Unravelling the hidden side of laundry: malodour, microbiome and pathogenome

Recent trends towards lower washing temperatures and a reduction in the use of bleaching agents in laundry undoubtedly benefit our environment. However, these conditions impair microbial removal on clothes, leading to malodour generation and negative impacts on consumer well-being. Clothing undergoes cycles of wearing, washing and drying, with variable exposure to microorganisms and volatilomes originating from the skin, washing machine, water and laundry products. Laundry malodour is therefore a complex problem that reflects its dynamic ecosystem. To date, comprehensive investigations that encompass the evaluation of both microbial community and malodorous volatile organic compounds throughout all stages of the wash-wear-dry cycle are scarce. Furthermore, the microbial and malodour profiles associated with extended humid-drying conditions are poorly defined.

Here we present olfaction-directed chemical and microbiological studies of synthetic T-shirts after wearing, washing and drying. Results show that although washing reduces the occurrence of known malodour volatile organic compounds, membrane-intact bacterial load on clothing is increased. Skin commensals are displaced by washing machine microbiomes, and for the first time, we show that this shift is accompanied by an altered pathogenomic profile, with many genes involved in biofilm build-up. We additionally highlight that humid-drying conditions are associated with characteristic malodours and favour the growth of specific Gram-negative bacteria.

These findings have important implications for the development of next-generation laundry products that enhance consumer well-being, while supporting environmentally friendly laundry practices.