Answer: Gas production is characteristic feature with turning of red color to yellow color by oxidative fermentation of \"carbohydrate containing phenol red medium\" normally with bacteria. This is indicative of positive result due to presence of carbohydrates in the medium. If there is no \"fermentation occurred in the medium with no gas production\" even in the presence of carbohydrates in the phenol red medium in after 18 - 24 hours of incubation\" is the indicative of that particular microbe is \"non-fermenter\" of carbohydrates. Therefore, color change & gas production (CO2) is the indicative of positive results & absence of these features in the presence of carbohydrates in the medium is the feature can you look at (within the phenol red broth tube) to ensure that this is not a false - negative result Ques-2: A 1.0% concentration be easier to work in the phenol red medium of Durham tube during this experiment than a 0.5% concentration because 1% of carbohydrate is \"isotonic for the growth & fermentation\" of microbial species. This 1% carbohydrates is adequate concentration to make bacterial cells isotonic to the medium to survive Explanation: Oxidative fermentation (OF): In the given sample, bacteria fermented the carbohydrate (glucose, sucrose) aerobically and the result is the indicative of acid production in the open culture Durham tube (aerobic respiration occurred) and oil covered culture tube (anaerobic respiration occurred). The resultant acid produced converts, bromthymol blue PH indicator colour from green to yellow. We can assess the PH of the fermented product based on its acidic nature. We cannot determine the amount of acid produced here and we cannot predict the gas (in the form of bubbles) liberated upon OF which is significant to identify a particular unknown bacteria inside the medium. The turbidity inside the yellow broth represents bacterial motility. Phenol red (PR) based broth is useful to ferment carbohydrates in presence of bacteria (gram negative) finally thereby production of gas (possibly CO2) and acids. PR based broth is useful to examine the ability to ferment the carbohydrates by the bacteria and the ability to degrade the amino acids. PR based broth in presence of carbohydrates with the above OF produces orange coloured turbidity with a proper optical density. In the absence of the carbohydrates bacteria cannot form orange colour due to absence of fermentation. Solution Answer: Gas production is characteristic feature with turning of red color to yellow color by oxidative fermentation of \"carbohydrate containing phenol red medium\" normally with bacteria. This is indicative of positive result due to presence of carbohydrates in the medium. If there is no \"fermentation occurred in the medium with no gas production\" even in the presence of carbohydrates in the phenol red medium in after 18 - 24 hours of incubation\" is the indicative of that particular microbe is \"non-fermenter\" of carbohydrates. There.

1. Answer:
Gas production is characteristic feature with turning of red color to yellow color by oxidative
fermentation of "carbohydrate containing phenol red medium" normally with bacteria. This is
indicative of positive result due to presence of carbohydrates in the medium. If there is no
"fermentation occurred in the medium with no gas production" even in the presence of
carbohydrates in the phenol red medium in after 18 - 24 hours of incubation" is the indicative of
that particular microbe is "non-fermenter" of carbohydrates. Therefore, color change & gas
production (CO2) is the indicative of positive results & absence of these features in the presence
of carbohydrates in the medium is the feature can you look at (within the phenol red broth tube)
to ensure that this is not a false - negative result
Ques-2:
A 1.0% concentration be easier to work in the phenol red medium of Durham tube during this
experiment than a 0.5% concentration because 1% of carbohydrate is "isotonic for the growth &
fermentation" of microbial species. This 1% carbohydrates is adequate concentration to make
bacterial cells isotonic to the medium to survive
Explanation:
Oxidative fermentation (OF):
In the given sample, bacteria fermented the carbohydrate (glucose, sucrose) aerobically and the
result is the indicative of acid production in the open culture Durham tube (aerobic respiration
occurred) and oil covered culture tube (anaerobic respiration occurred). The resultant acid
produced converts, bromthymol blue PH indicator colour from green to yellow. We can assess
the PH of the fermented product based on its acidic nature. We cannot determine the amount of
acid produced here and we cannot predict the gas (in the form of bubbles) liberated upon OF
which is significant to identify a particular unknown bacteria inside the medium. The turbidity
inside the yellow broth represents bacterial motility.
Phenol red (PR) based broth is useful to ferment carbohydrates in presence of bacteria (gram
negative) finally thereby production of gas (possibly CO2) and acids. PR based broth is useful to
examine the ability to ferment the carbohydrates by the bacteria and the ability to degrade the
amino acids. PR based broth in presence of carbohydrates with the above OF produces orange
coloured turbidity with a proper optical density. In the absence of the carbohydrates bacteria
cannot form orange colour due to absence of fermentation.
Solution
Answer:

2. Gas production is characteristic feature with turning of red color to yellow color by oxidative
fermentation of "carbohydrate containing phenol red medium" normally with bacteria. This is
indicative of positive result due to presence of carbohydrates in the medium. If there is no
"fermentation occurred in the medium with no gas production" even in the presence of
carbohydrates in the phenol red medium in after 18 - 24 hours of incubation" is the indicative of
that particular microbe is "non-fermenter" of carbohydrates. Therefore, color change & gas
production (CO2) is the indicative of positive results & absence of these features in the presence
of carbohydrates in the medium is the feature can you look at (within the phenol red broth tube)
to ensure that this is not a false - negative result
Ques-2:
A 1.0% concentration be easier to work in the phenol red medium of Durham tube during this
experiment than a 0.5% concentration because 1% of carbohydrate is "isotonic for the growth &
fermentation" of microbial species. This 1% carbohydrates is adequate concentration to make
bacterial cells isotonic to the medium to survive
Explanation:
Oxidative fermentation (OF):
In the given sample, bacteria fermented the carbohydrate (glucose, sucrose) aerobically and the
result is the indicative of acid production in the open culture Durham tube (aerobic respiration
occurred) and oil covered culture tube (anaerobic respiration occurred). The resultant acid
produced converts, bromthymol blue PH indicator colour from green to yellow. We can assess
the PH of the fermented product based on its acidic nature. We cannot determine the amount of
acid produced here and we cannot predict the gas (in the form of bubbles) liberated upon OF
which is significant to identify a particular unknown bacteria inside the medium. The turbidity
inside the yellow broth represents bacterial motility.
Phenol red (PR) based broth is useful to ferment carbohydrates in presence of bacteria (gram
negative) finally thereby production of gas (possibly CO2) and acids. PR based broth is useful to
examine the ability to ferment the carbohydrates by the bacteria and the ability to degrade the
amino acids. PR based broth in presence of carbohydrates with the above OF produces orange
coloured turbidity with a proper optical density. In the absence of the carbohydrates bacteria
cannot form orange colour due to absence of fermentation.