一株竹木质素降解菌的筛选及降解效果

A bamboo lignin-degrading strain:screening and degradation performance

【背景】竹子纤维素含量高,被认为是优质的生物精炼资源。然而,竹子中的木质素与纤维素结合紧密,降解木质素成为有效利用竹子纤维素的关键。【目的】筛选专一降解竹木质素的细菌,并探究其酶活活性及木质素降解效果。【方法】以木质素为唯一碳源的培养基进行初筛,苯胺蓝、刚果红培养基进行复筛,通过测定酶活性评估其木质素降解能力。通过扫描电镜、傅里叶变换红外光谱和X射线衍射分析竹子降解前后的形貌以及结构变化。【结果】从竹林中筛选分离出一株细菌XKG6,为食油假单胞菌(Pseudomonas oleovorans)。菌株XKG6分泌的漆酶、木质素过氧化物酶、锰过氧化物酶、滤纸酶和木聚糖酶活性最高分别为1 543.21、6 229.32、826.41、2 602.1和1 889.25 U/L。菌株XKG6降解碱木质素7 d后的降解率为14.04%。通过傅里叶变换红外光谱和扫描电镜发现竹木质素经菌株XKG6处理后结构有明显变化。【结论】本研究筛选获得了一株具有较强木质素降解能力的细菌,该菌株在降解竹木质素过程中保留了较多的纤维素,为纤维素资源的工业生产提供了潜在的替代菌株。

[Background]Bamboo is considered an excellent source for biorefining for its high cellulose content.However,the complex interactions between lignin and cellulose present an obstacle to the efficient utilization of bamboo.The process of lignin degradation is essential for the efficient utilization of bamboo.[Objective]To screen out the strains that specialize in degrading bamboo lignin and investigate their enzyme activities and effects of lignin degradation.[Methods]A culture medium with lignin as the solo carbon source was used for the primary screening,which was followed by the secondary screening with the media containing aniline blue and Congo red.The activities of enzymes were measured to assess the lignocellulose degradation performance.X-ray diffraction,Fourier-transform infrared spectroscopy,and scanning electron microscopy were employed to study the changes of bamboo appearance and structure after degradation.[Results]A strain XKG6 capable of degrading lignin was isolated from the bamboo forest and identified as Pseudomonas oleovorans.The maximum activities of lactase,lignin peroxidase,manganese peroxidase,filter paper enzyme,and xylanase secreted by the strain reached 1543.21,6229.32,826.41,2602.1,and 1889.25 U/L,respectively.The strain showed a degradation rate of 14.04%against alkaline lignin on day 7.Fourier transform infrared spectroscopy and scanning electron microscopy showed the significant structural changes in bamboo lignin after treatment with XKG6.[Conclusion]In this study,a bacterial strain with the ability to degrade lignin was screened out.This strain retained much cellulose while degrading bamboo lignin,serving as an alternative strain for the industrial production of lignocellulosic resources.