Biochemical Properties of Crude Alkaline Protease Produced by Bacillus thuringiensis dendrolimus IP 4A/4B under Solid-State Fermentation Conditions

Abstract

Objective: This paper aims to, study the biochemical properties of the crude enzyme, extracted from the bacterial strain Bacillus thuringiensis dendrolimus IP 4A/4B, such as the concentration of the enzyme, the duration of the enzymatic reaction, the effect of changing the temperature of the enzymatic reaction and the effect of the pH of the enzymatic reaction medium. Methods: Inoculum preparation, submerged and solid-state fermentation media, enzymes assays spectrophotometrically, protein determination were performed. Results: The results indicated that 0.181mg protein/mL of enzyme produced maximum alkaline protease activity (269U/mL/min) followed by 0.227mg protein/mL enzyme (260U/mL/min). The slope of the first period (up to 5min reaction time) exhibited steeper slope indicating reactions velocity near the theoretical initial velocity (Vmax) that has become lesser in value as the reaction was extended up to 120min. The maximum enzyme activity was at 60°C (246U/mL/min), while decreased gradually to reach (188U/mL/min) at 90°C. It was clear that the optimum pH was 9.0 when glycine-NaOH and Tris-HCl buffers were used. Conclusion: The optimum pH for the enzymatic reaction pH 9 indicates the potential for this crude enzyme to be used in many industries that require an alkaline pH, and at the same time, the optimum temperature for the enzymatic reaction of 60°C enhances this applicability; this temperature is widely available in many industries.