16S rRNA gene amplicons derived from six helminth species collected from four gut sections of 32 wild Apodemus flavicollis. Microbiota of parasitic helminths and the wild rodent gut niche

The symbiotic relationship between bacteria and multicellular organisms is such that the collective of bacteria in the gut (microbiota) has been described as the second genome, or undiscovered organ, owing to the large collective of genes, and their associated impact on host health. All multicellular organisms are expected to play host to a microbiota, including parasitic helminths, another key component of the gut biome. We describe, for the first time, the diversity and taxonomic composition of microbiota associated with the parasitic helminth community (six species and 2,045 helminths) of 32 naturally infected wild rodents (Apodemus flavicollis), and compare this microbiota with that of the corresponding gut niche in which the helminths co-occurred using 16S rRNA sequencing. Bacterial diversity of each helminth species was lower than that of the respective gut section that it parasitised. The composition of helminth-associated microbiota was significantly different from that of the host gut (distance-based redundancy analyses), with helminths being dominated by the phyla Firmicutes (mean per pool: 27.48%), Proteobacteria (34.07%), Tenericutes (25.78%) and/or Deferribacteres (5.44%, 0 - 80.29%), while the host was dominated by Firmicutes (55.02%), Bacteroidetes (24.75%) and Proteobacteria (15.66%). Helminth microbiota contained more potentially pathogenic bacteria than their corresponding host gut niche. This study provides the first in depth analysis of bacteria associated with parasitic helminths from naturally infected wild rodent hosts. Since microbiota could impact helminth survival, the results discussed here provide insight into possible parasite control.

细菌与多细胞生物间的共生关系使得肠道内的细菌群落——肠道菌群（microbiota）——被称为第二基因组或未被发现的器官，这源于其庞大的基因总量及其对宿主健康的显著关联影响。所有多细胞生物的体内均会定植肠道菌群（microbiota），而寄生蠕虫亦是肠道生物群系的另一关键组成部分。本研究首次针对32只自然感染的野生黄颈姬鼠（Apodemus flavicollis）体内寄生蠕虫群落（含6个物种、2045条蠕虫）的关联菌群多样性与分类学组成进行分析，并通过16S rRNA测序技术，将该菌群与蠕虫共存的对应肠道微生境菌群进行对比。结果显示，各寄生蠕虫物种的细菌多样性均低于其所寄生的对应肠道区段。基于距离的冗余分析（distance-based redundancy analyses）表明，寄生蠕虫关联菌群的组成与宿主肠道菌群存在显著差异：蠕虫菌群以厚壁菌门（Firmicutes，每混合样本平均占比27.48%）、变形菌门（Proteobacteria，34.07%）、软壁菌门（Tenericutes，25.78%）和/或脱铁杆菌门（Deferribacteres，5.44%，区间0~80.29%）为优势类群，而宿主肠道菌群则以厚壁菌门（55.02%）、拟杆菌门（Bacteroidetes，24.75%）和变形菌门（15.66%）为优势类群。寄生蠕虫菌群中潜在致病菌的占比高于其对应的宿主肠道微生境。本研究首次对自然感染野生啮齿类宿主的寄生蠕虫关联细菌进行了深度分析。鉴于菌群可影响寄生蠕虫的存活，本研究结果可为潜在的寄生虫防控策略提供理论参考。