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Bactbob
Bactbob, Public Health Laboratory Director
Category: General
Satisfied Customers: 39
Experience:  20 years as a Public Health Microbiologist/Director
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I'm trying to find out the properties of the microbes E., S.

Customer Question

i'm trying to find out the properties of the microbes E. coli, S. epidermidis and S. cerevisiae.
JA: The expert will know what to do. Please tell me everything you can so the expert can help you best.
Customer: I identified E. coli as a gram negative, mobile bacteria with catalase activity that grows best in a warm, dark, enviornment. I was told my discussion of characteristics associated with the VP were not evident and an appropriate description of the characteristics of properties was not complete,.
JA: Is there anything else the expert should be aware of?
Customer: Escherichia coli Reagents (if required) Observation of results Interpretation of resultsMethyl Red Voges-Proskauer Catalase Motility These are the questions I was supposed to answer. I believe that nothing with my S. epidermidis yielded the right results.Staphylococcus epidermidis Reagents (if required) Observation of results Interpretation of resultsMethyl Red Voges-Proskauer Catalase Carbohydrate Fermentation- Fructose Carbohydrate Fermentation- Glucose Carbohydrate Fermentation- Mannitol Motility Salt Tolerance:Nutrient broth with 1% NaCl Salt Tolerance:Nutrient broth with 7% NaCl Salt Tolerance:Nutrient broth with 15% NaCl Saccharomyces cerevisiae Reagents (if required) Observation of results Interpretation of resultsCarbohydrate Fermentation- Fructose Carbohydrate Fermentation- Glucose Carbohydrate Fermentation- Mannitol Salt Tolerance:Nutrient broth with 1% NaCl Salt Tolerance:Nutrient broth with 7% NaCl Salt Tolerance:Nutrient broth with 15% NaCl
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Submitted: 9 months ago.
Category: Microbiology
Expert:  Bactbob replied 9 months ago.

I have another commitment right now and will give you a full reply later today. Sorry for the inconvience

Customer: replied 9 months ago.

Thank you for your response. Later today will be great. Is what I need help with clear from the information i have given you?

Expert:  Bactbob replied 9 months ago.

Let me know if this answers your questions.
I've never tried growing the organisms at 15% NaCl, so have no direct experience with that concentration, but the literature seems to point to the results I've outlined

Even pure strains of the bacteria can have genetic mutations that allow them to tolerate different saline concentrations or ferment unusual compounds, nothing is 100% in microbiology, but that is the fun part.

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VP Test
Add potassium Hydroxide + creatine (KOH) & alpha-naphthol,
Shake vigorously, let stand ~ 5-10 minutes, some references indicate1-2 hours, exposed to air.

Negative (-) = light brown color, (E. coli), Positive is a pink color (Enterobacter)

MR-VP, usually run at the same time, Record the MR results (red+, yellow -) before adding the VP reagents

The corresponding Methyl Red test is Positive for E.coli (red) and Negative for Enterobacter

Staphylococcus epidermidis
Fructose Positive (Ferments)
Glucose Positive (Ferments)
Mannitol Negative (Staph aureus is Positive)
Motility Non Motile (Staph are cocci (round) and are not motile
Salt Tolerance 1% Growth
Salt Tolerance 7% Growth
Salt Tolerance 15% slow or no growth

Saccharomyces cerevisiae
Fructose Positive (Ferment)
Glucose Positive (Ferment) (prefers Glucose over Fructose)
Salt Tolerance 1% Growth
Salt Tolerance 7% Inhibition or No Growth
Salt Tolerance 15% No Growth

Customer: replied 9 months ago.
Just one thing I wasn't clear on. With S. cerevisiae, is carbohydrate fermentation mannitol positive?
Expert:  Bactbob replied 9 months ago.

It appears that Saccharomyces cerevisiae cannot ferment Mannitol, although some wild strains can and the yeast can be adapted to the sugar

Customer: replied 9 months ago.
Thank you so much. You have answered all my questions.