Production and Catalytic Properties of Amylases fromLichtheimia ramosaandThermoascus aurantiacusby Solid-State Fermentation

Abstract

The present study compared the production and the catalytic properties of amylolytic enzymes obtained from the fungiLichtheimia ramosa(mesophilic) andThermoascus aurantiacus(thermophilic). The highest amylase production in both fungi was observed in wheat bran supplemented with nutrient solution (pH 4.0) after 96 hours of cultivation, reaching 417.2 U/g of dry substrate (or 41.72 U/mL) and 144.5 U/g of dry substrate (or 14.45 U/mL) forL. ramosaandT. aurantiacus, respectively. The enzymes showed higher catalytic activity at pH 6.0 at 60°C. The amylases produced byL. ramosaandT. aurantiacuswere stable between pH 3.5–10.5 and pH 4.5–9.5, respectively. The amylase ofL. ramosawas stable at 55°C after 1 hour of incubation, whereas that ofT. aurantiacusmaintained 60% of its original activity under the same conditions. Both enzymes were active in the presence of ethanol. The enzymes hydrolyzed starch from different sources, with the best results obtained with corn starch. The enzymatic complex produced byL. ramosashowed dextrinizing and saccharifying potential. The enzymatic extract produced by the fungusT. aurantiacuspresented only saccharifying potential, releasing glucose monomers as the main hydrolysis product.