Study On Optimization Of Submerged Culture System And Mycelium Growth Kinetics Model Of Dictyophora

As we all known, Dictyophora is a kind of edible and medicinal fungi. It was called the queen of fungi and was very delicious. Modern research shows that it has many functions including immune, antitumor, antibacterial, anti-aging and so on. Because the yield of Dictyophora was low and the price was high, and it was not suitable for large-scale production, we should pay more attention to the research method of Dictyophora mycelium. In the paper, we studied the biological characteristics, laws, and appropriate method of submerged culture. Then further research on the mathematical model of Dictyophora mycelium was investigated.We first discussed the biological characteristics, main limiting factors and research methods of mycelium submerged culture of Dictyophora by reducing the interference resulted by the volume of mother culture, the nutrition of strain and hydrolytic enzymes. The results showed that there was a linear relationship between the cubic root of weight and culture time. After inoculating by bamboo chips strain, the germination rate, morphology and volume enlargement of mycelium were significantly superior to the agar or grain strain, moreover, the differences between replicates were not significant(P < 0.05); Compared with wet weight method and dry weigh method, the method of measuring weight by volume and density was acute and feasible. The effects of types of nutrients on growth rate were greater. We used single-factor test to determine that the most suitable carbon source, nitrogen source, inorganic salts of submerged culture are respectively the sugar, corn flour and magnesium sulfate. In a range of the concentration, a certain increase of inoculum can reduce the size of mycelial pellets and get more quantity of culture medium, which improve the utilization of nutrients and eventually increase the production of mycelium. When the inside of pellets stopped growing and decayed, the accumulation of metabolic waste became the main limiting factors of the submerged culture.Secondly, we studied the mathematical model of mycelium growth to control cultivation process effectively. On the basis of the growth law that is in compliance with the zero-order reaction, the same density of mycelial pellets, and the constant of the oxygen concentration in the culture medium, we calculated that the critical radius of mycelium pellets was 0.4 mm. When the inside of pellets stopped growing, the critical radius was about 0.8mm. Moreover, when the regional thickness of the external mycelial growth was thin, the critical radius was near 0.6mm. Above conclusions can explain the cause of the cube root growth in mycelial: when the radius was much larger than the thickness, oxygen proliferation in mycelial pellets was from one-dimensional spherical coordinate system into a stable transmission of one-dimensional cartesian coordinate system, which resulted that the external growth region had a unique thickness and growth rate. The relationship between the Mycelial growth speed and the specific growth rate, respiration rate, growth rate of oxygen was dr / dt = (Q o 2 (tanh( AL0 )/ A + L1 ) ? Lmo 2 )Yx ? /o2. The data derived from this model and actual observation was good, which could provide quantitative reference for establishing dynamic model and industrial production.