RESUMO
Rhizoctonia solani is a significant pathogen affecting various crops, including tobacco. In this study, a bacterial strain, namely Y246, was isolated from the soil of healthy plants and exhibited high antifungal activity. Based on morphological identification and DNA sequencing, this bacterial strain was identified as Bacillus safensis. The aim of this investigation was to explore the antifungal potential of strain Y246, to test the antifungal stability of Y246 by adjusting different cultivation conditions, and to utilize gas chromatography-mass spectrometry (GC-MS) to predict the volatile compounds related to antifungal activity in Y246. In vitro assays demonstrated that strain Y246 exhibited a high fungal inhibition rate of 76.3%. The fermentation broth and suspension of strain Y246 inhibited the mycelial growth of R. solani by 66.59% and 63.75%, respectively. Interestingly, treatment with volatile compounds derived from the fermentation broth of strain Y246 resulted in abnormal mycelial growth of R. solani. Scanning electron microscopy analysis revealed bent and deformed mycelium structures with a rough surface. Furthermore, the stability of antifungal activity of the fermentation broth of strain Y246 was assessed. Changes in temperature, pH value, and UV irradiation time had minimal impact on the antifungal activity, indicating the stability of the antifungal activity of strain Y246. A GC-MS analysis of the volatile organic compounds (VOCs) produced by strain Y246 identified a total of 34 compounds with inhibitory effects against different fungi. Notably, the strain demonstrated broad-spectrum activity, exhibiting varying degrees of inhibition against seven pathogens (Alternaria alternata, Phomopsis. sp., Gloeosporium musarum, Dwiroopa punicae, Colletotrichum karstii, Botryosphaeria auasmontanum, and Botrytis cinerea). In our extensive experiments, strain Y246 not only exhibited strong inhibition against R. solani but also demonstrated remarkable inhibitory effects on A. alternata-induced tobacco brown spot and kiwifruit black spot, with impressive inhibition rates of 62.96% and 46.23%, respectively. Overall, these findings highlight the significant antifungal activity of B. safensis Y246 against R. solani. In addition, Y246 has an excellent antifungal stability, with an inhibition rate > 30% under different treatments (temperature, pH, UV). The results showed that the VOCs of strain Y246 had a strong inhibitory effect on the colony growth of R. solani, and the volatile substances produced by strain Y246 had an inhibitory effect on R. solani at rate of 70.19%. Based on these results, we can conclude that Y246 inhibits the normal growth of R. solani. These findings can provide valuable insights for developing sustainable agricultural strategies.
RESUMO
The title compound, [Co(C(2)H(8)N(2))(3)](2)[SiMo(8)V(4)O(40)(VO)(2)]·6H(2)O, was prepared under hydro-thermal conditions. The asymmetric unit consists of a transition metal complex [Co(en)(3)](3+) cation (en is ethyl-enediamine), one half of an [SiMo(8)V(4)O(40)(VO)(2)](6-) heteropolyanion, two solvent water mol-ecules in general positions and two half-mol-ecules of water located on a mirror plane. In the complex cation, the Co(3+) ion is in a distorted octa-hedral coordination environment formed by six N atoms of the three chelating en ligands. One of the en ligands exhibits disorder of its aliphatic chain over two sets of sites of equal occupancy. The [SiMo(8)V(4)O(40)(VO)(2)](6-) heteropolyanion is a four-electron reduced bivanadyl-capped α-Keggin-type molybdenum-vanadium-oxide cluster. In the crystal, it is located on a mirror plane, which results in disorder of the central tetra-hedral SiO(4) group: the O atoms of this group occupy two sets of sites related by a mirror plane. Furthermore, all of the eight µ(2)-oxide groups are also disordered over two sets of sites with equal occupancy. There are extensive inter-molecular N-Hâ¯O hydrogen bonds between the complex cations and inorganic polyoxidoanions, leading to a three-dimensional supra-molecular network.