[Effect of trace element on the growth of white rot fungus and suppressing yeast in liquid medium].

Growth of white rot fungus in liquid medium with different trace element and effect of these medium on suppressing the growth of yeast under non-sterile were investigated in agitated Erlenmeyer flasks. Results showed that the size and amount of mycelium pellets in liquid medium with trace element and Fe 3.5 mg/L was more than that with trace element but no iron and without any trace element under sterile condition; moreover, the size and amount of mycelium pellets increased with the rise of the concentration of trace element and iron. In addition, if applying the mode of incubating under sterile condition and degrading under non-sterile condition, the decolorization of reactive brilliant red K-2BP in liquid medium without any trace element and with trace element but no iron was similar to that of degrading under sterile condition; but the decolorization in liquid medium with trace element and Fe 3.5 mg/L was less than the results under sterile condition. Through observing under microscope, it was found that the amount of yeast in liquid medium with Fe 3.5 mg/L was more than the medium without any trace element and with trace element but no iron. Therefore, trace element, especially iron, plays a very important role in suppressing yeast in liquid medium; furthermore, iron also is necessary to the growth of whit rot fungus. So that, to control the concentration of iron in liquid medium could reduce the invasion of yeast under non-sterile condition as long as it does influence the growth of white rot fungus.