The Superiority of Slime Slime is an underappreciated facet of bacterial biology. Bacteriologists have worked for decades with pure laboratory cultures, but bacteria generally don t produce slime in laboratory conditions. In nature, all bacteria secrete slime.
Slime is useful to bacteria for several reasons.
It allows limited movement of a cell so that it can adjust a little to the microenvironment even without obvious locomotory devices. Slime protects against radiation, so cells that depend on photosynthesis in very shallow water are less exposed to harm from UV radiation. Gas diffusion is perhaps 10,000 times slower through slime than through water, so it is easier for a slimy bacterium to survive periods of fluctuation in external chemistry. Gas bubbles can be trapped in slime and used for good adaptive reasons, as in stromatolites. On a higher level, slime helps to form complex structures.