Science topic

Fermentation - Science topic

Anaerobic degradation of GLUCOSE or other organic nutrients to gain energy in the form of ATP. End products vary depending on organisms, substrates, and enzymatic pathways. Common fermentation products include ETHANOL and LACTIC ACID.
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The literature on cyclic β-1,2 glucans mainly uses glutamate as nitrogen source, but it does not explain why glutamate is chosen. Want to ask for advice, you know? (Glutamate concentration is positively correlated with pigment production ability, and pigment will interfere with the synthesis and purification of target sugars.)
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Or what is the benefit of glutamic acid as a source of nitrogen for fermentation
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Hello everyone,
I am trying to optimize fermentation conditions in my enzymatic hydrolysate obtained after cellulase treatment. I am using S. cerevisiae MTCC 36 to carry out the experiment. Even though this strain has previously reported a high ethanol conversion rate, I am only getting 0.7% ethanol yield in a solution containing 13.4g/L of glucose. I am carrying out the experiment by supplementing the enzymatic hydrolysate (1L) with yeast extract (10 g) and peptone (20 g) adjusted to pH 5. Incubation is carried out at 30 degrees with 150 rpm in a baby modular fermenter. My culture volume was 300 ml and the fermentation rate started decreasing after 6 h.
I hope this is enough information. Thanks in advance.
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8/8/22
Dear Najya,
You are welcome. Anytime. Good luck w/ your research.
Bill Colonna
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Dear all,
I am carrying out fermentations in bioreactors using the haloarchaea strain Haloferax Mediterranei for the production of PHA with short fatty acids as the carbon substrate in a saline medium. The bacterial growth at the early stage is similar to what I obtained when the experiment was conducted in flasks. After several hours of fermentation (usually around 60h), an excessive foaming takes place, making the culture medium overflowing and disturbing pH and dissolved oxygen control. Nevertheless, the culture should be able to grow further and consume remaining substrate, as it is the case in flasks experiments. To prevent foaming, I used a solution of Antifoam A Concentrate (Sigma Aldrich) diluted in propylene glycol at 1%w. For a 2L bioreactor fermentation, up to 20mL of this antifoam solution was added, and foaming still could not be prevented after some time.
It is expected that exopolysaccharides are concomitantly produced during fermentation, which can increase viscosity of the medium and thus cause foaming.
Is it possible that antifoam is consumed or adsorbed by the microorganisms ?
Should I use a more concentrated antifoam solution, eventhough antifoam A concentrate (Sigma Aldrich) is hard to dissolve properly in propylene glycol (even worse in water as it is a silicon based polymer) ?
Should I reduce the airflow in the bioreactor (currently at 1vvm) to reduce foaming ?
Is it mandatory to add antifoam in a continuous way with an antifoam probe rather than add a consequent volume each day (10mL the first day, 5mL the other days) ?
Thank you,
Lucas Bonnet, PhD student
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Thanks all of you for your details answers.
For now, I have tried using an external pump so that antifoam is added at regular time intervals, starting after 50h of culture as I know there is no foaming before. I reduced gasflow by 2 and it seems that it worked well.
I will also try another antifoam which is water soluble (Struktol)
I do have an antifoam probe which seems not to work correctly, as it continuously detects foam in the reactor due to condensation, and not foaming itself... Did you have the same problem with such antifoam probe ? The reference is : Antischaumsonde komplett ; 8844461 ; B. Braun Biotech International GmbH
Cheers
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Mostly of my research was carried out by two- or three-stage reactor that operated under mesophilic temp., anaerobic digestion process via dark fermentation which I found that the concentration of hydrogen sulfide (H2S) will decrease when increasing the stage of reactor (H2S in first reactor > H2S in second reactor).
So, how possible that H2S will increase its concentration (H2S in first reactor < H2S in second reactor) in anaerobic digestion process and why?
Thank you in advance for your kindly guidance.
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I want to know difference between fermentation/biorafinery/ composting and is that fermentation and compostion are the sub-classes of biorefenery?
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Hi Karima,
Your question has been well answered by Christoph Wittmann.
I just wanted to share that composting has been successfully practiced in both aerobic and anaerobic ways, but aerobic systems are most common in practical applications.
In case you want to know more about carbon transformation during composting, pls refer the following document:
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Dear all,
I inoculated a 200 ml minimal medium with 50g/L glucose with an unknown yeast (shown in figures).
After an incubation of 72 hours, at 180 RPM and 28 C, the broth containing the yeast turned very viscous, slippery liquid. In HPLC, using H column with 5mM Sulphuric Acid as mobile phase and RID as well as UV detector, nothing was detected.
The colour of the yeast is not cream or white, but its like cantaloupe colour.
Any type of help in identifying this yeast or the viscous product shall be highly appreciated.
Best Regards
Arush
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@Arushdeep, I also recommend molecular identification.
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I am using vegetable oil as a carbon source for the bacteria and supplying air in the fermenter. During the course of fermentation, it is causing heavy foaming in reactor which is not getting controlled by 30% silicone antifoam. So, what can be the alternative for this?
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Puede ser usado aceite vegetal y un producto comercial llamado twin 80...
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I want to carry out a lab-scale fermentation of endophytic microorganisms in primary conical flasks. Please suggest a single fermentation media which would be suitable for both bacteria and fungi for metabolite production. thank you! :)
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I am processing some organic wastes with bacteria and yeasts I want to stop the fermentation after I get the end product, can I depend only on PH, or boiling or add some chemical to stop fermenation to preserve the final product for months.
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Dear Kasem,
It all depends on the physico-chemical characteristics of your molecules of interest.
If I understand you carry out solid fermentation, therefore, you can "stop" the fermentation by modifying the pH (pay attention also to the impact of the pH on your molecule of interest but also you risk weakening the microbial walls thus releasing other molecules that you will have to eliminate later). The temperature is another factor also with the same remarks as for the pH.
But if you want my own opinion, I will focus on the first stage of purification in order to recover, in part, your molecule of interest if it is extracellular via solvents for example or salting out. If your molecule is intracellular you will have to consider weakening the membranes of your micro-organisms via physical, mechanical or chemical processes such as solvent, pH, or detergents.
Best regards
benoît.
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In the fermentation experiment, whether the carbon and nitrogen source content at shaker level should be increased when applied to the fermentor tank level?
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In my previous experiments, the media scales nicely going from shaker flasks to fermenters from 1.5L up to 3000L. I've kept the same media throughout all stages. There can be delays in growth if ingredients are changed from lab grade to bulk grade, but generally the growth recovers.
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When the recombinant E. coli was cultivated in a 3L fermenter, the growth of the bacteria was normal before induced by lactose, and the parameters such as pH and DO were normal. But about 5 h after induction, the bacteria would autolyze at a fast rate, and the final OD600 is also low.
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Good point by Michael J. Benedik
Another option is protein toxicity (although it's hard to believe it will cause actual lysis unless you overexpress a membrane protein, a lysozyme, or a lipase). What happens if you grow the cells as above but don't add lactose? Or add 1/10 of the amount?
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Milk fermentation increased my samples' L* and whiteness index (WI) values.
I want to write a discussion sentence about it. I have found some papers which give the whiteness values of milk and fermented milk, but I couldn't see any technical description.
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I didn't explore exopolysaccharides' possible effect on whiteness in the literature. Thank you for your interpretive answer. I will search and think about this perspective.
Thanks and Best Regards,
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“Figure 1 presents effects of different nitrogen sources on cell concentration, CβGs concentration, and pH (a) -> Why is the data shown as a line graph?”
Does the reviewer mean that I should change it to a bar chart???
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Appropriate response - acknowledge and accept the comment and say it's corrected.
Your suggestion is more than enough. No need to apologize.
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What is the purpose of fermenting seed medium?(In fermentation experiment)
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The purpose of the seed medium is to enable the development of a sufficiently large inoculum to start the fermentation. The seed fermentation is designed to produce active biomass rather than product. Thus, the medium composition may be different from the production medium. However, the seed medium should be sufficiently similar to the production medium so that a lag phase is avoided in the product fermentation - for example, using the same carbon and nitrogen sources
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Am workin on neisseria spp i want to do carbohydrate fermentation test for identification , i have all the required material except cellobiose and melezitose . am looking for alternatives please any suggestion .
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W.J. Colonna well its kind of hard to get them as melezitose is not cheap , and enterotube system doesn't work on neisseria spp
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Isolation of endophytic fungi carried out for medicinal plant and started with fermentation for further extraction of secondary metabolites, is design expert is applicable for above mentioned fermentation processe?
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Six different isolation media: plain PDA, plain MEA, PDA supplemented with host plant powder (PHP), PDA supplemented with host plant water extract (PPE), MEA supplemented with host plant powder (MHP) and MEA supplemented with host plant water extract (MPE) were studied and the results showed that the isolated
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the aim of seed medium in the fermentation?
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Various articles available, I prefer you read this article help you understand the agenda better.
Thank you!
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I am currently confused about my research design.
In my research design, I fermented herbal extracts and I graphed their growth curve during fermentation. Do I need to graph a standard curve on the herbal extract fermentation or a standard curve on another media can be used for growth of yeast herbal extract fermentation?
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It is very likely that the growth rate of your microbes will be different in the two media, especially with regards to length of lag phase and the final cell mass. It is best practice to determine the growth curve on all different media
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Dear All,
I would like to ask for your expert views on Idli fermentation with a starter culture. Currently, I am working on the optimization of idli to enhance its shelf life and production in a more hygienic way. Please provide your valuable opinion on this topic for further possible research areas. One of the most important aspects is to be a clean label.
Best regards
Mehdi
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Thank you for your prompt reply.
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I am isolating lactic acid bacteria from fermented soy whey. Why is it that in most of the papers lactic acid bacteria are isolated on MRS agar at 37 degrees Cwhen that is not the fermentation temperature of the original sample. For example in my area, soy whey ferments at an average temperature of 25 degrees Celsius depending on the weather.
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If you want to isolate the dominant microbiota of fermentation use fermentation temperature. If you want to see the total biodiversity of culturable microorganisms use 22, 30, 37, 42 'C for growing.
Good luck!
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For measuring whether there is cellular growth occuring or not during syngas fermentation, what is the blank to be used for spectrophotometer?
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Ideally the blank would have the same composition as the uninoculated growth medium to compensate for any components that also absorb at the optical density being used to measure growth.
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Hello,
I am currently working on a two-step fermentation process. How do I use Response Surface Methodology or similar techniques to optimise the final output (from the second step) for a two-step process? The output of the first step does affect the second step but optimising the first step does not necessarily optimises the output of the second step. So the only objective is to maximise the output of the second step.
Can anyone point me to the right direction (method, keywords, papers etc.)?
Thank you in advance!
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Hi Eqwan Roslan ! Yeah, I believe you could just optimize your first-step yield, and then consider the best condition to get your biogas without having to reach that last step at intermediates states, hence saving some time and money :)
I assume that for your standardized biogas synthesis, you would need maximum yield in the first step. From this, I would suggest doing a Central Composite design (for 2 variables) or a Box-Behnken design (if you have 3 or more variables) using your final yield as a response, and then find that maximum response.
If you're not sure if your variables are at optimum conditions, then a more exploratory analysis, prior to these RSM, would came very in handy! Usually, you tend to "go" in the direction of the gradient which suggests the location of that maximum/minimum. All these stuff is very well explained in that Montgomery book I recommended before.
Take care!
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For bioethanol production brewers yeast is used. But which commercial yeast is preferred for higher productivity?
Thank you
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Saccharomyces cerevisiae
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Hi,
I do fermentation to produce a bunch of over expressed protein. while I check the total protein I have a very high concentration, even after checking the concentrated sup. with western blot. still have a very good concentration. I tried 2 different ways to purify this protein: 1. with buffer (imidazol) and 2. with dialysis. in both of the cases I loose half of it. do you know any method to purify protein from sup. and to keep the high concentration ?
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When you say that you lose half of the protein, is this by precipitation, adsorption onto the vessel, degradation or any other particular mode? This will guide potential responses.
Firstly - if it is precipitation, this suggests that you have exceeded the concentration at which the protein is stable in the conditions you are working under. Can you simply dilute the protein to a larger volume in the same buffer and avoid loss or do you need maximal concentration?
Based on your knowledge of the sequence, calculate the pI. If this is anywhere close to the pH you are working at, you may have problems with the protein aggregating due to neutral charge, and this may be resolved by changing concentration of salts in the buffer, pH of the buffer or a number of other options of reagents you can add to your buffer to assist solubility depending on what the problem is that you are encountering.
If the protein is binding to your vessel - is anything known about this family of proteins and propensity to bind to particular materials such as certain plastics etc. - again this may guide you to change to different materials or treat the vessel in a way that reduces losses.
if it is degradation - protease inhibitors, avoiding contamination of reagents, EDTA or similar to prevent protease activity reliant on presence of ions, keeping temperature low - are all possible approaches.
If you can give us some more information I am sure we can assist further. Best wishes, Robin
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Dear Experts
At the beginning of fermentation, the pH of the mixture of barley and maize is 4.5. However, the pH of barely alone is 5.3, and maize is 5. 6. Thus, what are the possible reductions in pH in the mixture?
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Dear @Reda Nemo You should access replies to a similar question at:
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I want to do glucose and lactic acid assays during lactic fermentation. During sampling, how should the samples be stored for analysis?
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Hello, if you want to stop lactic acid fermentation there is several possible ways. The optimum temperature for lactic acid fermentation in 30-42 *C. so
1 is keeping samples near 0 *C after sampling.
2 most effective way is. glucose-associated repression with the use of glycerol.
3 stopping fermentation by adding ethanol.
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Hi, I would like to ask, why my reverse transcriptase from fermenter is less active than reverse transcriptase produced from flasks?
Thank you for responses
Bohuš
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Antifoam from fermentation sticking to reverse transcriptase?
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I will start an SSF for fish and I want to know what is the best inoculum size to start with ? Is that different from one bacteria strain to another?
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There is what we call optimization, especially with response surface methodology (RSM) or artificial neural network (ANN). With this method, I determine how much of every factor is required to significantly contribute to the biosynthesis of a microbial metabolite. I could give you a list of my materials. Whether you use Bacillus or not, a lot depends on the phase of production; whether growth-associated or non-growth-associated.
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Hello all,
I'm quite new to this topic of research. I'm seeking advice on how to increase bacterial CFU and biomass yield on a fermenter level. The bacteria is one of the Bacillus species. The current yield is around 10^8 - 10^9 CFU/ml culture (24 hours culture duration, batch fermentation using BHI broth) and the (wet) biomass is around 7-8 g/L. I'm aiming for >10^10 CFU/ml titre and >10 g/L (or even higher) biomass yield.
Hope to get some great bits of advice here. Have a nice day!
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Thanks for your reply. If you are sure of your CFU/mL determinations I can tell you that they are actually good compared with other bacterial reports. I don´t know why your goal is to reach a growth of 10^10 CFU/mL. Did you get that reference value from the literature or previous work for your specific strain?
The wet biomass measurement that you described is not a very reliable determination. I suggest to obtain the dry biomass measurement using microfiltration membranes as I described before. With this value, you can compare with the literature in which you may find this value for your specific bacteria.
I also recommend to measure the optical density at 600 nm. Depending on the color of your culturing medium, you may need to wash with RO (distilled) water the biomass using centrifugation cycles (one or two washing cycles are ok). This will serve you as another way to compare your celullar growth with literature values.
I think these steps are ok for ensuring the proper characterization of your cell growth. I would start obtaining a growth kinetics curve of your reactor batch. From this information you will obtain the growth rate. Then you need to do the same for different substrate concentrations to obtain the growth rate equation, and perhaps the Monod-kinetics parameters (if it behaves accordingly).
From these cell-growth kinetics experiments now you will be in position to apply different approaches to try to improve your current cell yield, which may include different experimental designs, such as factorial analysis considering temperature, pH, substrates, activators, etc; as well as different bioreactor configurations.
Hope this is useful for your research.
Kind regards
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In my experiments, I found that different monoclonal cell lines from the same host cell produce similar concentrations of ammonium ion when using the same medium; but when the same monoclonal cell line cultured with different types of fermentation medium, the concentrations of ammonium ion vary greatly. Is it because which of the ingredients in the medium is different that makes this difference?
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Hello Xukun Xu
The components in the medium affect the concentration of ammonium ions. Thus, to minimize both lactic acid and ammonium production, glucose as well as glutamine may need to be simultaneously controlled or replaced. You may refer to the article attached for more information on this subject.
Best.
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The raw materials I'm using are pineapples, bananas and mangoes.
I’m thinking of using a rotary evaporator. Is that good enough? if that so, what's the best temperature, rotation, and duration for the distillation process?
#bioethanol #distillation #fermentation #chemicalengineering #biofuels
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Yes. In order to remove the moisture content and increase the purity of ethanol.
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How can I produce bioethanol that is not contaminated with methanol?
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Dear Rebiai,
Thank you for asking an interesting question on RG.
microbiological method for the control of methanol in fermented feedstock, is the use of methylotrophic yeast such as Pichia methanolica and Candida boidinii which have the capacity of utilizing pectin or methyl ester moiety of pectin and methanol, thus preventing the accumulation of methanol in fermented products. Finally, instead of an outright ban on traditional fermentation, because of methanol contamination, the mixed alcohol (ethanol and methanol) could be further processed and used as biofuel. Literature abounds on the use of methanol and ethanol as biofuels.
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I need high density large volume inoculum for fermentation. Inoculum density of Pesudomonas aeroginosa is at OD600=1.9, in 25 mL LB in 250 mL flask, while it is 1.6 in 50 mL medium in 250 mL flask. Then it drops down to OD600=0.8 in 100 mL medium in 500 mL flask. I increased the no of loops as well, but same result was obtained. (37 degree Celsius/150 rpm)
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Pseudomonas aeruginosa is a highly aerobic bacterium. Therefore you must consider increasing aeration with increased volume. If it exhausts the available oxygen in the medium, its growth rate will drop and inoculum density will drop as well. If it is a strain that can switch from oxidative metabolism to anaerobic respiration, still the relevant external electron acceptor must be available. As the bacterium is metabolically versatile, care must be taken to not overburden it with garbage in the medium.
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My project is on the biosurfactant production by Streptomyces sp. which utilized the MSM as the fermentation medium and refined palm oil as the sole carbon source, in submerged fermentation. However, even after the fermentation process, which took 7 days, the patches of oil in the medium can still be observed. Does this mean the bacteria does not fully utilized the carbon source provided ? If so, why did such thing occurs and what can be done to fix this problem ?
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Surfactant might emulsify the floating oil - could facilitate biodegradation.
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I am currently working on the biosurfactant production by Streptomyces sp. in batch mode using shake flasks (submerged fermentation). Based on several literature, the fermentation for this strain will be carried out for 168 hours on a rotary shaker, using the mineral salt medium (MSM) as the fermentation medium with refined palm oil as the carbon source.
However, from my observation, after 72 hours of incubation, contamination can be detected, by observing the characteristics of the medium. It turns milky white in color instead of clear and brownish color. I have been extra careful on the aseptic technique and even ensured that the contents of the medium are from a good source (not oxidized or not beyond its expiry date).
So, I am quite stuck at the moment on why this problem keeps on re-occurring. I have been struggling with this problem for few weeks and I still could not find the cause of this problem. I truly appreciate your assistance and views in this matter. Thank you in advance.
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I am working on biohydrogen production by dark fermentation. I need the method to perform HPLC analysis for some metabolites including ethanol, acetate, butyrate, and propanoate.
Does anyone know how to measure them using HPLC (parameters such as standards used in the analysis and mobile phase)?
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Thanks a lot, Mr. Colonna. I am very appreciated.
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I've been working on the heat exchanger design for fermentation systems, and found an explanation in the literature on how to calculate the cooling-coil length. However, I haven't found information on the volume or area that a cooling coil should occupy in a fermenter yet.
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For my 3rd year internship, I am looking for a modified strain of kluyveromyce marxianus with a good yield of ethanol on whey to make an alcoholic beverage.
Ps: This strain will only be used for my studies.
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You may use S. Cereviace.
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Fermentation is the decomposition of organic materials by microorganisms in the absence of oxygen. Biogas, which is mostly composed of methane and carbon dioxide, is one of the fermentation products. Multi-substrate fermentation can be carried out to boost output yield.
Fermentation methods are frequently used to stabilize liquid and solid waste. Biogas generation from agricultural wastes, animal dungs, municipal and industrial wastes has the potential to be a viable alternative energy source for many nations. A cubic meter of biogas may generate 2.1 kWh of electricity and 2.9 kWh of heat energy. Multiple benefits of biogas were discovered in the 1990s, as well as a wide range of biomass sources that may have been used to produce this resource. One of the techniques of usage is such production. Sugar wastewater, for example, is one of the wastes from the food sector that may be used in this way. Not only is biogas made up of methane(CH4) and CO2, but it also contains hydrogen(H2). Hydrogen is increasingly being referred to as the fuel of the future, and ways for producing it are the focus of extensive research. Sugar industry and cellulose manufacturing wastes, as well as other wastes with high carbohydrates concentrations, are one of the sources of bio-hydrogen, because to its high concentration with comparatively low nitrogen rate. It's also important thinking about the waste produced by watering plants. Plants reduce nitrogen levels, but wastes remain a major source of hydrogen. The creation of hydrogen from fermentation effluent is an intriguing solution. The process is a two-phase fermentation in which hydrogen is produced in the first phase and methane is produced in the second. Some algae, such as Laminaria japonica, can be used as a substrate, but food industry wastes can also be used, which is more useful from a recycling standpoint.
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Ok i will go through all these articles
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Atorvastatine with the commercial name lipitor is a statin based drug used to treat abnormal lipid levels for prevention of cardiovascular diseases. As far as I know, it is produced over several steps over a chemoenzymatic route.
My question would be, what is the reason there is no single-step fermentation based route to such drugs? In my understanding, it could be more efficient since atorvastatine for example contains chirality centers and enzymes in a isolated form therefore are used anyways in the current chemoenzymatic synthesis because of their advandageous enantioselectivity.
I also read a paper about a single-step fermentative procedure to a similar statin, the cholesterol-lowering drug Pravastatin.
However, since industry is not using fermentation to derive those statin drugs, there must be a reason the chemoenzymatic synthesis is favored or the only feasible route. Therefore, to improve my understanding, I wanted to ask what you think what are those reasons? Are cells currently not able to synthesize such a molecule like Atorvastatine, are the titers to low, is the purity with the enantiomeric excess not good enough, something like this.
I appreciate every answer very much.
Kind regards,
Thomas
(a biotechnology student)
In the appendix there is the structural formula of Atorvastatine
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In order to produce a drug by fermentation, there must be an organism that has the necessary metabolic pathway, which would require a set of enzymes, one for each step in the biosynthesis. Synthetic small-molecule drugs that are not natural products are usually produced by chemical synthesis because there is no existing enzymatic pathway for their synthesis in vivo. However, one or more of the starting materials for the chemical synthesis may have a natural origin. Some drugs are chemically modified versions of natural products. In addition, individual steps in the chemical synthesis may be catalyzed by purified enzymes in vitro.
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A bacterial strain was isolated from soil and identified as lactic acid bacteria, however, after fermentation on MRS medium for 24 hr, the clear supernatant of the fermented media was subjected to HPLC analysis and the results showed the presence of different organic acids but no trace of lactic acid was detected, how could this be explained since lactic acid bacteria must produce lactic acid in the fermentation medium ?
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It can be an HPLC detection problem. HPLC operational conditions have a huge effect on the resolution of detected peaks and as Lactic and Acetic acid peaks resolution time is really close to each other, they may have overlapped on each other. You may want to change the type, concentration, or pH of your mobile phase or temperature of the HPLC column to get a better resolution of peaks.
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Methane gas is produced from anaerobic fermentation of sewage sludge, and the process can be controlled to produce bio-hydrogen, so how can it be verified that the resulting gas is all hydrogen and how can its behavior be measured
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Of course you could controll the process to produce hdyrogen instead of methane. You can pretreat the sludge at 90-100 ℃ for 15-30 min to kill the methanogens and hydrogen-consuming bacteria and then fed it to the reactor. The gas content could be measured by gas chromatography.
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Hello Everyone,
I am trying to ferment the enzymatic hydrolysate I obtained after pretreatment to produce bioethanol. So, as a trial, I did the experiment in a fermenter using YPD and checked ethanol production using Saccharomyces strain purchased from a Supermarket locally. The yield I got was very low and the glucose consumption rate was also low. Can somebody please suggest where I can buy high-efficiency yeast strains from India that can be used for fermentation?. It would be a great help!.
Thanks in advance!
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Hellie Gonu dear, its not only yeast that can effect the production of ethanol. temperature, media ingredients and concentration can also play a vital role in it. what temperature are you using in fermentation?
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To stimulate the coagulation process by applying ultrasound.
Will this improve the fermentation process?
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I am working with a lab fermenter for the HCDC of e.coli in a defined medium and for adjusting pH I use ammonium hydroxide.
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Dear Abbas Abbasi,
It is not necessary to strelize ammonium hydroxide solution. But, as it has been mentioned by Mr. Vit Mateju, It is necesary to add it under sterile conditions.
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Hello,
I am running a plant based yoghurt fermentation (10 - 50kg bucket/tank batch) but after 16h the pH drop is quite poor (stops at 5.4 - 5.8). The yoghurt base is UHT treated before and consists of pea & faba bean protein, oil, sucrose, dextrose and salt and the culture is S.thermophilus and L. delbrueckii. It works on a benchtop level (300g jars) and then pH drops to 4.4. What could be the reason for failed acidification in scale up? Could it be that the heat is not evenly distributed and the core does not get to the target temperature? Or perhaps the medium could be supplemented with some extra nutrients for ST and LB to enhance growth?
Thanks in advance for your help!
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I completed a fed-batch fermentation with the addition of spent sulfite liquor (SSL) (a waste stream produced in the paper and pulp process) to S. cerevisiae that terminated with a 60 (v/v) % SSL concentration. Prior to this I completed a batch fermentation with 60 (v/v)% SSL, where I incubated the yeast (in YPX) for 24 hours prior to the addition of the SSL. The yeast was incubated in batch mode (in YPX) for 96 hours before the addition of smaller volumes of SSL (for the fed-batch fermentation).
The ethanol concentration only increased by 3.10 % from the batch mode to the fed-batch mode. I was expecting a much larger increase since the fed-batch mode conditions the yeast to the inhibitory compounds present in SSL. A previous study conducted managed to obtain a 50 % increase in ethanol concentrations using the same substrate. The difference is that the initial batch mode for the fed-batch fermentation was only for 48 hours as opposed to 96 hours (as in my study).
Is there any explanation for the drastic difference in the results obtained and the poor performance in my study?
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Hello Danielle Nel;
Regarding your question, congratulations for the detail that you gave to explain your experimental procedure. This is good so that one can give you a more accurate answer or advice.
As other collegues have mentioned, the long time you leave the batch reactor running could be the cause to lower ethanol productivity at the end of the fed-batch reactor. Your guess seems to be right regarding the growth phase at which you started the fed-batch stage; in that case you could have started in the stationary or death phase.
I suggest that you first characterize the cell growth in your batch reactor. It is recommendable to start the fed-batch in an active growth-stage of your batch (full exponential phase), prior to the stationary phase. Inicial cell concentration of the fed-batch stage may be also important for good yields, so that is why commonly it is used the late exponential growth-phase for fed-batch start. After you have this information, you can define the time at which you would start your fed-batch stage. An obligued reference for this is the classical text book by Bailey and Ollis, Biochemical Engineering Fundamentals.
Apart from this, you said that you are comparing your results to a report of the literature. In this regard, you have to take into consideration the biochemical characterization of the SSL used in both studies, as well as the yeast strains used for fermentation. These are both important parameters that would influence the yields of the reactor. As SSL is a biological waste stream, it can vary widely in its chemical composition even from batch to batch.
I hope this helps for your research.
Best regards.
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I need to purify a polysaccharide obtained from fermentation, is there any lab that can provide lab services for polysaccharide purification, as we don't have any chromatographic equipment available here.
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I am doing normal batch fermentation calculations (for the first time) and am confused about how to carry out some of the calculations. Specifically, I would like to know:
  • The equation for substrate uptake rate (g/L/h)
  • The equation for specific substrate uptake rate (g/g/h)
  • Whether it makes sense to do these calculations (in addition to yield and growth rate) for the overall batch or between each of the sample points
The calculation of specific/substrate uptake rate seems pretty easy from a dimensional analysis stand point. However, I am not sure whether to use the specific growth rate, μ (1/h), to account for the time dimension in calculating specific/substrate uptake rate or to use Δt instead (h). Each of them leads to different results it seems. I have seen answers that use either of them and now I am confused.
Any help would be highly appreciated.
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I am conducting fermentation experiments with Hydrogenophaga psuedoflava whereby sucrose is the main substrate. I tried adding up to 6.8 g/L sodium formate as a co-substrate and noticed that, at the higher concentrations of sodium formate, pH actually increases rather than decreasing over time as was the case normally when fermenting sucrose only (up to 10 g/L). Why is that?
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My thesis project is isolating bacteria from soil which may produce amino acid. My target is, growing them in a fermentation media then centrifuged it to collect the supernatant which may contain amino acid. Then further I will do TLC. So that's why I need a fermentation media composition.
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I completely agree with Selim opinion. I would like to add, that it is very important to use bacteria capable to excrete amino acids from the cell to the medium. Concerning the composition of the cultivation medium, please have a look at the attached paper.
Best regards
Vit
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Glycerol broth containing 1,3-PDO, ethanol and volatile acids (products of fermentation of glycerol with a yeast strain). How can I remove ethanol from the broth without entraining VOCs and PDO (downstream process)?
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Hi Savvina
is your broth an aqueous solution or more a „dry„ mixture?
in case of an aqueous matrix, a simple azeotropic vacuum destillation(stripping) or osmotic filtration of ethanol is thinkable.
if your mix is dry, a standard (vacuum) destillation or a removal via Zeoliths / Molecular Sieve 4A or
5A can be possible.
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I am making a research about the use of supercritical CO2 as a green technology specifically in the production of 1,3-Propanediol or Succinic Acid through fermentation reactions (bacteria or fungus). Is there any specific information on this? Is it feasible to separate 1,3-propanediol from the other organic acids and salts? How much CO2 can I capture per year with this technology? Are carbon credits a possible revenue to compensate the excessive energy requirements?
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Technically yes but economically no
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Which oxygen indicator you use while working with bacteria? I'm cultivating bacteria in Hungate tube, which is an anaerobic process and I need to add some oxygen indicator to the media to see if it's really without oxygen after flushing it with N2/C02. But it has to be non toxic to the cells, some colour changing indicator would be perfect.
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Resazurin
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Hi there,
If induced expression of an antibiotic through co-culture and am looking to scale up.
Is it possible to culture two bacterial strains in a fermenter to induce antibiotic production?
What are limitations of this?
Thanks
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This question appears to be a mix of several question.
  1. can you co-culture in fermenter - Yes!
  2. Everything other than point one - everything would depend on specifics and details which cannot be generalized or recommended without further information.
And basically one need to have trials and pilot project before moving to fermenter step and scaling-up.
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In LAB fermentation medium, potassium phosphate dibasic is used as one of the nutrient component. However, pH is also adjusted at various levels. In this case, what is the use of potassium phosphate? Does it have any role other than buffering capacity? Will the concentration of phosphate in the media affect glucan production?
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Both mono-potassium and di-potassium phosphates can supply phosphate to a culture media; this component is essential for microorganisms growth. But selection of one or the other phosphate salt is made function on the pH that is required to be obtained so as get a stabile buffered solution and optimal growth conditions. https://www.researchgate.net/post/What_is_the_difference_between_potassium_dihydrogen_phosphate_and_dipotassium_hydrogen_phosphate
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During fermentation, the optical density is read at intervals to monitor the growth profile of the organism. How will one convert the values to weight of organisms per ml of medium
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Dear Salami Abimbola,
It is necessary to prepare standard curve (Absorbtion-Concentration) which can be obtained before the main fermentation. It is exactly like the method of preparing growth curve.
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How can the efficiency of a yeast in the fermentation process be quantitatively characterized? Are there certain parameters that can be determined experimentally?
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Dear Laura Bulgariu,
For what purpose you are using yeast in the fermentation process?
You check the the production products of your interest or consumption of substrate (glucose) using HPLC & GC.
I have used yeast for the production BIOETHANOL from anaerobic fermentation of acid pretreated and enzymaticaly saccharified lignocellulosic biomass of wheatstraw. My thesis is availble on my Researchgate page.
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I am looking for some suggestions for internal standards that could be used in the fermentation process (using streptomyces). I have not found a single use of an internal standard in this matter, so any suggestions and ideas are helpful.
I would like to put this internal standard directly into the fermentation broth or the feeding solution at the beginning of the process without disturbing the process itself. For that, probably no intake of the standard should happen, it should not disturb the microorganism growth, also the standard should be non volatile and preferably detectable by LC-UV.
The use of this standard would be to control the fermentation broth evaporation (small scale), sampling and everything after the sampling (sample preparation).
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after fermentation, 3 different strains of Serratia marcesens were analyzed through PCR and gel electrophoresis, but all of them showed the absence of Chitinase A.
what could have happened...
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Hii,
I'm working with Pichia pastoris SMD1168 Strain. To proceed with fermentation I want to maintain pH around 5.5~6, however the fermentation media suggested by Invitrogen gets precipitated over pH 4.5. pH here is regulated by adding Ammonium hydroxide Can anyone suggest alternative media to reach high cell densities or another way to set pH?
Thanks !
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Hello, I want to add ellagic acid to the medium for fermentation transformation. According to the literature, I first dissolve ellagic acid in DMSO, and then add them to the medium together (ellagic acid: 20ppm , DMSO: 1/50), but after sterilization at 120°C for 15 minutes, flocculent substances appeared at the bottom of the medium. Is there any good way to add ellagic acid to the medium? Thank you.
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Dear Zmw Zhang,
It is necessary to sterilize the medium without adding ellagic acid (EA). The EA solution must be filtered–sterilized through nylon membranes of 25-mm diameter and 0.45-μm pore size. Then as soon as the temperature of the sterilized medium reach to 30°C, the EA solution could be added to the medium.
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hi
in fermentation of a-amylase after some hour my ph increase and my broth to be gel form, my guess is my bacteria lysis,
Why does this happen?
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Dear Cyrus Rahbari,
During fermentaion for producing amylase, the concentation of buffer solution changes and increases. So, it is necessary to adjust pH as soon as it changes.
Moreover, increasing the pH could lead to cell lysis, if the tolerance of pH for bacteria is limited. It is better to control pH automatically to adjut it with adding proper solution which has not negative effect on amylase productivity.
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If I take a frozen glycerol stock out of the freezer, can I leave to to defrost then immediately place it into the inoculating broth as my started culture and incubate it thereafter? I do not first want to streak the cells out, as the agar may contain contaminants; I want to avoid this, altogether.
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7/1/21
Dear Danielle,
If your yeast culture is pure (i.e., no contamination by other microbes) and it was stored frozen in a sterile vial, you should be able to transfer it directly to your inoculating broth. The freeze/thaw process will kill some of the yeast, but enough will survive to function as an inoculum.
If you want to streak the yeast out on agar just to be sure the cells are viable and the culture is pure, you can do so. It will cost you a day or two in time, but that's a minor problem. I don't understand your comment about the agar containing contaminants. If the agar is prepared and autoclaved properly, it will be sterile (i.e., uncontaminated).
I hope this information helps you.
Bill Colonna Ames, Iowa, USA williamjcolonna6@gmail.com
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I want to do a fermentation test for my yeast. I want to know if i can do it using YPD broth supplemented with phenol red as pH indicator. If can, how much phenol red would it needed, and how to formulate the broth as a whole. It would be very helpful if you attach some literature. Thankyou.
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I want to do a fermentation test for my yeast to know if they can ferment glucose or not. After some study i found that phenol red broth might be the media for it. But the example that using that broth is commonly for bacteria. So i want to know whether it can be used for yeast and how to formulate one. It would be very helpful if you give the literature for the formula. Thankyou
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Dear
The composition of Phenol Red Carbohydrate Broth has been introduced in the following link:
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Greetings, friends!
For understanding of my proof here:
Preprint APPLICATION OF THE FERMAT'S THEOREM FOR PRACTICAL PROBLEMS S...
you should also read this article here:
Article S-Shaped Growth Curves in Fermentations and Golden Ratio
.
Published article is here:
Article S-Shaped Growth Curves in Fermentations and Golden Ratio
.
For the first time in this article, I got an equation for extracting the roots of any powers from any differences of numbers:
if a^n+b^n=c^n, then
a = (c^n-b^n)^(1/n) = [(ε/γ)^(1/n)] {[(c^n)^(1/n) Φ^[(n-1)/n] – [φ^(n-1)/n] [(b^n)/γ)^1/n]}, where ε=Φγ-φγ^2, γ=b^n/c0, co=(c^n)/(Φ^2), Φ=1,6180339..., φ=0,6180339...
I would like to ask you to investigate my conclusions and give your answers.
Because, I offer the shortest and simplest proof of the Fermat's theorem.
In addition, I offer practical applications in biology. This application was known for me for about 29 years - I was engaged in modeling the growth of microorganisms in fermentation.
One problem was present - I did not know that I was working with Fermat's theorem up to May, 23-25, 2020, :)
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dear all,
i'am searching for some good reviews in the field of hydrogen out of dark fermentation including some financial data, scale up etc. maybe some studies with comparisons between electrochemical h2 and h2 out of dark fermentation.
please share your papers with me.
beste regards
torsten
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Does anyone know a piece of paper that discuss about protein concentration in the L. plantarum fermentation (using a MRS medium or similar)?
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Hi everyone, I hope that you're all well. I'm currently conducting batch fermentation of whey permeate and measuring its methanol production. I've generated the timely production data of it but want to conduct mathematical model of the production trends. Can anyone give me clue/reference on how to do this? Or is it better to follow other published model? But then, which model should be better to follow, the one with similar substrate? similar microbial starter? produced compounds?
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Thank you in advance.
Prof. Krebs, PhD.
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Thank you so much, Dr Kien Vu
kind regards!
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I have observed a cloudiness/film formation (image attached) on the surface of wine after the anaerobic fermentation. Anyone can explain the reason and how am i going to counteract this issue?
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Once on your glasses, this cloudiness is hard to remove. You could try soaking the glasses in vinegar to dissolve the minerals, or rub the affected areas gently with bicarbonate of soda or nail polish remover, and then washing and drying by hand. I've also heard effervescent denture cleaners can help! https://www.decanter.com/learn/cloudy-wine-glasses-ask-decanter-384113/
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#bioethanol #fermentation #yeast #pH
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I am struggling to determine which buffer and concentration to use in my fermentation with S.cerivisiae. I am going to use SSL (spent sulfite liquor) as a fermentation medium.
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I am required to input a cell density (between a range of say 1 - 2 g/L) of an inoculum into fermentation media but I am unsure of how to obtain the dry cell density of the sample in real time, without having the determine the calibration curve etc for the sample first.
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Good question.... Good
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This might sound silly, but I'm wondering as to why there is still residual sugar in the fruits after fermentation. Thanks!
#TSS #sugar #fermentation
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In a study, fermentation time significantly increased ( p<0.05) the titratable acidity, total soluble solids, fructose, glucose, total sugar, citric acid, lactic ... http://www.ukm.my/jsm/pdf_files/SM-PDF-47-10-2018/07%20Kong%20Fei%20Chai.pdf
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I have invitrogen Top10 competent cells that do not grow on defined medium containing leucine...What do you think the problem can be?Is another aminoacid essential?
Genotype: F-mcrA Δ(mrr-hsdRMS-mcrBC) φ80lacZΔM15 ΔlacΧ74 recA1 araD139 Δ(ara-leu) 7697 galU galK rpsL (StrR) endA1 nupG λ-
my medium also contains: ammonium chloride, ammonium sulfate, di-potassium hydrogen phosphate, sodium dihydrogen phosphate dihydrate, sodium sulfate, di-ammonium hydrogen citrate, l-leucine, glucose, magnesium sulfate, thiamine hydrochloride, trace metals
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What other best strategies are there in circumstances where you do not have regular access to collect fresh rumen liquor for your in vitro fermentation work? I have read that Rumen samples preserved at 4°C (for 72hrs) performs better than the one chilled /frozen ( -20 or -80 oC) as rumen samples preserved at these temperatures have low fermentative capacity?