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Protease enzyme is an enzyme that functions to break down proteins into oligopeptides and amino acids. The need for protease enzymes in the industry, especially probiotic foods, has developed very rapidly. However, Indonesia has not been able to produce these enzymes on a large scale. Protease production sourced from lactic acid bacteria (LAB) can be done more effectively and efficiently than from plants. The utilization of soybean peel waste containing nutrients is very large and the possibility of Lactic acid bacteria will increase the productivity of proteases. Soybean peel waste bacterial isolates and their characteristics that are suspected of LAB as a producer of protease enzymes have never been done before. The isolation process was carried out by fermenting soybean peel in the Nutrient broth medium for 24 hours (T1) and 48 hours (T2) with the addition of Leuconostoc mesenteroides starter. Identification of bacterial isolates includes morphological identification, antimicrobial activity test, acid resistance test, protease enzyme activity test, and phytochemical test. From the results of the study, it was found that T1 isolates were superior to T2. The number of T1 isolates growing on Nutrient agar was as much as 55 x 107 CFU/ mL with a small regular rounded colony shape, convex elevation, white color and produce purple in Gram staining. Acid resistance test showed turbidity at pH 2.0; 3.0; 4.0; 5.0 and 6.0, Antimicrobial activity test results in very strong inhibition zones against Shigella and E. coli bacteria of 20-28.5 mm with the protease enzyme activity of 1.43 mg/ mL. [ABSTRACT FROM AUTHOR]

Protease as protein hydrolyzer is an imported enzyme used in the food and pharmaceutical industries in Indonesia. To reduce imports, indigenous lactic acid bacteria can be used as a source of protease. This study aimed to determine the characteristics of indigenous Leuconostoc mesenteroides EN 17-11 protease and its stability during storage at cold and freezing temperatures. Protease activity was detected using the modified Horikoshi method. The protease stability after storage was tested at 0, 7, 14, 21, and 28 days. Relative protease activity with a value ≥50% indicates protease activity in stable conditions. All treatments were statistically analyzed using ANOVA. The results showed that the optimum protease activity of L. mesenteroides EN 17-11 was reached at pH 6.0 with activity of 0.9970 U/ml and temperature of 40°C with activity of 1.1166 U/ml (p<0.05). The protease stability at incubation time of 60 min was reached at pH 5.0–7.5 with a relative activity of 55.29–100.00%, and a temperature of 20–50°C with a relative activity of 51.92–100.00% (p<0.05). The protease stability at storage for 28 days with a relative activity of ≥50% at freezing temperature was higher than at cold temperature. The highest protease stability was reached at freezing temperature for 7 days with a relative activity of 77.31% (p<0.05). It was concluded that the protease stability of indigenous L. mesenteroides EN 17-11 was better at freezing than at cold temperature. [ABSTRACT FROM AUTHOR]