Iturin A6

Antifungal activity of endophytic Bacillus safensis B21 and its potential application as a biopesticide to control rice blast.[Pubmed:31836057]

Pestic Biochem Physiol. 2020 Jan;162:69-77.

Endophytic bacteria are potential biocontrol agents for the control of fungal diseases. Here, an endophyte strain, B21, was isolated from Osmanthus fragrans Lour. fruits and identified as Bacillus safensis by analysis of its 16S rDNA gene sequence and its biochemical and physiological characteristics. The culture filtrate showed antifungal activity against Magnaporthe oryzae, which causes rice blast disease, and the IC(50) of the methanol extract was 15.56 mug/mL, which was significantly lower than that of carbendazim (25.16 mug/mL). The antifungal activity of the methanol extract was stable at a wide range of pH values (1-9) and temperatures (40-100  degrees C). Two antifungal compounds were isolated by organic extraction, silica gel column chromatography and high-performance liquid chromatography (HPLC). Based on electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance spectrometry (NMR) analyses, the structures of the antifungal compounds were identified as iturin A2 and Iturin A6. Additionally, the hyphae treated with iturin (iturin A2 or Iturin A6) could be stained with the fluorescent dye propidium iodide (PI), indicating that these two compounds inhibited the growth of hyphae by changing the hyphal membrane permeability. In field experiments, spray treatment with fermentation broth resulted in a lower disease index than treatment with carbendazim, as did the culture filtrate. The results suggest that strain B21 and its bioactive compounds have the potential to be developed into a biopesticide for the biocontrol of rice blast.

Study of the antifungal activity of Acinetobacter baumannii LCH001 in vitro and identification of its antifungal components.[Pubmed:17534613]

Appl Microbiol Biotechnol. 2007 Aug;76(2):459-66.

An Acinetobacter strain, given the code name LCH001 and having the potential to be an endophytic antagonist, has been isolated from healthy stems of the plant Cinnamomum camphora (L.) Presl, guided by an in vitro screening technique. The bacterium inhibited the growth of several phytopathogenic fungi such as Cryphonectria parasitica, Glomerella glycines, Phytophthora capsici, Fusarium graminearum, Botrytis cinerea, and Rhizoctonia solani. Biochemical, physiological, and 16S rDNA sequence analysis proved that it is Acinetobacter baumannii. When the filtrate from the fermentation broth of strain LCH001 was tested in vitro and in vivo, it showed strong growth inhibition against several phytopathogens including P. capsici, F. graminearum, and R. solani, indicating that suppression of the growth of the fungi was due to the presence of antifungal compounds in the culture broth. Moreover, the antifungal activity of the culture filtrate was significantly correlated with the cell growth of strain LCH001. The active metabolites in the filtrate were relatively thermally stable, but were sensitive to acidic conditions. Three antifungal compounds were isolated from the culture broth by absorption onto macropore resin, ethanol extraction, chromatography on silica gel or LH-20 columns, and crystallization. The structures of the bioactive compounds were identified by spectroscopic methods as isomers of iturin A, namely, iturin A2, iturin A3, and Iturin A6. The characterization of an unusual endophytic bacterial strain LCH001 and its bioactive components may provide an alternative resource for the biocontrol of plant diseases.

Iturin A6 (CAS 83777-02-0) is a natural product offered by BioCrick for research applications. Customers can buy or order Iturin A6 from BioCrick, a supplier and manufacturer of research chemicals, with product specifications, purity, packaging, and pricing information available upon request.