I did ethanol production using 50g/L of glucose and xylose in fermentation broth. Now need to find ethanol productivity, their theoretical yield and fermentation efficiency, also consumption of pentose and hexose sugars. Kindly help me to get clear calculation (any papers or protocols) for all of this especially ethanol productivity calculation
Hello, you can distillate your fermentation liquid to have ethanol as distillate, then you can measure the about and percentage of ethanol received.
The theoretical yield from an anaerobic fermentation by equation
1-Glycose 2 -Xylose
1. C6H12O6 (aq) ————> 2C2H5OH (aq) + 2CO2(g) + 2ATP
2. C5H10O5 (aq) ————> 5/3 C2H5OH (aq) + 5/3 CO2(g) + 5/3ATP
The difference between theoretical calculation and what you will receive by real calculation will be the amount consumed during fermentation.
Karen A. Darbinyan Sir I did the assays and have ethanol concentration and dont know how to do the calculation for ethanol production with these sugars
Could you please provide information 50g/l is concentration of each sugar or total amount?
What amount of ethanol you received?
Karen A. Darbinyan 50g/L is concentration of each sugar (glucose -50g/L and xylose -50gL) and I got 7.2% ethanol concentration calculated using standard curve (ethanol - internal standard)
Hello, Merlin Sobia as I understood, you about the ethanol 7.2 %?
7.2% mean 7.2g in 100g or 72g/l
So, if you receive 72g/l ethanol from 50+50=100g/l monosaccharides solution it above the level of theoretical calculation with yield 72%:
If we carucate by equation.
Glycose = 2C2H5OH+ 2CO2 +Q (Energy)
Xylose = 1.66 C2H5OH+ 1.66CO2 +Q (Energy) (same as glycose)
by molecular weight glycose equation will be
180g/mol=2*46g/mol+2*44g/mol
at 100% conversation you will receive 92g/mol (51.2%) ethanol and 88 g/mol (48.8%) C02
100%= 51.2% + 48.8% so the theoretical maximal yield for ethanol is 51.2%
From 100g/l monosaccharides maximum the 51.2g/l ethanol can be formed.
Karen A. Darbinyan Thank You for your valuable time and answer sir. This is what i expected..
You need to calc the total fermentable sugar (FS) in the total volume of the broth using : Total volume of Broth* Glucose titre reading divided by 1000 ml. . Further calculate the FS percentage and multiply with 0.52 to calculate the Ethanol qty wt/wt or percentage in the broth. To get v/Wt, multiply by 1.29.
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