Search

[Objectives] Rape-seed cake compost (RC) is an important nutrient carrier for biocontrol microorganisms in the production of bio-organic fertilizer(BOF). To enhance BOF control efficiency, herein we are aiming to screen bacterial strains that efficiently inhibit Rahtonia solanacearum, the causative agent of bacterial wilt of tomato, by using RC as the sole nutrients. [Methods] Bacterial antagonists were selected from tomato rhizosphere soils on nutrient agar( NA)and RC(8% RC in water) plates. Greenhouse assay was carried out to evaluate the efficiencies of bacterial antagonists fortified with RC on the suppression of R. solaruwearum. [Results] Antagonistic strain NA-5 isolated from NA plate performed best in inhibiting R. solanacearum growth on NA plate; with an inhibition zone; diameter of 29.0 mm, while weak inhibition effect was observed on RC plate. Interestingly, strain RC-14 isolated from RC plates showed a remarkable inhibition zone diameter of 24 mm on RC plate. Greenhouse results showed that both NA-5 and RC-14 fortified BOF (coded as B0F5 and BOF 14,respectively) significantly reduced disease incidences. BOF14 ha 1 significant higher biocontrol efficiency(75.9%) than BOF5. The R. solanacearum population in the rhizosphere soil of BOF14 treatment was significantly lower than BOF5 and other treatments(soil amended with RC, biocontrol agents or nothing). Based on the results of morphologic characteristics and analysis of 16S rRNA gene sequences, Strain RC-14 was preliminarily identified as Geohacillus sp. [Conclusions] Our results clearly demonstrated that using this screen strategy (ran obtain novel potential biocontrol agents, as little information was found about application of Geohacillus sp. for biocontrol of R. solanacearum. Geohacillus sp. strain RC-14 might produce more antibiotics against R. solanacearum in tomato rhizosphere when RC was taken as the nutrient carrier. [ABSTRACT FROM AUTHOR]