Questions tagged [microbiology]

Microbiology is the study of extremely small organisms. This includes organisms like bacteria, fungi, protozoa, and viruses.

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4k views

Human Digestion of Cellulose?

Most animals can digest the cellulose in grass because of the anaerobic bacteria called Fibrobacter succinogenes living in their rumen (gut). The bacteria produces the enzyme cellulase and is ...
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Are single-celled organisms capable of learning?

I've read that the amoeba is capable of learning. Since these protists have no nervous system, it's safe to assume that even highly simplified learning mechanisms of the Aplysia are miles off in the ...
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Are viruses self-propelled?

So obviously, viruses are nonliving. But when my teacher was teaching viruses in the video (we're doing "flip" learning this semester), the way he described it, it seemed like the viruses responded to ...
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Sugar as a defence against bacteria?

An answer on another SE site mentions that sugar "at a certain level acts as a preservative". I've always been taught that microorganisms eat sugar and expel acids, that is why sugary food are ...
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Why do cell membranes have a lipid bilayer instead of a monolayer?

Many cells have a cell membrane composed of two layers of lipids. Why is it that they have two layers and not just one? What purpose do this arrangement serve?
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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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Short-term Lamarckism in asexual single cell organisms

I was reading through the Karr et al. (2012) whole-cell computational model. One of the things they did was to induce single-gene disruptions in their model. They observed several to be fatal, but: ...
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Could plasmids and conjugation mechanisms be used against antibiotic-resistant bacteria? [closed]

I'm surprised no one has mentioned something like this. Plasmids are often exchanged between bacteria, sometimes through conjugation. In particular, conjugation could be considered an "open-port&...
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Why is 70% ethanol preferred for aseptic techniques?

Are other concentrations (say 80%) less effective,or is this just for convenient manufacturing? Is the concentration chosen only because it is less volatile than 100 percent ethanol and hence safer?
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How much weight/volume do microbes occupy within the human body?

Microorganisms constitute the bulk of all the biomass on Earth. I weighed myself yesterday, and wondered how much less I would weigh if I were completely free of bacteria and microbes, inside and out. ...
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Why is triclosan not considered an antibiotic?

Triclosan is a chemical often referred to as a "biocide" instead of an "antibiotic". However, its mode of action seems to suggest that it is an antibiotic. Triclosan binds to bacterial enoyl-acyl ...
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What defines a microbial species?

I know that microbes are not capable of sexual reproduction, thus sorting them into species according to "groups that can interbreed and generate fertile offspring" should not apply.
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Why don't antiseptic agents kill 100% germs?

I've seen innumerable antiseptic, mouthwash, handwash advertisements that claim to be able to eliminate as much as 99.9% of all germs over a surface...but why not the remaining 0.1% (i.e- why can't ...
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If someone were to die on the moon, would their body decay?

I heard that the footprints of Neil Armstrong are still there, so I was wondering if someone were to die there, would they remain preserved, too? If not how long would it take for them to decay?
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How exactly can dsRNA be introduced to a cell?

Is it just by viruses or are there other means by which it gets into cells, such as plasmid uptake?
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How does botulinum toxin enter the blood stream from the digestive tract?

To my understanding, large polypeptides such as botulinum toxin cannot pass the intestinal lining intact. How, then, can it enter the bloodstream and cause botulism poisoning?
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Do beneficial viruses exist? If so, what examples are there?

Typically, people call viruses some kind of organic compounds that cannot reproduce autonomously and which lower the fitness of their hosts. Even the word "virus" means "venom" in Latin. But from the ...
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Is there an advantage to antibacterial soap?

There are plenty of different hand soaps out there, as well as hand sanitizers. Is there an advantage to soaps that claim that they're antibacterial vs soaps that just say soap? In particular I'm ...
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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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Does freezing microorganisms such as probiotics kill them?

Does freezing microorganisms such as probiotics kill them? If not, what is the process that allows them to "come back to life" after the temperatures are increased? As an example, lets say you ...
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1answer
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Does rainwater contain many fewer micro-organisms than river water?

From watching many documentaries on micro-organisms, I can tell water typically contains quite a lot of them. But what about rainwater? (before it hits the ground). I know nothing about any micro-...
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Do acetic acid bacteria use the electron transport chain when converting ethanol to acetic acid?

Do acetic bacteria use the electron transport chain when converting ethanol to acetic acid? And is wikipedia inconsistent here in its definition of fermentation. It says fermentation Fermentation ...
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1answer
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To understand clearly extraintestinal diseases

Extradistestinal disease seems to prefer to "bowel" diseases, I think this is about diseases outside gastrointestinal tract so stomach. Consider diseases ulcerative colitis and Crohn's disease (...
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Why are there no known photosynthetic archaea?

I'm taking a microbial physiology course and we noted that, while some archaea are phototrophic, there are no known photosynethetic archaea. Are there any physiological characteristics that make ...
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Alternatives to CFU plating for measuring number of viable cells?

I am hoping to measure growth rates of a bacterial culture in several growth conditions. I am concerned that these growth conditions may cause cell death, which would lead to a decreased ...
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Are all functions of a human cell known? [closed]

Please bear with me as I'm intruding into your world from a computer science background. In programming, once you have created a program, you know all functions of that program. Thus, 100% knowledge ...
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1answer
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How heavy are all foreign microorganisms in and on the human body?

I define "foreign microorganism" as a microorganism which is not produced by the human body (not antibodies or leukocytes) including bacteria, viruses, fungi, biofilm aggregates or small lifeforms ...
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Does avoiding medication that alleviates symptoms shorten the length of a cold?

People use over the counter (OTC) medications to relieve symptoms of the common cold. However, these symptoms are part of the immune response, right? They are driven by the body responding to the ...
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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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How many eukaryotes are there on Earth?

I have been reading: William B. Whitman, David C. Coleman, and William J. Wiebe, "Prokaryotes: The unseen majority", Proc. Natl. Acad. Sci. USA 95, pp. 6578–6583, June 1998. [Full Text] [PDF] ...
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What is the advantage of using plant-derived antibacterials rather than bacteria-derived antibacterials?

So obviously we have a big problem with antibiotic resistance. Most of our antibiotics originate from bacteria themselves (or are synthetic variations on scaffolds which originate from bacteria). I ...
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What are the most important factors influencing a person’s gut microbes?

You are your bacteria! The probiotics and the antibiotics... There has been on going discussions about how our gut bacteria is important for a healthy lifestyle. Figure 1: Schematic diagram ...
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1answer
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Is diarrhoea advantageous to the microbe?

Diarrhoea is a common side effect of many feco-orally transmitted bacterial infections. How does diarrhoea help the pathogen? Should it not have a selective evolutionary advantage? Do all symptoms of ...
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Why don’t different organisms have nucleic acid genomes containing different bases and sugar?

All organisms contain genetic material. Be it DNA or RNA, both of them have a fixed pentose group (deoxyribose and ribose). Also they contain the same types of nitrogenous bases, Adenine, Thymine(or ...
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Why are viruses considered microbes?

My question is simple. Why is a virus considered a microbe? Considering a microbe is considered to be a "living" unit of life, which viruses are not.
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Difficulty in developing certain vaccines

I have a college level background in Biology, say at the level of Campbell. I am very curious to know why it's extremely difficult to develop vaccines for certain diseases. Two cases which I am really ...
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1answer
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How can an infection of lower respiratory tract lead to a skin infection? [closed]

I am interested in the multifactorial process about infectious diseases of the lower respiratory system and their progression to a skin infection. Possible agens are zwitterions, viruses, fungi, ...
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We know that the hepatitis C virus can live on surfaces for at least six weeks. Maybe longer. The infectivity study ended after just six weeks; why?

Background A paper has found that the hepatitis C virus (HCV) can remain infective for at least six weeks on ordinary household surfaces. You can see the free full text, or a summary for busy ...
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Paper shows 2 hours of high humidity and hot temperatures kills corona virus, does this stop the spread of the virus?

I found this paper (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2863430/) which says these corona virus strains live for months at 4 degrees C, 20% relative humidity. But at 40 degrees C and 80% ...
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1answer
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How are antibodies specific for a disease detected in the blood if everybody produces a different antibody for the same antigen?

To break the title down into parts: There exist serology tests that detect the amount of an antibody (Ab) against a specific pathogen/antigen. Every human produces their own Ab for a specific ...
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Relationship between our microbiome and personalized nutrition

Recently, it has been asked whether there are 'metabolic types' between humans that can benefit from a sort of personalized nutrition. One answer suggested that one discerning factor could be the ...
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Can Naegleria fowleri enter through wounds into the bloodstream?

All the sources I've read said that Naegleria fowleri enters the brain through the nose. But lets say that someone had cuts on their arm or leg and they are swimming in water that is conducive to ...
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Is abiogenesis possible today?

Life on earth started about 3.5 billion years ago. I would assume abiogenesis happened because the conditions were right. Would the current earth conditions allow for new abiogenesis and completely ...
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Survival of E. coli on agar plate at -20 degree C without glycerol stock

If I kept E. coli transformed with plasmid at -20˚C without making glycerol stock, will it survive? Actually I have kept it this way for 18 hours. What will happen with it? Will it grow in fresh media?...
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How sterile is working next to a bunsen burner?

When I was still doing lab work, many people would just wear gloves and work next to a bunsen burner because the clean benches were all in use. This was mostly for plating bacteria like Bacillus ...
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1answer
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Scale up of Bacterial growth from 250mL to 1-5L?

I am currently growing up a specific strain of E.Coli with a knockout in 40mL of growth medium (LB) in a 250mL shaker flask... My ultimate goal is to scale up this process to a 1-5L large scale setup ...
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1answer
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What is the distinction between F' plasmid and R plasmid?

Is there a difference between an F' plasmid that has taken up a chromosomal gene that conveys antibiotic resistance, and an R plasmid? Is a bacterium containing an R plasmid and yet lacking an F+ ...
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What is the mechanism of oxygen uptake in E. coli?

How does E. coli uptake oxygen? Most of the literature I found is concerned with response to oxygen level supplied in the medium, as opposed to how much is actually transported inside. Can they shut ...
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1answer
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How specific are CRISPR-cas9 cuts?

CRISPR-cas9 uses a string of RNA that matches with DNA and makes a double stranded cut at that point. If the RNA is just a few letters in length, the enzyme would cut DNA in many places. It would be ...
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How do Gram + bacteria use a proton gradient for F-type ATPase?

Does anyone know of any papers showing how Gram positive Fermiculates or Actinobacteria use a H+ gradient for an F-type ATPase, It seems impossible since there is no outer LPS membrane to maintain ...