食用菌菌渣高温堆肥中木质纤维素高效降解菌的分离、鉴定与降解活性

Isolation,identification,and degradation activity of efficiency lignocellulosicdegrading microorganism in high-temperature composting of spent mushroom substrate

我国是世界第一大食用菌生产国,食用菌菌渣产量庞大.菌渣中较高的木质纤维素含量是制约其资源化利用的限制因素,筛选木质纤维素高效降解菌将为菌渣的高效循环利用提供有效途径.以菌渣好氧堆肥高温阶段(55℃以上)的原料为对象,开展高温木质纤维素高效降解菌的分离、鉴定与降解活性研究.通过苯胺蓝、刚果红平板初筛和液体发酵产酶活性复筛,获得目标菌株LC-10.结合形态、分子和生理生化鉴定,确定LC-10菌株为热紫链霉菌Streptomyces thermoviolaceus(GenBank登录号ON816008),该菌具有较高的高温内切葡聚糖酶、外切葡聚糖酶和木聚糖酶活性.LC-10菌株在秸秆和木屑降解培养基、50℃、130 r/min振荡培养20 d,对秸秆和木屑的降解率分别为70.77%±1.09%和12.72%±1.72%.降解过程中木质纤维素降解酶活性的结果表明,LC-10菌株分泌的滤纸酶、内切葡聚糖酶、外切葡聚糖酶和β-葡糖苷酶共同参与纤维素的降解,锰过氧化物酶和木质素过氧化物酶共同参与木质素的降解,而发酵液中缺乏漆酶.本研究获得了具有高效降解木质纤维素活性的放线菌,能够在高温条件下分泌多种胞外降解酶,具有应用于菌渣高温堆肥处理的潜力.(图3表2参41)

China is the world’s largest producer of edible mushrooms,resulting in a high output of spent mushroom substrates(SMS).The high lignocellulose content of SMS is a limiting factor restricting resource utilization.Screening of lignocellulose-degrading microorganisms can provide an effective way for efficient recycling of SMS.In this study,the isolation,identification,and degradation activities of high-temperature lignocellulosic-degrading microorganisms were studied using raw materials from the high-temperature stage(above 55℃)of SMS aerobic composting.The target strain,LC-10,was obtained via preliminary screening of aniline blue and Congo red plates,followed by further screening for liquid fermentation enzyme activity.Combined with morphological,molecular,physiological,and biochemical identification,LC-10 strain was identified as Streptomyces thermoviolaceus(GenBank accession number ON816008),which had high endo-1,4-β-D-glucanohydrolase,cellobiohydrolase,and xylanase activities.Strain LC-10 degraded straw and sawdust at rates of 70.77%±1.09% and 12.72%±1.72% after 20 d of shaking incubation at 50℃ and 130 r/min in straw and sawdust degradation media.Analysis of lignocellulose-degrading enzyme activity during degradation showed that filter paper,endo-1,4-β-D-glucanohydrolase,cellobiohydrolase,and β-D-glucosidase secreted by LC-10 strain were involved in degrading cellulose,manganese peroxidase and lignin peroxidase were involved in degrading lignin,and laccase was lacking in the fermentation broth.We found an actinomycete can degrade lignocellulose highly efficiently via secretion of a variety of extracellular degrading enzymes under hightemperature conditions.This strain shows potential for use in high-temperature composting of SMS.