Colletotrichum species are important fungal pathogens causing anthracnose of tropical and subtropical fruit and vegetable crops. Dual culture assay indicated that Bacillus velezensis CE 100 was a strong antagonist against C. acutatum, C. coccodes, C. dematium, and C. gloeosporioides. The volatile organic compounds produced by B. velezensis CE 100 affected mycelial growth of Colletotrichum species tested in our study and caused twisted hyphal structures of all these fungal species. Chloroform crude compounds of B. velezensis CE 100 inhibited four Colletotrichum species in a concentration-dependent manner and induced severe damage in hyphal morphology of these fungal pathogens, including swelling, bulging, and multiple branching. Moreover, the active cyclic dipeptide, cyclo-(D-phenylalanyl-D-prolyl), was isolated from chloroform crude extract and identified by nuclear magnetic resonance (NMR) and mass spectrometry. The inhibitory effect of cyclo-(D-phenylalanyl-D-prolyl) on conidial germination of C. gloeosporioides occurred in a concentration-dependent manner. The conidial germination rate was completely inhibited by a concentration of 3 mg/mL of cyclo-(D-phenylalanyl-D-prolyl). Scanning electron micrographs revealed that the exposure to cyclic dipeptide resulted in seriously deformed hyphae and conidia with shriveled surfaces in dipeptide-treated C. gloeosporioides. Therefore, active dipeptide-producing B. velezensis CE 100 is a promising biocontrol agent for Colletotrichum species causing anthracnose.

The aim of this study was to determine the plant growth-promoting effect of Bacillus subtilis PE7 on growth of melon plants. B. subtilis PE7 isolated from kimchi was identified based on colonial and microscopic morphology along with analyses of 16S rRNA and pycA gene sequences. Strain PE7 showed different levels of inhibition on phytopathogens and was able to grow at variable temperatures and pH values. Strain PE7 had the ability to produce siderophores, indole-3-acetic acid (IAA), ammonia, exopolysaccharides, and 1-aminocyclopropane-1-carboxylic acid deaminase, as well as solubilize insoluble phosphate and zinc. The IAA secretion of strain PE7 showed a concentration-dependent pattern based on the concentration of l-tryptophan supplemented in the fertilizer-based culture medium. The LC-MS analysis indicates the presence of IAA in the culture filtrate of strain PE7. Treatment of the B. subtilis PE7 culture containing different metabolites, mainly IAA, significantly promoted melon growth in terms of higher growth parameters and greater plant nutrient contents compared to treatments with the culture without IAA, fertilizer, and water. The cells of B. subtilis PE7 attached to and firmly colonized the roots of the bacterized melon plants. Based on our results, B. subtilis PE7 can be utilized as a potential microbial fertilizer to substitute chemical fertilizers in sustainable agriculture.

Microbial biocontrol agents have become an effective option to mitigate the harmfulness of chemical pesticides in recent years. This study demonstrates the control efficacy of Bacillus velezensis ce 100 on the anthracnose causal agent, Colletotrichum gloeosporioides. In vitro antifungal assays revealed that the culture filtrate and volatile organic compounds of B. velezensis ce 100 strongly restricted the mycelial development of C. gloeosporioides. Moreover, a bioactive compound, butyl succinate, was isolated from the n-butanol crude extract of B. velezensis ce 100 (bce), and identified by HR-ESI-MS and 1D- and 2D-NMR. Treatment with purified butyl succinate at a concentration of 300 μg mL⁻¹ strongly controlled conidial germination of C. gloeosporioides with an inhibition rate of 98.66%, whereas butyl succinate at a concentration of 400 μg mL⁻¹ showed weak antifungal action on the mycelial growth of C. gloeosporioides, with an inhibition rate of 31.25%. Scanning electron microscopy revealed that the morphologies of butyl succinate-treated hyphae and conidia of C. gloeosporioides were severely deformed with shriveled and wrinkled surfaces. Furthermore, butyl succinate was able to control carbendazim-resistant C. gloeosporioides, demonstrating that it could be a promising agent for the suppression of other carbendazim-resistant fungal pathogens. An in vivo biocontrol assay demonstrated that the strain ce 100 broth culture and butyl succinate showed higher control efficacy on apple anthracnose than bce. Our findings provide insight into the antifungal potential of B. velezensis ce 100 and its butyl succinate for efficient control of phytopathogenic fungi, such as C. gloeosporiodes, in plant disease protection. This is the first study to demonstrate the antifungal potential of bacteria-derived butyl succinate for control of C. gloeosporioides.

Shinorine is a mycosporine-like amino acid isolated from laver (Porphyra dentata), and interest in its functionality has increased recently due to increased production using yeast. There have been few reports on the pharmacological activity of shinorine, and we sought to find the pharmacological significance of shinorine. In the present study, we investigated the pharmacological effects of shinorine purified from Porphyra dentata on ARPE-19 cells. First, when ARPE-19 cells were treated with bis-retinoid N-retinyl-N-retinylidene ethanolamine (A2E) and blue light (BL), cytotoxicity increased, and apoptosis was observed. We investigated the effects of shinorine on A2E- and BL-induced cytotoxicity and changes in apoptotic factors, inflammation, and carbonyl stress. A2E and BL exposure increased ARPE-19 cell apoptosis, but this increase was attenuated by shinorine in a concentration-dependent manner. Treatment with A2E and BL induced ARPE-19 cell apoptosis, but treatment with shinorine decreased the apoptotic factors, such as MAPKs. Shinorine reduced p-JNK and p-P38, which were increased by A2E and BL. In addition, shinorine was found to regulate inflammatory proteins and proteins associated with carbonyl stress. In conclusion, shinorine may suppress cell damage caused by A2E treatment and BL exposure at the cellular level by regulating various cell death and inflammatory response pathways.