A Seed-Endophytic Bacillus safensis Strain With Antimicrobial Activity Has Genes for Novel Bacteriocin-Like Antimicrobial Peptides

Bacillus safensis from Sauerkraut Alleviates Acute Lung Injury Induced by Methicillin-Resistant Staphylococcus aureus through the Regulation of M2 Macrophage Polarization via Its Metabolite Esculin

Sauerkraut contains various fermentative microorganisms that produce active metabolites, enhancing immunity and resistance to infections. However, its effects on methicillin-resistant Staphylococcus aureus (MRSA)-induced acute lung injury (ALI) remain unclear. Using RAW264.7 cells and a mouse model, we demonstrated that Bacillus safensis SK14 (BS SK14), an understudied fermentative bacterium, has an immunomodulatory effect on MRSA-induced ALI. BS SK14 significantly reduced the inflammatory responses. Supplementation with live BS SK14 or its culture supernatant increased survival rates, reduced lung damage, and attenuated inflammation in ALI model mice. LC-MS/MS analysis identified esculin as the key metabolite responsible for these effects. BS SK14 produces esculin via the gut-lung axis, inhibiting the TLR2-MyD88-NF-κB pathway, reducing Keap1 levels, and activating the Nrf2-ARE pathway. This decreased MRSA-induced M1 polarization and increased M2 polarization, enhancing antioxidant and anti-inflammatory activities in mice. Collectively, these results reveal that BS SK14 and its metabolite esculin exert therapeutic effects on MRSA-induced ALI through a multifactorial strategy.

Bacillus safensis LS01 provides biological control of potato common scab with potential effects from secondary metabolites

AIMS

Potato common scab (CS), caused by pathogenic Streptomyces, is a devastating disease affecting potato crops worldwide. Antagonistic microorganisms have been used as biological control agents to inhibit Streptomyces scabies and reduce the use of synthetic pesticides. However, identifying beneficial microorganisms for controlling CS remains undetermined.

METHODS AND RESULTS

Strain LS01 was isolated from the geocaulosphere soils of healthy potato tubers. In vitro and pot experiments demonstrated that strain LS01 significantly inhibited the mycelial growth and sporulation of S. scabies, thereby reducing the severity of CS. Sequencing of the 16S rRNA of LS01 indicated that the strain belonged to the species Bacillus safensis. Whole-genome sequencing, metabolomic analysis with liquid chromatograph mass spectrometer, and uultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry analyses indicated that hygromycin B and plantazolicin may be the active secondary metabolites by which B. safensis LS01 inhibits S. scabies.

CONCLUSIONS

Bacillus safensis LS01 is a potential biocontrol agent for CS, with its secondary metabolites exerting effective inhibitory effects.

Whole Genome Sequencing of Bacillus velezensis AMR25, an Effective Antagonist Strain against Plant Pathogens

The most serious problems for cultivated grapes are pathogenic microorganisms, which reduce the yield and quality of fruit. One of the most widespread disease of grapes is "gray mold", caused by the fungus Botrytis cinerea. Some strains of Bacillus, such as Bacillus halotolerans, Bacillus amyloliquefaciens, and Bacillus velezensis, are known to be active against major post-harvest plant rots. In this study, we showed that the endophytic bacteria B. velezensis strain AMR25 isolated from the leaves of wild grapes Vitis amurensis Rupr. exhibited antimicrobial activity against grape pathogens, including B. cinerea. The genome of B. velezensis AMR25 has one circular chromosome with a length of 3,909,646 bp. with 3689 open reading frames. Genomic analysis identified ten gene clusters involved in the nonribosomal synthesis of polyketides (macrolactin, bacillene, and difficidin), lipopeptides (surfactin, fengycin, and bacillizin), and bacteriocins (difficidin). Also, the genome under study contains a number of genes involved in root colonization, biofilm formation, and biosynthesis of phytohormones. Thus, the endophytic bacteria B. velezensis strain AMR25 shows great promise in developing innovative biological products for enhancing plant resistance against various pathogens.

Bacillus-based biocontrol beyond chemical control in central Africa: the challenge of turning myth into reality

Agricultural productivity in the Great Lakes Countries of Central Africa, including Burundi, Rwanda, and the Democratic Republic of Congo, is affected by a wide range of diseases and pests which are mainly controlled by chemical pesticides. However, more than 30% of the pesticides used in the region are banned in European Union due to their high toxicity. Globally available safe and eco-friendly biological alternatives to chemicals are virtually non-existent in the region. Bacillus PGPR-based biocontrol products are the most dominant in the market and have proven their efficacy in controlling major plant diseases reported in the region. With this review, we present the current situation of disease and pest management and urge the need to utilize Bacillus-based control as a possible sustainable alternative to chemical pesticides. A repertoire of strains from the Bacillus subtilis group that have shown great potential to antagonize local pathogens is provided, and efforts to promote their use, as well as the search for indigenous and more adapted Bacillus strains to local agro-ecological conditions, should be undertaken to make sustainable agriculture a reality in the region.

Microbiome Signature of Endophytes in Wheat Seed Response to Wheat Dwarf Bunt Caused by Tilletia controversa Kühn

Wheat dwarf bunt leads to the replacement of seeds with fungal galls containing millions of teliospores of the pathogen Tilletia controversa Kühn. As one of the most devastating internationally quarantined wheat diseases, wheat dwarf bunt spreads to cause distant outbreaks by seeds containing teliospores. In this study, based on a combination of amplicon sequencing and isolation approaches, we analyzed the seed microbiome signatures of endophytes between resistant and susceptible cultivars after infection with T. controversa. Among 310 bacterial species obtained only by amplicon sequencing and 51 species obtained only by isolation, we found 14 overlapping species by both methods; we detected 128 fungal species only by amplicon sequencing, 56 only by isolation, and 5 species by both methods. The results indicated that resistant uninfected cultivars hosted endophytic communities that were much more stable and beneficial to plant health than those in susceptible infected cultivars. The susceptible group showed higher diversity than the resistant group, the infected group showed more diversity than the uninfected group, and the microbial communities in seeds were related to infection or resistance to the pathogen. Some antagonistic microbes significantly suppressed the germination rate of the pathogen's teliospores, providing clues for future studies aimed at developing strategies against wheat dwarf bunt. Collectively, this research advances the understanding of the microbial assembly of wheat seeds upon exposure to fungal pathogen (T. controversa) infection. IMPORTANCE This is the first study on the microbiome signature of endophytes in wheat seed response to wheat dwarf bunt caused by Tilletia controversa Kühn. Some antagonistic microbes suppressed the germination of teliospores of the pathogen significantly, which will provide clues for future studies against wheat dwarf bunt. Collectively, this research first advances the understanding of the microbial assembly of wheat seed upon exposure to the fungal pathogen (T. controversa) infection.