Which Organism Survives The Longest Exposure Why


Which Organism Survives The Longest Exposure Why?

Which organism survived the longest exposure? Why? B. subtilis survived the longest because of the presence of spores.

How long would you like to expose the plate to UV light?

Thus 20-25 minutes exposure to UV light seemed adequate for disinfection and 30 minute exposure time is recommended for UV disinfection. The efficacy of inactivation of various organisms at the distance of eight feet from UV source and exposure time of 30 minutes is shown in the figure.

Does UV light have different effects on gram negative and gram positive organisms based on your data?

Does UV light have differential effects on gram-negative and gram-positive organisms based on your data? Gram positive vs gram negative do not differ in their response to UV light. Organisms capable of sporulation are able to survive such exposure due to the thick coats of spores.

Is Columbia CNA a defined or undefined medium because of what ingredient s )?

Is Columbia CNA agar a defined or an indefine medium? Provide the reasoning behind your choice and explain why this formulation is desirable. It is undefined due to the casein animal tissue yeast extract beef extract and corn starch in the medium.

What is the application of Columbia CNA?

Columbia CNA Agar is used with blood for the selective isolation of Gram-positive cocci in a laboratory setting. Columbia CNA Agar is not intended for use in the diagnosis of disease or other conditions in humans.

Why was there still E coli growth after UV exposure?

The control was the side of plate that was NOT exposed to UV light. Why was there still E. … Coli still has repair mechanisms for UV radiation which is why we saw it have growth will shorter exposure.

What happens when bacteria is exposed to UV light?

In simple terms when bacteria or another type of microbe is directly exposed to certain types of UV light the DNA (its fundamental building block) of the cell is damaged preventing it from replicating. If a cell cannot reproduce then the cell cannot cause infection which is how UV light kills bacteria.

Which organism survived the longest in your UV light radiation experiment and why?

B. subtilis survived the longest because of the presence of spores. Why were you told to remove the plate covers prior to exposing them to UV? UV doesn’t penetrate well and if the plate lids had been left on the organisms would have not bee exposed to much UV radiation.

Why is direct exposure to UV light important?

Triggers vitamin D – UV from the Sun is needed by our bodies to produce vitamin D. Vitamin D helps strengthen bones muscles and the body’s immune system. It may also lower the risk of getting some kinds of cancers such as colon cancer.

Which bacteria is more resistant to UV light?

faecium both Firmicutes) were more resistant to UV irradiation than two Gram-negative bacteria (E. coli and P. aeruginosa phylum Proteobacteria and Firmicutes respectively) which could be due to the thicker peptidoglycan layer in Gram-positive organisms protecting the cells from UV damage.

Is EMB a defined or undefined medium?

Eosin methylene blue agar (EMB) is an undefined medium. EMB is a complex medium consisting of peptone dipotassium phosphate lactose eosin Y (dye) and agar. In Undefined media the exact biochemical composition of the nutrient is not known and provides the growth of wide varieties of microorganisms.

Is MacConkey agar a defined or undefined medium?

Is MacConkey agar a defined or an undefined medium? Provide the reasoning behind your choice and explain why this formulation is desirable. It is undefined due to the pancreatic digests of gelatin and casein peptic digest of animal tissue and bile salts in the medium.

Which ingredient S in MSA supply ies a carbon?

The ingredients in Mannitol Salt Agar (MSA) which supplies:

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(a) Carbon: Proteose peptone beef extract and d-mannitol.

What grows MacConkey agar?

Altogether MacConkey agar only grows gram-negative bacteria and those bacteria will appear differently based on their lactose fermenting ability as well as the rate of fermentation and the presence of a capsule or not.

Which Staphylococcus species in addition to S aureus also produces coagulase?

Which of the following tests should be used to differentiate Staphylococcus aureus from Staphylococcus intermedius? The production of acetoin by S. aureus from glucose or pyruvate differentiates it from S. intermedius which is also coagulase positive.

What is the application purpose of MacConkey agar?

MacConkey agar is used for the isolation of gram-negative enteric bacteria. It is used in the differentiation of lactose fermenting from lactose non-fermenting gram-negative bacteria. It is used for the isolation of coliforms and intestinal pathogens in water dairy products and biological specimens.

Why is Bacillus subtilis resistant to UV light?

subtilis are 5 to 50 times more resistant to UV radiation than are the corresponding growing cells. This elevated spore UV resistance is due to: a) the photochemistry of DNA within spores as UV generates few if any cyclobutane dimers but rather a photoproduct (Fig.

Why is E coli sensitive to UV light?

Ultraviolet (UV) radiation is known to inhibit cell growth and induce gene damage (1). coli were exposed to UV light with a wavelength of 254 nm. … The number of CFUs under control and UV-exposed conditions were measured after 24 and 48 hours.

Why does UV irradiation inhibit microbial growth?

Ultraviolet light inactivates microorganisms by forming pyrimidine dimers in RNA and DNA which can interfere with transcription and replication (Goosen and Moolenaar 2008 Cutler and Zimmerman 2011).

What type of radiation is UV?

Ultraviolet (UV) radiation is a form of non-ionizing radiation that is emitted by the sun and artificial sources such as tanning beds.

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Is Penicillin an antimicrobial?

Penicillins are a group of antibacterial drugs that attack a wide range of bacteria. They were the first drugs of this type that doctors used.

What can UV rays do to DNA?

Ultraviolet (UV) light kills cells by damaging their DNA. … The resulting thymine dimer is very stable but repair of this kind of DNA damage–usually by excising or removing the two bases and filling in the gaps with new nucleotides–is fairly efficient.

What kind of bonds must bacteria be able to repair to survive UV light?

UV irradiation breaks the hydrogen bond between adenine and thymine of DNA. Forms a covalent bond between the thymine groups. The new covalent bond is much stronger than the hydrogen bond it replaces.

Can bacteria become resistant to UV light?

Objectives: No-touch disinfection systems like xenon- or mercury-based ultraviolet (UV) are now commonly being used for hospital room disinfection. However serial exposure to UV light can potentially lead to the development of bacterial resistance.

How do bacteria survive UV radiation?

Bacteria especially extremophiles inhabiting harsh environments permanently exposed to damaging solar radiation have evolved different strategies to cope with UV stress mainly relying on efficient DNA repair mechanisms and/or active defense against UV-induced oxidative stress and consequently need to tightly …

Where is the sun the strongest?

Latitude – The sun’s rays are strongest at the equator where the sun is most directly overhead. This is why in southern states like Florida or Texas you may be more likely to get sunburned than in northern states like Maine.

Which country has the lowest UV rays?

Colour palette
Rank Country PAF
1 New Zealand 96.3%
2 Australia 96.1%
3 Norway 92.6%
4 Switzerland 92.0%

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Which UV rays are most harmful?

UVB rays which affect skin’s top layer cause skin cancer and most sunburns. Although UVA and UVB rays pose the greatest risk for sun damage people who work with welding torches or mercury lamps may be exposed to UVC rays the most dangerous type of UV radiation.

Which microorganism is most resistant to ionizing radiation?

Deinococcus radiodurans

Deinococcus radiodurans is an extremophilic bacterium and one of the most radiation-resistant organisms known. It can survive cold dehydration vacuum and acid and therefore is known as a polyextremophile. It has been listed as the world’s toughest known bacterium in The Guinness Book Of World Records.

Which is more resistant to UV damage DNA or RNA?

RNA is more UV resistant than DNA: the formation of UV-induced DNA lesions is strongly sequence and conformation dependent. Chemistry.

Why is UV light bactericidal?

UV light especially UVC light impairs DNA to induce pyrimidine dimers and then inhibits cell proliferation elicits apoptosis and finally induces cell death [20 21]. UVC light has the strongest bactericidal effects and particularly around 254 nm of UVC is absorbed mostly to DNA.

Can Staphylococcus epidermidis grow on GSA?

Staphylococcus is the only organism that cannot grow on the GSA.

What is blood agar made of?

Blood agar consists of a base containing a protein source (e.g. Tryptones) soybean protein digest sodium chloride (NaCl) agar and 5% sheep blood.

What organism can grow on GSA?

Glucose Salts Agar (GSA): is a simple defined medium. Only organisms that can make all their cellular components from glucose and inorganic salts are able to grow on this medium.

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