Prevalence of Microbial biofilms on selected fresh produce and household surfaces
Do you wash your vegetables after purchasing them from the store? Do you wipe down your counter, sink, and cutting boards after every use? If not, you may want to start. A group of scientists went to the grocery store and bought carrots (bulk and bagged), tomatoes, lettuce, and mushrooms to test if there is any bacteria living on these veggies. They discovered that there was a presence of a biofilm on every vegetable they purchased. A biofilm is a thin layer on the surface of objects that is created by bacteria. The scientists also decided to test whether there were bacterial communities living on sponges, wooden cutting boards, wet and dry towels, as well as wet and dry socks. They came up with the same results; bacterial biofilms were growing on every surface. Unfortunately the scientists also concluded that not much can be done to completely sanitize your vegetables or towels. Typical detergents and soaps are not able to break through that biofilm layer and properly disinfect your veggies or linens. But there is good news; if you rinse your food with chlorine, or acidic detergents you can inhibit further growth on those surfaces.
This paper gives the results from testing multiple surfaces in a domestic environment for the presence of biofilms and other microbial communities. They tested tomatoes, lettuce, carrots, and mushrooms from the grocery store, as well as cutting boards, sponges, wet and dry towels, and wet and dry socks. They used Cryostage scanning electron microscopy and light microscopy to detect microbes, and Alcian blue staining to expose a biofilm layer. The results revealed that there was an exopolymeric associated biofilm layer on every vegetable surface and household item, plus the results indicated a presence of fungal growth on sponges, socks, and towels. Unfortunately typical detergents and sanitizers are unable to break through that biofilm layer and kill the bacteria inside. The scientists reference literature where not even multiple chlorine rinses were able to completely sanitize these items. Rinsing with chlorine, acidic, or alkaline detergents can only decrease the viability of the organisms creating the biofilm, but not completely rid the layer. Because the biofilm on these surfaces is hard to remove, there is an increased possibility of those surfaces carrying pathogenic bacteria. The end result is that there are microbes living on most surfaces that you may encounter in everyday life.
Joanna Rayner, Richard Veeh, Janine Flood, Prevalence of microbial biofilms on selected fresh produce and household surfaces, International Journal of Food Microbiology, Volume 95, Issue 1, 2004, Pages 29-39, ISSN 0168-1605, https://doi.org/10.1016/j.ijfoodmicro.2004.01.019 (https://www.sciencedirect.com/science/article/pii/S0168160504000820)