Endophytic and Biological Control Potential of Bacillus mojavensis and Related Species

The identity of a patented endophytic bacterium was established by 16S rRNA sequence analysis as a strain of Bacillus mojavensis, a recently erected species within one of the B. subtilis subgroups. This strain of B. mojavensis is antagonistic to the fungus Fusarium moniliforme, an endophytic mycotoxin-producing pathogen of maize and other plants. There are five other species within this subgroup: Bacillus amyloliquefaciens, B. atrophaeus, B. licheniformis, Brevibacterium halotolerans, Paenibacillus lentimorbus, and P. popilliae. The objectives of this research were to screen other isolates of B. mojavensis, B. subtilis, and the other closely related Bacillus species for endophytic colonizing capacity and to determine the in vitro antagonism to F. moniliforme in an effort to survey the distribution of these traits, which are desirable biological control qualities within the Bacillaceae. Antagonism was determined on nutrient agar, and endophytic colonization was established with maize plants following recovery of rifampin-resistant mutants generated from all strains used in the study. The study established that all 13 strains of B. mojavensis, isolated from major deserts of the world, endophytically colonized maize and were antagonists to F. moniliforme. The endophytic colonization of maize by B. subtilis and other species within this subgroup of the Bacillaceae varied, as did antagonism, to F. moniliforme. Thus, this study suggests that endophytic colonization is another characteristic of the species B. mojavensis. The endophytic habit and demonstrated antagonism to the test fungus indicate that isolates of this species might prove to be important biological control organisms where the endophytic habit is desired.