Antagonist capacity of bacteria isolated from cape gooseberry cultures (Physalis peruviana L.) for biological control of Fusarium oxysporum

Vascular wilt caused by Fusarium oxysporum is the most damaging disease in cape gooseberry (Physalis peruviana L.) production. In this study, we isolated and biochemically characterized endophytes and rhizospheric bacterial isolates with antagonistic activity against F. oxysporum from cape gooseberry plants. Bacterial isolates were evaluated under in vitro conditions for their antagonistic capacity against a highly virulent isolate of F. oxysporum, as well as production of lytic enzymes, biosurfactants and volatile organic compounds. Twenty-four antagonistic bacteria were selected, out of which Bacillus sp. MB015 and Pseudomonas sp. MB108 exhibited the best biocontrol activity in vitro, with inhibition levels of 80.6% and 79.9%, respectively. However, under greenhouse conditions, P. fluorescens MB103 and B. megaterium MB112 presented the best antagonistic capacity with 83.3% control of vascular wilt incidence. P. fluorescens MB103 was one of most effective in reducing the disease severity with an area under the disease of progress curve (AUDPC) of 7.5, compared with the negative control (soil infested with Fox17 without test bacteria), which presented an AUDPC of 36.8. These results suggest that P. fluorescens MB103 is a good candidate for use as a biocontrol agent against vascular wilt caused by F. oxysporum in cape gooseberry under field conditions.