血红密孔菌高产漆酶菌株的筛选及其对烟梗的生物降解

白腐菌是目前已知的唯一能将木质素彻底降解的微生物,而漆酶在木质素分解过程中起着重要的作用,被广泛应用于农作物秸秆或甘蔗渣等多种类型生物质的生物预处理和生物降解。本研究利用白腐菌产漆酶发酵培养基对30株血红密孔菌Pycnoporus sanguineus菌株进行筛选,得到了多株漆酶高产菌株,并研究了血红密孔菌发酵粗酶液和菌丝对烟梗的生物降解条件。研究结果表明:血红密孔菌及其产生的漆酶表现出了对烟梗木质素较强的生物降解能力。在漆酶浓度为40U/mL、温度30℃、pH4.5的条件下处理24h,烟梗中木质素的降解率可达到50.4%,纤维素和半纤维素的降解率分别为17.5%和17.3%;漆酶浓度为5U/mL、温度30℃、pH4.5的条件下处理48h,木质素降解率可达到65.1%。血红密孔菌菌丝也表现出对烟梗较好的生物降解效果,接种培养7d后烟梗中木质素降解率可达30%以上,21d后木质素的降解率可达79.1%,而纤维素和半纤维素的降解率仅为20%和12%左右。本研究不但为生物质材料的生物预处理和生物降解提供了优质的白腐菌及漆酶资源,还为通过烟梗的生物预处理提高烟草梗丝和卷烟品质提供了重要参数,具有一定的应用前景。

Highly laccase-yielding strains of Pycnoporus sanguineus and their activities on tobacco stem biodegradation

Laccase-producing white-rot fungi are known for their activities to degrade lignin and widely applied to biodegradation of crop straw, sugar cane bagasse, etc. In this study, thirty strains of Pycnoporus sanguineus producing laccase highly were screened and their laccase activity was detected, and then they were applied to biodegrade the tobacco stem. The results showed that the mycelia of P. sanguineus strains and their laccases could degrade strongly the lignin in tobacco stem. Under concentration of 40U/mL at temperature 30°C and pH 4.5, the degradation rate of lignin could reach 50.4% in 24h, and that of cellulose and hemicellulose were 17.5% and 17.3%, respectively. Lignin degradation rate could reach 65.1% under 5U/mL laccase concentration in 48h at the same temperature and pH. After incubation for 7 days, the lignin degradation rate in tobacco stem was over 30%, and 79.1% of the lignin was degraded in 21 days, while the degradation rate of cellulose and hemicellulose was only about 20% and 12%, respectively. These white-rot fungi and their laccases showed a good application prospect for biological pretreatment of tobacco stem to improve the quality of cigarette.