The role of iturin A from B. amyloliquefaciens BUZ-14 in the inhibition of the most common postharvest fruit rots

Abstract

The aim of this work was to elucidate the role of the secondary metabolites produced by B. amyloliquefaciens BUZ-14 against B. cinerea, M. fructicola, M. laxa, P. digitatum, P. italicum and P. expansum both in vitro and in planta. The entire cell free supernatant (CFS) and the lipopeptide fraction (LPF) showed similar antifungal activities, completely inhibiting all the fungi at dilutions of 1:24 or even lower, whereas the nonbutanolic fraction (NBF) barely inhibited the fungi. However, when the LPF and CFS were applied on fruit, only brown rot in peaches and blue rot in apples was totally inhibited. The main families of metabolites in the LPF were iturin A, fengycin and surfactin with maximum concentrations of 407, 853 and 658 µg mL-1 , respectively. Subsequently, a TLC-bioautography revealed iturin A as the key metabolite in the inhibitions and allowed us to establish in vivo MICs of 16.9 and 33.9 µg mL-1 for Monilinia species and P. expansum, respectively. The application of 24 hold BUZ-14 cultures supressed brown rot in peaches and also blue rot in apples but failed to inhibit the other diseases. However, BUZ-14 was only able to grow and produce iturin A in peaches so we can deduce that the amount of iturin A brought with the cultures (36 ± 14 µg mL-1) could be enough to control both diseases. The strong antifungal activity of the iturin A present in the BUZ-14 CFS suggests that it could be successfully used for postharvest disease control. However, future research is necessary to maximize the iturin A production by B. amyloliquefaciens BUZ-14 in order to optimize a commercial application.

Genomic Analysis and Secondary Metabolites Production of the Endophytic Bacillus velezensis Bvel1: A Biocontrol Agent against Botrytis cinerea Causing Bunch Rot in Post-Harvest Table Grapes

“…Previous studies have reported that the treatment of plant tissues (fruits, leaves) with cell suspensions, cell cultures, and cell free culture supernatant from BCAs gave very low values (<1–2 μg/g plant tissue) [ 14 , 54 , 55 ], raising questions about how to achieve the accumulation of active metabolites near or over the threshold levels required for antibiosis and/or induction of host plant defense mechanisms [ 54 ]. Recent studies have shown that bacterial colonization may generate microcolonies on the target tissue, where secondary metabolites are accumulated in micromolar amounts in microniches [ 56 ].…”

“…Thin layer chromatography (TLC) analysis of ESC1 and ESC2 and bioautography was conducted as described previously [ 54 ]. TLC was performed using silica gel 60 F254 plates (20 × 20 cm; layer thickness, 0.20 mm; Merck) and chloroform–methanol–water (65:25:4, v / v / v ) as mobile phase.…”

The Mode of Action of Bacillus Species against Fusarium graminearum, Tools for Investigation, and Future Prospects

“…Bacillomycin L is presumed to act by inducing membrane permeabilization and disruption, as well as by targeting intercellular structrues [91]. Iturins have been found to be effective against a number of plant pathogenic fungi, which include Botrytis , Penicillium, Monilinia [92], R. solani [93], Colletotricum [94], F. oxysporum [95,96,97], and F. graminearum [19,26].…”

Biological control of fungal phytopathogens: A comprehensive review based on Bacillus species

“…[23][24][25][26] Iturin exhibit the antifungal activity against a number of fungal phytopathogens including F. graminearum, F. oxysporum, R. solani, Penicillium, Monilinia, Botrytis and Colletotricum. 26,[27][28][29] Surfactin: Surfactin are lipopeptides composed of β-hydoxyhepta cyclic depsipeptides with potential combinations of alanine, valine, leucine or isoleucine amino acids at positions 2, 4 and 7 in the cyclic depsipeptide moiety and variations of C13 to C16 in the chains of β-hydroxy fatty acids. 30 Surfactin exhibits naturally antifungal activity and produce by Bacillus spp.…”