AO-02: Kinetics of production of a neutral protease by Aspergillus oryzae Ahlburg (Cohen) 1042.72 on optimized medium based on orange waste

Abstract

Subject description: In order to improve the conduct of fermentation in enzyme manufacturing processes, it is essential to realize the kinetics of growth of the microorganism and the kinetics of production of the enzyme for determine where the maximum production of enzyme is obtained.

Objectives: The objectif is to define the type of association between these two parameters.

Methods: The kinetic of the production of a neutral protease was monitored on a medium based on orange waste. Sampling every 4 hours over a period of three days made it possible to establish the growth curve of the mould and the evolution of enzymatic activity.

Results and discussion: The microbial biomass evolves in four phases, a first latency phase which lasts 8 hours. From the 8th hour until the 36th hour the growth becomes rapid, it is the exponential phase where the dry weight of the biomass reaches its maximum value (15.42g/l), the synthesis of the protease begins. From the 36th hour to the 56th hour it is the stationary phase during which we observe the cessation of growth, the weight of the mycelium is constant but we note an increase in proteolytic activity (2635 U). It is during the stationary phase that the increases in activity are greatest.

Conclusion: The production of proteases is therefore of the “partially associated” type with growth. The decay phase begins from the 56th hour. It is characterized by a decrease in dry weight which goes from 14.26g/l to 6.70g/l and corresponds to the decrease in viable cells following their autolysis under the action of the enzymes of the cells themselves