Analysis of bacterial community in vegetable compartment of refrigerators and on surface of toilets using high-throughput sequencing

Microbial populations in indoor environments, where we live and eat, are important for public health. The refrigerator in kitchen could load microbiota in storage space and be direct origins of foodborne illness, it has been studied to monitor pathogens and the investigation of microbiota in refrigerator is significant in food safety. We observed and compared between bacterial communities from vegetable compartment of refrigerator and surface of toilet, which is recognized as highly colonized place by microorganisms, in 10 houses by culture-dependent and culture-independent techniques. Phyla of Proteobacteia, Firmicutes, Actinobacteria and Bacteroidetes were dominant in both of refrigerator and toilet samples. However, Proteobacteria was more abundant in refrigerator, and Firmicutes was more abundant in toilet. Genera of Pseudomonas, Sphingobacterium, and Pantoea were dominant groups in refrigerators, while Moraxella, Pseudomonas, and Streptococcus were dominant genera in toilet. Obtained microbial communities were compared with bacterial community from human skin and gut to identify a potential source of them. Bacterial communities from both of refrigerators and toilets were shared more with human skin bacteria than gut bacteria as previously reports. Opportunistic pathogens, which can cause illness to immunocompromied person, as Propionibacterium acnes, Bacteroides vulgates, Staphylococcus epidermidis were observed in shared species with human skin and gut. Results in this study provided useful information of refrigerator microbiota and a necessity of the molecular microbial studies in other house spaces for public health.