The White Rot Fungus Mixed Culture Laccase Production And Its Mechanism, And Decolorization

Mixed culture of microorganism or fermentation is more effective than single culture.Many researches about mixed culture have been published and used in practice,but the screen of co-culture fungi—pair is blind due to its unclear mechanism.Laccase is produced by white-rot,mainly used in pulping,food and textile,and. Coriolus versicolor Lz-8 was a fungus with good laccase production capability. Mixed culture was carried out using Lz-8 and other laccase-production_fungi or cellulase-production_fungi.The results showed that laccase activity from mixed culture of Rigidoporus sp W1 and Coriolus versicolor Lz-8 was 1.6 times higher, compared with single culture of Lz-8 in the 7^thday.Inoculum proportion and inoculation time were optimized and showed that when inoculum was 1:1,and Rigidoporus sp W1 inoculated one day before,the laccase activity researched 40.96 IU/ml,3.35 times and 4.84 times higher than single culture of laccase activity of Coriolus versicolor Lz-8 and Rigidoporus sp W1 respectively in the 9^thday incubation.The optimum pH of the laccase is 2.5 and laccase is stable in range of pH 5.0-9.0.The optimum temperature is 55℃and laccase activity is about 53%and 36% when it was stored at 50℃and 60℃respectively.It was found that the two fungi could co-cultured well in the PDA medium and produced pigments in the dividing line.Crude laccase produced by the two fungi using single culture were mixed in the 5^th,7^th,9^th,11^thday,laccase activity assay showed that there was no synergistic effect between the two laccases.The fermentation of single culture of the two fungi were mixed in the 3^rdand 4^thday,it was found that laccase production increased highly in 24 hours.Single culture of the two fungi were filtered and added into culture of each other,the laccase activity was improved highly during culture of Coriolus versicolor Lz-8,but little influence on culture of W1,showed some substance which stimulated laccase production existed in culture of Rigidoporus sp W1 in the 4^thday.Active dyeing of laccase from_single culture and mixed culture showed there was visible difference between these laccases.Laccase produced by mixed culture in 9 day incubation were used for dye decolorization_.Decolorization was carried out in citrate phosphate buffer(50 mM,_pH 4.0)in a final volume of 5 ml and dosage of laccase was 0.58 IU/ml.All of the six dyes(RBBR,Bromophenol blue,Malachite green,Crystal violet,Methyl orange and Rhodamine B)_{concentration:200 mg/l}could be decolorized by the laccase. Especially,over 90%of color was_decolored in 1 h for RBBR and Bromophenol blue. Experiments results of the decolorization conditions of RBBR and Bromophenol blue showed there was little difference in 0-180 rpm,20-70℃and 200-600 mg/l concentration of dyes.The absorption of RBBR and Bromophenol blue atλmax(nm) disappeared after laccase treatment.