Why do you have to use an older culture of Bacillus for the spore stain?
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.
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.
Do you think you would find more endospores in a freshly prepared culture less than 24 hours old or in an older culture of Bacillus explain?
Old cultures because spores are not produced until starvation, about 72 hrs. Thus older cultures are more likely to contain endospores.
What is the appropriate age of the bacterial culture if you need to use spore stain technique?
between 18 and 36 hours old Using aseptic technique, smear a bacterial colony into the liquid to produce a thin, even layer. Note: Endospores generally do not form in young cells; therefore, the culture is recommended to be between 18 and 36 hours old (9).
Why was a 48 hour culture of B subtilis used rather than a fresh culture for the endospore stain?
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.
What might affect the results of the endospore stain?
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 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 should your culture for a spore stain be a least 48 hrs old?
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.
Why is using cultures older than 24 hours not advisable in Gram staining method?
Old cultures tend to lose the peptidoglycan cell walls, which predisposes gram-positive cells to be gram-negative or gram variable.
Why do gram-positive cells more than 24 hours old?
Why do gram-positive cells more than 24 hours old stain gram-negative? Because the cell wall begins to deteriorate and change.
Why are cultures 48 hours and older used to test for endospores?
1. Why does this exercise call for an older (48-hour or 5-day) culture of Bacillus? –Young cultures of spore-forming microbes may not demonstrate any endospores because the vegetative cells may not have been subjected to sufficient stress to stimulate sporulation.
What does Bacillus subtilis need to grow?
subtilis will grow anaerobically, either by using nitrate or nitrite as a terminal electron acceptor, or by fermentation. How B. subtilis alters its metabolic activity according to the availability of oxygen and alternative electron acceptors is but one focus of study.
What bacteria is Bacillus?
Bacillus (Latin "stick") is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum Bacillota, with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural Bacilli is the name of the class of bacteria to which this genus belongs.
What is Bacillus in microbiology?
bacillus, (genus Bacillus), any of a genus of rod-shaped, gram-positive, aerobic or (under some conditions) anaerobic bacteria widely found in soil and water. The term bacillus has been applied in a general sense to all cylindrical or rodlike bacteria. The largest known Bacillus species, B.
How does the age of a culture affect the Gram stain reaction?
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.
Why are older bacterial cells more easily Decolorized than younger colonies?
Answer: Older bacterial cells are decolorized more easily than younger cells, because as cells age their cell walls become "leaky" and allow molecules to pass more readily out of the cell. In the Gram stain, the crystal violet-iodine complex is more readily lost during the decolorization step.
Why is it important to use 24 hour old culture in Gram staining?
Cultures more than 24 hours old may lose their ability to retain the crystal violet-iodine complex. 3. The organism itself. Some Gram-positive bacteria are more able to retain the crystal violet-iodine complex than others.
Why will old 48 Hour cultures of Gram positive bacteria stain as gram-negative?
Old cultures tend to lose the peptidoglycan cell walls, which predisposes gram-positive cells to be gram-negative or gram variable.
Do you think you would find more endospores in a freshly prepared culture or in an older culture of Bacillus subtilis?
You would find more endospores in an older culture of Bacillus subtilis because endospores don't form until starvation and nutrients are depleted.
How does Bacillus grow?
Bacillus subtilis bacteria have been considered strictly aerobic, meaning that they require oxygen to grow and they cannot undergo fermentation. However, recent studies show that they can indeed grow in anaerobic conditions making them facultative aerobes.
What is Bacillus subtilis culture?
Bacillus subtilis is one of the best characterized bacteria and is used as a model organism for Gram-positive bacteria. B. subtilis is a rod-shaped bacterium, which produces endospores that allow the survival of extreme environmental conditions including heat and desiccation.
Why is Bacillus important?
Bacillus species are used in many medical, pharmaceutical, agricultural, and industrial processes that take advantage of their wide range of physiologic characteristics and their ability to produce a host of enzymes, antibiotics, and other metabolites.
What does Bacillus do to the human body?
Definition. Bacillus cereus is a foodborne pathogen that can produce toxins, causing two types of gastrointestinal illness: the emetic (vomiting) syndrome and the diarrhoeal syndrome. When the emetic toxin (cereulide) is produced in the food, vomiting occurs after ingestion of the contaminated food.
Why do gram-positive cells more than 24 hours old stain Gram-negative?
Why do gram-positive cells more than 24 hours old stain gram-negative? Because the cell wall begins to deteriorate and change.
What factors may change the reaction of a bacterial species to the Gram staining?
The many variables that can affect this stain are age of the culture, amount of decolorizer used, the time of decolorization, the type of organism (acid-fast bacteria and spores do not stain well), thickness of the smear, and the general care of the stainer.
How does the age of a culture affect the Gram stain reaction what is an optimum culture age for a valid gram reaction?
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.
Why is decolorization important in Gram staining?
The length of decolorization is a critical step in gram staining as prolonged exposure to a decolorizing agent can remove all the stains from both types of bacteria.
Why does the age of the bacterial culture matter for Gram staining?
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.
How does age of culture affect Gram stain?
Old cultures tend to lose the peptidoglycan cell walls, which predisposes gram-positive cells to be gram-negative or gram variable. Gram stain is not useful for organisms without a cell wall like Mycoplasma species, and for smaller bacteria like Chlamydia and Rickettsia species.