Is there any method to quantificate amount of EPS (exopolysaccharides) that bacterial strain produce? some staining, measurement of optical density or so?
There are a number of methods, but the one we use is to precipitate the EPS with ethanol or acetone, redissolve it, precipitate a second time, and then do a phenol-sulfuric acid total carbohydrate analysis. If the EPS is dilute, we may concentrate the initial culture fluid by diafiltration. The exact protocols depend on the structure and MW of the EPS, which is species-dependent.
As said above, after extracting EPS, these molecules can be quantified using the Dubois et al, (1956) protocol.
You can also check this paper:
https://link.springer.com/article/10.1007/BF00174477
We are trying to quantification EPS in sourdough. We centifugate the sample, then the clear supernatant was collected, and the EPS was precipitated by adding ethanol overnight. The precipitate was recovered by centrifugation and dissolved in distilled water. At this point we have the problem that the solution is not dissolved well and it is turbid. How we can obtain a clear dissolution with out pellet?
EPS solution + the same quantaty of isopropyle alchcol than let for pricipetation at room temperature or 2 volumof cold ethanol than let for pricipetation at refrigerator. tke the extracted EPS and dry in the oven from 50 to 70 c for two days then weight it.
also this it explain EPS quantification using OD
https://www.ijcmas.com/vol-3-5/P.C.Prathima,%20et%20al.pdf
EPS Quantification Total sugars from final solutions were determined by Anthrone method (Morris 1948), measuring absorbance at 630nm using glucose solutions as standards. A standard solution of Glucose was prepared by dissolving 5 mg in a minimal quantity of distilled water and made up the volume to 100 ml in a volumetric flask to give a final concentration of 50mg/L. A series of dilutions were prepared from this standard solution to have glucose concentration s ranging from 5 25 g/0.5 ml. 2.5 ml of the Anthrone solution was added for developing the colour. The standard curve was drawn by plotting the optical density against glucose concentration at 630nm. Five hundred micro liters of the diluted samples was treated with 2.5 ml of Anthrone solution in a capped tube. It was heated at 100 C for 15 minutes followed by cooling and color was read at 630nm. The obtained O.D value (Y) was substituted in the standard curve equation to get the value for X which gives concentration of EPS in 0.5 ml of the sample. Conversion factor is used to calculate the EPS produced per litre of fermented DP Whey medium. EPS (mg/L) = {(X / 0.5 * 10) * 1.1} * 100 The values for EPS were calculated by subtracting the amount of back ground interference in uninoculated media (control) from the amount detected in fermented broth EPS= TS (fermented broth) TS (control)
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