Investigation of the effect of inhibitors on ethanol production with immobilized Saccharomyces cerevisiae cells in calcium alginate

Today, most of the energy is obtained from fossil fuels. Given the rapidly depleting energy sources, this situation led developed countries to find alternative ways. Ethanol is produced with pure sources or lignocellulosic raw materials. While ethanol production from pure carbon sources consists of fermentation and distillation stages, ethanol production from lignocellulosic materials is generally carried out in four steps, including pre-treatment, hydrolysis, fermentation and distillation. During these processes, inhibitors are formed that may have negative effects on the environment. In this study, immobilized Saccharomyces cerevisiae cells were used for ethanol production. In the study, HMF, furfural, phenol, acetic and formic acid were used as inhibitors in different concentrations. Mix fermentations with 10 different trial patterns were obtained with Plackett-Burman Dizayn. As a result of the fermentations, 8 g/L HMF showed an inhibitory effect. In fermentations with furfural addition, 8 g/L furfural showed inhibitory effect. In fermentations with the addition of phenol, 5 g/L phenol showed an inhibitory effect. In fermentations performed the addition of acetic acid, 7,5 g/L acetic acid showed an inhibitory effect. In the fermentations performed the addition of formic acid, 1,5 g/L formic acid showed an inhibitory effect. In the obtained statistical results, it was seen that the effect of furfural concentration was more effective than other inhibitors in mixed fermentations. In the other part of the study, 10 different mathematical models were applied to the fermentations with the best ethanol. MMF for ethanol was selected in the control fermentation. MGM for ethanol was selected in the addition of 2 g/L HMF and furfural. Baranyi for ethanol was selected in the addition of 0,5 g/L phenol. MGM for ethanol was selected in the addition of 2,5 g/L acetic acid. MMF for ethanol was selected in the addition of 0,5 g/L formic acid. In mix fermentation numbered 10, Weibull was chosen as suitable model for ethanol. As a result of the study, tolerance intervals of immobilized cells against inhibitors such as HMF, furfural, phenol, acetic and formic acid were determined. In addition, the tolerance range of the cells was observed in a different way with fermentations where these inhibitors were used as mix. Compared with the literature, it was seen that immobilization process extended the tolerance range and protected the cells. At the same time, it is positive in terms of time, material and energy to predict whether or not to perform pre-treatments with the specified tolerance ranges.