E. coli poses a significant threat to public health worldwide thus exploring and preforming pragmatic tests on the theory of E. coli iron memory could help better our understanding of its bacterial antibiotic tolerance .One important functional type of media that can help us in the laboratory is MacConkey agar due to its selective and differential nature it is a viable culture media for working with E. coli species.
A few of the basics.....
This practical media exhibits inhibition for gram + and displays fermentation, making this agar extremely versatile. The MacConkey agar is Selective due to components within the agar which selects for gram negative bacteria and the gram positives will not grow. Bile salts and crystal violet within the media itself inhibit growth of the gram positive bacterial colonies. Fermenting lactose can help with isolation of certain bacterial species . PH can also be monitored and allows for differentiation of gram negative species. The colonies of those that release acidic products are red .
There are different types modifications we can do the the medium for testing making it so useful . Differentiating glucose fermentation from glucose non fermenting bacilli is a helpful
identification, but note that glucose is not actually in the MacConkey agar itself. Modifications to the MacConkey agar can be minus the crystal violet which helps with differentiating enteric organisms. Swarming effects of some species are reduced or lowered by different modifications and PH can also be monitored for microorganisms such as E.coli. When fermentation lowers the PH and causes dye to be absorbed and change color aiding in identification. A few more examples are as follows
MacConkey agar containing mannitol salt instead of lactose
MacConkey agar replacement of lactose with saccharose
MAcConkey agar and Columbia agar with 5% sheep blood
Due to the selective and differential nature of the media it exhibits inhibition for gram + and displays fermentation making this agar extremely versatile. The MacConkey agar is Selective due to components within the agar which selects for gram negative bacteria and the gram positives will not grow. Bile salts and crystal violet within the media itself inhibit growth of the gram positive bacterial colonies. Fermenting lactose can help with isolation of certain bacterial species. Among the gram negatives that we are growing we can distinguish lactose fermenters versus non-fermenters This media has exhaustive uses aiding in the identification of multiple different colonies.
Theory!
It's theorized that different encounters with stimuli can change the iron memory in E. coli. It is possible we can use this agar to study important within-group variables and influences such as stress, environment, presence ratios of hemoglobin, and genetic factors. This research helps with better understanding of the diverse mechanisms employed by E. coli in developing resistance to antibiotics. Using MacConkey agar we can subject E. coli to different culture medias and document different adaptive strategies employed by E. coli. While the implementation of prudent antibiotic stewardship practices are extremely important this special agar might play a small role in helping scientist better understand these mechanisms.
Holly White
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