Optimization of determination conditions for protease in landfill

Protease was a key hydrolase in nitrogen transformation in landfill. The activity could show transformation states of nitrogen, that had important significance to study the biotransformation of organic nitrogenous substances in landfill. This paper designed six factors and five levels (L25 (56)) orthogonal test to measure the activity of protease in landfill. The results showed that the optimal experimental conditions for protease in landfill were 16h of culture period, 30 degrees C of culture temperature, 6mL 1% casein, 0.3mL toluol, 0.2mL 0.1N H2SO4 and 1.5mL 20% Na2SO4. The experimental results were 84.23% to 368.86% more compared with that by the method of traditional method. In the optimized tests, the Relatively Standard Deviation (RSD) was less than 3.37%, and average recovery rates was 97.15%. The result showed the designed optimal experiments could provide more accurate and stable experimental data.