Effect of concentration of salts in ethanol production from acid hydrolysis of cladodes of opuntia ficus indica var. Atlixco

Abstract

Acid hydrolysis from cladodes of Opuntia ficus indica var Atlixco was performed. The total reducing sugars released showed a linear relation to the concentration of phenolic compounds released. Three wild microorganisms were isolated, which showed fermentative capacity on nopal hydrolysates. Molecular identification of isolated showed the presence of Candida intermedia, Saccharomyces paradoxus and Zygosaccharomyces bailii; microorganisms that proved capable of producing ethanol. The results showed that pH is the principal factor that impacted ethanol production, and that when associated with conditions of oxygen limitation generated yields (Yp/s) of 48 % compared to the maximum theoretical value. Also, adding magnesium salt to the culture medium at a concentration of 0.5 g/L had the greatest effect on ethanol production for S. paradoxus and Z. bailii. In other results, a slight reduction in product formation was observed for Z. bailii when (NH4)2SO4 was used as the nitrogen source, while for S. paradoxus, ethanol production increased slightly, from 1.64 to 2.11 g/L when the hydrolized is used with 5 g/L of nitrogen salts. These results show that, in general, adding the nitrogen source did not promote product formation.