Questions tagged [fermentation]

Questions pertaining to the conversion of sugar to ethanol, gas, or acids by bacteria or yeast.

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Does more ATP present mean that a microbe can ferment more and decrease the pH? [closed]

I noticed that EMP produces 2 ATP and EDP produces 1 ATP. Does that mean that if more ATP is present that would give more energy for fermentation and lowering the pH of a system?
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What pH ranges are used in industrial scale fermentation?

When reading Hans-Peter Meyer, Wolfgang Minas, and Diego Schmidhalter (2017) Industrial-Scale Fermentation. Industrial Biotechnology: Products and Processes, First Edition. Edited by Christoph ...
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What is the typical range of volumetric productivity and cell density in aerobic fermentor bioreactors for microes?

Im doing research on biomass production. Its hard to find data for this question. I need citations to calculate the production rate of microbial biomass in bioreactors (e.g aerated fermentator). ...
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Why is it possible to make yoghourt with lactose free milk?

The function of the Lactobacillus bulgaricus and Streptococcus thermophilus cultures is to ferment lactose to produce lactic acid. The increase in lactic acid decreases pH and causes the milk to clot,...
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Stoichiometric equation for growth under aerobic

I am currently studying for my exams, and I came to wonder what the typical stoichiometric equation for growth under aerobic conditions is? Where glucose is used as substrate and biomass and CO2 are ...
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How to grow Bacillus subtilis spores for making natto?

I enjoy making fermented foods, one of them is natto, which is cooked soybeans fermented with B. subtilis. I usually buy the B.s. spores online, but they are somewhat expensive and often hard to find....
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What is the role of lactic acid bacteria (such as L. acidophilus and L. bulgaricus) in glycolysis during yogurt fermentation?

I am trying to prove that an increase in monosaccharides (glucose, fructose, galactose) that have been added to milk during fermentation will result in a decreased pH. My current argument is: "The ...
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How exactly do birds get drunk eating fruit? Fermentation should be anaerobic

The Washington Post article Drunk birds are causing havoc in a Minnesota town. Police say they’ll sober up soon. describes birds becoming intoxicated after eating berries: “The Gilbert Police ...
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Is gut bacteria Succinivibrionaceae's low methanogenesis understood well enough for GM of cattle gut bacteria to be considered?

After watching the Periodic Table of Videos episode linked in this question I watched the episode Wallabies and Methane where Sir Poliakoff says (a bit after 02:00):...
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Acetone–butanol–ethanol fermentation

Source Source Source Acetoacetyl-CoA is a C3 unit. 3-Hydroxybutyryl-CoA / Butyryl is a C4 unit. Where does the additional C atom come from? I'm suspecting it's another Acetyl-CoA -> CoA reaction, ...
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Why does vinegar made from wine contain only about half as much acid as the original alcohol? [closed]

It is my understanding that the fermenting bacteria process the alcohol into acetic acid. But why is it about half the percentage of volume? For example table wine is often 12% ethanol, but vinegar is ...
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What are the meaning the nomenclature in high cell density cultivation for the production of a protein? [closed]

I'd like to know the meaning of these terms in a HCDC studies of a modified strain. Max specific yield (mg/g DCW) Max volumetric product yield (g/l) Specific product formation rate Qp (mg/g DCW/h)
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What molecules does amylase enzyme work on?

I know that in the human body cellulose cannot be broken down by enzymes; however, I am confused as to which molecules amylase enzymes during fermentation. I also looked at https://en.wikipedia.org/...
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fermentation in soil bacteria

I am doing a project on microbial fuel cell. For the purpose of the efficiency of the question, MFCs can be summarized to: Devices that use anaerobic bacteria as the catalysts to oxidize organic ...
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1answer
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What is this grainy surface on my two-week-old sourdough starter?

I'm baking bread at home as a hobby, using sourdough. After skipping one baking day, I haven't used my sourdough starter for two weeks. When opening the jar in which I keep it, I saw the surface had ...
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Health benefits & enzymes different between Thermophilic and Mesophilic Probiotic cultures?

Is there a difference between the Enzymes produced by Thermophilic vs Mesophilic Probiotic cultures ? are there any other differences in health benefits between the two types of cultures ?
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What do different fermentation products have in common?

I met with the following question in my masters course: What do different fermentation products have in common? Thinking about this, I have difficulty in identifying the similarities between ...
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E.coli fermentation - process flow

I have an engineering background and have been assigned a project to look into to failures during E.coli fermentation process using the data available before/during/after the process I have learnt ...
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Why do some yeast flocculate on top an other at bottom?

When fermenting beer normally after the fermentation has completed the yeast flocculate and drop to the bottom. However occationally they form a foamy layer on top of the beer. The difference is ...
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Preparation of dihydroxyacetone phosphate from glycerine by fermentation

I read on Wikipedia that dihydroxyacetone (DHA) can be obtained from fermentation of glycerin. I would like to obtain dihydydroxyacetone phosphate (DHAP) for a science experiment but, since I'm 15, I ...
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Can yeast ferment maltose directly?

I have been taught that yeast can act only on simple sugars (monosaccharides) and breaks them down into ethanol and CO2 I also know that yeast can break down maltose (disaccharide) and maltotriose (...
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What chemical conversions are involved , and what's the name for the process, when the muscles use lactate as an energy source?

I understand that muscles do anaerobic metabolism, specifically, "lactic acid fermentation", which I understand produces lactate. I'm not asking about that process. What chemical conversions are ...
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Does Glycolysis produce lactate, or pyruvate?

EDIT- Somebody suggested that this is the same question as this, it isn't. This one is asking about the definition of glycolysis. That one was asking about the definition of fermentation. Does ...
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Why is carbon dioxide produced in alcohol fermentation but not in lactic acid fermentation?

From my understanding, alcohol fermentation takes place in yeast and lactate production takes place in humans. These two pathways take place only when there is insufficient oxygen, because the other ...
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1answer
500 views

Fermentation of bananas [closed]

I may have access to huge quantities of freshly picked bananas. Searching the web, I have found that the sugar content of the average banana is 14g of fructose (could stand to be corrected on this) ...
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Thermophilic yoghurt bacteria survivability in the gut

Would they mostly not simply perish since they need much higher than body temperatures to thrive? Are mesophilic ones (such as kefir) much better at that and thus have better probiotic functions?
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How are bubbles formed and how do they make dough rise in bread?

So we took in biology that carbohydrate is broken into $\ce{CO2}$ and ethanol. But all I see in my mind here is that since gas is inside the dough then the gases will try to get out expanding the ...
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Is hydrochloric acid suitable for pickling food?

I was wondering whether it is possible to pickle food using hydrochloric acid (HCl), rather than acetic acid. I am not very familiar with the biology of the fermentation process involved in pickling ...
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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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Is glycolysis the beginning part of fermentation, or does fermentation follow glycolysis?

Is glycolysis the beginning part of fermentation, or does fermentation follow glycolysis? I see conflicting information from different sources https://honchemistry.wikispaces.com/Lactic+Acid+and+...
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Are humans capable of both anaerobic respiration, and lactic acid fermentation?

Are humans capable of both anaerobic respiration, and lactic acid fermentation? And if so, when do they do each? I understand that the difference between respiration and fermentation is that ...
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6k views

How is NAD+ used in lactic acid fermentation after it is oxidized from NADH?

I am confused with the whole process of glycolysis and the fate of the products of this reaction. So, I understand that anaerobic glycolysis results in 2 pyruvate + 2 NADH and 2 net ATP. Is the whole ...
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Reason behind using inducible promoter for heterologous expression

Protocols often seem to use regulatable promoters when expressing a heterologous gene in a host like yeast where they add something like IPTG to induce expression from (say) the lac promoter. Is ...
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What fruits will naturally ferment?

If left unpicked after the fruit ripens, what fruits may ferment instead of just rotting? My perception is that most fruits just rot. I know figs will ferment. I'm guessing that this is because the ...
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Do all prokaryotes have ATP synthases and an electron transport chain?

I was looking this up and I'm wondering if so far I'm correct about the following: For the most part eukaryotes do aerobic respiration, which involves glycolysis, the Krebs cycle and oxidative ...
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How do I measure fermentation rate?

I'm doing a lab soon and I need to find a way to measure fermentation rate to a relatively high degree of accuracy without using a specialized sensor. It should ideally be done with easy to find tools ...
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What concentration of sugar is optimal for baker's yeast fermentation?

I'd like to do an experiment on what concentration of sugar would be best for fastest yeast fermentation. I'm thinking to put some active dry yeast into different concentrations of sugar water and ...
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How are at home fermentations without starter cultures controlled?

When making fermented food at home, particularly those that are made without the addition of a starter culture, how does one ensure that the correct types of bacteria are carrying out the fermentation?...
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331 views

Can yeast in a primary fermentation of wine be used as a source of yeast for new fermentation?

So if I were to pitch bread yeast, and get to primary fermentation, which as I understand it, is the point at which regular cellular respiration can no longer continue due to a lack of oxygen , which ...
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Cellular Respiration/Fermentation Problem Leading to Lack of Energy

A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and ...
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Why can't there be fructification of mycelium in submerged culture?

I am very new at this. I am wondering why fed batch cultures produce a lot of mycelia but no fruit. I thought the more mycelia you had, the greater chance of it forming a fruit body. I am refering to ...
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Why not use lactase to aid the break down of lactose when making biofuels?

I did an experiment using nine different substrates (Lactose + lactase, corn, sugar cane, glucose control, wood, grass, no yeast control and yeast control) and observed their fermentation rates. ...
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Why would yeast grow but not produce alcohol?

I'm studying for my intro to microbiology test and I have a question asking why a culture of yeast responsible for producing alcohol would be growing, but not producing alcohol? The multiple choice ...
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796 views

Fermentation to acetic acid

How much time is needed for the fermentation to acetic acid production cycle, and the conversion of apple vinegar in a sealed container incubated at 37 °C? Should be in the fully closed? What is ...
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Does “Garbage Enzyme cleaner” contain cleaning enzymes?

There are many recipes which call for using fruit peel fermentation process to make a concentrated enzyme cleaner solution, some variations call to add bakers yeast. So the question arises that does ...
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Are Lambic beers the product of quorum sensing?

Lambic beers are a Belgian specialty which is still made by open-air "inoculation" by airborne microbiota first, followed by additional yeasts, LAB bacteria and more joining in at the time of ...
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What's the point of glycolysis in fermentation?

In order to initiate glycolysis, 2 ATP are necessary. In the glycolytic process, you generate an additional 4 ATP, which results in a net gain of 2 ATP. If you don't undergo glycolysis, however, then ...
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Aerobic vs anaerobic respiration comparison

The following graphs compare glucose decomposition in yeasts (in anaerobic vs aerobic conditions respectively) My question is, why doesn't the first one look like a straight line as the second one ...
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Speciation and Phylogeny of Lactobacillus

The lactobacillus, also called Döderlein's bacillus is a genus of facultative aerobic bacteria. There are several species such as Lactobacillus acidophillus and Lactobacillus reuteri. I have several ...
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Why do yeast ferment Equal sweetener

I had my students conduct a fermentation experiment manipulating sugar amounts (number of sugar packets in solution) and measuring CO₂ production via capture in a balloon and measuring circumference (...