Biocontrol of tomato bacterial wilt by the new strain Bacillus velezensis FJAT-46737 and its lipopeptides

Abstract

Background: There is an urgent need to discover biocontrol agents to control bacterial wilt. This study reports on a new lipopeptide-producing biocontrol strain FJAT-46737 and explores its lipopeptidic compounds, and this study investigates the antagonistic effects of these compounds. Results: Based on a whole genome sequence analysis, the new strain FJAT-46737 was identified as Bacillus velezensis, and seven gene clusters responsible for the synthesis of bioactive secondary metabolites in FJAT-46737 were predicted. The antimicrobial results demonstrated that FJAT-46737 exhibited broad-spectrum antimicrobial activities in vitro against three bacteria and three fungi. Pot experiments showed that the control efficiencies for tomato bacterial wilt of the whole cultures, the 2-fold diluted supernatants and the crude lipopeptide of FJAT-46737 were 66.2%, 82.0%, and 96.2%, respectively. The above results suggested that one of the antagonistic mechanisms of FJAT-46737 was the secretion of lipopeptides consisting of iturins, fengycins and surfactins. The crude lipopeptides had significant antagonistic activities against several pathogens (including Ralstonia solanacearum, Escherichia coli and Fusarium oxysporum) and fengycins were the major antibacterial components of the lipopeptides against R. solanacearum in vitro. Furthermore, the rich organic nitrogen sources (especially yeast extracts) in the media promoted the production of fengycin and surfactin by FJAT-46737. The secretion of these two lipopeptides was related to temperature fluctuations, with the fengycin content decreasing by 96.6% and the surfactins content increasing by 59.9% from 20°C to 40°C. The optimal temperature for lipopeptide production by FJAT-46737 varied between 20°C and 25°C. Conclusions: The B. velezensis strain FJAT-46737 and its secreted lipopeptides could be used as new sources of potential biocontrol agents against several plant pathogens, and especially the bacterial wilt pathogen R. solanacearum.

A Novel Rhizospheric Bacterium: Bacillus velezensis NKMV-3 as a Biocontrol Agent Against Alternaria Leaf Blight in Tomato

“…Several synthetic fungicides have been used by farmers for the control of early blight of Tomato [42]. But, due to their continuous usage and also non-adherence to prescribed dosages, resistance build-upof resistance has been observed [43] [21,50]. This research articles is the rst report of a B. velezensis strain isolated from major tomato growing regions of Tamil Nadu, India which is effective against A. solani.…”

“…Among Bacillus spp., B. velezensis is one of the potential biocontrol agent [19,20]. Literature reports numerousstrains of B. velezensis strains capable of controlling the major plant pathogens (bacteria & fungi) and nematodes [19][20][21][22][23].…”

The Potency of Bacillus siamensis LDR as Biocontrol Agent Against Fungal Phytopathogen

“…Bacillus simplex 30N-5 and Bacillus subtilis 30VD-1 can inhibit growth of Fusarium spp. Chen et al [16] reported B. velezensis FJAT-46737 as potential biocontrol agent for Fusarium oxysporum.…”

Biological control of important fungal diseases of potato and raspberry by two Bacillus velezensis strains

“…B. velezensis strains are known as biological control agents that suppress certain dangerous plant diseases caused by R. solanacearum on tomato (Chen et al, 2020), Fusarium graminearum on corn (Wang et al, 2020), and Botrytis cinerea on strawberry (Toral et al, 2020). In addition to biocontrol, B. velezensis strains may promote plant growth (Fan et al, 2018;Myo et al, 2019;Torres et al, 2020).…”