For energy saving purposes, lower washing temperatures are increasingly used in domestic washing processes. In addition, consumers often use liquid detergents, which lack bleach and are less effective against microorganisms. As a result, biofouling in machines and unpleasant odors may develop. Dispersin-amended detergents were recently shown to modify bacterial community composition in washing machines and to reduce laundry malodor. In this study, Oxford Nanopore sequencing of full-length 16S rRNA gene amplicons and quantitative PCR were used to qualitatively and quantitatively examine bacterial communities in two machine parts — sump water and pump sump — after washing with either a dispersin-amended detergent or the same detergent without dispersin. DNA was extracted from all samples in a standardized manner. Full-length 16S rRNA gene sequences (~1.5 kb) revealed the presence of less malodour-associated taxa, such as Rhizobium and Agrobacterium, in machines washed with the dispersin-containing formulation. qPCR showed that biosoil increased markedly after washing without dispersin particularly in the pump sump, whereas it remained nearly unchanged or decreased after washing with dispersin. Overall, the dispersin-amended detergent demonstrated higher cleaning efficiency and prevented biosoil formation, highlighting the potential of dispersin to improve hygiene in domestic laundering.
