Production of an enzymatic cocktail by Aspergillus japonicus in a stirred-tank bioreactor for application in animal feed.

Abstract

New enzymatic sources need to be explored to meet the increasing demand for bioactives used in the supplementation of non-ruminant animals. Phytase and xylanase are widely used in animal nutrition due to their ability to degrade phytic acid and xylan, respectively. This study aimed to (i) produce phytase and xylanase by culturing Aspergillus japonicus on medium containing wheat bran + soybean bran (1:1 w/w) as alternative carbon sources in a stirred-tank bioreactor and (ii) compare this process with that conducted in Erlenmeyer flasks. The resulting enzymatic cocktails and commercial enzymes were evaluated for their ability to hydrolyze poultry diets (D1–D9). The production peaks of phytase and xylanase in the bioreactor occurred at 120 h (842.30 ± 43.62 U/L) and 144 h (3211.29 ± 274.98 U/L), respectively. After 144 h of cultivation, protein concentration in the bioreactor was approximately twice that observed in Erlenmeyer flasks. ECPAjBr displayed the highest hydrolytic activity for inorganic phosphate in diet D6 (42.34 ± 2.20 mg/g), followed by diet D7 (38.67 ± 0.46 mg/g). Regarding reducing sugars, ECXAjBr exhibited the highest activity in diets D1 and D8, releasing 147.71 ± 18.18 mg/g and 145.83 ± 11.39 mg/g, respectively. All tested diets, regardless of their composition, indicated a synergistic interaction between commercial enzymes and those present in the A. japonicus enzyme cocktail, which exhibits a broad spectrum of hydrolytic activities, including high levels of accessory enzymes. The application of this cocktail in animal diets holds great potential for increasing nutrient bioavailability in non-ruminant animal production.

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Keywords: Animal diet; Bench-scale bioreactor; Enzymes; Submerged cultivation; Synergism.