Bacillus amyloliquefaciens (BA) and Bacillus subtilis (BS) are usually used as feed supplements directly or bacterial inoculants in biological feeds for animals. However, few research have reported the effects of BA and BS on fermentation characteristics and bacterial community successions of whole-plant corn silage during ensiling. If the BA and BS inoculants have positive effects on silages, then they could not only improve fermentation characteristics, but also deliver BA or BS viable cells to ruminants, which would play its probiotic effect. Therefore, the objectives of this study were to investigate the effects of BA and BS on the fermentation, chemical characteristics, bacterial community and their metabolic pathway of whole-plant corn silage. Freshly chopped whole-plant corn was inoculated without or with BA and BS, respectively, and ensiled for 1, 3, 7, 14 and 60 d. Results showed that BA and BS inoculations increased lactic acid concentrations of whole-plant corn silages compared with control, and BA inoculation decreased acetic acid concentrations, whereas BS inoculation decreased fiber contents and increased crude protein (CP) content. Higher water-soluble carbohydrate contents and lower starch contents were observed in BA- and BS-inoculated silages compared with that in control. The decreased CP content and increased non-protein nitrogen content were observed in BA-inoculated silage, which was consistent with the higher amino acid metabolism abundances observed in BA-inoculated silage. In addition, it was noteworthy that BA and BS inoculations increased the metabolism of cofactors and vitamins, and decreased the relative abundances of drug resistance: antimicrobial pathways. We also found that the bacterial metabolism pathways were clearly separated into three clusters based on the ensiling times of whole-plant corn silage in the present study. There were no significant differences in bacterial community compositions among the three groups during ensiling. However, BA and BS inoculations decreased the relative abundances of undesirable bacteria such as Acetobacter and Acinetobacter. Our findings suggested that the BS strain was more suitable as silage inoculants than the BA strain in whole-plant corn silage in this study.

中文翻译：

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解淀粉芽孢杆菌和枯草芽孢杆菌对全株玉米青贮饲料发酵、菌群动态及其功能转变的影响

解淀粉芽孢杆菌 (BA) 和枯草芽孢杆菌 (BS) 通常直接用作饲料补充剂或动物生物饲料中的细菌接种剂。然而，很少有研究报道BA和BS对青贮期间全株玉米青贮饲料发酵特性和细菌群落演替的影响。如果 BA 和 BS 接种剂对青贮饲料有积极作用，那么它们不仅可以改善发酵特性，还可以将 BA 或 BS 活细胞传递给反刍动物，从而发挥其益生菌作用。因此，本研究的目的是研究BA和BS对全株玉米青贮饲料的发酵、化学特性、细菌群落及其代谢途径的影响。将新鲜切碎的整株玉米分别接种不含或含 BA 和 BS，青贮 1、3、7、14 和 60 天。结果表明，与对照相比，BA 和 BS 接种增加了全株玉米青贮饲料的乳酸浓度，BA 接种降低了乙酸浓度，而 BS 接种降低了纤维含量，增加了粗蛋白（CP）含量。与对照相比，在接种 BA 和 BS 的青贮饲料中观察到较高的水溶性碳水化合物含量和较低的淀粉含量。在 BA 接种青贮饲料中观察到 CP 含量降低和非蛋白质氮含量增加，这与在 BA 接种青贮饲料中观察到的较高氨基酸代谢丰度一致。此外，值得注意的是，BA和BS接种增加了辅因子和维生素的代谢，降低了耐药性的相对丰度：抗菌途径。我们还发现，在本研究中，根据全株玉米青贮饲料的青贮时间，细菌代谢途径明显分为三个簇。青贮期间三组细菌群落组成无显着差异。然而，BA 和 BS 接种降低了不良细菌如醋杆菌和不动杆菌的相对丰度。我们的研究结果表明，在本研究中，在全株玉米青贮饲料中，BS 菌株比 BA 菌株更适合作为青贮饲料接种剂。青贮期间三组细菌群落组成无显着差异。然而，BA 和 BS 接种降低了不良细菌如醋杆菌和不动杆菌的相对丰度。我们的研究结果表明，在本研究中，在全株玉米青贮饲料中，BS 菌株比 BA 菌株更适合作为青贮饲料接种剂。青贮期间三组细菌群落组成无显着差异。然而，BA 和 BS 接种降低了不良细菌如醋杆菌和不动杆菌的相对丰度。我们的研究结果表明，在本研究中，在全株玉米青贮饲料中，BS 菌株比 BA 菌株更适合作为青贮饲料接种剂。