Edeines, a group of cationic antimicrobial peptides produced by the soil bacterium Brevibacillus, have broad biological effects, such as antimicrobial, anticancer and immunosuppressive activities. However, the yield of edeines in wild-type (WT) Brevibacillus is extremely low, and chemical synthesis of edeines is a time-consuming process. Genetic engineering has proven to be an effective approach to produce antibiotics with high yield. In this study, the edeine biosynthetic gene cluster (ede BGC), which is involved in edeine production, was identified and characterized in Brevibacillus brevis X23. To improve edeine production in B. brevis X23, the ede BGC promoter was replaced with six different promoters, P mwp , P spc , P xylA , P shuttle-09 , P grac or P 43 , through double-crossover homologous recombination. The new promoters significantly increased the expression of the ede BGC as well as edeine production by 2.9 AE 0.4 to 20.5 AE 1.2-fold and 3.6 AE 0.1to 8.7 AE 0.7fold respectively. The highest yield of edeines (83.6 mg l À1 ) was obtained in B. brevis X23 with the P mwp promoter. This study provides a practical approach for producing high yields of edeines in B. brevis.

Phytopathogenic fungi infect crops, presenting a worldwide threat to agriculture. Polyene macrolides are one of the most effective antifungal agents applied in human therapy and crop protection. In this study, we found a cryptic polyene biosynthetic gene cluster in Actinokineospora spheciospongiae by genome mining. Then, this gene cluster was activated via varying fermentation conditions, leading to the discovery of new polyene actinospene (1), which was subsequently isolated and its structure determined through spectroscopic techniques including UV, HR-MS, and NMR. The absolute configuration was confirmed by comparing the calculated and experimental electronic circular dichroism (ECD) spectra. Unlike known polyene macrolides, actinospene (1) demonstrated more versatile post-assembling decorations including two epoxide groups and an unusual isobutenyl side chain. In bioassays, actinospene (1) showed a broad spectrum of antifungal activity against several plant fungal pathogens as well as pathogenic yeasts with minimum inhibitory concentrations ranging between 2 and 10 μg/mL.

Edeines are a group of non-ribosomal antibacterial peptides produced by Brevibacillus brevis. Due to the significant antibacterial properties of edeines, increasing edeine yield is of great interest in biomedical research. Herein, we identified that EdeB, a member of the ParB protein family, significantly improved edeine production in B. brevis. First, overexpression of edeB in B. brevis X23 increased edeine production by 92.27%. Second, in vitro bacteriostasis experiment showed that edeB-deletion mutant exhibited less antibacterial activity. Third, RT-qPCR assay demonstrated that the expression of edeA, edeQ, and edeK, which are key components of the edeine biosynthesis pathway, in edeB-deletion mutant X23(ΔedeB) was significantly lower than that in wild-type B. brevis strain X23. Finally, electrophoretic mobility shift assay (EMSA) showed that EdeB directly bound to the promoter region of the edeine biosynthetic gene cluster (ede BGC), suggesting that EdeB improves edeine production through interaction with ede BGC in B. brevis.

A novel series of cycloproply derris dihydrazone derivatives 3a～3p were designed and synthesized by reacting substituted aldehydes/ketones with intermediate (2R)-5-[(5',6'-dimethoxy-1',1'a,2',7'b-tetrahydrocyclopro-pa[c]chromen-7'byl)(hydrazono)methyl]-2-(prop-1"-en-2"-yl)-2,3-dihydrobenzofuran-4-ol (2), which was synthesized via the reactions of the rotenone, dimethyloxosulphonium methylide and hydrazine hydrate. Their structures were characterized by 1 H NMR and LRMS. The results of bioassay indicated that the title compounds exhibited potent fungicidal activity against Rhizoctonia solani, Sclerotonia sclerotiorum and Blumeria graminis. Compounds 3d and 3o showed 55.1% and 55.5% control rates against Rhizoctonia solani at 500 mg/L, respectively, compounds 3a, 3c, 3e, 3h and 3k showed 76.8%, 87.0%, 70.6%, 72.5% and 65.2% inhibition rates against Sclerotonia sclerotiorum at 25 mg/L, respectively, and compounds 3a, 3c, 3g, 3i and 3l showed 80.0%～90.0% control rate against Blumeria graminis at 500 mg/L.

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