宏基因组学解析蚯蚓粪中微生物种群及耐药基因的组成

为判定蚯蚓粪作为微生物肥料的潜力，本研究采用宏基因组学的方法，对污泥、牛粪与蔬菜蚯蚓粪样品抽提的DNA进行测序，并将结果进行物种注释及功能注释，以揭示不同蚯蚓粪中功能性微生物的种群结构.结果表明：污泥、牛粪和蔬菜蚯蚓粪分别检测到117505、81182、81104条scaftigs.变形菌门、拟杆菌门、疣微菌门与放线菌门为3种蚯蚓粪的优势菌门.氮磷代谢途径分析表明，蚯蚓粪中富含固氮菌（Rhizobium、Mesorhizobium、Bradyrhizobium、Azospirillum）、硝化菌（Nitrosomonas、Nitrosospira、Nitrosococcus、Nitrospira）和溶磷菌（Flavobacterium、Pseudomonas、Arthrobacter、Streptomyces）等肥料功能菌.相比而言，蔬菜蚯蚓粪微生物肥料潜力较高.相对于蔬菜蚯蚓粪（371条Unigenes），污泥（2461条Unigenes）和牛粪（965条Unigenes）蚯蚓粪中存在较多的病原菌.而且，污泥、牛粪与蔬菜蚯蚓粪中耐药基因相对丰度高达0.93×10^-3、0.32×10^-3和0.32×10^-3，主要为β-内酰胺类、氨基糖苷类、大环内酯类及四环素类耐药基因等.研究结果显示，蚯蚓粪中有益的功能菌群和有害微生物同时存在，其生物污染物的环境风险值得关注.

Composition of microbial community and antibiotic resistance genes in vermicomposts revealed by metagenomic analysis

This study aimed to explore the potential of vermicomposts used as microbial fertilizer by analyzing their microbial communities using metagenomics. For this, the metagenomic sequences of 16S rDNA from three common vermicomposts of dewatered sludge, cow dung, and vegetable waste were annotated to distinguish bacterial species and function. The scaftigs of 117505, 81182, and 81104 were obtained in the vermicomposts of sludge, cow dung and vegetable waste, respectively. The dominant bacterial phyla in three vermicomposts were Proteobacteria, Bacteroidetes, Verruca, and Actinobacteria. The analysis of the metabolism pathway for nitrogen and phosphorus showed that Rhizobium, Mesorhizobium, Bradyrizobium, and Azospirillum were dominated as nitrogen fixing bacteria and Nitrosomonas, Nitrosospira, Nitrosoccus, and Nitrospira were predominated as nitrifying bacteria in the vermicomposts. Moreover, phosphate solubilizing bacteria were dominated by Flavobacterium, Pseudomonas, Arthrobacter, and Streptomyces. In contrast, the vermicompost of vegetable waste exhibited a higher potential as a microbial fertilizer. Compared with vegetable waste vermicompost (371Unigenes), the greater numbers of human pathogenic bacteria were detected in vermicomposts of sludge (2461Unigenes) and cow dung (965Unigenes). In addition, the relative abundances of antibiotic resistance genes from sludge, cow dung, and vegetable wastes were 0.93×10^-3, 0.32×10^-3, and 0.32×10^-3, respectively, with the main types of antibiotic resistance belonging to β-lactams, aminoglycosides, macrolides, and tetracyclines. This study suggests that a great number of beneficial and harmful microorganisms are simultaneously inhabited in the vermicomposts, and thus the environmental risks of their biological pollutants deserve attention.