复合菌系降解玉米秸秆过程中群落演替与秸秆降解的关系

Microbial community succession associated with corn straw degradation in a bacterium consortium

摘要:

[目的] 为了获得木质素降解复合菌系LDC降解玉米秸秆的适宜条件，明确秸秆降解过程中可能发挥重要作用的功能微生物类群。[方法] 以培养温度、pH、培养基装液量和接菌量等单因素试验结果为依据，采用响应面法优化复合菌系降解玉米秸秆的培养条件，利用Miseq高通量测序技术，分析不同降解时期复合菌系的群落结构变化规律。[结果] 复合菌系对秸秆最佳降解条件为：培养温度32℃、初始pH为8.2、装液量为40%，接菌量为10%。此条件下木质素最大降解率为44.5%，相比未优化处理提高13.3%。在门水平上，变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）和厚壁菌门（Firmicutes）是复合菌系LDC的优势菌门。在玉米秸秆降解过程中，降解初期的优势菌属为Proteiniphilum（11.9%）、Sphaerochaeta（8.4%）、Ruminofilibacter（8.4%）、Pannonibacter（6.7%）、Pseudomonas（6.1%）和Rhizobium（5.7%）；在降解高峰期时，Anaerocolumna（24.0%）、Caenispirillum（9.2%）和Thauera（7.0%）的丰度显著上升，分别是其在降解初期的16.5倍、3.0倍和5.9倍，而Ruminofilibacter（10.9%）的丰度仍然很高且排在第二位。在降解末期的优势菌属为Ruminofilibacter（25.4%）、Pseudomonas（9.7%）、Sphaerochaeta（8.8%）、Caenispirillum（8.4%）、Pannonibacter（4.3%）、Thauera（4.0%）以及Desulfomicrobium（3.4%）。[结论] 明确了玉米秸秆降解复合菌系的最佳培养条件以及在不同降解时期微生物群落结构变化规律，在玉米秸秆降解过程中发挥重要作用的微生物类群为Pseudomonas、Pannonibacter、Thauera、Ruminofilibacter和Anaerocolumna。

Abstract:

[Objective] The aim was to attain the optimal conditions for the degradation of corn straw by microbial lignin-degradation consortium and define the functional microbes that are important for the degradation of corn straw. [Methods] Based on the results of single factor experiments, such as culture temperature, pH, media loading quantity and inoculation concentration, the response surface method was adopted to optimize the culture conditions for the degradation of corn straw by the consortium. The changes of community structure in different stages of degradation were analyzed by high-throughput sequencing of bacterial 16S rRNA amplicons. [Results] The optimum degradation conditions were as follows:fermentation temperature 32℃, pH 8.2, loading volume 40%, inocula concentration 10%, under which the degradation rate of lignin was up to 44.5%. Compared with the non-optimized treatment, the increased rate of lignin degradation was 13.3%. At the phylum level, Proteobacteria, Bacteroidetes and Firmicutes were dominant. The dominant genera included Proteiniphilum (11.9%), Sphaerochaeta (8.4%), Ruminofilibacter (8.4%), Pannonibacter (6.7%), Pseudomonas (6.1%) and Rhizobium (5.7%) in initial stage. In the peak stage of lignin degradation, the abundance of Anaerocolumna (24.0%), Caenispirillum (9.2%) and Thauera (7.0%) increased significantly, it was 16.5, 3.0 and 5.9 times higher than that at the initial stage of degradation. Meanwhile, the abundance of Ruminofilibacter (10.9%) was still very high and ranks second. The mainly dominant genera at the end of degradation were Ruminofilibacter (25.4%), Pseudomonas (9.7%), Sphaerochaeta (8.8%), Caenispirillum (8.4%), Pannonibacte (4.3%), Thauera (4.0%) and Desulfomicrobium (3.4%). [Conclusion] The optimal conditions of corn straw degradation and the dynamic changes of bacterial consortium structure were clarified. Pseudomonas, Pannonibacter, Thauera, Ruminofilibacter and Anaerocolumna were main bacteria that have played an important role in the process of corn straw degradation.