Eucalyptus Nursery Five-Strain Bacterial Inoculant Consortium

A five-strain synthetic consortium of Eucalyptus-derived bacteria — Bacillus subtilis, Paraburkholderia caribensis, Methylobacterium tardum, and two strains representing putative novel species in Paenibacillus and Mesorhizobium — assembled from isolates of Eucalyptus rhizosphere and roots and selected for complementary functional traits in nitrogen cycling and rhizosphere colonisation. Applied to three Eucalyptus clones in a large tree-nursery field experiment and assessed after 13 weeks, the inoculant did not change bacterial richness or diversity but did alter root microbial community structure; two genotypes showed improved seedling quality and one showed mortality fall from 21.8% to 6.7%. The record captures a case where a defined inoculant reshapes community composition and host outcome without shifting diversity metrics, and where the response is genotype-dependent rather than uniform.