蚯蚓摄食污泥对其肠道功能区微生物种群及耐药基因的影响

以赤子爱胜蚓(Eisenia fetida)为实验蚓种, 研究蚯蚓消化污泥前后, 其肠道各功能区微生物种群结构及耐药基因(ARGs)丰度的变化情况.为表征活体功能性微生物, 所取新鲜样品均采用叠氮溴化丙锭(PMA)预处理后, 再进行DNA相关分析.结果表明: 蚯蚓消化污泥5d后, 细菌16S rDNA和真核生物18S rDNA的丰度在其胃中分别显著增加了28.2倍和42.2倍(P<0.05), 而在砂囊和后肠中均显著性降低(P<0.05).此外, 蚯蚓消化污泥使其砂囊中的优势菌门由变形菌门变为软壁菌门, 胃中的优势菌门由拟杆菌门变为厚壁菌门, 而对后肠微生物种群结构的影响较小.对于ARGs而言, 大环内酯类耐药基因ermF、四环素类耐药基因tetX和磺胺类耐药基因sul2在蚯蚓胃中的丰度分别显著升高了1.9×10²倍、8.4×10⁵倍和25.9倍(P<0.05), 而在其砂囊和后肠中ARGs总丰度分别显著下降了11.0倍和45.2倍(P<0.05).基于网络分析结果显示, 蚯蚓摄食污泥可影响其肠道内ARGs宿主细菌的结构多样性.

Effects of excess sludge fed by earthworms on microbial community and antibiotic resistance genes in their intestinal functional area

This study aimed to investigate the changes of microbial community structure and their antibiotics resistance genes (ARGs) abundances in the intestinal tract of Eisenia fetida, via detecting the sludge passing through different functional areas in earthworms' gut. Prior to the DNA extraction, all fresh samples were pretreated with propidium monoazide (PMA) to characterize active functional microorganisms. The results showed that the abundances of bacterial 16S rDNA and eukaryotic 18S rDNA significantly increased (P<0.05) by 28.2 and 42.2 times in stomach, and they significantly decreased (P<0.05) in the gizzard and hindgut, after 5 days of earthworm digestion. In addition, the sludge digested by earthworms changed dominant proteobacteria to tenericutes in gizzard, and modified dominant bacteroidetes to firmicutes in stomach. However, the digestion process of earthworms had little effect on bacterial community structure in hindgut. For the ARGs, the abundances of ermF, tetX and sul2 significantly increased (P<0.05) by 1.9×10², 8.4×10⁵ and 25.9 times in stomach of earthworm, respectively. While the total abundances of ARGs in gizzard and hindgut significantly decreased (P<0.05) by 11.0 and 45.2 times, respectively. Moreover, network analysis revealed that the feeding behavior of earthworms for sludge could indicate effects on the structural diversity of host bacteria of ARGs in their intestine.