Medicinal Fungus Polyporus He-ne Laser And Ultraviolet Mutagenesis Breeding Research

In this paper, the starting strain of medicinal fungus-Polyporus umbellatus were mutagenized by He-Ne laser, UV and the multiple-irradiation of both the two mutagens. The colonial diameters of mutants were measured to define the mycelial growth rates and to screen out the strain- L3-7, U1-7, LU-7- with higher growth rates.Then the mycelial dry weight, the yields of crude extracellular polysaccharide and activities of three extracellular enzymes of the pre-selected mutants were tested to select the mutant strain LU-7 with the good characteristics in the three aspects. The analysis of the isoenzyme zymogram of esterase indicated that the mutants' esterase isoenzyme patterns and Rf value were different from the starting strain. The stabilitis on the growth rates and extracellular polysaccharide of different generations of the mutant strain were investigated. All these showed that the mutant's genetic substances had changed and had the good genetic stability.The liquid medium components and part of the culture conditions for this mutant were optimized, including carbon source, nitrogen source, inorganic elements, ventilatory condition, culture temperature and the addition of the natural material extract. It was found that the addition of the extract of C.glauca sawdust did good effect on the mycelial growth and extracellular polysaccharide yields. The greatest mycelial dry weight of LU-7 in the optimized medium was 165.5mg/30ml which was 74.9% higher than the starting strain in the basic medium. Its yields of crude extracellular polysaccharide was 5.42mg/ml which is 95.0% higher than the starting strain in the basic medium.The extracellular crude polysaccharide of the mutant was prepared by ethanol precipitation from fermentation product of the mutant. The protein in it was removed by the Sevag procedure. It was further purified by SephadexG-50 and SephadexG-150 column chromatography respectively. It was homogenous as determined by UV-spectrum, gel filtration and polyacrylamide gel electrophoresis. The components of the polysaccharide of the mutant and the starting strain were identified by TLC and PC. Results showed that the two kinds of polysaccharide were composed of mannose. The infrared spectrometry analysis showed that the polysaccharide of the mutant and the starting strain had the same characteristic absorption peaks and that proved the polysaccharide of the mutants was similar to the starting strain.