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The whole process is called osmosis. In it there is the flow of liquid along a concentration gradient. Water then flows from the side which contains the low concentration of dissolved molecules (this can be salts or sugar for example) to the side with the higher concentration until it reached equilibrium. This principle is shown in the image below (all ...
9
Keep in mind that the citrate utilizing strain appeared after over a decade. Also, Escherichia coli could always metabolize citrate, but the citrate transporter that brings it into the cell is only expressed under anaerobic conditions [1]. The strain that evolved to import citrate under aerobic conditions had a duplication of the transporter gene which put ...
9
Short answer
Weak organic acids are more effective for food preservation then strong mineral acids, mainly because undissociated weak acids can cross the cell membrane and disrupt cell physiology from within.
Background
Natural fermented, or pickled materials are traditionally cured in a brine solution (salt, water, sometimes spices and sugar). Desirable ...
7
"Forma asexualis" as explained in another paper
The authors favor the use of the expression forma asexualis (f.a.) in the
description of anamorphic species of the genus
Cystobasidium and this decision follows the current
practice of reclassification of asexual yeast taxa (see
e.g. Lachance 2012; Groenewald and Smith 2013;
Daniel et al. 2013; ...
6
Your sugar substrate was sucrose. Yeast cells metabolise this by secreting an enzyme, invertase, which splits the disaccharide into glucose and fructose both of which can be fermented by yeast to produce CO2.
According to this site
Equal Original (blue packaging) is a zero calorie sweetener that contains aspartame and acesulfame potassium as its sweetening ...
5
In eukaryotic cells there is no difference between a mother and a daughter cell - the later is an exact copy of the mother cell. This is true for yeasts as well for example for human cells. The only thing that happens over time is that the telomeres at the end of the chromosomes get shorter (unless the cell has an active telomerase which most cells doesn't) ...
5
http://www.protocol-online.org/biology-forums/posts/26634.html
I found this link - it says 'we don't really know'. It says PEG binds DNA, I assume shielding the membrane from its negative charge and allowing internalization to happen.
I would guess that the amphipathic nature of PEG, being partly hydrophobic, also helps soften up the membrane. ...
4
It depends upon exactly what you have done.
The standard way of using a yeast intergrating plasmid (YIp) is for it to integrate into the genome by recombination between a piece of yeast DNA that the YIp carries and the same DNA in the genome. This is often, but not necessarily, the selectable marker. So for example a YIp carrying the URA3 gene as its only ...
4
I have never worked much with yeast, but I can still give some answers:
Salmon sperm is used as a the so called "carrier DNA". It is thought to bind to the yeast cell wall and thus prevents that the DNA which shall be transformed does so. This raises the transformation efficiency. See here for more details: "Transformation of yeast by lithium acetate/single-...
4
Background to the different theories of ageing.
This video, from a senior lecturer at the University of Liverpool who specialises in ageing, discusses the theories of ageing. He touches on the DNA damage theory.
DNA damage theory of ageing.
Note that when talking about DNA damage theory, we are specifically talking about damage to the process of cell ...
4
There is a relatively simple (and yet logical) answer: You can use the media as soon as they are cold enough for your desired culture temperature. So if you want to use the media at 30°C, there is no need to wait longer. The media will only warm up again in the incubator until this temperature is reached.
The addition of antibiotics is also uncritical, ...
4
The standard way to measure growth in a liquid culture is to measure the optical density (OD) of the solution – basically, how cloudy it is. Bacteria or yeast in a solution will absorb light that passes through it, making it more cloudy (or turbid). Within a certain range of turbidity, the OD of the solution is directly proportional to the concentration of ...
3
Yeast integrating plasmids are known to be stable, even in absence of a selective medium but can revert like most homologous recombination plasmids.
Quoting from the book Yeast Gene Analysis (pg476):
YIps are generally more stable than YRp or YEp plasmids. As a result
it is safe to grow most YIp-bearing strains in rich media, although it
is good ...
3
This is a question which is not easy to answer, especially the 50.000bp number (which I haven't found anywhere in there literature). However, I found some evidence, partly derived from plant and mammal artificial chromosomes (references 1 and 2), partly from the original publication from Murray and colleagues (reference 3).
The problems with small ...
3
Not well, they need dextrose. Use YBT:
20 g Casein Peptone Tpe-M
10 g Yeast Extract
20 g Dextrose
17 g Agar
q.s. to 975 mls in di-water.
pH to 6.2 w 5M NaOH
q.s. to 1L with di-water.
Autoclave for 45 min at 121C
Aseptically dispense in Petri dishes.
Store at 4C for up to 12 weeks.
If you want to grow Co-culture do so in LB supplemented with 20g/L ...
3
Yes, it is possible to reuse yeast in both beer and wine fermentation - commercial brewers do it all the time for cost savings and batch reproducibility, and although I'm not as familiar with making wine, many sites including this one say it's perfectly fine, as long as the viability of the cells is high enough.
The yeast aren't necessarily in stress-...
3
Turgor Pressure(T.P) is defined as the amount of pressure inside a cell solely due to its water content, whereas Osmotic Pressure(Pi) is defined as the pressure required to stop osmotic flow between the cell and a pure solvent when the pressure exerted by water is zero.
Osmotic Pressure is often given as the negative of the Osmotic Potential(or Solute ...
3
This is usually the way this kind of inhibitors are used. There needs to be a way that they come into the cells (if they stay in solution and cannot reach their target they will be useless), but then they inhibit their targets.
What usually needs to be done is to determine which concentrations are needed in the cell culture (or the medium) to be effective ...
3
Yeasts are living organisms, they do not evaporate. However it is true that in most fermented food we eat, yeast are no longer there. So why is it so?
It is not the reaction with sugar and warm water that makes them disappear. Most of the time they get killed later in the food making process. For instance, if you consider yeasts in bread, like french ...
3
Basic answer: Yes, they can survive, but only if they do not need to undergo cellular respiration. I quote from Microbiological Research, Volume 169, Issue 2-3, p. 185-195:
Mitochondrial DNA (mtDNA) is a compulsory genetic component for encoding essential respiratory enzymes in all eukaryotic cells.
In other words, for cellular respiration to occur, the ...
3
There is at least one bacteriophage ("phage") that targets bacteria that spoil wine:
The Gluconobacter phage GC1 is a novel member of the Tectiviridae family isolated from a juice sample collected during dry white wine making. The bacteriophage infects Gluconobacter cerinus, an acetic acid bacterium which represents a spoilage microorganism during wine ...
2
If the yeast strain A is auxotrophic for AA 1 and the yeast strain B is auxotrophic for AA 2, neither would be able to grow in minimal medium by itself. But combined they complement the lack of AA1 in strain A by strain B and vice versa. That is metabolic complementation.
2
I think that you could try a similar approach to GSFS:
use transduction in proteins (if you don't know star code, then you must use 3 strings for each gene)
use a basic tool (a stand alone like UNIPROT tools) to identify the proteic domain type (chain alpha, ..)
divide the genes by proteic domain type (pdt): which contains which pdt and the pdt order ...
2
One very important resource is EUROSCARF. http://web.uni-frankfurt.de/fb15/mikro/euroscarf/
It is one of the very famous and dedicated strain repository for yeast (S. cerevisiae) strains. You can even find some very useful yeast plasmids here.
Another resource I would recommend will be the original labs, which made the mutant strains/plasmids. Yeast ...
2
The Saccharomyces Genome Database has a list of sources here. One of them is the Japanese Yeast Genetic Stock Center: I checked their site out and found that they charge ¥390 per strain which is around USD4. There is also a USD5 fee on all orders. I searched for a couple of standard strains, and these were in the catalogue, so it looks like a good ...
2
I don't have a definitive answer to this, but a little over a decade ago I was in an undergraduate lab that had a similar thing happen - a small amount of metabolism of a "control" group of bacteria fed artificial, sugar/calorie free sweeteners instead of sugar.
Our running theories at the time were:
Contamination. Always a problem in laboratory ...
2
I've published a paper comparing different measures of specificity, if that is of any help. But if you plan to have, e.g., measures of performance on carbon sources, pH, and temperature, then you'll have three measures of specificity (i.e. one for each).
Also, worth to have a look at Graham Bell's inconsistency and responsiveness, as used by Venail et al. ...
2
Heat shock proteins - HSP70 and HSP30.
You may also have ribosomal subunits as well.
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