Hot answers tagged microbiology
17
There are two convincing papers (1,2) arguing that the observed "nanobacteria" are in fact mineral/protein complexes and not any living organisms.
In (1) Martel and Young created very similar looking particles from calcium carbonate in vitro. The calcium carbonate precipitations can even look similar to dividing cells:
After 5 days of serum incubation, ...
17
The sub-type is named for the broad classes of the hemagglutinin (HA) or neuraminidase (NA) surface proteins sticking through the viral envelope. There are 16 HA sub-types (designated H1 - H16) and 9 NA sub-types (designated N1 - N9). All of the possible combinations of these influenza A subtypes infect birds, but only those containing the H1, H2, H3, H5, H7 ...
15
The initiation of gut flora come from maternal cervical and vaginal flora (Bezirtzoglou, 1997)1. These predominantly include facultative anaerobes (e.g., Staphylococcus, Enterobacteriaceae and Streptococcus). Birth by caesarean section can cause problems because these bacteria are not passed on in the usual manner.
Vael et al. (2011)2 found an association ...
15
Subtype is denoted using the HxNy notation for the variant of hemagglutinin and neuraminidase.
Strain names are specified as: [virus type]/[location of origin]/[sequential number of isolation]/[year of isolation] ([subtype]), such as "A/Alabama/AF2070/2010(H1N1)"
Virus type would be A, B, or C for the various forms of influenza (influenza A being the most ...
15
No
There are several reasons why this might not be true, as Alexander has discussed. An antibiotic often has a molecular target that isn't present in all bacteria, it's extremely hard to get antibiotics to certain parts of your body, and some bacteria will be defended against a antibiotic attack by biofilms, resistance mechanisms, and sheer statistical ...
13
Growth can be quite slow for some species under certain conditions when the concentration of cells is too low. Log-phase growth is powerful, and so one would like to keep cells in this state for the experiment at hand. Different genes are expressed then compared to a stationary phase.
In addition, you'd like your culture to out-compete a contaminant if ...
13
Just a quick answer: No, there is no way to kill all bacteria in your body once they are there. The only way to keep a person sterile is to prevent any bacteria entering the guts during and all time after the birth. Look for gnotobiology and gnotobionts to learn more about these organisms (including humans).
Here are some reasons why:
Most antibiotics ...
13
Simply put, old habits die hard; physicians and other medical personnel have grown up with the old species designations so will continue to use them. This is somewhat the reverse of the case with E. coli, where 80-90% of the genome is variable across strains.
Lin-Hui gives a brief history, where strains identified early were given specific names within ...
12
There are two types of food poisoning:
Alimentary intoxication
This is the case when you consume food which is contaminated with some toxins, and those are responsible for development of the poisoning symptoms. The source organisms of these toxins might not be present anymore (killed by heating during cooking, for example). In this case there is no massive ...
12
I'd like to know what is the reference for amoebic learning. I cannot comment directly on this, but there is some evidence for "adaptive anticipation" in both prokaryotes and single-celled Eukaryotes which do not have a nervous system.
In the case of E. coli, it has been shown that the bacteria can anticipate the environment it is about to enter. E. coli ...
11
GMO foods have a huge potential to make food cheaper to produce and more nutritious.
The most common GMO foods have at least one gene added to them - an enzyme that makes the plant resistant to RoundUp - an herbicide made by the same company (Monsanto). this makes the farmers able to grow their crops with much less intensive labor to keep the plants ...
10
No.
There is nothing special about a piece of GM DNA when compared to any other random piece of DNA. If this phenomenon happened at any detectable level, we'd have found eukaryotic DNA in bacterial genomes/plasmids long before the introduction of genetically modified crops. And that would be front page news in the field of horizontal gene transfer! Which ...
10
The gastrointestinal tract of a normal fetus is sterile. During birth and rapidly thereafter, bacteria from the mother and the surrounding environment colonize the infant's gut. Immediately after vaginal delivery, babies may have bacterial strains derived from the mothers' feces in the upper gastrointestinal tract.[15] Infants born by caesarean section ...
9
Adding to the other answers posted:
Hemagglutinin (HA or H) - Helps the virus enter the cell by binding to sialic acid receptors on cell membrane. It then unfolds in a lysosome and fuses the viral and lysosome membranes.
Neuraminidase (NA or N) - Helps the virus exit the cell by cleaving the terminal sialic acid residues at the progeny virus release.
9
does the microbiome affect food metabolism?
Most definitely (and not surprisingly). The Arumugam paper [1] notes that
The drivers of [enterotype 1] seem to derive energy primarily from carbohydrates and proteins through fermentation, … because genes encoding enzymes involved in the degradation of these substrates (galactosidases, hexosaminidases, ...
9
nope - the test contains antibodies to HIV proteins, but nothing from HIV itself. The 'antigen test' tests for antigens, it doesn't itself contain any antigens.
Antibodies are proteins that animals (like humans) produce to fight of viral and bacterial infections, they don't come from viruses.
Even if the test did contain HIV proteins, it could not ...
8
When I took Microbio we had a entire lecture on this. My professor's view was that they do not survive due to the pH of the stomach. He told us that there are microbiologist on both sides as to whether they do make it to the intestine (or enough of them to make much difference) or that they do survive and help. I have added a link below to a article by the ...
8
No, Naegleria fowleri is a free-living excavate form of protist that lives in warm fresh water. Fowleri finds its way into the brain by eating through the olfactory neurons in the nose where it multiplies itself greatly by feeding on nerve tissue.
Once it penetrates the nervous tissue, fowleri's feeding results in significant necrosis of and hemorrhaging ...
7
The two letters represent the type of hemagglutinin (H) and neuraminidase (N) present on the viral surface. Those are the major surface proteins of the influenza virus and therefore crucial for the immune response.
From Immunology and Evolution of Infectious Disease
HA and NA reactivities with antibodies define the subtypes of
influenza A (Cox and ...
7
In addition to the excellent response up top (by Poshpaws), one can also imagine how these systems work by looking at recent synthetic examples of single-celled organism memory.
It is possible to design various bistable switches using protein pathways, RNAi, or other means that will latch a particular state. In that way, an organism could effectively ...
7
There have been some studies regarding the use of intensive UV light installations in surgical wards or other settings as a anti-microbial tool. Generally speaking, these are part of a general interest in non-cleaning based anti-microbials in hospitals, such as UV light, O3-based machines, and copper/silver coated surfaces.
The answer to your question will ...
7
This may be related to this question on Skeptics SE: Does regular handwashing with antibacterial soap prevent disease? Since it is closely related, I will copy my answer from there to here:
See this related answer.
To answer your specific questions:
Has something changed?
Well, we have access to these products now, whereas we didn't before.
...
7
I agree that a starter culture would out-comete a contaminant (especially if there is no antibiotic in the media).
Another advantage of inoculating with starter culture is that your results concerning plasmid preps or preparing competent cells will be easily reproducible. By inoculating with a colony, the starter number of cells is different each time you ...
7
On the example of "golden rice" already raised here I took the liberty of looking up some literature about this GMO varietal. This article by Beyer et al. describes the introduction of the beta-carotene biosynthetic pathway into the strain of rice. About a decade later, Tang et al. followed this up with a clinical trial to measure how much beta-carotene a ...
7
I would not expect this to be any different than other animals - they get the flora from the environment. Key components of the environment for newborns are:
Birth canal
Den / living quarters
Skin / fur of mother, especially near the teats
Diet
Feces of family members (animals sniff this and aren't so clean)
7
@AlanBoyd's calculations are reasonable, I think the estimate is off though. The human microbome includes other bacteria which are not necessarily E.coli equivalent.
The human microbome projects give estimates that microbes are 1-3% total body mass. i.e. several pounds of bacteria.
The GI tract alone has most of the microbome mass - faeces is ~60% ...
6
I went to the Yeastbank website at Weihenstephan for some info. The keyword here is "Stamm," which is German for stem, clade, clan, or strain. So, I would take this to mean that the 34/70 is an isolate (#70) of strain 34. Two of 34/70's strengths, according to the link above are it makes clean beer and gives a pleasant taste profile due to its low yeast-like ...
6
I don't know about ruminants, but baby rabbits (and presumably other lagomorphs) apparently acquire the necessary intestinal flora by consuming their mother's cecotropes.[1]
[1] Johnson-Delaney, C.A. (2006), "Anatomy and Physiology of the Rabbit and Rodent
Gastrointestinal System" (PDF)
6
Yes, the microbiome affects food metabolism and the diet affects the composition of the microbiome. +1 to Konrad for his response. This is an area of research in which I and colleagues are engaged. Frankly, it is easier to assess the changes to the microbiome based on diet rather than looking at the fecal material to determine (unused) metabolic energy or ...
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