Activity of Fengycin and Iturin A Isolated From Bacillus subtilis Z-14 on Gaeumannomyces graminis Var. tritici and Soil Microbial Diversity

Abstract

Bacillus subtilis Z-14 can inhibit phytopathogenic fungi, and is used as a biocontrol agent for wheat take-all disease. The present study used the soil-borne fungus Gaeumannomyces graminis var. tritici (Ggt), which causes wheat take-all disease, and the soil microbial community as indicators, and investigated the antifungal effects of fengycin and iturin A purified from strain Z-14 using high performance liquid chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, respectively. The results showed that fengycin destroyed the internal structure of Ggt cells by digesting the cytoplasm and organelles, forming vacuoles, and inducing hyphal shrinkage and distortion. Iturin A induced cell wall disappearance, membrane degeneration, intracellular material shrinkage, and hyphal fragmentation. A biocontrol test demonstrated a 100% control effect on wheat take-all when wheat seedlings were treated with fengycin at 100 μg/ml or iturin A at 500 μg/ml. Iturin A and fengycin both reduced the relative abundance of Aspergillus and Gibberella. At the genus level, iturin A reduced the relative abundance of Mortierella and Myrothecium, while fengycin reduced that of Fusarium. Only fengycin treatment for 7 days had a significant effect on soil bacterial diversity.

The lipopeptides fengycin and iturin are involved in the anticandidal activity of endophytic Bacillus sp. as determined by experimental and in silico analysis

“…The treated cells looked deformed with loss of cellular integrity and budding capability, indicating that cell membrane disruption and division impairment are major mechanisms of action of the K7 bioactive metabolites, consistent with previous reports of anticandidal action of lipopeptides (Sharma et al 2020). The presence of multiple 'empty' CA cells, devoid of any discernible cellular material in the K7 extract-treated set suggests the destruction of the cell membranes, a typical feature of antimicrobial biosurfactant molecules (Xiao et al 2021).…”

“…The presence of multiple ‘empty’ CA cells, devoid of any discernible cellular material in the K7 extract‐treated set suggests the destruction of the cell membranes, a typical feature of antimicrobial biosurfactant molecules (Xiao et al . 2021).…”

Comparison of Antifungal Activity of Bacillus Strains against Fusarium graminearum In Vitro and In Planta

“…Notably, the secretome of the B. subtilis strain 168 has been studied extensively for its ability to produce many compounds that are beneficial for industry [ 29 , 47 , 48 ]. In addition, treatment of CFS with heat and proteinase K did not decrease the activity of the CFS against Fg -K1-4 indicating that the antagonistic compounds are thermostable and not proteinaceous but possibly antimicrobial compounds such as fengycin and iturin A [ 49 ]. In other studies where compounds were purified, the minimal inhibitory concentrations were found to be in the range of 50 to 128 µg/mL for iturin A and fengycin A [ 24 , 45 , 50 ].…”

Genomic analysis uncovers laccase-coding genes and biosynthetic gene clusters encoding antimicrobial compounds in laccase-producing Acinetobacter baumannii

“…Fengycins are lipopeptides produced by Bacillus spp. that display potent antifungal activity against plant pathogens and multidrug-resistant foodborne pathogens 18 , 19 . This compound has great potential for application as a biocontrol agent in the agriculture and food industries.…”