High levels of weak organic acids leads to acidification of the yeast cytoplasm and that causes a depletion in the ATP pool due to an alteration of ATP by ATPases present in the plasma membrane that pumps H+ions into the cell surroundings to regulate intracellular pH [30]. Cheng et al. [22] studied the optimization of pH and acetic acid concentration in the bio-conversion of hemicellulosic hydrolysate from corncobs into xylitol by Candida tropicalis.These authors evaluated various concentrations of acetic acid in fermentation media and noted that concentrations around 2 g L−1 acetic acid inhibited the production of xylitol, reducing its production by about 9%. In the present study, it was observed that the concentration of acetic acid in the CABH-1 was below the inhibitory concentration cited by these authors. In turn, the presence of acetic acid below 1 g L−1 favored xylitol production by a strain of C. guilliermondii, but when above 3 g L−1 it becomes an inhibitory compound [23]. Castro et al. [29] also evaluated xylitol production by a strain of C. guilliermondii and noted that the strain was able to metabolize 62% of the acetic acid present in eucalyptus hydrolysate medium, which corresponded to a concentration of 5 g L−1 of the acid.