College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA, United States of America.
Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America.
PLoS One. 2020 Nov 13;15(11):e0242108. doi: 10.1371/journal.pone.0242108. eCollection 2020.
The concept of successional trajectories describes how small differences in initial community composition can magnify through time and lead to significant differences in mature communities. For many animals, the types and sources of early-life exposures to microbes have been shown to have significant and long-lasting effects on the community structure and/or function of the microbiome. In modern commercial poultry production, chicks are reared as a single age cohort and do not directly encounter adult birds. This scenario is likely to initiate a trajectory of microbial community development that is significantly different than non-industrial settings where chicks are exposed to a much broader range of environmental and fecal inocula; however, the comparative effects of these two scenarios on microbiome development and function remain largely unknown. In this work, we performed serial transfers of cecal material through multiple generations of birds to first determine if serial transfers exploiting the ceca in vivo, rather than the external environment or artificial incubations, can produce a stable microbial community. Subsequently, we compared microbiome development between chicks receiving this passaged, i.e. host-selected, cecal material orally, versus an environmental inoculum, to test the hypothesis that the first exposure of newly hatched chicks to microbes determines early GI microbiome structure and may have longer-lasting effects on bird health and development. Cecal microbiome dynamics and bird weights were tracked for a two-week period, with half of the birds in each treatment group exposed to a pathogen challenge at 7 days of age. We report that: i) a relatively stable community was derived after a single passage of transplanted cecal material, ii) this cecal inoculum significantly but ephemerally altered community structure relative to the environmental inoculum and PBS controls, and iii) either microbiome transplant administered at day-of-hatch appeared to have some protective effects against pathogen challenge relative to uninoculated controls. Differentially abundant taxa identified across treatment types may inform future studies aimed at identifying strains associated with beneficial phenotypes.
演替轨迹的概念描述了初始群落组成中的微小差异如何随着时间的推移而放大，并导致成熟群落的显著差异。对于许多动物来说，早期生活中接触微生物的类型和来源已被证明对微生物组的群落结构和/或功能有重大且持久的影响。在现代商业家禽生产中，雏鸡被饲养为单一年龄组，并且不会直接接触成年鸟类。这种情况很可能会引发微生物群落发展的轨迹，与非工业环境有很大的不同，在非工业环境中，雏鸡会接触到更广泛的环境和粪便接种物；然而，这两种情况对微生物组发展和功能的比较影响在很大程度上仍然未知。在这项工作中，我们通过多代数的鸟类进行了回肠材料的连续转移，首先确定是否通过体内回肠的连续转移，而不是外部环境或人工孵化，来产生稳定的微生物群落。随后，我们比较了接受这种传递的雏鸡（即宿主选择的）回肠材料与环境接种物的微生物组发育情况，以检验这样一个假设，即刚孵化的雏鸡首次接触微生物决定了早期胃肠道微生物组结构，并可能对鸟类的健康和发育产生更持久的影响。我们跟踪了两周的回肠微生物组动态和鸟类体重，其中一半的鸟类在 7 天龄时接受了病原体挑战。我们报告：i）经过一次移植回肠材料的传递，就可以获得一个相对稳定的群落；ii）与环境接种物和 PBS 对照相比，这种回肠接种物显著但短暂地改变了群落结构；iii）在孵化当天给予的任何一种微生物组移植似乎都对病原体挑战有一定的保护作用，与未接种对照相比。在不同处理类型中鉴定的差异丰度分类群可能为未来旨在鉴定与有益表型相关的菌株的研究提供信息。
