In this study,we investigated the potential nitrification and community structure of soil-based a mmonia-oxidizing bacteria(AOB)in apple orchard soil during different growth periods and explored the effects of environmental factors on nitrification activity and AOB community composition in the soil of a Hanfu apple orchard,using a culture-dependent technique and denaturing gradient gel electrophoresis(DGGE).We observed that nitrification activity and AOB abundance were the highest in November,lower in May,and the lowest in July.The results of statistical analysis indicated that total nitrogen(N)content,NH4+-N content,NO3--N content,and pH showed significant correlations with AOB abundance and nitrification activity in soil.The Shannon-Winner diversity,as well as species richness and evenness indices(determined by PCR-DGGE banding patterns)in soil samples were the highest in September,but the lowest in July,when compared to additional sampled dates.The DGGE fingerprints of soil-based 16S rRNA genes in November were apparently distinct from those observed in May,July,and September,possessing the lowest species richness indices and the highest dominance indices among all four growth periods.Fourteen DGGE bands were excised for sequencing.The resulting analysis indicated that all AOB communities belonged to theβ-Proteobacteria phylum,with the dominant AOB showing high similarity to the Nitrosospira genus.Therefore,soil-based environmental factors,such as pH variation and content of NH4+-N and NO3--N,can substantially infl uence the abundance of AOB communities in soil,and play a critical role in soil-based nitrification kinetics.
LIU Ling-zhiQIN Si-junLü De-guoWANG Bing-yingYANG Ze-yuan
氨氧化细菌是参与土壤氮素循环的重要微生物类群之一,其基因组DNA提取质量的准确分析,可直接影响后续分子实验的可行性和精确性。本试验针对3株异养氨氧化细菌的纯培养菌株,应用琼脂糖凝胶电泳、微量紫外分光光度计和Qubit荧光计分别检测不同提取方法获得的基因组DNA的浓度,同时结合细菌通用引物扩增16S r DNA全长来判定提取DNA的质量,进而筛选出可用于检测可培养氨氧化细菌基因组DNA浓度的方法。研究结果表明,针对不同浓度的DNA样品,尽管3种检测方法获得的结果表现出明显差异,但在16S r DNA-PCR中均仍能获得良好的扩增结果。与微量紫外分光光度法相比,Qubit方法对基因组DNA浓度的检测结果更为精确,特别在低浓度DNA检测中,能够较真实的反映基因组DNA的实际情况。
