Bioprospecting bacterial strains for biological control of white mold on soybean

Abstract

 The search for efficient biocontrol agents in agriculture has been achieved in several pathosystems. Thus, we carried out experiments under controlled conditions in greenhouse and laboratory, involving the use of bacteria Bacillus alcalophilus, Bacillus cereus GC subgrupo B, Stenotrophomonas maltophilia, Yersinia bercovieri and Photorhabdus luminescens-luminescens obtained from biofertilizers and bovine and suine manure. The bacterial strains were multiplied in nutrient-agar medium (NA) for 48 hours to evaluate the efficiency in inhibiting the mycelial growth and the development of Sclerotinia sclerotiorum in antagonism assays in Petri dishes containing BDA medium; or in aqueous suspension adjusted in 109 ufc.mL-1 by Mac Farland scale, to seeds microbiolization and spraying the aerial parts of soybean plants, totalizing three assays. The bacterial strains BB-4 (Bacillus cereus GC subgrupo B), BS-3 (Photorhabdus luminescens-luminescens), BB-1 (Bacillus alcalophilus) and BB-6 (Yersinia bercovieri) tested were shown to be effective for inhibition of mycelial growth of the pathogen, with values between 31% and 46%, and disease development in soybean seeds and plants, with values above 50% and the same levels of control treatments with thiophanate methyl + fluazinan and thiophanate methyl. These results demonstrate the presence of promising strains in control of white mold alternatively the use of chemical fungicides