Studies on The Hungate technique for ethanol fermentation of algae Spirogyra hyalina using Saccharomyces cerevisiae

In this study, the feasibility of the Hungate technique was studied using the alga Spirogyra hyalina. This study aimed to determine the effect of different types of gas, culture pH and the duration of fermentation on cell biomass, total reducing sugars, and total ethanol produced from the fermentation of Spirogyra hyalina hydrolysates using Saccharomyces cerevisiae. The experimental trials were carried out in batches with two types of gas (nitrogen and hydrogen), three pH levels (pH 4, 5, 6), and four fermentation times (0, 24, 48 and 72 hours). The fermentation process was carried out under anaerobic conditions. Anaerobic conditions were ensured using the Hungate technique, namely by injecting nitrogen gas or hydrogen gas into the fermentor. The results show that the average levels of ethanol produced tended to be higher in the presence of hydrogen gas when compared to the presence of nitrogen gas. The highest level of ethanol was achieved in the presence of hydrogen gas at pH 4 after 72 hours of fermentation.