Indoor dust sample from Helsinki Finland. Determinants of bacterial and fungal microbiota in Finnish home dust: impact of environmental biodiversity, pets, and occupants

The indoors is where many humans spend most of their time, and are strongly exposed to indoor microbiota, which may have multifaceted effects on health. Therefore, a comprehensive understanding of the determinants of indoor microbiota is necessary. We collected dust samples from 295 homes of families with young children in the Helsinki region of Finland and analyzed the bacterial and fungal composition based on the 16S rRNA and ITS DNA sequences. Microbial profiles were combined with extensive survey data on family structure, daily life, and physical characteristics of the home, as well as additional external environmental information, such as land use, and vegetational biodiversity near the home. Using permutational multivariate analysis of variance we explained 18 % of the variation of the relative abundance between samples within bacterial composition, and 17 % of the fungal composition with the explanatory variables. The fungal community was dominated by the phyla Basidiomycota, and Ascomycota; the bacterial phyla Proteobacteria, Firmicutes, Cyanobacteria, and Actinobacteria were dominant. The presence of dogs, multiple children, and firewood were significantly associated with both the fungal and bacterial composition. Additionally, fungal communities were associated with land use, biodiversity in the area, and the type of building, while bacterial communities were associated with the human inhabitants and cleaning practices. A distinction emerged between members of Ascomycota and Basidiomycota, Ascomycota being more abundant in homes with greater surrounding natural environment, and potential contact with the environment. The results suggest that the fungal composition is strongly dependent on the transport of outdoor environmental fungi into homes, while bacteria are largely derived from the inhabitants.

人类绝大多数时间都处于室内环境中，且会持续大量接触室内微生物群（microbiota），后者对人体健康可能产生多维度影响。因此，全面解析室内微生物群的影响因素至关重要。本研究从芬兰赫尔辛基地区295户有幼儿的家庭中采集了尘埃样本，并基于16S核糖体RNA（16S rRNA）与转录间隔区（ITS）DNA序列，分析了样本中的细菌与真菌群落组成。研究将微生物群落特征数据，与涵盖家庭结构、日常生活、住宅物理特征的详尽调研数据，以及住宅周边土地利用、植被生物多样性等额外外部环境信息进行整合。本研究采用置换多元方差分析（permutational multivariate analysis of variance），通过解释变量分别解释了细菌群落组成中样本间相对丰度变异的18%，以及真菌群落组成中样本间相对丰度变异的17%。真菌群落以担子菌门（Basidiomycota）与子囊菌门（Ascomycota）为主；细菌群落则以变形菌门（Proteobacteria）、厚壁菌门（Firmicutes）、蓝细菌门（Cyanobacteria）及放线菌门（Actinobacteria）为优势类群。家中饲养犬只、多名幼儿以及使用柴火，均与真菌及细菌群落组成存在显著关联。此外，真菌群落还与区域土地利用、生物多样性及建筑类型相关，而细菌群落则与居住者及清洁习惯密切相关。子囊菌门与担子菌门类群存在显著差异：在周边自然环境更优越、与外界环境接触更多的住宅中，子囊菌门的相对丰度更高。研究结果表明，真菌群落组成高度依赖于室外环境真菌向室内的迁移过程，而细菌群落则主要来源于居住者自身。