Animal Waste Management and Environment Research Division, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), 2 Ikenodai, Tsukuba, Ibaraki, 305-0901, Japan.
Dairy Production Research Division, Hokkaido Agricultural Research Center, NARO, 1 Hitsujigaoka, Sapporo, Hokkaido, 062-8555, Japan.
Appl Microbiol Biotechnol. 2017 Sep;101(17):6779-6792. doi: 10.1007/s00253-017-8398-y. Epub 2017 Jul 7.
The potential denitrification activity and the composition of the denitrifying bacterial community in a full-scale rockwool biofilter used for treating livestock manure composting emissions were analyzed. Packing material sampled from the rockwool biofilter was anoxically batch-incubated with N-labeled nitrate in the presence of different electron donors (compost extract, ammonium, hydrogen sulfide, propionate, and acetate), and responses were compared with those of activated sludge from a livestock wastewater treatment facility. Overnight batch-incubation showed that potential denitrification activity for the rockwool samples was higher with added compost extract than with other potential electron donors. The number of 16S rRNA and nosZ genes in the rockwool samples were in the range of 1.64-3.27 × 10 and 0.28-2.27 × 10 copies/g dry, respectively. Denaturing gradient gel electrophoresis analysis targeting nirK, nirS, and nosZ genes indicated that the distribution of nir genes was spread in a vertical direction and the distribution of nosZ genes was spread horizontally within the biofilter. The corresponding denitrifying enzymes were mainly related to those from Phyllobacteriaceae, Bradyrhizobiaceae, and Alcaligenaceae bacteria and to environmental clones retrieved from agricultural soil, activated sludge, freshwater environments, and guts of earthworms or other invertebrates. A nosZ gene fragment having 99% nucleotide sequence identity with that of Oligotropha carboxidovorans was also detected. Some nirK fragments were related to NirK from micro-aerobic environments. Thus, denitrification in this full-scale rockwool biofilter might be achieved by a consortium of denitrifying bacteria adapted to the intensely aerated ecosystem and utilizing mainly organic matter supplied by the livestock manure composting waste-gas stream.
采用规模化岩棉生物滤池处理畜禽粪便堆肥排放物，分析了其潜在反硝化活性和反硝化细菌群落组成。在存在不同电子供体（堆肥浸提液、铵盐、硫化氢、丙酸盐和乙酸盐）的情况下，将取自岩棉生物滤池的填充材料进行无氧批量孵育，并与来自畜禽废水处理设施的活性污泥的响应进行了比较。过夜批量孵育表明，添加堆肥浸提液后，岩棉样品的潜在反硝化活性高于其他潜在电子供体。岩棉样品中的 16S rRNA 和 nosZ 基因数量分别在 1.64-3.27×10和 0.28-2.27×10拷贝/g 干重之间。针对 nirK、nirS 和 nosZ 基因的变性梯度凝胶电泳分析表明，nir 基因的分布在垂直方向上扩散，而 nosZ 基因的分布在生物滤器内水平方向上扩散。相应的反硝化酶主要与 Phyllobacteriaceae、Bradyrhizobiaceae 和 Alcaligenaceae 细菌以及从农业土壤、活性污泥、淡水环境和蚯蚓或其他无脊椎动物肠道中回收的环境克隆有关。还检测到一个与 Oligotropha carboxidovorans 的核苷酸序列具有 99%同一性的 nosZ 基因片段。一些 nirK 片段与微需氧环境中的 NirK 有关。因此，这种规模化岩棉生物滤池中的反硝化作用可能是由适应强烈充气生态系统的反硝化细菌联合体实现的，主要利用畜禽粪便堆肥废气流供应的有机物。
