Microbiology is the study of organisms that are too small to be seen with the naked eye. This includes organisms like bacteria, fungi, protozoa, and others.

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How do I measure bacterial growth in agar dishes (either by cell mass or by cell count)?

I am doing an experiment in which I am growing S. mutans in agar dishes, and I am not sure how I would measure the growth of the S. mutans. I am also not sure if I would do this by measuring cell mass ...
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62 views

observed luminescence in a piece of plaice

A plaice fish bought for human feed has been cleaned and cooked. Some parts of the raw body have been left out of the fridge at about 22°C for about 15 hours. During the following night a ...
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What are the characteristic structures of bacillus M. tuberculosis and what they cause?

I answered to this question: In most forms of the disease, the bacillus M. tuberculosis spreads slowly and widely in the lungs, causing the formation of hard nodules (tubercles) in the ...
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How can fresh cavities form at the margins of sliver amalgam fillings on teeth?

Silver amalgam fillings predominantly contain silver a known bactericidal agent and mercury which a known toxin and has bactericidal property. So how is it that the plaque bacteria survive near the ...
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50 views

What is it the most common reason for community acquired pneumonia?

This is a difficult question because there are many types of community-acquired pneumonia (CAP): typical acute, atypical acute and chronic. Most common microorganisms are also different among ...
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Why does the mixture of infant formula with saliva provide an ideal breeding ground for disease-causing micro-organisms?

From: http://www.nal.usda.gov/wicworks/Topics/FG/Chapter4_InfantFormulaFeeding.pdf Discard any infant formula remaining after a feeding. The mixture of infant formula with saliva provides an ideal ...
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38 views

How to Diagnose this hepatitis A, B and C case?

Male patient who is working in the hospital and may be infected with contaminated blood had hepatitis with genome IA 5 years ago. His hepatitis A at that time was confirmed with the rise of anti.HAV ...
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56 views

Is this necrotizing skin infection caused by Staphylococcus aureus?

A 5-year-old boy returns from summer camp with several minor cuts and abrasions on legs. He has fever and extensive cellulitis, subcutaneous tissue and muscles are involved. Necrotic tissues were ...
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Elevated transaminases after blood transfusion?

This sparks HCV immediately in my mind. However, there may be other possibilities too. What can you deduce from elevated transaminases if you only know that the healthy adult patient received blood ...
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45 views

How can a respiratory infection lead to a skin infection?

Example of a case: 5 children develop a bright red rash on the face and turns violet after a few days and then disappears. Then maculopapular rash appears on the trunk, buttocks and extremities. It ...
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39 views

Can acid-fast M. tubercolosis obstruct alveoli?

I am not sure which word is the best here for colonisation of alveoli by acid fast-mycobacteria. I found this question, and I am getting confused by the term obstruction of alveoli because I tend to ...
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35 views

Which strains of C. diphteria are causing Diphteria toxin?

I got this question: Diphteria toxin is produced only by those strains of C. diphtheria that have which of the following characteristics? Encapsulated glucose fermenters lysogenic for b-prophage ...
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303 views

Factor causing Methicilin-resistance in MRSA?

I think the main reason is the natural selection that is causing methicillin-resistance. However, I am not completely sure what this means practically. Here, the original question: MRSA was isolated ...
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589 views

Can Naegleria fowleri enter through your ear?

Is it possible to get infected with the amoeba, Naegleria fowleri, through your ears, or is the nose the only way it can enter to cause infection? How commonly is it found in your stool as well?
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1answer
219 views

How to deduce if RNA virus infection or DNA virus infection

Is there any general rule to say this must be RNA virus infection and the other one DNA virus infection? Example of a case: 5 children develop a bright red rash on the face and turns violet after a ...
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1answer
117 views

Is this case Histoplasma capsulatum?

A 62­ year-­old male was admitted to the hospital complaining of shortness of breath. His chest X­-ray showed a rightsided cavitary lesions. His medical history indicated he had smoked one pack of ...
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122 views

Any food crops that could grow in a desert provided that they get fertilizer and water

I am working on an idea to provide nearly unlimited amounts of water in desert regions. To make this commercially viable. I would use the water to irrigate desert sand and grow crops. Given my ...
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1answer
92 views

Is iodised salt harmful to the lactofermentation process?

I was discussing sauerkraut recipes with someone on IRC a minute ago, and they warned me not to use iodised salt in the process. My first (and so far, the only successful) batch is one I made with ...
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How to obtain bacteria samples at home?

As the original question went from hold to closed, I thought I would write up a more appropriate question. How should one go about getting bacterial samples to look at under a microscope at home? ...
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Why do kefir grains stop growing in soy milk?

Kefir is a fermented milk drink made with kefir grains. It usually is prepared by inoculating cow, goat or sheep milk with kefir grains. I would like to prepare the drink with soy milk, which worked ...
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Why do cell membranes have a lipid bilayer?

Many cells have a cell membrane composed of two layers of lipids, why is it two layers and not just one? What purpose do the membranes serve?
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1answer
40 views

Do toxin producing strains of E. coli constantly produce toxin or only under certain conditions?

Background E. coli is prevalent everywhere but only some strains produce toxins harmful to humans, such as E. coli O157:H7. Questions 1) Would anyone know if these strains are always producing ...
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157 views

How to learn biomathematics?

I'm currently an undergraduate math student and researching on the internet I discover that exists an area called "biomathematics". Looks so interesting. They use the graph theory and topology to ...
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190 views

How to obtain bacteria samples?

Would anyone know how to go about obtaining samples of Salmonella or E. coli for purely educational purposes? Note: I just want to look at the stuff under a microscope.
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Can someone explain the color-changing unit (CCU) to me?

I've been physically carrying out serial tenfold dilutions on samples of Ureaplasma to work out the color-changing units (CCU). As a definition, the CCU is the highest dilution at which there is a ...
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E. coli, risk of infection?

There has been a warning about E. coli contaminated water in South Florida. Now I'm wondering are there empirical data or historic cases which show a correlation between E.coli levels in tap water and ...
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1k views

What are the differences between G+ and G- bacteria?

The distinction between Gram-positive and Gram-negative bacteria is based upon the Gram staining method, that reflects the bacterial wall physical properties. However, this classification involves ...
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Are there any bacteria, in our environment, able to break down nitrate under aerobic conditions?

Given a fix volume of water saturated with dissolved oxygen through aeration. Suppose that ammonium, Nitrosomonas, and Nitrobacter are always available in the water. We know that some of the ammonium ...
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256 views

Is there a practical upper limit to amount of nucleotides or genes in a transformed plasmid?

I'm currently working on a synthetic biology project which involves working with lots of different parts. I would ultimately like to integrate these genes by transforming a single plasmid. I've heard ...
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1answer
34 views

First genomic survey of human skin fungal diversity

"The researchers found that a single type of fungus, belonging to the genus Malassezia, is predominant on the head and trunk. Hands, which harbor a great diversity of bacteria, are home for relatively ...
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Endophytic Xylariaceae: diversity and taxonomy inferred from rDNA sequence analyses

"Thailand is considered as one of the areas containing a high percentage of unknown taxa of Xylariaceae (Rogers 2000). In Thailand, several studies on endophytic fungi have been documented, namely, ...
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156 views

By what mechanism is Streptococcus bovis acting as a risk factor for colorectal cancer?

Streptococcus bovis bacteremia/endocarditis is considered a risk factor for colorectal cancer. What pathophysiological mechanism may link the two together?
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858 views

Writing methods section on PCR amplication in a paper

Considering that I am writing a paper for a journal, could the following phrase be understood? or should I put the 'step-by-step' way by giving numbers? PCR Amplification and sequencing PCR ...
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53 views

“Oblong to Allantoids” … Is it valid?

I read on the text book: The characteristic of Dinemasporium are: superficial, cupulate to Discoid conidiomata with brown satae, Phialid conidiogenous cells that give rise to hyaline, oblong to ...
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Is it possible for a person to become “reinfected” with the same strain of a virus?

If a person contracts a virus, viral conjunctivitis for example, is it possible for the individual to become "reinfected" with the exact same strain of the virus once the person has it treated and the ...
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123 views

Highly spherical Radiolaria; does this image accurately depict the organism?

If I understand correctly, Cenosphaera spp. is a type of Radiolaria, which is a type of zooplankton. The following is an image of Cenosphaera spp. is from the supplementary material (Figure S2) of ...
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1answer
40 views

What is a good review book/source for microbiological diagnosis?

I am trying to find the diagnosis figure for different bacteria where phases are illustrated. I am using at the moment: 1) First Aid for the USMLE Step 1 2013 and 2) Medical Microbiology by Murray et ...
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128 views

Lineage selection in plasmid evolution

I've been reading through Paulsson (2002) and I am not sure what he means by "lineage selection" in the second to last section. The paper deals with plasmid replication, and mostly concentrates on the ...
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2answers
256 views

What type of photosynthesis is performed by phytoplankton?

I am not a biologist, but I know there exist three variants of photosynthesis, namely C3, C4 and CAM. I would like to know what type is used by the ocean's phytoplankton? It might also be that ...
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35 views

How is the appropriately-stratified gut microbiome acquired in organisms performing horizontal transmission?

I am studying horizontal transmission of primary symbionts in insect reproduction. This reminded me of an earlier question I had asked, in which I learned that humans analogously acquired their ...
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1answer
180 views

What molecular processes are involved in pseudopodial extension?

I am curious as to the processes and mechanisms involved in the extension of pseudopodia in amoeba. How does the cell know and control the direction and extent of pseudopodia formation at a molecular ...
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477 views

How is the exogenous DNA protected from degradation during bacterial transformation?

During transformation, a bacterium can take up DNA from its environment. A small fraction of bacterial species are known to be naturally competent, meaning that they can engage in this sort of ...
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429 views

Definition of Dye- Reduction Test?

Can some one give a simple explanation or definition on what a dye-reduction test is.
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28 views

Multiplication to formalize Microbiological Processes

I am not from the field, but have a question regarding modeling in biology: I know that some processes can be modeled with the mathematical multiplication operation, and wondered if anyone could ...
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1answer
219 views

Where would Saccharomyces cerevisiae be found in highest concentrations in environment?

I have bakers asthma specifically to 'Sc' yeast, and know to avoid bakeries, breweries, etc... I have figured out to not disturb rotting leaf piles, and fermenting bark mulch. Where else? What ...
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1answer
2k views

Why are pili more common in Gram negative bacteria than in Gram positive?

Although pili have been observed in some species of Gram positive bacteria, the preliminary research that I have done indicates that pili are significantly more common in Gram negative bacteria. Is ...
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2answers
172 views

Is every part of a virus important for replication?

Is every component of a virus absolutely essential for its infection and replication in a host cell? Or can you just have parts of it to cause infection?
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42 views

Can viral proteins cause infection? [duplicate]

Possible Duplicate: HIV Rapid Tests Can proteins found on the surface of RNA viruses cause infection without the presence of the actual RNA and other components used in the virus?
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155 views

HIV Rapid Tests

The hiv antigens that are used in the oral rapid tests, are they infectious? The tests do not contain any actual virus but I am curious if the antigens themselves could somehow create the virus on ...
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If re-boiling does not curdle the milk, can that be taken as an indicator that the milk hasn't developed the bacteria (and their toxins)?

Usually when left in hot temperature, the milk curdles (which I know when I boil it and it starts separating). If the re boiling does not curdle the milk, can that be taken as an indicator that the ...