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Is phenylethyl alcohol agar differentia or selective?
Phenylethyl alcohol agar is a selective medium used for the isolation of gram-positive bacteria as it inhibits the growth of gram-negative bacteria. It is not typically used for differentiation purposes.
Which ingredient in a phenylethyl alcohol agar supplies carbon and nitrogen?
Peptone in phenylethyl alcohol agar supplies both carbon and nitrogen to support the growth of microorganisms. Peptone is a mixture of partially digested proteins that serve as a nutrient source for microbial growth.
What is phenyl ethyl alcohol agar?
Phenylethyl alcohol agar (PEA) is a selective media used to cultivate Gram (+)microorganisms. The active ingredient, phenylethyl alcohol, inhibits or reduces growth of Gram (-) microorganisms by interfering with DNA synthesis.
Why PEA contains 0.25 percent phenylethyl alcohol because high concentration inhibits both gram negative and gram positive?
At higher amounts, phenylethyl alcohol would most likely also inhibit gram positive organisms because it would be able to break down their membrane permeability barrier, thus allowing influx of substances ordinarily blocked and leakage of large amounts of cellular potassium. This ultimately disrupts or halts DNA synthesis.
Is the Bacillus species aerobic or anaerobic?
The Bacillus species are predominantly aerobic bacteria, meaning they require oxygen for growth and metabolism. Some species within the genus Bacillus can also perform anaerobic respiration in the absence of oxygen.
Does Bacillus cereus hydrolyze starch?
Yes, Bacillus cereus is known to hydrolyze starch. It produces enzymes, such as amylase, which break down starch into simpler sugars that the bacteria can use as an energy source for growth and metabolism. This ability to break down starch is one reason why Bacillus cereus can survive and grow in diverse environments.
How does Bacillus Cereus get its food?
Bacillus cereus is a type of bacteria that is capable of using a wide range of nutrients for growth, including sugars, peptides, and amino acids. It can break down organic matter from its surroundings to obtain the necessary nutrients for survival and growth. Additionally, some strains of Bacillus cereus are known for their ability to produce toxins which can help in obtaining nutrients by inhibiting the growth of other microorganisms in the environment.
Is phenylethyl alcohol agar differentia or selective?
Phenylethyl alcohol agar is a selective medium used for the isolation of gram-positive bacteria as it inhibits the growth of gram-negative bacteria. It is not typically used for differentiation purposes.
Which ingredient in a phenylethyl alcohol agar supplies carbon and nitrogen?
Peptone in phenylethyl alcohol agar supplies both carbon and nitrogen to support the growth of microorganisms. Peptone is a mixture of partially digested proteins that serve as a nutrient source for microbial growth.
Would removing phenylethyl alcohol from PEA alter the medium and sensitivity or specificity?
Removing phenylethyl alcohol from PEA (Phenylethyl Alcohol Agar) would likely alter the medium's effectiveness in inhibiting the growth of gram-negative bacteria while allowing gram-positive bacteria to thrive. This could lead to decreased sensitivity for the detection of certain organisms, as the selective pressure provided by phenylethyl alcohol would be lost. Consequently, the specificity of the medium might also be affected, potentially allowing for the growth of unwanted gram-negative organisms that would normally be suppressed.
Which ingredient in phenylethyl alcohol agar supplies nitrogen?
The ingredient in phenylethyl alcohol agar that supplies nitrogen is peptone. Peptone is a protein digest that provides essential amino acids and nitrogen sources for the growth of certain bacteria. This makes it a crucial component for supporting the growth of organisms while inhibiting the growth of gram-negative bacteria in the medium.
What are bacillus cereus pH growing conditions?
Bacillus cereus thrives in a pH range of 4.5 to 9.5, with optimal growth typically occurring around neutral pH levels of 6.0 to 7.0. This bacterium is highly adaptable, allowing it to survive in various environments, including food products. However, extreme pH levels can inhibit its growth, making it essential to monitor pH in food storage and preparation to prevent contamination.
What is phenyl ethyl alcohol agar?
Phenylethyl alcohol agar (PEA) is a selective media used to cultivate Gram (+)microorganisms. The active ingredient, phenylethyl alcohol, inhibits or reduces growth of Gram (-) microorganisms by interfering with DNA synthesis.
What does bacillus cereus produce?
Bacillus cereus produces a range of toxins, including emetic and diarrheal toxins. The emetic toxin, known as cereulide, is associated with food poisoning from rice dishes, while the diarrheal toxins include enterotoxins that lead to gastrointestinal issues. Additionally, this bacterium can produce enzymes that facilitate its survival and growth in various environments. Overall, B. cereus is known for causing foodborne illnesses linked to improperly stored or cooked foods.
What has the author Susan DeWitt Nester written?
Susan DeWitt Nester has written: 'Contamination and growth of Bacillus cereus and Clostridium perfringens in Mexican-style beans' -- subject(s): Food contamination, Beans
What constitutes good growth on phenylethyl alcohol agar plate?
Good growth on phenylethyl alcohol (PEA) agar is characterized by the presence of well-defined, opaque colonies. The medium inhibits the growth of Gram-negative bacteria, so the expected growth mainly comprises Gram-positive organisms, often appearing creamy, white, or yellowish. Additionally, the colonies should be evenly distributed and not overly wet or mucoid, indicating healthy growth conditions. Overall, good growth reflects the organism's ability to thrive in the selective environment provided by PEA agar.
Does sweet curdling cause bloating in UHT milk?
Sweet curdling could be caused by growth of spores that were not killed during sterilisation. Bacillus cereus spores commonly causes this issue later in shelf life.
