Study On Aromatic Compounds Biodegraded By White Rot Fungus Fermenting In Straws Substrates

The typical aromatic compounds and the straws were selected as research object and cosubstrates in this paper. By studying on the ways and mechanisms of promoting the biodegradation rates of aromatic compounds in different biodegradation systems when the lignocellulose was degraded by white rot fungi, some conclusions about cometabolism were obtained, which will strengthen the theoried on refractory aromatic compounds biodegraded by white rot fungi through cometabolism and provide some valid methods to solve the pollution problem of refractory contamination. The research will play important roles in the environmental treatment.A comparative research on dyes decolorized and biodegraded by Pleurotus ostreatus BP in different liquid and solid state biodegradation systems accompanied with crop straw was showed in this paper. The results indicated that adopting solid state fermentation could biodegrade the dyes effectively. The decolorization and biodegradation of dyes by the white rot fungus could be accelerated in presence of the rice straw compared to the other crop straws,the decolorization rate of malachite green, bromophenol blue and crystal violet could reach 87.23%, 84.68% and 82.19% respectively during 13 days incubation in rice straw medium. The coexist system of rice straw and dyes was chosen as the main biodegradation system.The mechanisms of triphenylmethane dyes biodegraded by Pleurotus ostreatus BP in rice straw medium were also studied. Different systems were used to analyze the biodegradation process of triphenylmethane dyes. These systems included biodegradation system of dyes by the crude enzymes extracted and the white rot fungus in rice straw medium, biodegradation system of lignocellulose by the white rot fungus, biodegradation system of dyes by the fungus in different components and soluble and unsolvable media.The results indicated the process of dyes-biodegraded in solid medium was a dynamic intercommunion between adsorption and biodegradation. Different declorization efficacy would be obtained in different fermentation systems, for example, the rate of decolorization of malachite green was 27.6% and 98.15% in unsolvable and solid medium, respectively. The solid medium improved the capability of secreted enzyme of the white rot fungus. With the using and biodegrading of the solid medium by the white rot fungus, the dyes could also be decolored and biodegraded. The biodegradation mechanism of dyes by the white rot fungus depended on cometabolism based on the enzymes secreted by the white rot fungus in rice straw medium. The decolorization of dyes was influenced by the enzymes secreted, and the decolorization rate of malachite green, bromophenol blue and crystal violet by the crude enzymes could reach 69.76%, 76.71% and 27.24% respectively. Different mechanisms occurred among biodegradation of dyes with different structures, the biodegradation of bromophenol blue depended mainly on enzymes, the biodegradation mechanism of malachite green combined co-metabolism with enzymes and crystal violet was biodegraded by co-metabolism.In selected liquid and solid biodegradation system, the white rot fungus was used to biodegrade the quinoline and indole, they could be biodegraded effectively by the white rot fungus in different fermentation systems. The enzyme activity and biodegradation rate of quinoline or indole were higher in the solid medium than those in the liquid medium,for instance, the biodegradation rate of quinoline (C250) could reach 93.47% in solid fermentation system, but the corresponding value was only 62.80% in liquid-cultured system during the same period of incubation. The enzyme activity, biomass and the rate of degradation of quinoline had not corresponding relation. The results detected by HPLC showed that quinoline or indole could be biodegraded effectively in solid state fermentation system, but the intermediates were produced in liquid state fermentation system.