Meneghine Aylan K, Nielsen Shaun, Varani Alessandro M, Thomas Torsten, Carareto Alves Lucia Maria
Department of Technology, São Paulo State University (Unesp), School of Agricultural and Veterinarian Sciences, Jaboticabal, São Paulo State, Brazil.
Centre for Marine Bio-Innovation, University of New South Wales, Sydney, New South Wales, Australia.
PLoS One. 2017 Dec 21;12(12):e0190178. doi: 10.1371/journal.pone.0190178. eCollection 2017.
Microbial communities drive biogeochemical cycles in agricultural areas by decomposing organic materials and converting essential nutrients. Organic amendments improve soil quality by increasing the load of essential nutrients and enhancing the productivity. Additionally, fresh water used for irrigation can affect soil quality of agricultural soils, mainly due to the presence of microbial contaminants and pathogens. In this study, we investigated how microbial communities in irrigation water might contribute to the microbial diversity and function of soil. Whole-metagenomic sequencing approaches were used to investigate the taxonomic and the functional profiles of microbial communities present in fresh water used for irrigation, and in soil from a vegetable crop, which received fertilization with organic compost made from animal carcasses. The taxonomic analysis revealed that the most abundant genera were Polynucleobacter (8% relative abundance) and Bacillus (10%) in fresh water and soil from the vegetable crop, respectively. Low abundance (0.38%) of cyanobacterial groups were identified. Based on functional gene prediction, denitrification appears to be an important process in the soil community analysed here. Conversely, genes for nitrogen fixation were abundant in freshwater, indicating that the N-fixation plays a crucial role in this particular ecosystem. Moreover, pathogenicity islands, antibiotic resistance and potential virulence related genes were identified in both samples, but no toxigenic genes were detected. This study provides a better understanding of the community structure of an area under strong agricultural activity with regular irrigation and fertilization with an organic compost made from animal carcasses. Additionally, the use of a metagenomic approach to investigate fresh water quality proved to be a relevant method to evaluate its use in an agricultural ecosystem.
微生物群落通过分解有机物质和转化必需养分来驱动农业地区的生物地球化学循环。有机改良剂通过增加必需养分的含量和提高生产力来改善土壤质量。此外，用于灌溉的淡水会影响农业土壤的质量，主要是由于存在微生物污染物和病原体。在本研究中，我们调查了灌溉水中的微生物群落如何影响土壤的微生物多样性和功能。采用全宏基因组测序方法，研究了用于灌溉的淡水以及施用动物尸体制成的有机堆肥的蔬菜作物土壤中微生物群落的分类学和功能特征。分类学分析表明，蔬菜作物的淡水和土壤中最丰富的属分别是多核杆菌（相对丰度约8%）和芽孢杆菌（相对丰度约10%）。鉴定出蓝藻菌群的丰度较低（0.38%）。基于功能基因预测，反硝化作用似乎是此处分析的土壤群落中的一个重要过程。相反，淡水样本中固氮基因丰富，表明固氮作用在这个特定的生态系统中起着关键作用。此外，在两个样本中均鉴定出致病岛、抗生素抗性和潜在毒力相关基因，但未检测到产毒基因。本研究有助于更好地了解一个农业活动频繁、定期灌溉且施用动物尸体制成的有机堆肥的地区的群落结构。此外，利用宏基因组方法研究淡水质量被证明是评估其在农业生态系统中应用的一种有效方法。
