Streptomyces araujoniae Produces a Multiantibiotic Complex with Ionophoric Properties to Control Botrytis cinerea

Abstract

A recently described actinomycete species (Streptomyces araujoniae ASBV-1(T)) is effective against many phytopathogenic fungi. In this study, we evaluated the capacity of this species to inhibit Botrytis cinerea development in strawberry pseudofruit, and we identified the chemical structures of its bioactive compounds. An ethyl acetate crude extract (0.1 mg ml(-1)) of ASBV-1(T) fermentation broth completely inhibited fungus growth in strawberry pseudofruit under storage conditions. The crude extract was fractionated by preparative high-performance liquid chromatography; the active fraction was further evaluated by tandem mass spectrometry. ASBV-1(T) produced a multiantibiotic complex with ionophoric properties. This complex contained members of the macrotetralides class (including monactin, dinactin, trinactin, and tetranactin) and the cyclodepsipeptide valinomycin, all of which were active against B. cinerea. Furthermore, the addition of 2 mM MgSO4 and 1 mM ZnSO4 enhanced macrotetralide and valinomycin production, respectively, in the culture broth. These compounds are considered to be the main active molecules that S. araujoniae produces to control B. cinerea. Their low to moderate toxicity to humans and the environment justifies the application of ASBV-1(T) in biological control programs that aim to mitigate the damage caused by this phytopathogen.

Community Structures and Antifungal Activity of Root-Associated Endophytic Actinobacteria of Healthy and Diseased Soybean

“…A mixture of dinactin ( 7 ), trinactin and the major component tetranactin ( 6 ) is known as commercial pesticides polynactin (liuyangmycin in China), which can effectively control spider mites under wet conditions [71]. In addition, tetranactin ( 6 ) also exhibited significant antifungal activity against plant pathogen Botrytis cinerea with a minimum inhibitory concentration (MIC) of 24 µg·mL –1 [72]. Besides dinactin ( 7 ) and tetranactin ( 6 ), the monomer ( 4 ) and dimer ( 5 ) of polynactin were also isolated in this study, all of which were active against S. sclerotiorum .…”

Isolation and evaluation of endophytic Streptomyces endusOsiSh‐2 with potential application for biocontrol of rice blast disease

“…The effect of extract on growth of M. oryzae was determined as described above, and the extract with the best inhibition activity was conducted to characterize the antifungal metabolites on a Acquity UPLC I‐Class system coupled to a Xevo TQ‐S triple quadrupole mass spectrometer (Waters, Milford, MA, USA) with positive electrospray ionization (ESI + ) mode and multiple reaction monitoring. The operating parameters of the instrument were as described previously by Silva et al . The nigericin standard used for identification was obtained from InvivoGen (San Diego, CA, USA).…”

Identification of antimicrobial metabolites produced by a potential biocontrol Actinomycete strain A217

“…Streptomyces strains, as prolific microbial sources of a large number and wider variety of new antibiotics (Wei et al ), and it can play an important role in the prevention and control of agricultural and human diseases(Tang et al ;). Several Streptomyces strains that suppress the growth of fungi and bacteria produce antibiotic compounds such as phosphazomyzin, albopeptin B, tautomycin, tautomycein and ezomycin (Silva et al ; Cordovez et al ). Diversity in the chemical structure of these metabolites reduce the chances of pathogens developing resistance (Uemura ; Hu et al ).…”