Screening and Identification of a Strain of Antagonistic Bacteria against Copper Blight of Cunninghamia lanceolata

Purpose To provide strain resources and theoretical basis for the biocontrol of copper blight of Cunninghamia lanceolata caused by Pestalotiopsis microspora.

Methods Strain SMTR-1, screened from the rhizosphere soil of healthy C. lanceolata and showed high antagonistic activity against copper blight, was identified by morphological observation, physiological and biochemical determination and molecular biology methods; and its antibacterial effect was evaluated using the dual culture method (double dish method for volatile substances), spore germination assay, and mycelial growth rate method.

Results Strain SMTR-1 was identified as Pseudomonas aeruginosa. Its sterile filtrate, fermentation broth, and volatile substances all exhibited significant inhibitory effects on P. microspora. Among these, volatile substances showed the most significant inhibitory effect, with an inhibition rate of 79.86%. Microscopic observation revealed a teratogenic effect on the hyphae of P. microspora, manifesting as distortion and deformation of pathogenic hyphae, swelling of some cells, varying thickness, and eventual rupture.

Conclusion The results of this study will provide microbial strain resources for the biological control of copper blight of C. lanceolata and offer a reference for the research and development of related biocontrol agents and formulations.