Study on active capacity and detergent application potential of low-temperature alkaline serine protease produced by new strain Exiguobacterium indicum 1.2.3

Abstract

Microorganisms have long captivated researchers for their potential to produce enzymes with diverse industrial applications. Efficient production of proteases from new strains is crucial as these enzymes play a vital role in breaking down protein bonds, enabling their use in industrial applications. Therefore, a novel Exiguobacterium indicum 1.2.3 was isolated (Istanbul, Turkiye) and characterized in this study. This strain produced alkaline serine protease, which works in lower temperatures (20-40 °C) with casein as a specific substrate. The protease was utterly stable for 3 h at 30 °C. The enzyme was also highly stable in the pH range of 8-11. The optimum activity was obtained at pH 10. The crude enzyme activity was enhanced by various metal ions and retained 147%, 125%, 124%, and 117% of its activity within 1 mM Ca²⁺, Mn²⁺, Cu²⁺, and Mg²⁺, respectively. The crude enzyme was inactive with phenylmethylsulfonyl fluoride, indicating a serine residue on the active side. The enzyme exhibited a significant proteolytic effect in the presence of surfactants and oxidizing agents. The addition of Tween 80, Triton X-100, and sodium perborate improved enzymatic activity up to 135%, 109%, and 105%, respectively. According to the washing results, the crude enzyme effectively removed the blood on different types of standard pre-stained textiles at 30 °C. In conclusion, Exiguobacterium indicum 1.2.3 is a promising candidate for protease production, with its diverse applications spanning various industrial sectors, particularly detergents.

Keywords: Exiguobacterium indicum; Alkaline protease; Enzymatic activity; Industrial enzymes; Low-temperature detergent.

Fig. 1

Growth curve and protease activity profile of E. indicum 1.2.3. All experiments were performed in triplicate with calculated mean standard deviation

Fig. 2

Effect of pH on protease activity (a) and stability (b)

Fig. 3

Effect of temperature on protease activity (a) and stability (b)

Fig. 4

Effect of metal ions and inhibitors on protease activity

Fig. 5

Effect of surfactants and oxidizing agents on protease activity

Fig. 6

Enzyme washing performance in detergent formulation