TABLE 1.

Length scales relevant for interactions between soil particles and microbes

Size (μm)	Biological relevance	Soil relevance	Interaction
<1	Viral particle sizes,a E. coli cells deform (300 nm)b	Particle surface roughness promotes selective adhesion of specific bacterial species (10–100 nm)c	Lysogeny and gene transfer,d bacterial shape deformation,b surface attachmentc
1–2	Bacterial cell sizeb	Pores within soil microaggregatese	Nitrogen fixationf
1–15	Fungal hyphal diam,g bacterial biofilm thickness in (0.12-mm-diameter) sandh		Fungal mycelia reinforce aggregate tensile strength,i bacterial biofilm EPS production binds soil particles togetherj
10–30	Distance at which majority of bacterial cell interactions occur (<20 μm)k	Pores between soil microaggregates, can retain water against gravity for multiple dayse	Denitrification,l quorum-sensing bacteria exhibit inhibited cell divisionm

^aWilliamson et al. (134).

^bMännik et al. (137).

^cHol and Dekker (127).

^dCanchaya et al. (64).

^eWatt et al. (36).

^fChotte et al. (44).

^gFriese and Allen (138).

^hOr et al. (139).

ⁱRillig et al. (140).

^jAlami et al. (141).

^kRaynaud and Nunan (35).

^lLensi et al. (43).

^mBoedicker et al. (142).