Biomass Production and Partial Characterization of Agavinase from Aspergillus kawachii via Submerged Fermentation: New Insights for a Sustainable Future

Aspergillus kawachii is a filamentous fungus widely used in the production of Japanese alcoholic and brewing beverages due to its enhanced saccharification capacity of structural polysaccharides such as cellulose, hemicellulose, and pectin. Agavin is a reserve polysaccharide in agave plants, which may be used as a carbon source for fungal metabolites production. A submerged fermentation was carried out with A. kawachii with glucose, saccharose, and agavin as a carbon source to study the production of the enzyme agavinase. Biomass production, pH, and total sugars were measured during the cultivation to analyze the fungal growth and the feasibility of the secretion of agavinase. The enzyme activity to detect agavinase was carried out using agavin and fractions of crude culture broths from the three substrates. A chromatography of molecular size exclusion was applied to desalt and separate the enzyme extract from the rest of the components to identify agavin activity. Agavin activity was not detected in glucose extracts; low values were shown in the sucrose extract and were better for the agavin extracts. Agavinase is demonstrated to be produced inductively by Aspergillus kawachii in agavinrich media, and the glucose as substrate evidenced the absence of agavinase, and then it is not a constitutive enzyme for the fungus.