Screening Of Mutated Sporotrichum Thermophile With High Endoglucanase Activity

The developing and applying of fuel ethanol,one kind of new energies,is very important to helping relieving the energy crisis and improving the environment conditions. Taking reducing the production cost of fuel ethanol into accounts,cellulose stuff is obviously the best choice for the production of fuel ethanol.Therefore,getting the best strain which can decompose cellulose effectively is the great point.As one thermophilic mycelial fungus,Sporotrichum thermophile can decompose cellulose.When cultivated on solid PDA culture,the hyphae of Sporotrichum thermophile are branching with dissepiments.The hyphae produce conidiophores from the top and the side.Sporotrichum thermophile was identified closest to Scytalidium thermophilium and Humicola insolens by ITS-PCR analysis.The conditions for decomposing bagasse under liquid fermentation was optimized by observing the growth and determining the concentration of reduce sugar and the decrement of bagasse.The optimum conditions were bagasse 30 g/L,NH₄NO₃ 11.45 g/L,initial pH value 4.0,inoculation 15%(spore concentration 10⁶ spores/mL).On the base of Sporotrichum thermophile,using the technology of UV and HNO₂ complex mutation,12strains with larger limpidity circle were obtained by Sodium Carbonxymethylcellulose-congo red culture screening.On behalf of the activity of endoglucanase,the ratios of limpidity circle diameter and colony diameter were anyalyzed. The result shows that the activity of endoglucanase of 66-22strain is the highest and the optimum culturing condition for it is the following:45℃,NH4NO3 1.5 g/L,initial pH value 6.0.Under the above optimum condition,at two days and three days after inoculation,the activity of endoglucanase reaches the top and comes to fall at four days after inoculation.The difference between two days and three days is not obvious.Cultivated on the optimum cluture respectively,the activity of endoglucanase of strain 66-22 was as 1.19 times and 1.29 times as that of Sporotrichum thermophile ATCC 36347 at second day and third day after inoculation.