trying to improve methods for 27. You are a microbiologist working for a food bi
ID: 189490 • Letter: T
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trying to improve methods for 27. You are a microbiologist working for a food biotechnology company that is making lactose-free milk. One common that will cleave lactose (a 12-carbon, 2-ring suga lactose-free milk often tastes sweeter...the glucose and galactose are sensed as being sweeter than However, for long term storage of the milk, the added enzyme typically needs to be removed or degraded, e.g. by heating. However, these inactivation processes can negatively affect the flavor of the milk. Your company is looking for a newllactase enzyme that will cleave lactose but which will be optimally active at temperatures near 040 and easily/quickly inactivated at moderate temperatures Your company asks you to search for microbes that might possess such enzymes. You know that microbes that can ferment lactose will possess such an enzyme. Below, describe a plan that would allow you to enrich for and isolate these microbes of interest. In your description, list specific ingredients you would include and/or not include in the medium, and your reason for doing so. Also, include a method that vou could use to screen vour potential isolates for ability to ferment lactose. method for removing lactose is to add an enzyme to milk such as lactase r) into its two components, glucose and galactose (this is why lactose).Explanation / Answer
Plan--The lactase producing bacteria sample specimens can be collected from Alaska region which has an extremely cold temperatures. The bacteria species having cold resistant enzyme lactase are called as Rahnella. They grow at pH=8.0-8.5 and grow properly at temperartures till 30oC. The bacteria was isolated from various such ice cold regions and grown on microbiological plates containing media. These strains are positive for the catalase enzyme and negative for the oxidase enzyme. The temperatures were varied from 5-50 degree centigrade and pH range was varied from 4.0-8.0. The beta-hemolytic activity of the strains was checked by growing them in sheep blood agar medium at 15 degree centigrade for 3 days.
Ingredients-- The ingredients include brain heart infusion media containing 1% lactose at 4oC.
Methods--The substrate ONPG( ortho-nitrophenyl galactopyranoside) was used as a substrate to check the enzyme activity of the cleavage of lactose to galactose and glucose. The X-gal and zymogram assay was performed to check the activity of the enzymatic cleavage reaction by beta-galactosidases and formation of the blue band on the gel.
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