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Why Does This Exercise Call For An Older Culture Of Bacillus

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Why Does This Exercise Call For An Older Culture Of Bacillus?

why does the gram stain work the way it does? … why does the endospore stain call for an older (5-day) culture of Bacillus species? older bacteria are under greater nutritional stress so there will be more endospores present. what does a positive result for the spore stain indicate about the organism?why does the gram stain work the way it does? … why does the endospore stain call for an older (5-day) culture of Bacillus species? older bacteria are under greater nutritional stress so there will be more endospores

endospores
An endospore is a dormant tough and non-reproductive structure produced by some bacteria in the phylum Firmicutes. … In endospore formation the bacterium divides within its cell wall and one side then engulfs the other. Endospores enable bacteria to lie dormant for extended periods even centuries.

Why do you need to use older cultures of Bacillus for Endospore staining?

Endospore staining is considered a structural stain b/c it is used to highlight a specific structure in the cell. … To improve the odds that spore formers can be detected most methods suggest using cultures that are 18-36 hours old. Older cultures are more nutrient depleted causing sporulation.

Why was a 48 hour culture of B subtilis used rather than a fresh culture?

Why is a 48 hour culture required for an endospore stain? Endospores form under environemental stress. If you wait 48 hours the bacteria will be lacking nutrients.

How might the age of the culture affect the results of the endospore stain?

How does culture age affect the results of a spore stain? old cultures tend to have more spores bacteria produce more endospores when they get older.

What is the relationship between age of a culture and number of endospores?

What is the relationship between age of a culture and number of endospores? Young cultures had more vegetative cells and the old culture had endospores. The older the age the vegetative cell will die and release the spore. – Counterstain with safranin stain for 1 minute.

Why is an old culture necessary for finding spores?

Bacterial bodies and flagella will stain _____________. … Why was it necessary to use an old culture of Bacillus for the spore stain and not a fresh one? Because endospores are being formed in an older culture because essential nutrients are not available. 2.

How does the culture affect the results of an Endospore stain quizlet?

How does the culture affect the results of an endospore stain? If the culture is a harsh environment there would be more spores than vegetative cells. The same goes vise-versa. What color are endospores after a Gram stain is performed?

Why does the Endospore stain exercise call for an older 48 hour or 5 day culture of Bacillus?

why does the gram stain work the way it does? … why does the endospore stain call for an older (5-day) culture of Bacillus species? older bacteria are under greater nutritional stress so there will be more endospores present. what does a positive result for the spore stain indicate about the organism?

What is the function of the Z ring in binary fission?

What is the function of the Z ring in binary fission? It controls the replication of DNA. It forms a contractile ring at the septum.

Why would older gram positive cultures stain incorrectly?

Why would older gram-positive cultures stain incorrectly? Older gram-positive cultures lose the ability to retain the crystal-violet iodine complexes and give false gram-negative results. What part of a bacterial cell wall enables an organism to be gram positive? … The culture smear was not heat fixed?

How might an old culture affect the results of a Gram stain?

Older cultures contain more ruptured and dead cells. Cells from old cultures may stain Gram negative even if the bacteria are Gram positive. At this time the exact mechanism of the Gram stain reaction is not yet known.

How does the age of the culture affect the results of the Gram stain for gram-positive bacteria?

How does the age of a culture affect the gram stain reaction? a. Old cultures can convert to gram-variable or gram-negative giving erroneous results. … If done too long gram-positive can look gram-negative and if done too short gram-negative and look gram-positive.

What is the function of mordant?

A mordant or dye fixative is a substance used to set (i.e. bind) dyes on fabrics by forming a coordination complex with the dye which then attaches to the fabric (or tissue). It may be used for dyeing fabrics or for intensifying stains in cell or tissue preparations.

What does endospore mean?

Endospore – A differentiated cell formed within cells of certain Gram-positive bacteria that are extremely resistant to heat and other harmful conditions and agents. Endopsore are the resting stage during the life cycle of some bacteria formed in response to adverse conditions.

What does the endospore do?

It allows the bacterium to produce a dormant and highly resistant cell to preserve the cell’s genetic material in times of extreme stress. Endospores can survive environmental assaults that would normally kill the bacterium.

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Why is it important to determine the location of the endospore within the bacterial cell?

Location. The position of the endospore differs among bacterial species and is useful in identification. … Bacteria having a centrally placed endospore include Bacillus cereus. Sometimes the endospore can be so large the cell can be distended around the endospore.

What is the purpose of Bacillus structure?

The cell wall of Bacillus is a structure on the outside of the cell that forms the second barrier between the bacterium and the environment and at the same time maintains the rod shape and withstands the pressure generated by the cell’s turgor.

Why do bacteria produce spores?

One of the most common coping mechanisms for bacteria is forming spores to protect themselves against ecological degrading agents. … Endospores germinate back into vegetative cells (an active bacterial cell that undergoes metabolism) when surrounding environmental conditions favor bacterial growth and reproduction.

Which of the following are characteristic of the genus Bacillus?

Bacillus species are rod-shaped endospore-forming aerobic or facultatively anaerobic Gram-positive bacteria in some species cultures may turn Gram-negative with age. The many species of the genus exhibit a wide range of physiologic abilities that allow them to live in every natural environment.

How does an endospore containing cell look after Gram staining quizlet?

How does an endospore appear when gram stained? Sporulated cell appear purple or pink with circular holes within the cell.

How does an endospore containing cell look after Gram staining?

In the Gram staining protocol two different colored stains can result. … Lastly in endospore staining Vegetative cells will be stained red by the Safranin counterstain. If endospores are present in the sample these will retain the malachite green stain and appear bluish-green in color.

Why is a Gram stain generally done prior to an endospore stain?

Before the endospore staining procedure the gram stain is frequently employed in order to classify isolated microbes into the broadest groups. However alternative stains allow for considerably higher accurate determination.

Why is endospore staining important?

Why is endospore staining important? … It helps in identifying the few medically important genera that produces endospores. It separates bacteria from protozoans under the microscope. It helps in identifying the few medically important genera that produces endospores.

What does a positive result for the endospore stain indicate about the organism quizlet?

what does a positive result for the endospore stain indicate about the organism? … because an endospore stain is a differential type of staining procedure. it allows us to see both spores and vegetative cells. therefore including a separate negative control consisting of only vegetative cells isn’t necessary.

What types of bacteria does an endospore stain differentiate between?

The main purpose of endospore staining is to differentiate bacterial spores from other vegetative cells and to differentiate spore formers from non-spore formers.

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What is the function of the Z ring in binary fission quizlet?

What is the function of the Z ring in binary fission? It forms a contractile ring at the septum.

What factors regulate the formation of the Z ring at mid cell site during binary fission?

In vegetatively growing bacilli which divide by binary fission the Z ring forms at the cell midpoint. This medial positioning is negatively regulated by the Min proteins and the state of the chromosome [3].

Why do bacteria have different generation times?

The cells divide at a constant rate depending upon the composition of the growth medium and the conditions of incubation. The rate of exponential growth of a bacterial culture is expressed as generation time also the doubling time of the bacterial population.

Why a bacterium that should be gram-positive might turn out gram-negative?

When over-decolourized by either prolonged exposure to decolourizer or using acetone alone. When cell wall gets damaged by exposure to lysozyme or cell wall acting antibiotics such as Penicillin.

Why do Gram positive bacteria and gram negative bacteria appear different in Gram staining?

Due to differences in the thickness of a peptidoglycan layer in the cell membrane between Gram positive and Gram negative bacteria Gram positive bacteria (with a thicker peptidoglycan layer) retain crystal violet stain during the decolorization process while Gram negative bacteria lose the crystal violet stain and …

Why is crystal violet used in Gram staining?

The gram stain utilizes crystal violet as the primary stain. This basic dye is positively charged and therefore adheres to the cell membranes of both gram negative and positive cells. … The mordant is Gram’s Iodine. This binds to the crystal violet making a large complex that adheres to the cell membrane.

Why is gram stain called a differential stain?

It is called a differential stain since it differentiates between Gram-positive and Gram-negative bacteria. Bacteria that stain purple with the Gram staining procedure are termed Gram-positive those that stain pink are said to be Gram-negative.

What is the result of Gram staining?

What do the results of a gram stain mean? … Because of the staining technique used gram-positive bacteria will appear purple under a microscope and gram-negative bacteria will appear pink. The shape size and quantity of bacteria present will also provide information about your infection.

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Why is culture Age important in the Gram reaction quizlet?

what is an optimum culture age for a valid gram reaction? old cultures of gram positive cells may not retain stain as well as younger cultures and could give false negative results (ex) pink cells. Cultures that are 16-18 hrs are best.

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