Isolation of Heavy Metal-Tolerant and Anti-Phytopathogenic Plant Growth-Promoting Bacteria from Soils

In this study, multifunctional soil bacteria, which can promote plant development, resist heavy metals, exhibit anti-phytopathogenic action against plant diseaes, and produce extracellular enzymes, were isolated to improve the effectiveness of phytoremediation techniques. In order to isolate multifunctional soil bacteria, a variety of soil samples with diverse characteristics were used as sources for isolation. To look into the diversity and structural traits of the bacterial communities, we conducted amplicon sequencing of the 16S rRNA gene on five types of soils and predicted functional genes using Tax4Fun2. The isolated bacteria were evaluated for their multifunctional capabilities, including heavy metal tolerance, plant growth promotion, anti-phytopathogenic activity, and extracellular enzyme activity. The genes related to plant growth promotion and anti-phytopathogenic activity were most abundant in forest and paddy soils. <i>Burkholderia</i> sp. FZ3 and FZ5 demonstrated excellent heavy metal resistance (≤ 1 mM Cd and ≤ 10 mM Zn), <i>Pantoea</i> sp. FC24 exhibited the highest protease activity (24.90 μmol tyrosine·g-DCW^-1·h^-1), and <i>Enterobacter</i> sp. PC20 showed superior plant growth promotion, especially in siderophore production. The multifunctional bacteria isolated using traditional methods included three strains (FC24, FZ3, and FZ5) from the forest and one strain (PC20) from paddy field soil. These results indicate that, for the isolation of beneficial soil microorganisms, utilizing target gene information obtained from isolation sources and subsequently exploring target microorganisms is a valuable strategy.