OPTIMIZATION OF ENZYMATIC PRODUCTION OF RHIZOPUS OLIGOSPORUS USING RESPONSE SURFACE METHODOLOGY

Abstract

In the present study, we aimed to optimize the levels of abiotic factors involved in maximizing the production of extracellular fermentative Rhizopus oligosporus (R. oligosporus) enzymes using substrates such as soy and dextrose. In the first trial, we determined the effect of environmental factors on R. oligosporus growth. The redundancy analysis showed that three levels, namely temperature (X₁), carbon dioxide concentration (CO₂; X₂), and light intensity (X₃), which accounted for 34.3% of the variation observed in the organoleptic characteristics of micelles, including color and spore quantity. In the second trial, a three-level and three-factor Box–Behnken design with one replicate was used to study the interaction of the significant abiotic factors (X₁, X₂, and X₃) with alkaline protease (AlkP; Y ₁), acid protease (AcP; Y₂), lipase (LiP; Y₃), and carbohydrase (Cbh; Y₄). Three levels, namely temperature (28, 30, and 32 °C), CO₂ concentration (385, 436, and 494 ppm), and light intensity (0, 53, and 100 lux), were optimized using the response surface methodology. Analysis of variance showed that X₁ and X₃ were significant factors for the yield of AlkP, AcP, and Cbh. X₁ and X₂ significantly affected the LiP yield. The desirability surface plot indicated that the optimal yields of AlkP, AcP, and Cbh (0.557, 0.387, and 0.098 U/mg, respectively) were recorded at 25 °C and 0 lux. A LiP yield of 0.0752 U/mg was obtained at 25 °C of temperature and 494 ppm of CO₂ concentration. Taken together, the present study provides conditions for the optimal production of R. oligosporus enzymes using soy and dextrose as substrates. The present data can be used to improve soy fermentation in the search for protein-rich foods with excellent digestibility.