Antifungal Activity of Isolated Bacillus amyloliquefaciens SYBC H47 for the Biocontrol of Peach Gummosis

Abstract

The gummosis disease is caused by Botryosphaeria dothidea (Moug. ex. Fr) Ces. et de Not., and it is one of the most important diseases of stone fruits worldwide. The use of biocontrol as an alternative approach to synthetic chemical fungicides has aroused general concern about how to control plant diseases that are caused by phytopathogens. The aim of this study is to isolate Bacillus strains from raw honeys with the capacity to inhibit B. dothidea and to explore the mechanisms by which they could be used in the biocontrol of peach gummosis. Bacillus amyloliquefaciens SYBC H47 was isolated and identified on the basis of its physiological and biochemical characteristics and its 16S rRNA and gyrB gene sequences. The cell suspension and the cell-free supernatant of its culture showed significant antifungal activity against Aspergillus niger, Mucor racemosus, Fusarium oxysporum, Penicillium citrinum, and Candida albicans by agar-diffusion assays. The primary antifungal substances were bacillomycin L, fengycin, and surfactin, which were analyzed by HPLC LC/ESI-MS/MS. Bacillomycin L showed the best inhibitory effect against conidial germination of B. dothidea, followed by fengycin and surfactin. Surfactin had limited effects on mycelial growth, contrary to those of bacillomycin L and fengycin. However, a mixture of the three lipopeptides had a synergistic effect that disrupted the structure of the conidia and mycelia. In order to reduce the production cost, the use of waste frying peanut oil and soy oil as the sole carbon source increased the lipopeptide yield levels by approximately 17% (2.42 g/L) and 110% (4.35 g/L), respectively. In a field trial, the decreases in the infected gummosis rate (IGR) and the disease severity index (DSI) through cell suspension treatments were 20% and 57.5% (in 2014), respectively, and 40% and 57.5% (in 2015), respectively, in comparison with the control. In conclusion, B. amyloliquefaciens SYBC H47 could inhibit the germination of conidia and the growth of mycelia from B. dothidea; therefore, this strain behaves as a potential biocontrol agent against the gummosis disease.

Antibacterial activity againstRalstonia solanacearumof the lipopeptides secreted from theBacillus amyloliquefaciensstrainFJAT‐2349

“…; Li et al . ). Lipopeptide ingredients were significantly influenced by the culture medium and temperature.…”

“…), Botryosphaeria dothidea (Li et al . ) and Botrytis cinerea (Zhang et al . ), among others; surfactin analogues demonstrate high levels of suppressive activity against Fusarium oxysporum (Gu et al .…”

“…Li et al . () reported that three types of LPs including bacillomycin L, C 16 –C 17 fengycinA/B and C 13 –C 15 surfactin, existed concurrently in the metabolites produced by B. amyloliquefaciens SYBC H47. The Bacillus licheniformis strain MB01 could only yield surfactins with the C 12 –C 15 fatty acid chain (Chen et al .…”

Bacillomycins – The Effective Molecules in Plant Disease Management

“…To reduce this high production costs researchers have utilized low cost raw substrates to produce AMPs or lipopeptides such as rice straw (Zhu et al, 2013), potato (Fox et al, 2000), orange peels (Ghribi et al, 2011) and waste frying oils (Li et al, 2016).…”

“…In order to raise the lipopeptide yield levels waste frying peanut oil and soy oil as the sole carbon source was utilized and in field trial, the decrease in infected gummosis rate (IGR) and disease severity index (DSI) through cell free suspension treatments of B. amyloliquefaciens SYBC H47 was observed (Li et al, 2016 (Suneeta et. al., 2016a).…”