We are working on yeast isolates and are interested to screen high ethanol producing isolates. Since the number of isolates is quite high ( >200), it is not possible for us to analyze the whole set with GC-MS. Hence we are looking for a reliable biochemical method to separate high ethanol producing isolates first, later, which will be subjected to GC-MS analysis.
Kindly note, the potassium dichromate and sulfuric acid method [Caputie A, Ueda M, Brown T (1986). Spectrophotometeric determination of ethanol in wine. Am. J. Enol. Vitic, 19:60-65 ] is not effective at our current laboratory environment, and hence cannot be adopted. If anyone can suggest any other methods, it would be a great help.
Thank you.
Dear Bhaskar,
I can advise you an alcometer. This device is too easy to use and also cheap. It will give you the right information that you need. But if you have GC (not with MS) in your lab, it will do a better work. You can try that, too.
But please note that, the EtOH production is a function of fermentatıon medıum and temp., pH, etc. So, the isolate that gives no EtOH in your un-optimized fermentation medium does not mean that the strain do not produce EtOH.
Good luck!
I suggest you use alcohol dehydrogenase (EC 1.1.1.1), a commercially available enzyme, to measure the alcohol concentration. The reaction is ethanol + NAD acetaldehyde + NADH. The reaction is monitored as an increase in absorbance at 340 nm. Compare the rate of the reaction in culture supernatants to the rates with a set of standards of known ethanol concentration.
Instead of measuring ethanol, you could measure the CO2 production. This can be done easily by measuring the weight loss of the flasks or vials used to test your yeast isolates. The correlation between the weight loss and the alcohol concentration is straightforward : one mol of CO2 being produced with each mol of ethanol, so for each gram of produced ethanol, you'll get a weight loss of nearly one gram. Of course, you have to avoid water loss. This is easily achieved by restricting diffusional gas exchange through the vessel opening. In other words, close your flask or vial, and maintain only a small opening as gas outlet. We have successfully applied this technique down to 1 ml culture volumes ! Don't forget that Saccharomyces requires some O2 for growth (sterol synthesis, directly involved in ethanol tolerance), while you can't aerate your cultures if you use the proposed method. Your culture medium must therefore contain some ergosterol.
Dear Bhaskar J N
I am sure that your could try for get your answer via title"s paper Fed - bath Alcoholic Fermentation of Palm Juice (Arenga pinnata Merr): Influence of the feeding rate on Yeast, Yield and Productivity,www.iet-journals.org
Thank you everyone for your reply. I will try to follow these methods. Thank you.
- Badges
- Science method
- Similar topics
- Chemistry
- General Biochemistry
- Biochemical Methods