Microbiology of cleaning

What is actually alive on a surface, why it persists, and why removing what you can see is not the same as removing what is there.

Listed alphabetically.

• Cellulolytic microorganisms

  The fungi and bacteria that digest cotton, linen and paper by converting the fibre itself into sugar. The damage is not staining, it is the material being eaten.

• Fungal spores

  Already everywhere, water-repellent, and resistant to drying out. Removing them is not the goal, because it is not achievable — denying them moisture is.

• Growth beneath a floor covering

  A dark, absorbent, slow-drying layer with no airflow. The pile can feel dry to the hand while the padding under it has not dried for weeks.

• House dust mites

  Not a hygiene failure and not removable by cleaning alone. They live on shed skin in soft furnishings, and humidity governs them more than vacuuming does.

• Keratinophilic fungi

  The fungi that feed on protein fibres. Wool and silk are less susceptible than cotton — which is not the same as being safe from it.

• Kitchen sponge microbiota

  The most-studied surface in a domestic kitchen, and the honest finding is narrow: the published methods clean the sponge and are not claimed to eliminate what is in it.

• Mould fungi

  The organisms behind the marking. Around 1.5 million species, each with its own conditions — and killing them does not end the exposure they created.

• Washing machine microbiota

  Established communities living on the wet surfaces of a domestic washing machine — which is why the smell returns on a schedule after every treatment.

Nothing here says that a surface is sterile, germ-free or safe, and none of it is medical advice. A figure measured on a test organism under controlled laboratory conditions is a fact about that test rather than about your worktop.