瘤胃微生物强化醋糟厌氧消化及其机制

Bio-Augmented Anaerobic Digestion of Vinegar Residue by Rumen Microbes and Its Mechanisms

针对醋糟中木质纤维素利用效率低的问题,通过接种瘤胃微生物可强化木质纤维素水解.采用逐步提升体系有机负荷的方式,考察瘤胃微生物生物强化对醋糟厌氧消化性能的提升效果,并运用绝对定量实时聚合酶链锁反应(Q-PCR)技术探究其微生物学强化机制.结果表明:长期连续运行成功塑造了高效的木质纤维素瘤胃强化体系.该体系的最高有机负荷达8.90 g/(L·d)(以VS计),是强化前的1.53倍,该有机负荷下半纤维素和纤维素降解率分别达73.9%和40.1%,单位质量底物沼气和甲烷产量相应地分别达到451和261 mL/g(以VS计),半纤维素和纤维素较高的降解率是该体系维持高产气性能的主要原因.生物相机制研究表明,瘤胃微生物强化体系中与木质纤维素水解密切相关的GH5(糖苷水解酶家族5)水解菌逐步富集,其基因拷贝数从初始的964×10^10 copies/g升至最高有机负荷下的6.83×10^11copies/g,这是底物在高有机负荷下仍能被高效生物转化的根本原因.研究显示,瘤胃微生物的介入可有效强化体系底物的降解能力,促进醋糟产甲烷性能的提升.

In order to overcome the low bioavailability of lignocellulose in the vinegar residue,hydrolysis of lignocellulose was bio-augmented by inoculating rumen microbes.By gradually increasing organic loading rates,the bio-augmentation effect on the promotion of anaerobic digestibility was investigated and its underlying microbiological mechanism was also elucidated by absolute Q-PCR(Quantitative Real-time Polymerase Chain Reaction).The results showed that a rumen bio-augmented system with highly efficient lignocellulose degradation was successfully established by the long-term continuous operation.The highest organic loading rates reached 8.90 g/(L·d)(calculated in VS),which was 1.53 times that of the one without bio-augmentation.Under this OLR,the degradation efficiencies of hemicellulose and hemicellulose reached 73.9%and 40.1%.And the corresponding biogas and methane production per unit substrate reached 451 and 261 mL/g(calculated in VS).High hemicellulose and cellulose degradation efficiencies were the main reasons for the high biogas production in the bio-augmented system.Moreover,studies on its biological mechanisms indicated that the GH5(glycoside hydrolase family 5)hydrolyzing bacteria,which had close relation with lignocellulose hydrolysis,were enriched gradually in the bio-augmented system.The number of GH5 gene increased from 9.64×10^10 copies/g(initial time)to 6.83×10^11copies/g(the highest organic loading rates),which was the basic reason for the efficient degradation of substrate under high organic loading rates.Thus,this study proved rumen microbes as inoculum could effectively enhance the degradation efficiency,therefore improving the methane production performance of the substrate.