Gram Positive And Negative Consequences Of Gram Staining Essay

836 Words Nov 23rd, 2016 4 Pages
Gram staining was used to distinguish the unknown microbes between gram-positive microbes from gram-negative microbes. Gram-positive microbes contain a thick peptidoglycan with only one outer cell membrane, thus dying the microbes dark purple. Gram-negative microbes contain a thin peptidoglycan with an outer and inner cell membrane, dying the microbes pink when a gram stain test is done. Microbes A and C were gram- positive because of purple dye seen under the microscope. Microbe B was a gram-negative because of the light pink dye seen under the microscope. The gram stain tests can be seen in figure 1. The endospore stain was used to verify that microbe C contained endospores. When tested, microbe C did have endospores.
Table 4 describes selective media tests. EMB was used for lactose fermentation and growth of gram-negative bacteria . Microbe A and microbe B turned dark purple and were able to produce lactose fermentation while Microbe B was not able to turn purple but pink which was interpreted as a negative result for lactose fermentation. PEA test was used because it inhibited gram-negative cell growth. Microbe B was verified as a gram-negative bacteria because it did not have any growth. MAC was used for lactose fermentation as well. Neither microbe A or microbe C was able to grow but microbe B grew and turned a slight pink color indicating lactose fermentation. MSA was used for mannitol fermentation and both microbe A and microbe B had a yellow ring around each…

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