used in media to prevent growth of susceptible microbes. Is gentamicin media a selective, differential or enrichment media? B. Sorbitol is a sugar alcohol that all Escherichia bacteria can normally ferment into an acidic waste compound. This acidic end product is detected by including a pH indicator in the agar and noticing a color change. The strain of Escherichia that is a common food pathogen, E. coli O157:H7, however can not ferment sorbitol. It will grow similar to other E. coli, but not change the agar color. Is sorbitol in nutrient agar a selective, differential or enrichment media?
A. Antibiotics, such as gentamicin, are used in media to prevent growth of susceptible microbes. Is gentamicin media a selective, differential or enrichment media?
B. Sorbitol is a sugar alcohol that all Escherichia bacteria can normally ferment into an acidic waste compound. This acidic end product is detected by including a pH indicator in the agar and noticing a color change. The strain of Escherichia that is a common food pathogen, E. coli O157:H7, however can not ferment sorbitol. It will grow similar to other E. coli, but not change the agar color. Is sorbitol in nutrient agar a selective, differential or enrichment media?
Antibiotics are medicines prescribed to patients who are suffering from a bacterial infection. The antibiotic works by directly killing the bacteria once ingested. It can also work by interfering with specific enzymes of the bacteria, such as the enzyme required to synthesize the bacterial cell wall. Without the bacterial cell wall, the bacteria will easily die.
Agar is often used to prepare media as it supports the growth of a wide spectrum of bacteria. However, depending on the nutritional needs of bacteria media are selected to grow specific bacteria. There are three types of media that are normally used
Selective media: Media which contain nutrients that favor the growth of a specific species of microbes but not others.
Differential media: Media that help to distinguish the presence of a particular type of bacteria due to a color change in the media.
Enrichment media: Contains nutrients such as agar that encourage the growth of a wide range of bacteria.
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