甲酸和木醋液对苜蓿青贮细菌群落结构的影响

Effects of Formic Acid and Wood Vinegar on Bacterial Community Composition of Alfalfa Silage

为探讨抑制型青贮添加剂对苜蓿青贮细菌群落结构的影响,以木醋液和甲酸为添加剂,按6 mL/kg的剂量与干物质含量为(23.02±0.70)%的苜蓿混匀制作青贮,以等量蒸馏水替换添加剂的处理作为对照,45天后运用高通量测序技术分析苜蓿青贮的细菌群落结构。结果表明,对照组以变形菌门(Proteobacteria)肠杆菌科(Enterobacteriaceae)未知属为优势,以厚壁菌门(Firmicutes)肠球菌属(Enterococcus)为次优势;木醋液组则以厚壁菌门肠球菌属为优势,以变形菌门肠杆菌科未知属为次优势;甲酸组以蓝藻细菌门链型植物目(Streptophyta)未知科属为优势。与对照组相比,苜蓿青贮中肠球菌属丰度在木醋液组显著提高而在甲酸组显著降低,木醋液和甲酸组均显著降低了肠杆菌科丰度且甲酸组降幅显著高于木醋液组;甲酸组显著提高了细菌群落丰富度指数(Chao1和ACE)但降低了优势度指数(Simpson)。主成分分析表明,苜蓿青贮细菌群落结构与其营养和发酵主要指标可解释苜蓿青贮88.786%的信息,在样品分布上,木醋液组居甲酸组和对照组之间但更趋向于对照组。综上,甲酸和木醋液均改善了苜蓿青贮细菌群落结构,其中甲酸主要是抑制菌群发酵,而木醋液则有助于促进乳酸菌发酵。

To investigate the effects of inhibitory silage additives on bacterial community composition of alfalfa silage,the experiment was conducted with formic acid and wood vinegar as the additives,alfalfa silage was made by mixing alfalfa with dry matter content of(23.02±0.70)%with the additive of 6 mL/kg,the treatment with equivalent distilled water replacing additive was used as the control,and the bacterial community was analyzed through High-throughput sequencing method after 45 days.The results showed that in the control group,the Enterobacteriaceae unknown genus of Proteobacteria was dominant,followed by Enterococcus of Firmicutes;in the wood vinegar treatment,the Enterococcus of Firmicutes was dominant,followed by Enterobacteriaceae unknown genus of Proteobacteria;while in the formic acid treatment,the dominant bacteria community was unknown family and genus of Streptophyta in Cyanobacteria.Compared with the control,the relative abundance of Enterococcus was increased significantly in the wood vinegar treatment,but decreased significantly in the formic acid treatment;both of the two additives significantly reduced the relative abundance of Enterobacteriaceae,and the decrease of formic acid treatment was significantly higher than that of wood vinegar treatment;the formic acid treatment significantly increased the abundance indices(Chao1 and ACE)of bacterial community but decreased the dominance index(Simpson).According to the principal component analysis,the indices of bacteria community and main nutrition and fermentation quality could explain 88.786%information of alfalfa silage.From the distribution of samples,the distribution of wood vinegar treatment was between the formic acid treatment and the control but closer to the control.In conclusion,according to the bacterial community analysis,both the formic acid and wood vinegar could improve the bacterial community composition of alfalfa silage,in which formic acid could mainly inhibite bacterial fermentation but wood vinegar is helpful to promote lactic acid bacteria fermentation.