The biodiversity hypothesis that contact with natural environments (e.g. native vegetation) and biodiversity, through the influence of environmental microbes, may be beneficial for human commensal microbiota has been insufficiently tested. We aimed to study the association between living near natural environments in the urban context, and gut microbiota diversity and composition in young infants. Based on data linkage between the unique Urban Primary Land and Vegetation Inventory (uPLVI) for the city of Edmonton and 355 infants in the CHILD Cohort Study, infant exposure to natural environments (any and specific types, yes/no) was determined within 500 m and 1000 m of their home residence. Gut microbiota composition and diversity at age 4 months was assessed in infant fecal samples. Adjusted for covariates, we observed a reduced odds of high microbial alpha-diversity in the gut of infants exposed to any natural environment within 500 m [Shannon index aOR (95%CI) = 0.63 (0.40, 0.98) and Simpson index = 0.63 (0.41, 0.98)]. In stratified analyses, these associations remained only among infants not breastfed or living with household pets. When doubly stratifying by these variables, the reduced likelihood of high alpha-diversity was present only among infants who were not breastfed and lived with household pets [9% of the study population, Shannon index = 0.07 (0.01, 0.49) and Simpson index = 0.11 (0.02, 0.66)]. Differences in beta-diversity was also seen (p = 0.04) with proximity to a nature space in not breastfed and pets-exposed infants. No associations were observed among infants who were fully formula-fed but without pets at home. When families and their pets had close access to a natural environment, Verrucomicrobiales colonization was reduced in the gut microbiota of formula-fed infants, the abundance of Clostridiales was depleted, whereas the abundance of Enterobacteriales was enriched. Our double-stratified results indicate that proximity to a natural environment plus pet ownership has the capacity to alter the gut microbiota of formula-fed infants. Further research is needed to replicate and better interpret these results, as well as to understand their health consequences.

尚未充分测试过通过环境微生物的影响与自然环境（例如本地植被）和生物多样性接触的生物多样性假说可能对人类共生微生物有益的事实。我们旨在研究在城市环境中居住在自然环境附近与婴幼儿肠道菌群多样性和组成之间的关联。根据埃德蒙顿市独特的城市主要土地和植被清单（uPLVI）与CHILD队列研究中的355名婴儿之间的数据链接，确定婴儿在500 m内暴露于自然环境（任何和特定类型，是/否）和他们的家庭住宅1000 m。在婴儿粪便样本中评估了4个月大时肠道菌群的组成和多样性。调整协变量 我们观察到暴露于500 m以内任何自然环境中的婴儿的肠道中高微生物α多样性的几率降低了[香农指数aOR（95％CI）= 0.63（0.40，0.98）和辛普森指数= 0.63（0.41，0.98） ]。在分层分析中，这些关联仅存在于没有母乳喂养或与家庭宠物生活在一起的婴儿中。当按这些变量进行双重分层时，仅在非母乳喂养且与家养宠物生活的婴儿中出现高α-多样性的可能性降低[占研究人群的9％，香农指数= 0.07（0.01，0.49）和辛普森指数= 0.11（0.02，0.66）]。在没有母乳喂养和暴露于宠物的婴儿中，也接近自然空间，也发现了β多样性差异（p = 0.04）。在完全由配方食品喂养但在家中没有宠物的婴儿之间未发现任何关联。当家庭及其宠物接近自然环境时，配方奶喂养婴儿的肠道菌群中疣状微生物的定殖减少，梭菌的数量减少，而肠杆菌的数量增加。我们的双重分层结果表明，接近自然环境以及拥有宠物拥有改变配方奶喂养婴儿肠道菌群的能力。需要做进一步的研究来复制和更好地解释这些结果，并了解它们对健康的影响。我们的双重分层结果表明，接近自然环境以及拥有宠物拥有改变配方奶喂养婴儿肠道菌群的能力。需要做进一步的研究来复制和更好地解释这些结果，并了解它们对健康的影响。我们的双重分层结果表明，接近自然环境以及拥有宠物拥有改变配方奶喂养婴儿肠道菌群的能力。需要做进一步的研究来复制和更好地解释这些结果，并了解它们对健康的影响。