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Sclerotinia sclerotiorum is a soil fungus, phytopathogenic for over 400 plant species, including many economically important crops such as beans, cotton, soybeans, among others, reducing crop yields. Rhizobacteria inhabit the rhizospheric soil layer, where they compete with many microorganisms, including fungi, for the acquisition of resources, presenting control mechanisms to survive and, therefore, have potential antagonistic activity against fungi. The aim of this study was to evaluate the antagonist potential of rhizobacteria against the mycelial growth of S. sclerotiorum. Twenty-six bacterial isolates from rhizosphere belonging to the microbiological collection of the Laboratório de Biotecnologia Microbiana (LABIM) and a strain of S. sclerotiorum isolated from soybean were used in the assays. The antagonist activity was evaluated on Potato Dextrose Agar (PDA) plates using a dual culture technique. Five-day-old fungal discs (8mm diameter) of previously PDA cultured S. sclerotiorum were placed on the center of 9-cm-diameter Petri dishes while 10 uL of bacterial isolates (adjusted to 0.5 on saline solution 0,85% by McFarland scale) in 4 points equidistant 1cm from the edge of the plate. The plates were incubated at 24°C for up to 5 days with a 24-hour photoperiod to assess the diameter of inhibition obtained (mm). The experiment was carried out three times in duplicate and the data obtained were submitted to analysis of variance, with p<0.5, using the software PRISMA v8. The isolates were characterized for cell wall type by Gram stain of 24 hours bacterial culture and for the ability to produce endospores by Wirtz-Conklin stain of seven-day-old bacterial culture. All isolates were classified as Gram-positive, with rod-shaped morphology and endospore production capacity. All 26 isolates were able to inhibit the mycelial growth of S. sclerotiorum, being 12 isolates with an average inhibition diameter ranging from 11.50mm to 14.88mm, 15 isolates with an average inhibition diameter ranging from 15.33mm to 19 .63mm and an isolated 1 with the highest average inhibition diameter, which was 22.58mm. The microscopic classification of rhizobacterias suggests that at all isolates belong to the Bacillus genus and the antagonism assay showed that the 26 rhizobacteria can control the mycelial growth of S. sclerotiorum and 16 of them had a high average inhibition diameter, greater than 15mm, showing biotechnological potential for further studies and biological products development.

  • 1 Departamento de Microbiologia / Centro de Ciências Biológicas / Universidade Estadual de Londrina
  • 2 Centro de Ciências Biológicas / Universidade Estadual de Londrina
Eixo Temático
  • Microbiologia Ambiental
Biological Products
Microbial biotechnology