Concerning the present microbiological knowledge system, we can only isolate and culture a small fraction of microbes with the existing microbial culture techniques, leaving the vast majority of microorganisms in the natural environment unculturable. This article summarizes some microbial cultivation techniques and strategies, including space separation, prolongation of cultivation, and simulation of the natural environmental conditions. Much attention is paid to the effects of the medium nutrient levels on microbial culturability. This article also briefly summarizes the physiology and ecology of oligotrophic bacteria, as well as how nutrient concentration affects microbial growth. It is proposed that microbial culturability would be improved via rational design of culture medium and applying proper culture conditions.
