复合菌系GF-20低温降解玉米秸秆过程中群落演替与理化特性

Microbial community succession and straw degradation characteristics at low temperature in the composite microbial system GF-20

摘要:

[背景] 秸秆的生物降解具有高效率和环保等特点而备受关注。[目的] 明确复合菌系GF-20秸秆降解过程中发挥重要作用的功能微生物类群及其与降解特性的关系。[方法] 将复合菌系GF-20在10℃条件下恒温培养，定期取样测定其生长特性及秸秆分解特性，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GF-20在接种后1 d内进入对数生长期，pH值迅速下降至6.98，总糖含量迅速降低至0.22 mg/mL；3 d后体系可溶性化学需氧量降低至4.77 g/L，氧化还原电位迅速降低至-303 mV，并高效分泌纤维素酶；培养15 d时玉米秸秆降解率为31.97%，木质素、纤维素和半纤维素降解率分别为32.30%、44.85%和43.84%。在玉米秸秆降解过程中，降解初期（2、5 d）的优势菌属为Cellvibrio （29.55%）、Chryseobacterium （7.35%）、Hydrogenophaga （3.86%）和Pseudomonas （3.42%）；降解中期（7、10 d）的优势菌属为Azospirillum （9.92%）、Rhizobium （6.99%）、Nubsella （5.06%）和Stenotrophomonas （3.37%）；降解后期（12、15 d）的优势菌属为Taibaiella （13.82%）、Pleomorphomonas （13.69%）、Flavobacterium （14.89%）、Cellulomonas （7.18%）、Devosia （7.36%）、Pedobacter （4.32%）和Sphingomonas （2.23%）。[结论] 明确了复合菌系GF-20在不同降解时期微生物群落结构演替规律以及秸秆降解特性动态变化，为复合菌系的合理化利用提供理论依据。

关键词:玉米秸秆;复合菌系;秸秆降解特性;微生物多样性

Abstract:

[Background] Straw biodegradation has been the focus of increasing amounts of attention because of its high degradation efficiency and environmental friendliness. [Objective] The key functional microbes in the process of straw degradation of composite microbial system GF-20 and their relationship with the characteristics of degradation were clarified. [Methods] GF-20 was cultured at 10℃, and the dynamics of growth and straw decomposition characteristics were determined, enabling the estimation of corn stalk decomposition by GF-20. Furthermore, the microbial community succession in different degradation periods was analyzed using MiSeq high-throughput sequencing technique. [Results] The composite microbial system GF-20 grew logarithmically, the pH value rapidly dropped to 6.98, and the total sugar content of the fermentation system quickly decreased to 0.22 mg/mL within 1 d after inoculation. The soluble chemical oxygen demand declined to 4.77 g/L after 3 d, and the oxidation-reduction potential rapidly reduced to -303 mV. The GF-20 efficiently secreted cellulose, and rate of degradation of corn stalk, lignin, cellulose and hemicellulose were 31.97%, 32.30%, 44.85% and 43.84%, respectively, after 15 days of fermentation at 10℃. The dominant genera included Cellvibrio (29.55%), Chryseobacterium (7.35%), Hydrogenophaga (3.86%) and Pseudomonas (3.42%) during the initial stage (2 d, 5 d) and the key functional microbes Azospirillum (9.92%), Rhizobium (6.99%), Nubsella (5.06%) and Stenotrophomonas (3.37%) during the mid-term stage (7 d, 10 d). The abundances of Taibaiella (13.82%), Pleomorphomonas (13.69%), Flavobacterium (14.89%), Cellulomonas (7.18%), Devosia (7.36%), Pedobacter (4.32%) and Sphingomonas (2.23%) increased significantly during the late stage (12 d, 15 d). [Conclusion] The dynamic changes in bacterial consortium structure and the characteristics of straw degradation during different periods of degradation were clarified and provide a theoretical basis for the rational utilization of composite microbial system GF-20.

Key words:corn stover;composite microbial system;straw degradation characteristics;microbial diversity