Bacteria Isolated from Treated Wastewater for Biofertilization and Crop Protection Against Fusarium spp. Pathogens

Bacteria isolated from bioaerosols emitted by a clarifier in a wastewater treatment plant (Dobre Miasto, Kosyn, Poland) were analyzed. A total of 27 morphologically different bacterial colonies were isolated, and 14 strains antagonistic towards Fusarium culmorum in vitro were selected for analysis. Most of the analyzed bacteria did not increase the germination capacity or the height of wheat seedlings. The only exception was strain PSDM20 which was characterized by multiple plant growth–promoting properties, but also by the lowest metabolic activity and lowest substrate assimilation. Strain PSDM16 deteriorated the status of wheat seedlings. Bacterial strains PSDM3, PSDM6, PSDM10, PSDM13, PSDM14, PSDM17, and PSDM20 prevented the deterioration of the biometric parameters of wheat seedlings exposed to F. culmorum and F. graminearum. Strains PSDM3, PSDM6, PSDM10, and PSDM17 most effectively protected wheat seedlings against infections caused by the above pathogens. Strain PSDM6 produced indole acetic acid (IAA), and it significantly contributed to plant elongation. Correlations were not observed between the growth-promoting properties, metabolic activity, and fungistatic properties of the evaluated bacteria. Pseudomonas putida PSDM3, Proteus penneri PSDM6, Enterobacter hormaechei PSDM10, and Advenella sp. PSDM17 were most effective in limiting the spread of Fusarium spp. infections in spring wheat, and they can be used as biological fungicides. The results of this study indicate that bacteria isolated from non-agricultural ecosystems are capable of protecting and fertilizing crops. The growth-promoting properties of bacterial strains of the genus Proteus are comparable with those of the widely investigated Pseudomonas spp. strains.