Burkholderia gladioli strain KJ-34 exhibits broad-spectrum antifungal activity

Abstract

IntroductionPlant pathogens are one of the major constraints on worldwide food production. The antibiotic properties of microbes identified as effective in managing plant pathogens are well documented.MethodsHere, we used antagonism experiments and untargeted metabolomics to isolate the potentially antifungal molecules produced by KJ-34.ResultsKJ-34 is a potential biocontrol bacterium isolated from the rhizosphere soil of rice and can fight multiple fungal pathogens (i.e. Ustilaginoidea virens, Alternaria solani, Fusarium oxysporum, Phytophthora capsica, Corynespora cassiicola). The favoured fermentation conditions are determined and the fermentation broth treatment can significantly inhibit the infection of Magnaporthe oryzae and Botryis cinerea. The fermentation broth suppression ratio is 75% and 82%, respectively. Fermentation broth treatment disrupted the spore germination and led to malformation of hyphae. Additionally, we found that the molecular weight of antifungal products were less than 1000 Da through semipermeable membranes on solid medium assay. To search the potentially antifungal molecules that produce by KJ-34, we used comparative and bioinformatics analyses of fermentation broth before and after optimization by mass spectrometry. Untargeted metabolomics analyses are presumed to have a library of antifungal agents including benzoylstaurosporine, morellin and scopolamine.DiscussionThese results suggest that KJ-34 produced various biological control agents to suppress multiple phytopathogenic fungi and showed a strong potential in the ecological technologies of prevention and protection.

Characterization of a broad-spectrum antifungal strain, Streptomyces graminearus STR-1, against Magnaporthe oryzae

“…The blast fungus M. oryzae strain Guy11 were used throughout this study. Guy11 was grown on CM medium or tomato oat medium at 28°C for 10 days and its spore suspension was prepared for inoculating rice plants as previously described ( Yang C. et al, 2023 ).…”

“…Thus, the paste extracts of ethyl acetate were dissolved with methanol at a concentration of 1 mg/mL for the next round of extraction by silica gel column chromatography. Using thin layer chromatography (TLC), the optimal condition of developing solvent for separation was determined as a combination of n-hexane and ethyl acetate at a ratio of 15:1 ( Yang C. et al, 2023 ).…”

“…A 7 mm diameter agar block grown with M. oryzae or other fungal strains was inoculated onto the center of CM plates containing filtrate fermentation solution of STR-1. The inoculated plates were cultured for 7 days in a 28°C incubator as previously described ( Yang C. et al, 2023 ). The growth of M. oryzae was monitored and recorded throughout the growth period.…”

“…Rice total RNA was extracted from leaves using Trizol agent after grounding into powder by liquid nitrogen. Reverse transcription of RNA was performed using TaKaRa’s reverse transcription kit ( Yang C. et al, 2023 ), and quantitative PCR was then conducted with specific primer pairs for detecting the expression levels of pathogenesis-related genes (PRs) and other defense-related genes ( Table 1 ). Relative gene expression was normalized by comparing with the expression of Ubiquitin and analyzed using the 2 −ΔΔCT method ( Park et al, 2012 ).…”

Identification and application of an endophytic fungus Arcopilus aureus from Panax notoginseng against crop fungal disease

“…Medicinal plants and their associated microflora are important resources for the development of antioxidant products, and antifungal and anticancer drugs ( Luo et al., 2023 ; Yang et al., 2023 ). However, information on endophytic fungi associated with the medicinal plant Panax notoginseng is limited.…”