546 MICR ONIOLOGY: LAPORATOIT THEORY AND APPLICATION Q u ESTI o N S 1 why does t

Question

546 MICR ONIOLOGY: LAPORATOIT THEORY AND APPLICATION Q u ESTI o N S 1 why does this exercise call for an older (Saday alture of Bacillusi 2 what does apositive result for the spore stain indicate about the organism what does a negative result for the spore stain indicate about the organismi 3 whyisit not necessary to include a negative control for this stain procedure? 4 spores do not stain easily Perhaps you bave seen them as unstained white objects inside Bacillus species in other staining procedures. If they are visible as wnstained objects in other stains, ofwbat wse is the en- dospore stain? Hint: See Figure 3-107)

Explanation / Answer

1. Young cultures for spore-forming microbes may not demonstrate any endospores because the vegetative cells may not have been subjected to sufficient stress to stimulate sporulation. To improve the odds that spore formers can be detected, most methods suggest using cultures that are 18 to 36 hours old. Older cultures are more nutrient depleted causing sporulation. This is the reason why we use an older culture.

2. Positive results: shows cell has ability to produce spores, which narrows down indentification of bacteria to a few genera of bacteria
Negative reults: Non-spore producing bacteria

3. Endospore stain is a differential staining procedure that allows to see both spores and vegetative cells, thus including separate negative control consisting of only vegetative cells is not required.

4. Unstained objects can be something other than an endospore, such as lipid granules.

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