菌团HBB降解竹纤维素纤维及微生物群落功能分析

Microbial consortium HBB for bamboo cellulose fiber degradation and analysis of microbial community and function

摘要:

采用“纯系短短芽孢杆菌（BB）”、“竹浆携带微生物区系（HM）”“BB HM（HBB）”三种微生物策略降解竹纤维素纤维（BCF），通过摇瓶发酵实验探究不同微生物策略的产酶和降解功能。借助铜乙二铵黏度法、XRD、FTIR表征手段和16S rRNA高通量测序技术分析最佳功能组底物结构和各时期细菌群落组成。结果表明：三种微生物策略下，BCF均受到不同程度的分解，发酵结束时干物质损失率分别为41.92%、60.74%、77.65%。相比BB和HM，HBB体系表现出主解期最高的CMCase酶活力和漆酶活力，以及丰富的木聚糖酶活力。BCF尺寸迅速减小、碳水化合物和木质素联接键（LCC）的破坏及去除，结晶区缺陷等结构特征的早期获得有助于酶水解作用的有效发挥，是BCF实现有效和加速降解的重要原因。HBB菌群微生物涵盖了18门，26纲，64目，97科，170属，优势菌门为厚壁菌门（Firmicutes）和变形菌门（Proteobacteria），以及一定数量的拟杆菌门（Bacteroidota）、放线菌门（Actinobacteriota）、疣微菌门（Verrucomicrobiota）。在属水平上（相对丰度＞1%），主解期和降解后期菌属类型和丰度差异较大。德沃斯氏菌属（Devosia）、苍白杆菌属（Ochrobactrum）、Taibaiella、短波单孢菌属（Brevundimonas）在主解期相对丰度较高，而假黄单孢菌属（Pseudoxanthomona）、科恩氏菌属（Cohnella）、未分类黄杆菌目（unclassified_o_Flavobacteriales）在降解后期相对丰度较高。门水平和属水平的主坐标PCoA分析和Anosim分析表明降解的两个典型时期样本中HBB群落结构有差异，但无统计学意义。研究表明，与仅在BB或HM作用下相比，菌团HBB能加速BCF的降解，获得相对高的干物质损失率；且在降解过程中表现出一定的稳定性和可靠性；短芽孢杆菌属（Brevibacillus）、Devosia、Ochrobactrum、Taibaiella、Pseudoxanthomona、固氮螺菌属（Azospirillum）、纤维单孢菌属（Cellulomonas）是BCF高效降解的主要功能菌属。

Abstract:

Bamboo cellulose fiber (BCF) were degraded by three microbial strategies, pure Brevibacillus brevi (BB), microflora carried by BCF (HM) and a combination of BB and HM (HBB). The enzyme production and degradation functions of different strategies were investigated by shaking flask fementations. The BCF’s structure and microbial community composition of optimal treatment group at different stages during degradation were analyzed, which were assisted by the viscosity method in cupri-ethylene-diamine, XRD, FTIR and 16S rRNA high-throughput sequencing technologies. The results indicated that under the three microbial strategies, BCF showed a certain degradation effects, which dry matter loss rate were 41.92%, 60.74% and 77.65%, respectively, when the fermentation was finished. Compared with BB and HM groups, HBB systerm showed the main degrading period’s highest CMCase and laccase activity, as well as abundant xylanase activity. Early acquisition of structural characteristics, such as the substrate’s size reduced sharply, carbohydrate-lignin linkages destroyed and removed, as well as the defect in crystallization zone, was of benefit to the availability of enzymatic hydrolysis, which was an important reason for BCF’s degradation effectively and speedily. Bacterial species of HBB covered 18 phyla, 26 classes,64 orders, 97 families, 170 genera. Firmicutes, Proteobacteria, as well as Bacteroidota, Actinobacteriota,Verrucomicrobiota were the dominant phyla in HBB. There were significant differences between the main and late degrading periods in microbial species and relative abundance at genus level. Devosia, Ochrobactrum, Taibaiella, Brevundimonas had a relatively high relative abundance in the main degrading period than that of in the late stage, while Pseudoxanthomona, Cohnella, unclassified_o_Flavobacteriales were relatively abundant in the late degrading stage. PCoA and ANOSIM analysis at phylum and genera levels indicated that there were differences in community structure of HBB samples obtained from the two typical degrading periods, but no statistical signigicance. The results showed that HBB could accelerate the degradation of BCF and obtain a relatively high dry matter loss rate compared with BB or HM alone. HBB showed a certain stability and reliability during degrading. Brevibacillus、Devosia, Ochrobactrum, Taibaiella, Pseudoxanthomona, Azospirillum, Cellulomonas were the main functional species of HBB for BCF degradation in efficiency.