Bioethanologenesis. Whether you use whole microbial cell or its product, the enzyme, the process is the same.

For simple ethanol fermentation you need sugar solution. Don't exceed 20g of sugar per 100g of solution, because it may slow down fermentation process. If you use standard S. cerevisiae (normal yeasts from supermarket) keep fermentation in room temperature. If you use other strains of yeasts it is worth to check their optimal working temperature. Alcohol concentration above 10% of volume will slow down fermentation process. And remember to drive the process in anaerobic condition (without oxygen), in aerobic conditions you will get acetic acid instead of ethanol. During fermentation high amount of CO2 is produced, so be sure that it has a possibility to get out. Otherwise it may blow up your fermenter.

Saccharomyces cerevisiae yeasts have natural invertase. They'll transform saccharose into glucose and fructose. Depending on how concentrated is your saccharose solution, you should inoculate at a different ratio and I recommend you use active dried yeasts - ADY (wine strains are the best) : 100 mg / L of ADY when saccharose concentration is lower than 150 g / L until 300 mg / L when you have 300 mg / L. ADY have to be rehydrated under specific timing and temperature : it's usually written or explained on the TDS or on the label of the packet.

O2 is necessary after 1/3rd of fermentation : it helps S.cerevisiae to increase its sterol content which allows a safer ending of fermentation. Your yeasts will need assimilable nitrogen (amino acids and ammonia): check the content of your solution before inoculating the yeast.

Hope this will help.

Because the theoretical yield of ethanol from saccharose is 60 % and the maximum concentration of ethanol in fermentation broth for common yeast Saccharomyces cerevisiae can be approx. 10 % to 11 %vol., the starting concentration of saccharose would be approx 150 to 200 g.L-1 (taking into account all possible losses).

Best regards

Vit