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In presumptive tests for coliforms, lactose broth is preferred over glucose broth because many coliforms can ferment lactose, producing gas and acid, which are indicators of their presence. While glucose can also be fermented by some bacteria, it is less specific for coliforms. The use of lactose broth helps ensure that the test is more selective for lactose-fermenting organisms, making it a better choice for detecting coliforms in water and food samples.
What else can I help you with?
Saline lactose broth sterilization method?
If the broth contains only saline and lactose, it can be autoclaved. However, it it contains peptide growth factors depending on the application, it will have to be filtered prior to use since protein-containing media is sensitive to heat.
Why is lactose converted into glucose and galactose during food processing?
Converting lactose into glucose and galactose allows lactose-intolerant people to consume milk products. Glucose and galactose also taste sweeter than lactose so the need for additional sweeteners in flavored milk products is reduced. As glucose and galactose are more soluble, it gives ice-cream a smoother texture. Glucose and galactose can be fermented by bacteria more quickly so the use of these monosaccharides shortens the production time of cottage cheese and yogurt.
Why does Bacillus cereus ferment Glucose and not Lactose or Sucrose?
Because bacillus cereus is a Gram-positive, spore-forming, and rod-shaped, it\'s only able to ferment glucose.
What would happen to the lac operon if a bacterium were growing in the presence of both glucose and lactose?
In the presence of both glucose and lactose, the lac operon would be repressed. Glucose inhibits the production of cAMP, which is needed to activate the lac operon. Since glucose is the preferred energy source, the bacterium would utilize glucose and the lac operon would remain inactive.
Can yeast ferment galactose and lactose?
check out this link: http://www.madsci.org/posts/archives/2005-11/1132509463.Cb.r.html what it basically says is that yeasts cannot use lactose becasue they cannot break it down into its components (galactose and glucose), so they can only use lactose when they are genetically engineered to produce lactase (an enzyme which breaks down lactose into its constituent sugars).
The lac operon enables a bacterium to build the proteins needed for lactose metabolism only when what is presented?
Only when lactose is present; if glucose is present the cell will metabolize glucose over lactose due to glucose being easier for the cell to metabolize.
Does lactose contain nitrogen?
No. Lactose is a sugar containing only carbon, hydrogen, and oxygen.
Saline lactose broth sterilization method?
If the broth contains only saline and lactose, it can be autoclaved. However, it it contains peptide growth factors depending on the application, it will have to be filtered prior to use since protein-containing media is sensitive to heat.
What happens when e coli is mixed with glucose sucrose and lactose?
E. coli can metabolize glucose and grow well. It can also metabolize sucrose, but usually not as efficiently as glucose. However, E. coli typically cannot metabolize lactose unless it carries the necessary enzymes, such as beta-galactosidase from the lac operon. Without the ability to metabolize lactose, E. coli will not grow as well in a mixture of glucose, sucrose, and lactose compared to a mixture of only glucose and sucrose.
Why is lactose converted into glucose and galactose during food processing?
Converting lactose into glucose and galactose allows lactose-intolerant people to consume milk products. Glucose and galactose also taste sweeter than lactose so the need for additional sweeteners in flavored milk products is reduced. As glucose and galactose are more soluble, it gives ice-cream a smoother texture. Glucose and galactose can be fermented by bacteria more quickly so the use of these monosaccharides shortens the production time of cottage cheese and yogurt.
What will happen when yeast is added to a solution of lactose?
Since yeast will only have a reaction when it is able to break down an enzyme nothing will happen when it is added to lactose. Lactose does not contain the proper enzymes or glucose to cause a reaction.
Why does Bacillus cereus ferment Glucose and not Lactose or Sucrose?
Because bacillus cereus is a Gram-positive, spore-forming, and rod-shaped, it\'s only able to ferment glucose.
Do egg whites contain lactose?
Yes.
The lac operon enables a bacterium to build the proteins needed for lactose metabolism only when?
Lactose is present, otherwise the lac operon is not needed and is shut off.
What would happen to the lac operon if a bacterium were growing in the presence of both glucose and lactose?
In the presence of both glucose and lactose, the lac operon would be repressed. Glucose inhibits the production of cAMP, which is needed to activate the lac operon. Since glucose is the preferred energy source, the bacterium would utilize glucose and the lac operon would remain inactive.
What is the function of lactose?
Lactose is broken down by lactase to form galactose and glucose which are then absorbed by the small intestine.
Does milk fat contain lactose?
Lactose, or milk sugar, is a natural component of milk. In regular milk, the lactose portion is 5%. In butter, the lactose portion is about 0.1%. Therefore, butter cannot be considered lactose-free.
