In soil, microorganisms live in complex associations, and to illustrate these associations, microcosms testing the effect of
co-inoculating different bacteria and/or fungi have been developed (Leyval and Berthelin, 1989, 1991; Toro et al.,
1997). Koele et al. (2009) tested the effect of co-inoculating mycorrhizal fungi (Laccaria bicolor or Scleroderma citrinum)
and efficient mineral-weathering bacteria (B. glathei or Collimonassp.) in P. sylvestris microcosms (Fig. 2B).