Talmudic Question #33

 

Imagine that we could completely get rid of the microbial biofilms found on all natural surfaces, including rocks and soil particles in and out of water. I don’t mean by scrubbing each one with a brush, but by some equally implausible process. What would be the consequences for the biogeochemical cycles of the planet?

 
 

 
 

Comments

[David Lipson]

Ah, life in a Teflon world. First of all, microbes love surfaces, so removing all biofilms would probably remove most of the biomass (from soil, anyway). I don't know exactly what proportion of microbes in soils are surface-associated, but my guess is at least 90%. So biogeochemical cycling would slow down at least by a factor of 10. In particular, decomposition of complex organic matter would slow, as degradation of cellulose involves major complexes of extracellular enzymes which are often anchored to the outside of cells (for bacteria anyway), in other words, biofilms. Finally, plant roots would have a very hard time: the "rhizosphere effect" greatly speeds up mineralization around roots. Removing root-associated biofilms is bound to eliminate most of those helpful rhizosphere dwellers. Planktonic microbes might eventually fill this niche, but they would have to chase the roots as they wind through the soil (all the good exudate comes from near the growing tip).

So C and N cycling would slow down to a crawl, and microbes would be cast adrift, washed to lower horizons and out to sea at the mercy of the rain...