Does anyone have experience with the use of suction cups to somehow capture soil bacterial communities in solution? It is very suspicious that I can't find any literature on this. Maybe the pore diameter of these systems is too small?
I don't find it suspicious that you can't find any literature on using a suction cup to obtain a sample of the microbial population in the soil. Normally soil samples for microbial population determinations are shaken into solutions (e.g. buffers, saline, etc.) and the suspension or filtrate is used for further determinations. As a practical matter, it is not obvious why you are considering using a suction cup. Using a suction cup is much more labour intensive and would take much more time to prepare the sample. This is probably why nobody uses it and why you can't find any mention of it in the literature.