A new study published in the journal Microbiome highlights potential unintended consequences of increased disinfectant use in urban environments, suggesting that efforts to create sterile living spaces could be fostering the growth of novel microbial strains.
The research, led by Dr Xinzhao Tong, an assistant professor at Xi’an Jiaotong-Liverpool University (XJTLU) in China, investigates how everyday behaviours, particularly heightened cleaning protocols following the COVID-19 pandemic, are influencing the composition of microorganisms in indoor settings. Dr Tong emphasises that built environments—such as residential areas, subways, and public facilities—present unique conditions that differ significantly from natural habitats.
“Areas with many buildings lack the traditional nutrients and essential resources that microbes need for survival,” Dr Tong explains. “Consequently, these environments develop a distinct microbiome.”
To understand how these microorganisms adapt to urban life, researchers collected 738 samples from various built environments across Hong Kong, including residences, subways, piers, and even human skin. Using advanced shotgun metagenomic sequencing, the team analysed the genomic content of these samples, revealing how urban conditions impact microbial survival and evolution.
The study uncovered 363 previously unidentified microbial strains residing on our skin and in the environment around us. Notably, some of these strains possess genetic material enabling them to metabolise substances typically found in cities, including various manufactured products. One significant discovery was a strain of the Candidatus phylum Eremiobacterota, previously known only from Antarctic desert soil.
Dr Tong highlights the implications of this discovery: “The genome of this novel strain of Eremiobacterota enables it to metabolise ammonium ions present in cleaning products. Additionally, it contains genes for alcohol and aldehyde dehydrogenases, allowing it to break down residual alcohol from common disinfectants.”
The researchers contend that microbes equipped with enhanced abilities to utilise limited resources and withstand manufactured products—including disinfectants and metals—are more likely to thrive and evolve in built environments. This adaptation raises concerns about potential health risks, particularly if these resistant strains prove pathogenic.
The findings prompt critical questions about urban sanitation practices. As the use of disinfectants and cleaning products rises in an effort to combat the spread of pathogens, it appears that microbial populations are not only surviving but adapting in ways that could challenge public health.
The study underscores the need for a more nuanced understanding of urban microbiomes and the long-term effects of disinfectant usage. It suggests that while cleanliness is essential for public health, there is a delicate balance to be struck to ensure that our efforts do not inadvertently foster the emergence of harmful microbial strains.
As urban environments continue to evolve, the research serves as a timely reminder of the complex interactions between humans and microorganisms in our built spaces. The implications of these findings could shape future policies on sanitation practices, urging a re-evaluation of how we maintain cleanliness in the wake of the pandemic.