Proportion of novel isolates among all isolates, separately for each time point for marine microorganisms (○), non-spore-forming soil microorganisms (■), and spore-forming soil microorganisms (□). In all cases, the isolate was considered novel if its 16S rRNA gene sequence shared less than 99% identity with previously reported isolates. Note the low value of R2, indicating that the percentage of novel isolates does not depend on the time required to form a visible biomass.