Institute for Genome Research and Systems Biology, Center for Biotechnology, Bielefeld University, D-33594 Bielefeld, Germany.
J Biotechnol. 2013 Sep 10;167(3):334-43. doi: 10.1016/j.jbiotec.2013.07.021. Epub 2013 Jul 20.
Silage is green fodder conserved by lactic acid fermentation performed by epiphytic lactic acid bacteria under anaerobic conditions. To improve the ensiling process and the quality of the resulting silage, starter cultures are added to the fresh forage. A detailed analysis of the microbial community playing a role in grass ensiling has been carried out by high throughput sequencing technologies. Moreover, the influence of the inoculant Lactobacillus buchneri CD034 on the microbial community composition was studied. For this purpose, grass was ensiled untreated or inoculated with L. buchneri CD034. The fresh forage as well as silages after 14 and 58 days of fermentation were characterized physico-chemically. Characteristic silage conditions such as increased titers of lactic acid bacteria and higher concentrations of acetic acid were observed in the inoculated silage in comparison to the untreated samples. Taxonomic community profiles deduced from 16S rDNA amplicon sequences indicated that the relative abundance of Lactococci diminished in the course of fermentations and that the proportion of bacteria belonging to the phyla Proteobacteria and Bacteroidetes increased during the fermentation of untreated silage. In the inoculated silage, members of these phyla were repressed due to an increased abundance of Lactobacilli. In addition, metagenome analyses of silage samples confirmed taxonomic profiles based on 16S rDNA amplicons. Moreover, Lactobacillus plantarum, Lactobacillus brevis and Lactococcus lactis were found to be dominant species within silages as analyzed by means of fragment recruitments of metagenomic sequence reads on complete reference genome sequences. Fragment recruitments also provided clear evidence for the competitiveness of the inoculant strain L. buchneri CD034 during the fermentation of the inoculated silage. The inoculation strain was able to outcompete other community members and also affected physico-chemical characteristics of the silage.
青贮是一种通过在厌氧条件下由附生乳酸菌进行乳酸发酵来保存的绿色饲料。为了改善青贮过程和青贮饲料的质量，向新鲜饲料中添加了发酵剂。通过高通量测序技术对在草青贮过程中起作用的微生物群落进行了详细分析。此外，研究了接种菌 Lactobacillus buchneri CD034 对微生物群落组成的影响。为此，将草未经处理或接种 L. buchneri CD034 进行青贮。对新鲜饲料以及发酵 14 和 58 天后的青贮饲料进行了理化特性分析。与未处理的样品相比，接种青贮饲料中观察到特征性青贮条件，如乳酸菌滴度增加和乙酸浓度升高。从 16S rDNA 扩增子序列推断出的分类社区概况表明，在发酵过程中乳球菌的相对丰度减少，而在未处理青贮饲料的发酵过程中属于变形菌门和拟杆菌门的细菌比例增加。在接种的青贮饲料中，由于乳杆菌丰度增加，这些门的细菌受到抑制。此外，基于 16S rDNA 扩增子的分类群分析通过对宏基因组序列进行片段招募来对青贮样品进行了元基因组分析。此外，通过对完整参考基因组序列的元基因组序列读数进行片段招募分析，发现植物乳杆菌、短乳杆菌和乳球菌 lactis 是青贮饲料中的优势种。片段招募还为接种菌株 L. buchneri CD034 在接种青贮饲料发酵过程中的竞争力提供了明确证据。接种菌株能够与其他群落成员竞争，并影响青贮饲料的理化特性。
