The use of synthetic fungicides has caused major problems such as soil and water pollution and negatively affects non-target species. Microbial biocontrol agents are needed for crop disease management to reduce agrochemical use. Bacillus and related genera produce secondary metabolites with agricultural applications, such as the pathogen-control agent Bacillus velezensis. We isolated B. velezensis TSA32-1 from soil and identified its characteristics by sequencing its 16S rRNA. B. velezensis TSA32-1 showed enzyme activity and antimicrobial effects against phytopathogenic fungi by inhibiting the growth of Fusarium graminearum, F. fujikuroi, Alternatia alternate, and Diaporthe actinidiae. Additionally, B. velezensis TSA32-1 protected diseases in corn and pepper seeds caused by F. graminearum and Pythium ultimum. The complete genome of B. velezensis TSA32-1 was 4.05 Mb with a G+C content of 46.3 mol % and possessed the bacillaene biosynthesis cluster, a polyketide that inhibits protein biosynthesis. We also detected a surfactin synthesis cluster, known as non-ribosomal peptide synthetases, which biosynthesizes the antibacterial substance lipopeptide. Surfactin, and fengycin family compounds, secondary metabolites known as key factors in biological control, also detected B. velezensis TSA32-1 which shows potential as a biocontrol agent for controlling plant pathogens in agriculture.

Global climate change poses a significant threat to plant growth and crop yield and is exacerbated by environmental factors, such as drought, salinity, greenhouse gasses, and extreme temperatures. Plant growth-promoting rhizobacteria (PGPR) help plants withstand drought. However, the mechanisms underlying PGPR–plant interactions remain unclear. Thus, this study aimed to isolate PGPR, Bacillus megaterium strains CACC109 and CACC119, from a ginseng field and investigate the mechanisms underlying PGPR-stimulated tolerance to drought stress by evaluating their plant growth-promoting activities and effects on rice growth and stress tolerance through in vitro assays, pot experiments, and physiological and molecular analyses. Compared with B. megaterium type strain ATCC14581, CACC109 and CACC119 exhibited higher survival rates under osmotic stress, indicating their potential to enhance drought tolerance. Additionally, CACC109 and CACC119 strains exhibited various plant growth-promoting activities, including phosphate solubilization, nitrogen fixation, indole-3-acetic acid production, siderophore secretion, 1-aminocyclopropane-1-carboxylate deaminase activity, and exopolysaccharide production. After inoculation, CACC109 and CACC119 significantly improved the seed germination of rice (Oryza sativa L.) under osmotic stress and promoted root growth under stressed and non-stressed conditions. They also facilitated plant growth in pot experiments, as evidenced by increased shoot and root lengths, weights, and leaf widths. Furthermore, CACC109 and CACC119 improved plant physiological characteristics, such as chlorophyll levels, and production of osmolytes, such as proline. In particular, CACC109- and CACC119-treated rice plants showed better drought tolerance, as evidenced by their higher survival rates, greater chlorophyll contents, and lower water loss rates, compared with mock-treated rice plants. Application of CACC109 and CACC119 upregulated the expression of antioxidant-related genes (e.g., OsCAT, OsPOD, OsAPX, and OsSOD) and drought-responsive genes (e.g., OsWRKY47, OsZIP23, OsDREB2, OsNAC066, OsAREB1, and OsAREB2). In conclusion, CACC109 and CACC119 are promising biostimulants for enhancing plant growth and conferring resistance to abiotic stresses in crop production. Future studies should conduct field trials to validate these findings under real agricultural conditions, optimize inoculation methods for practical use, and further investigate the biochemical and physiological responses underlying the observed benefits.

The present study aimed to evaluate the probiotic characteristics of certain microbial strains for potential use as feed additives. Three bacterial strains and a yeast previously isolated from different environments were investigated. The strains were subjected to molecular identification and established as Lactobacillus paracasei CP133, Lactobacillus plantarum CP134, Bacillus subtilis CP350 and Saccharomyces cerevisiae CP605. Lactobacillus sp. CP133 and CP134 exhibited antibiosis, antibiotic activity, and relative odor reduction ability. Bacillus subtilis CP350 was thermotolerant, reduced hydrogen sulfide gas and showed significant proteolytic activity, whereas Saccharomyces cerevisiae CP605 exhibited high acid and bile salt tolerance. In general, the isolates in this study demonstrated improved functional characteristics, particularly acid and bile tolerance and relative cell adhesion to HT-29 monolayer cell line. Results in this work provides multifunctional probiotic characteristics of the strains for potential development of probiotics and cleaning of the environment.

Brown leaf spot disease caused by Alternaria spp. is among the most common diseases of potato crops. Typical brown spot symptoms were observed in commercial potato-cultivation areas of northern Korea from June to August 2020–2021. In total, 68 isolates were collected, and based on sequence analysis of the internal transcribed spacer (ITS) region, the collected isolates were identified as Alternaria spp. (80.9%). Phylogenetic analysis revealed that a majority of these isolates clustered within a clade that included A. alternata. Additionally, the ITS region and rpb2 yielded the most informative sequences for the identification of A. alternata. Pathogenicity tests confirmed that the collected pathogens elicited symptoms identical to those observed in the field. In pathogenicity tests performed on seven commercial cultivars, the pathogens exhibited strong virulence in both wound and non-wound inoculations. Among the cultivars tested, Arirang-1ho, Arirang-2ho, and Golden Ball were resistant to the pathogens. Furthermore, among the fungicides tested in vitro, mancozeb and difenoconazole were found to be effective for inhibiting mycelial growth. In summary, our findings suggest that A. alternata plays a critical role in leaf disease in potato-growing regions and emphasise the necessity of continuous monitoring and management to protect against this disease in Korea.

Probiotics can modulate the composition of gut microbiota and benefit the host animal health in multiple ways. Lactic acid bacteria (LAB), mainly Lactobacillus and Bifidobacterium species, are well-known microbes with probiotic potential. In the present study, 88 microbial strains were isolated from canine feces and annotated. Among these, the four strains CACC517, 537, 558, and 566 were tested for probiotic characteristics, and their beneficial effects on hosts were evaluated both in vitro and in vivo; these strains exhibited antibiosis, antibiotic activity, acid and bile tolerance, and relative cell adhesion to the HT-29 monolayer cell line. Byproducts of these strains increased the viability and decreased oxidative stress in mouse and dog cell lines (RAW264.7 and DH82, respectively). Subsequently, when the probiotics were applied to the clinical trial, changes in microbial composition and relative abundance of bacterial strains were clearly observed in the experimental animals. Experimental groups before and after the application were obviously separated from PCA analysis of clinical results. Conclusively, these results could provide comprehensive understanding of the effects of probiotic strains (CACC517, 537, 558, and 566) and their industrial applications.

During weaning, piglets experience various stressor events that disrupt their gut microbiota and immune balance, decrease growth parameters, and increase mortality rates. In this study, we assessed the efficacy of Pediococcus pentosaceus CACC616 as a probiotic supplement. We characterized this strain and evaluated its effect on improving growth performance, modulating gut microbiota composition, and reducing noxious odor components in weaned piglets compared to a non-supplementary diet (control). During the 26-day period, 40 crossbred weaned piglets were randomly assigned to pens with 20 animals each in two groups: control and treatment groups with CACC616. On day 26, the treatment group exhibited a lower feed conversion ratio (FCR) and a significant alteration in gut microbial composition, correlating with improved growth parameters and gut health (p < 0.05). The treatment group also exhibited significantly reduced digestibility- and intestinal-environment-related noxious odor components (p < 0.05). The CACC616 strain effectively reduced pathogenic genera numbers, including Campylobacter, Mogibacterium, Escherichia–Shigella, and Desulfovibrio spp., with the treatment group exhibiting lower fecal calprotectin levels than the control group (p < 0.05). Overall, this study revealed that the functional probiotic CACC616 contributes to enhanced FCR and effectively modulates weaned piglets’ inflammation and intestinal microbiota.