Optimization Of Laccase Culture Medium For White Rot Fungi And Degradation Of Azoxystrobin

With the large-area application of pesticides,how to reduce the pesticides remnant in the environment has become an important scientific research content at this stage.Biodegradation of non-pollution,universality and effectiveness has become one of the primary technologies in multi-disciplinary researches.As a biodegrading fungi,white-rot fungi has an efficient degrading effect to pesticides by various enzyme systems produced,especially laccase.Therefore,how to determine white-rot fungi producing laccase and improve laccase production has been a key of studying degrading pesticides.This test researched white-rot fungi collected on Sifeng Mountain in Kiamusze,to preliminarily screen 8 kinds of white-rot fungi producing laccase by applying guaiacol medium,optimize medium,improve laccase production and measure laccase activity by applying ABTS method.4 fungi producing laccases most were selected to be used for degradation of azoxystrobin,a pesticide remnant in soil of greenhouse in northeast,to calculate degradation rate by using HPLC to test residual quantity of azoxystrobin.The results showed that:1.To inoculate collected white-rot fungi to medium containing guaiacol after separation and purification could make medium produce trametes orientalis,hirsute trametes,phellinus igniarius,whorl stereum hirsutum,artist's conk,fomitopsis pinicola,wild lentinula edodes and pycnoporus cinnabarinus of red and lavender.2.It could be obtained according to the screening of nutritional factors and culture condition of medium,:Glucose and potassium nitrate were carbon and nitrogen sources of most white-rot fungi,metal cations such as Cu2+,K+,Mg2+ had facilitation to white-rot fungi producing laccase,Ca2+ had inhibiting effect to enzyme production,while Zn2+ had no effects on producing laccase.The temperature and pH had significant impacts on white-rot fungi producing laccase,the amount of laccase production under acidic condition would be best with 25-30?.3.After medium optimization of 8 white-rot fungi,it could be obtained that: the highest laccase activity produced by trametes orientalis was 133.14 U/ml,which was 1.93 times of laccase activity produced by PDA medium;the highest laccase activity produced by hirsute trametes was 73.05 U/ml,which was 1.50 times of laccase activity produced by PDA medium;the highest laccase activity produced by phellinus igniarius was 31.48 U/ml,which was 1.85 times of laccase activity produced by PDA medium;the highest laccase activity produced by whorl stereum hirsutum was 157.36 U/ml,which was 2.72 times of laccase activity produced by PDA medium;the highest laccase activity produced by artist's conk was 59.05 U/ml,which was 1.52 times of laccase activity produced by PDA medium;the highest laccase activity produced by fomitopsis pinicola was 127.17 U/ml,which was 1.70 times of laccase activity produced by PDA medium;the highest laccase activity produced by wild lentinus edodes was 448.16 U/ml,which was 1.42 times of laccase activity produced by PDA medium;the highest laccase activity produced by pycnporus cinnabarnus was 137.77 U/ml,which was 2.36 times of laccase activity produced by PDA medium.4.To cultivate wild lentinus edodes,whorl stereum hirsutum,pycnporus cinnabarnus,trametes orientalis screened according to the most laccase production with the best medium,to extract crude enzyme for degradation to oil from greenhouse which contained residuary azoxystrobin pesticide.The results indicated that: The degradation rate of wild lentinus edodes was highest,which achieved as 99.99%,and degradation rates of both whorl stereum hirsutum and pycnporus cinnabarnus were up to above 90%,respectively was 94.35% and 93.93%.The degradation rate of trametes orientalis was lowest,which was 82.63%.