Bioprocess Engineering - Science topic

I haven't verified that it can be analyzed correctly, but it seems to be possible with Elisa as well.

Similar kits are available from other manufacturers.A number of melatonin antibodies themselves are also available.

The kit targets human-derived samples, and the sample type is limited, but melatonin itself is a small molecule. Yeast (cells or culture supernatant?) might require pretreatment, but just for reference.

For a somewhat related discussion, see: https://www.researchgate.net/post/How_can_I_avoid_the_formation_of_air_bubbles_when_hydrogels_are_made_by_gamma_irradiation_technique

To prevent recombination events in your Lactococcus lactis strains, you can consider knocking out genes involved in homologous recombination. The genes involved in the homologous recombination process in Lactococcus lactis include recA, recB, recC, and recD. By disrupting these genes, it is possible to prevent homologous recombination and reduce the likelihood of recombination events in your plasmids.

Additionally, you can also consider reducing the growth rate of the bacteria during your culture phase, which may help to reduce the rate of recombination events. This can be achieved by adjusting the temperature, pH, or nutrient conditions, or by modifying the composition of the growth medium to reduce the rate of bacterial growth.

Hope it helps

PTa (Phosphate Acetyltransferase) promoter is involved in the regulation of the acetyl-CoA metabolic pathway in bacteria. In the presence of high levels of Acetyl-CoA, the Pta promoter is activated, leading to increased transcription of genes involved in the utilization of acetyl-CoA. This helps the bacteria to efficiently utilize acetyl-CoA as a carbon source and maintain metabolic balance.

You may want to check also this RG thread: https://www.researchgate.net/post/How_do_I_calculate_impeller_speed_of_a_bioreactor_from_impeller_power_number

Dear Pierre, thank you very much..

Dear Sahil Sharma

As previous scientists said before me, CO₂ stripping must induce such pH increase.

Looking at the dissolved CO₂ equilibrium in water:

CO₂ + H₂O <==> H₂CO₃ <==> 2H⁺ + CO₃^2-

Sparging air engender a decrease of dissolved CO₂ then reduction of free proton H⁺ and pH increase.

Best regards,

Paul R. Jr BROU

Dear Hendrik,

maybe these recent publications on ¹³C metabolic flux analysis in biofilm-forming P. aeruginosa and agar plate-grown E. coli might be of help:

Best,

Michael

Try this website protocols

http;//www.BioDataCenter.ir

The Italian norm on BMP test (UNI/TS 11703:2018) states that the inoculum/substrate ratio must be comprised between 2 and 3 for general biomass digestion (i.e. 0.5 to 0.33 if you define as substrate/inoculum). Nevertheless, it also states that some substrates (glycerol, fats, industrial effluents containing inhibitors like olive mill wastewater, etc.) may require teh test to be performmed with I/S >= 5. This must be established by the lab operator and stated in the report of the test. For a discussion on the pros and cons of the Italian , German and IWA draft on BMP assay, please see chapter 6 of my book https://www.crcpress.com/Managing-Biogas-Plants-A-Practical-Guide/Rosato/p/book/9781138626614

A propeller type that promotes vertical movement downward is best for different densities. Baffles are almost always needed even if they are removable through nozzles in the top.

For larger reactor a pump around loop with mixing jet inductor is helpful.

Hello, see attached info.

Good luck!

Dear Dr. Pourkhaloee

I stored cellulase and pectinase stock at -20 centigrade for a month without any problem. I think it could be right.

Best wishes

Dear Kaila,

In order to figure out which model should be used, it necessary to investigate which one fits experimental results better. I could find the following paper, which concerns determination of kinetic parameters of phenol biodegradation (competitive inhibition by the substrate itself):

Hill, Gordon A., and Campbell W. Robinson. "Substrate inhibition kinetics: phenol degradation by Pseudomonas putida." Biotechnology and Bioengineering 17.11 (1975): 1599-1615.

In this paper:

Kumar, Arinjay, Shashi Kumar, and Surendra Kumar. "Biodegradation kinetics of phenol and catechol using Pseudomonas putida MTCC 1194." Biochemical Engineering Journal 22.2 (2005): 151-159.

the authors used a linearized Haldane model for the determination of inhibition constant.

I hope the above-mentioned papers will help.

Best regards

Szymon

Normally we get an yield of 95-100%. Mass of biodiesel  ( mass of oil + mass of alcohol - mass of glycerol - mass of unreacted chemicals  ) it could be greater than the mass of oil. Theoretically it possible to have an yield slightly higher than 100%.

Method : measure weight of row oil before the reaction and weigh biodiesel after reaction and post treatment.

2. Ester Content (%)= cumulative mass of methyl esters/ mass of biodiesel.

It is very important to understand that biodiesel does not means that its 100% methyl ester (or pure) it may even contain un-reacted triglyceride and partially reacted mono-glyceride and di-glycerides. Fatty acid methyl ester /ester content could calculate using EN-14103 method. According to EN-14103 minimum ester content should be 96.5%. we should use an internal standard like C17. In GC area of a peak is proportional to the concentration of that component.

a. take a known amount of internal standard (x gram) and mix with known amount of biodiesel (y gram).

b. perform Gc test

c. find out area corresponding to C17 ( area A)

d. find total area (Area B)

Please try to understand that y gram biodiesel does not contain y gram of methyl ester it contain 'U' gram of methyl ester and 'V' gram of contaminants ( we dont know value of U and V , test doing to find these values)

Area A proportional to x gram

total area corresponds to x+U gram not for x+y/ x+U+V

Area B proportional to x+U gram

Area (B-A) proportional to U gram

ester content = U/y

U= (B-A)*x/A

ester content = (B-A)*x/(A*y)

It denotes amount of raw oil converted to methyl esters.

1. If the ester content is above the limit (96.5%) then other physical properties like density and viscosity will be within the limit.

2. if you loose biodiesel during washing or though any other way , it reduces the yield and there by conversion efficiency but not ester content value.

A few questions would give me a better idea of what you are trying to accomplish.

Simply put, you can't measure OD bigger then ~1.0

Once the density of bacteria (think of them as particles) is increasing beyond ~1.0 you start having optical side effects such as shading and biological once such clamping. This is true for any measurement of suspended particles.

So measure OD of your cells re-suspended in water, calculate how much more concentrate they need to be, and adjust your final re-suspension volume accordingly.

Yoram

You can measure the absorbance of your extract from solid state fermentation. With a standard curve of abs x pigment concentration, you will find the concentration of pigment on your solution. Finally, you have to multiply the result of concentration of pigment on the extract by the volume of liquid you have used per gram of bagasse for extracting the pigment from the solid fermented material.

a rather old but useful references:

1 g of 100% pure and dry cellulose should only give 1.11 g/g glucose (extra 0.11 g in weight from the H and OH added during hydrolysis), so it is possible you are getting 100% glucose out (plus a bit error to bring it up to 1.15 g).

But if your feedstock is not 100% pure and dry cellulose, then it could possibly be due to an interference, e.g. Discoloured solution that is affecting your colorimetric measurement. If this is not the case, you are measuring how many equivalents of DNS is converted, and converting this to mass using glucose equivalents. If the molecular weight of your reducing molecules are less than that of glucose, then you end up with an overly large mass.

If you care about what's in there, likely you will have to set up a HPLC process to investigate. If you only care about glucose then you will need a glucose-selective quantification method. For example, a colorimetric process using glucose oxidase. Many conventional blood-glucose meters will work well in a buffered solution, and typically selectively quantify glucose between 2 and 10 mM (but not every model works selectively or works quantitatively in an enzymatic broth, so a calibration curve would be required). 

Thank you for your time and guidance, it is very useful paper. 

Hi, Ahamed!

You are correct. I think it is obvious that the "66.07" is a typographical error, as 6 and 3 are next to one another on a computer keypad.

Also, you mean "... if 1 mol of ammonium sulphate ...", not "1 M", just to be clear.

And if I remember correctly, IUPAC switched to spelling sulfur with an "f" in 1990. :D

regards,

Daniel

1. plant-based platform for commercial production of recombinant protein is usually considered as more cost-effective platform (ex. no need of a constant controlled environment), and a scalable-production platform to allow large-volume manufacturing, when compared to other systems. Grow yeast also have contamination worry.

(1) For yeast, one major concern for producing therapeutic glycoprotein for human application is that yeast N-glycosylation is of the high-mannose type, which confers a short half-life in vivo and hyper–immunogenicity and thus render the therapeutic glycoprotein less effective. (attached paper)

3. If you want to isolate those recombinant proteins, I think yeast should be much easy to do that

I think it is not necessary to  autoclave media twice because single time autoclaving is much enough to sterilize it. If you will do it second time then important nutrients can denature, as well as salt concentration will  be increased and change in pH can effect the growth of microbe. I have experience with this media and never had the problem to for autoclaving it twice. 

PHA granules are actually food reserves in the organisms and therefore nitrogen and phosphorous values increase.

I once speculated too about immobilized cells as a solution to avoid solvent toxicity and to overcome sporulation/programmed cell death. But I'm not an expert in the field of fermentation, so I cannot technically answer your question. I know that removing solvent from the medium alleviates reaching toxic solvent concentrations and that controlling pH just before entering the acid shift allows to propagate the exponential growth phase and to induce some retaking of acids and direct solvent formation from substrate. Yet I don't know if there's a way to reach a continuously efficient solvent production without triggering sporulation, unless you're working with a sporulation mutant, which is in turn probably not the most efficient solvent producer because of poor solventogenic enzyme induction. So I guess you need a flexible time schedule in your continuous fermenter (with some device for solvent removal from the medium if you intend to recirculate) to do a lot of trial and error with the best strains you have... In the end, assuming you have an outlet filter to avoid lost of biomass, probably cells won't care whether they are immobilized or not as long as they are not compelled to sporulate... :-)

Best regards,

José

Dear Miss/Mrs Mandep,

I guess you should mixed up the air environment with nitrogen gas so that the air redox potential < 7 (microaerophilic condition).

cmc what concentration you r adding to which salt..... and what is the purpose?

cmc is a surfactant ...need to dissolve in water to get the foam

wheather the salt is added to cmc solution or direct to cmc?

pl make clear.... toanswer

Dear colleague,

You are using WCO (high FFA%) as feedstock oil and you chosen base homogeneous catalyst (KOH) for this reaction. In my opinion, you were not right in this  case because the saponification reaction is very easy to occur and lead to form soap. The big amount of soap make the transeserification stop soon.

So you need do esterification reaction first by using acid catalyst (H2SO4). After finished this step (FFA% will significant decrease), you can use KOH for next step (transesterification).

About washing process, your idea is not good. Because the hydrolysis reaction can occur if you use distilled water soon. For this reason, the amount of ester (ester content) will unexpected decrease.   

For the better idea, after finished reaction, glycerol phase should be removed from biodiesel phase. After that, you can wash biodiesel phase by distillated water. This process should be repeated 6 times (3 times without stirring and 3 times for stirring or slow shaking).

I hope this comment will be useful for you.

Good morning, Lenis, I have just seen your question. Your assertion was correct, in my opinion. However, for start-up and acclimatisation at the same time, even an inoculum/substrate ratio of 2 would be far too high. For example, just to carry out biomethane potential tests using already acclimatised biomass we use a ratio >6 to minimise potential stress. Now, we operate full-scale food waste AD plants in the UK. We have done it for over 10 years now and the volumetric loading to our 16000m3 plant is around 300m3/day => 50 days HRT.  I see that your are probably starting in semi-batch mode, but at that initial loading I am surprised the pH has not dropped further. If it was me, I would start at an inoculum/substrate >25 and monitor biogas composition more regularly, if possible. It CH4>50% increase OLR gradually. I normally control start-up on the basis of biogas CH4 content and flow. Since you are looking at start-up and acclimatisation (i.e., you are not using an inoculum from a food waste digester), I would expect start-up to take a long time, as Rowayda indicated (or longer!). Can you not get some UASB solids to start-up. I hope this is useful.  

At the moment there is no commercial provider of CDH. There are only about 20 research groups that produce it and use it.

The keratin  can be dissolved in alkaline buffer at pH 9 and above and used as substrate for keratinase assay. 

Yes. The Stirrer Speed in RPM

Liquid/liquid displacement method and gas/liquid displacement method, the pore is filled by liquid (says liquid 1), where certain pressure is applied to gas or liquid 2 to displace liquid 1. It uses Laplace equation to determine the pore radius and its distribution. In laplace equation, pore radius is inversely According to the Laplace equation the required pressure is proportional to the interfacial tension and inversely proportional to the pore radius.

delta P = 2*gamma*cos(theta)/r

Where gamma is surface tension, r is radius, and theta is contact angle. For more detailed procedure, please check in this paper :

L. Germic, K. Ebert, R.H.B. Bouma, Z. Borneman, M.H.V. Mulder, H. Strathmann (1997). Characterization of polyacrylonitrile ultrafiltration membranes. Journal of Membrane Science 132 131-145

You can find the contents of "Biochemical Engineering & Biotechnology" from added file here.

HRT should be designed considering the growth kinetics of the microbial consortia. Fermentative consortia have faster growth kinetics compared to methanogens in the second stage, thus the HRT in the methanogenic stage i.e. second stage is higher than the first stage. 

The stirrer speed depends on the power number according to the definition: P = Np rho N^3 D^5. To calculate the speed you need the net power input. This can be measured inaccurately via the electric power (correction for system friction) or using strain gauges. Apparently this is no option at that size of reactor or if you are dealing with design. So you have to choose a power input (depending on your system between 1 to 3 W/kg. (5 W/kg is very heavy and not very useful when using the impellers primarily for gas dispersion) ). In general you want to operate above flooding, keeping reduced power input of the lower impeller (somewhat) higher than the power introduced by the gas g×vGs (power per mass equals gravity field strength times superficial gas velocity). All this provided that you are using aqueous fluid.

Note that there are serious inaccuracies in the assumptions you use: Np = 5.2 (+/- 0.8 (?) for (standard) Rushton); The reduction in power draw by gas of 0.7 (can easily be 0.4 for larger gas flows) for both impellers (the upper one is less loaded as a result of shortcut flow around the upper impeller). So it is not possible to calculate the stirrer speed exactly (as function of power), only to estimate it.

Success

The waste converted with biological approach to biodegradable hazardous materials to harmless and stabilized by products with help of microorganisms under elevated temperature. In-vessel composting reactors are of two general types: plug flow reactors (vertical and horizontal) and agitated-bed reactors. The increased temperature, typically 50 to 70⁰C  results from heat released by microorganisms during the degradation of the organic materials. Aerobic composting is used to degrade sewage sludge whereas anaerobic processes are more suitable for hazardous waste treatment. The in-vessel composting of contaminated soil utilizes a bulking agent, such as saw dust or animal waste, to increase the porosity of the media. Conveyors must be used to transport materials in the compost-based reactor system.

And also in rural pit are created underground about dimension L,B,D(4X5X6) mtr.dump waste material and cow dung or bacteria generated waste to be added. And covered air tight so that oxygen cannot be introduced. After some time anaerobic bacteria convert all waste in compost fertilizers.

Composting technology can be applied to municipal sludge, soils, and lagoon sediments contaminated with biodegradable organic compounds. It has been demonstrated that composting is suitable for pentachlorophenol (PCP), refinery sledges, insecticides contained in cannery wastes, explosive-contaminated soil, ethylene glycol contained in landfill sludges, and polycyclic aromatic hydrocarbons (PAHs). High rate composting is conducted in an enclosed reactor and the curing may be conducted in a reactor.

Please find attached herewith suitable literature.

Regards

Prem Baboo

Masson trichrome staining procedure contains three solutions 1) sol A- Acid fuschin- 5 min, 2) Sol B phosphomolybdic acid - 5 min ,3)Sol C- Methyl blue - 2-5 min. Before enter into Sol A,B and C. The tissue sections were subjected to celestine blue staining for 5 min , followed by Hematoxylin for 5 min and then blueing using tap water and then differentiate it with  1% Acid alcohol then go for Sol A, B and C. 

Thank you for your responds. The protocol I use for purification is just simply using activated carbon. Is it enough or I need more complicated methods?

Use TOC instead

Hello Karim.

I would contact the manufacturer (Eppendorf) and ask for advice.

Perhaps your exhaust gas flowrate is out of range (0.5 to 1.0 L/min) or the pressure is too high (0.5psig max).

I would also calibrate it before each use, you can buy specific gas mixtures from compressed gas suppliers.

Good luck.

Dear Smit,

What kind of cells are you growing, i.e., bacteria, yeast, animal cells? Is the medium OK., i.e., have all the necessary ingredients? If it is a commercial medium, check the expiration date as certain ingredients, e.g., vitamins, can lose potency over time. If it is "home-made", you may have left something out. Is the pH correct? Sometimes the pH can change during sterilization (autoclaving) and may require use of a buffer, or adjustment w/ sterile acid or base after autoclaving. Did you use a large enough inoculum? Do the cells require that the Bioreactor be sparged w/ sterile air or oxygen, and agitated w/ an impeller? If you have animal cells, the Bioreactor's impeller may be causing the problem. Animal cells lack cell walls, and are less robust vs. bacteria. Impellers used for bacteria, yeast, etc. are not appropriate for animal cells, as they can cause shear, i.e., they can tear the cells open. For animal cells, a pitched-blade impeller is recommended, as it provides gentle, non-shearing agitation (See R. Mirro & K. Voll, BioProcess International, Jan. 2009, P. 52-57.). Pitched-blade impellers are, unfortunately, expen$ive. If you can't get one, try lowering the agitation rate of the conventional impeller. Also, if you have animal cells, it's a good idea to add an anti-shear ingredient to the medium, e.g., Pluronic F-68.

I hope this helps you. If you need more information, I am available @ wcolonna@iastate.edu.

Bill Colonna, Iowa State University, Ames, Iowa, USA

Dear Samuel Erhigare Onoji,

Here is the like which may kelp to you.

Regards,

B.Thangagiri

 Dear Zakaria Al-Qodah,

Maybe I misunderstand what you mean to say, but I do have some deviating opinion.

Ionic strength is not likely to change much during the experiment. But it does have a lowering effect on solubility. As such it may lower DO, but ionic strength may also increase mass transfer (smaller bubbles), resulting in a higher DO.

Broth viscosity as such does not reduce solubility unless it increases the ionic strength. Of course the presence of compounds in larger quantities may influence the measured solubility of the broth. But, indeed, higher viscosity (above 20 mPas) leads to strong coalesence, reduced mass transfer and hence lower DO. But again it is not likely to occur during the experiment. However, it is often the reason for not being able to control DO any more at a certain stage of the fermentation.

Two kinds of vortex formation may result from stirring. Vortices behind the blades result in turbulence and better dispersion of the gas, leading to higher mass transfer and higher DO. Also a vortex from the top surface may arise, possibly leading to the entrainment of gas from the headspace. This may result in a higher DO, depending on the composition of the gas.

No, because you are protecting the acetyl group of dopamine. Any excess of acetyl radicals will first remove this protection (chemical kinetics)  Remove HBr with Argon bubbling only. 

Hi,

Aber Futura, work with two types of on-line biomass measurements, optical and capacitance. The second one, takes a measurement of available cells in the medium. You should ask them, the range of capacitance depending of your type of cells and the type of medium (sometimes there a lot of nutrients that can affect the capacitance measurements).

In the attached file, you can have an idea of this.

Best Regards.

Gurumoorthi,

     Water will remove the PEO.  However the real questions are:1. Are the Chitosan and the PEO phase separated in your fibers and 2. If they are, what do the phase domains look like?  If your Chitosan phase domain is continuous through out the fiber, then you will have a continuous(although likely void filled) structure.  If the Chitosan domains are discrete, then you will not maintain your fiber/textile structure.  You are more likely to maintain a continuous network with lower PEO content.  Either way, you are very likely to get an irregular morphology for the material that is left.  If your application requires  high surface area structure(like filters or sensors) this could be a good thing.  If you application is structural, then perhaps not so much.  Hope this helps.

Regards,

JMD

I have used at 0.5MHz and couldn't get the capacitance values over period of time. 

 I would suggest the following strategies: 1. You may want to streak plate your culture and inoculate a single colony for seed culture to rule out contamination in the seed culture itself. 2. Increase the inoculum volume 3. Increase the amount of methanol in the culture media. This apart, you may like to re-ensure that all the steps are being carried out asceptically as well as check for any leak in the fermentation vessel as well as its proper sterilization. Hope this helps....All the best!

I propose you use de "SuperPro 9" software (Intelligent Inc.) for process simulation. This software is very strong for simulation process and economics evaluation (raw materials, materials, human resources, single use technology, clasified areas, etc). Into software help existing an example for antibody production with single use technology. Regards

I have used saline pouches similar to blood bag for inoculation and the pouches were tested till 50 bar pressure. There is no leakage and cross contamination..hope it could be tested at more pressure condition. Thanks everyone.

You can use the book "Piping and Pipeline Calculations Manual" to me has helped me. In conclusion I think you should consider the following:

- Theoretical needs of the productive system.

- Type of fluid: related to auxiliary systems and process lines.

- Type of material: to define friction losses, pressure drops.

Helena is completely right with her answer. In order to obtain high Mw PLA, you should use ROP from lactides.

cheers,

Miguel

what seed? Maybe you have impurities in your oil and need it a filtration. You can dissolve your oil in DMSO

I have no information on this. Sorry.

Ben

Enzyme activity by set protocol and applying these enzymes for particular target reaction are totally different things. Factors influencing the target reaction might have significant effect on the enzyme from your three organisms. So I suggest choose your organism based on the actual performance in your target reaction and then further investigate the parameters influencing the enzyme activity such as temperature, pH, solvents, buffer etc. 

Make sure you follow the exact same procedure for your standard curve. You might be having problems with your extraction step. I dont know what protocol you are using though. Depending on what organism you are using you might need some harsher methods to break open the cells. I would recommend 30% warm NaOH solution treatment and then chloroform extraction at a milder temperature like 37C. Ratio of chloroform phase to sulphuric acid is important as well. I use crotonic acid method all the time and time or reaction is critical. Treat sulphuric acid mixture at 80C for at least an hour. Crotonic acid is usually a very reliable method TGA might need special expertise.  Hope this is useful.

Many bioreactors are having a different set up for measuring the cell viability,.since the probe of the bioreactors is  not much accurate best way to do is you take 1-5 ml of sample asceptically and measure the cell count by using trypan ble exclusion method. One more advantage is that you can also see if any contamination occured.

all the best

Dear Chen,

I suggest you to go for Plackett-Burman design to screen the major factors and exclude the minor factors. After screening, Box-Behnken design or Box-Wilson design may be used to determine optimal settings.

Please refer the link below for clear idea:

Yes, you are correct. The alcoholic fermentation is conducted by yeast of the genus Saccharomyces. The two common species involved are S. cerevisiae and S. bayanus. These two species are closely related, and the subject of a continuing debate among taxonomists as to whether they constitute separate species or races of the same species. Saccharomyces converts the glucose, fructose and sucrose found in grape must and juice into ethanol via the process of fermentation. In fermentation, an organic

compound, in this case acetaldehyde, serves as terminal electron acceptor. This leads

to the production of ethanol. In aerobic respiration an exhaustive consumption of amino acids occur, but in anaerobic respiration fewer amino acids are consumed. 

Also available at: Application of bioreactor systems for large scale productio...

Have you checked the intracellular fraction? The protein might not make it all the way through the secretory pathway for a number of reasons, so it is important to find out if this is a case of no expression at all, or failure to be secreted.

typically it is 20% (10-30%) from the original value

Dear  Dr. Ahil;

I hope it is not too late. The following attached book is an extremely important one in the area you are working in. Regards

Dear Ahil,

Apart from the solutions menthioned above, you could from oil emulsions.  I would suggest forming an emultion and adding this using an acurate second feed pump.  

you use 240 g/l, it is known that at high concentration of the carbon source the yield is lower therefore to get higher yield you can use the glucose fed-batch, I would use the initial concentration not more than 50 g/L, the glucose feed concentration can be 70%-solution that does not increase the volume so much.

Thank you Lorena

Hello Mohd. By nature lignified structure are more resistant to microbial / enzymatic attack; influence of LC content on biodegradability is quite well established. (see for instance "Towards new indicators for the prediction of solid waste anaerobic digestion properties"  in Water Science Technology 2006 53(8) pp 233) ;

Nitrogen loss is usually not associated to lignocellulosic compounds, but with proteins degradation.

Temperature is the one which controls the microbial community since there three types of microbes psychrophiles, mesophiles and thermophiles based on temperature. mesophiles are the organisms which could live in temperature above 20 degrees to 37 degrees. during the starting stages of compost the material in the com[post will degrade once degradation is in process the heat increase in the material will automatically increase the temperature to thermophilic which supports the organisms which grows above 40 degrees and again when the degradation of the material completes the temperature will automatically down to mesophilic which supports the spores of thermophiles and streptomycetes and actinomycetes. 

Most of the time 70-80 % ethanol (chilled) works, i think it should work

Dear Zhang, Lactose is a naturally occurring sugar (diasaccharide of glucose and galactose) which is metabolized by a number of prokaryotes and Eukaryotes. However IPTG is a synthetic and structural analogue of allolactose which can be used as a substrate but cannot be metabolized. The beauty of IPTG is that since it cannot be metabolized by the organism its concentration remains constant during the entire course of experiment. Moreover it is used for induction of lac operon in in the concentration range of 100 μM to 1.5 mM.

The amount of Lactose or IPTG used for induction depends on the binding and dissociation constant of the IPTG and lactose to the lac repressor and I believe that that two have different binding constants for sure. Hope I could partially answer to your question

Vlado, we are using Tetrabutylammonium.. the problem that we are encountering is of salt precipitation.. that increases column pressure with time...

Please refer eplantscience.com for clear-cut calculations

The choice of the detector will depend on the concentration of acetic acid that you are trying to analyze. For lower concentrations, PDA works better as suggested above.

You may use filtration.

Algae for biodiesel requires extremely large production. Sterilze water cannot be used at very large scale. Keep this in mind before you make any technology claims. You can only use sterile water at small scale, may be in the initial seed preparation stages.

In our lab, we do perpetual algae consortia with high lipid content using seawater with no treatment.

Natural carbon source is generally referred to glucose, starch and sucrose. Many crop products or crops itself contains large amount of natural carbon sources. Also the extracts from the crop residues acts a cheap carbon source for PHB production.

As PHB is produced under nutritional stress conditions, so instead of using crops/ natural products... I suggest you to go for distillery waste effluent (also called as Molasses). It contains sugar content in abundant quantity. Also, the discarded and degraded food grains from godowns can be used as rich natural carbon source.

Thanks,