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

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.