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What type of media should be inoculated using zig-zag motion across the surface of the media?
agar slant
Why is it necccessary to place the inoculated molten agar cultures in an iced water bath for their rapid solidification?
to ensure that the cells remain dispersed in an iced water bath.
What is agar well diffusion?
The extracts obtained from the plants or any antibiotic preparations were used for studying their antibacterial activity. A loop full of bacterial strain was inoculated in 30 ml of Nutrient broth in a conical flask and incubated for 72 hrs to get active strain by using agar well diffusion method. Muller Hinton Agar was poured into Petri dishes. After solidification 0.25 ml of test strains were inoculated in the media separately. Care was taken to ensure proper homogenization. The experiment was performed under strict aseptic conditions. After the medium solidified, a well was made in the plates with sterile borer (5mm).The extract compound (50 μl) was introduced into the well and plates were incubated at 37°C for 72 hrs. All samples were tested in triplicates. Microbial growth was determined by measuring the diameter of zone of inhibition14. A control with standard antibiotic was kept for all test strains and the control activity was deducted from the test and results were recorded.
What is the color of urease agar when inoculated with an urease negative organism?
The agar slant will remain the original color (yellow). However, most labs use the broth.Two media types are commonly used to detect urease activity. Christensen’s urea agar is used to detect urease activity in a variety of microorganisms. Stuart’s urea broth is used primarily for the differentiation of Proteus species.
Why does bacteria on agar plates need to be removed from the incubator after 24-48 hours?
To avoid overgrowth of the bacteria you have inoculated. Depending on the type of media you use, you could also have a false reading if it is left in there for the wrong amount of time.
What type of media should be inoculated using zig-zag motion across the surface of the media?
agar slant
Why can the agar pour tubes be rinsed in the sink after the agar is transferred to the Petri plate?
The ending agar is significantly diluted. If the undiluted agar is pured in sink, it will solidify and block up the sink.
Why did you stab the peptone iron agar instead of inoculating only the surface?
Because the peptone iron agar is used to detect ANAEROBIC bacteria. If you stab it deep into the agar you allow the bacteria to grow in the absence of oxygen. If you only inoculated the surface the bacteria wouldn't grow.
Why is it necccessary to place the inoculated molten agar cultures in an iced water bath for their rapid solidification?
to ensure that the cells remain dispersed in an iced water bath.
Why do you heat agar in flask before dispensing into tubes to make agar slants?
If you are talking about heating the agar before using it, then you are not talking about making the agar from scratch. You are talking about agar that has already been prepared and has been allowed to solidify in a flask. Heating is necessary because the agar must go from its solid state to a liquid state so that it can bePOURED into a tube where it can solidify inside of the slanted position of the tube.
Does Saccharomyces cerevisiae ferment mannitol?
Mannitol salt agar inoculated with Micrococcus luteusshowing no fermentation of mannitol (pink medium). The colonies show a yellow pigment which is characteristic of M. luteus.
Why is it important that the Tryptic Soy Agar slant be inoculated with a pure bacterial culture instead of a mixed culture?
So that you can be sure that the results are due only to one specific species.
How do you inoculate agar butt?
In microbiological testing, a "butt" refers to the bottom of a tube filled with agar. Its most common use is in conjunction with the term "slant". These agar-filled tubes are typically allowed to solidify at an angle so that a larger amount of surface area is available to inoculate by streaking. After incubation, both the slant surface and the butt have to be evaluated because growth on the slanted surface (next to air/oxygen) will indicate one kind of information and the bottom (butt) will indicate additional information about the bacterial growth--usually indicated by a difference in color. For example, in the TSI test (Triple Sugar Iron), a combination where the slant is red and the butt is yellow means that fermentation of glucose has occurred. In a TSI test, the butt is not actually inoculated. However, in a motility test, which does not require a slant, the agar is inoculated by stabbing a straight wire covered with an inoculum of sample down to the bottom of the tube. If the bacteria can grow away from the stab into the agar, they are motile. If growth is confined to the stab length, they are non-motile.
Prewarm agar plates?
before bacterial culture, the media containing agar i.e. solid agar should dry in the incubator, that is prewarm agar plate.
a.Why is Muller Hinton agar used in experiment described in lab lesson H instead of TSA?
. If Muller hinton agar is poured very thin , what would be the probable result wrt zone size?
What is agar well diffusion?
The extracts obtained from the plants or any antibiotic preparations were used for studying their antibacterial activity. A loop full of bacterial strain was inoculated in 30 ml of Nutrient broth in a conical flask and incubated for 72 hrs to get active strain by using agar well diffusion method. Muller Hinton Agar was poured into Petri dishes. After solidification 0.25 ml of test strains were inoculated in the media separately. Care was taken to ensure proper homogenization. The experiment was performed under strict aseptic conditions. After the medium solidified, a well was made in the plates with sterile borer (5mm).The extract compound (50 μl) was introduced into the well and plates were incubated at 37°C for 72 hrs. All samples were tested in triplicates. Microbial growth was determined by measuring the diameter of zone of inhibition14. A control with standard antibiotic was kept for all test strains and the control activity was deducted from the test and results were recorded.
Why must the temperature of the agar be no lower than 45C and no higher than 50C when being poured into the plates?
the bacteria will dentaure and die off
