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Journal Article
- Description of Fervidibacillus gen. nov. with Two Species, Fervidibacillus albus sp. nov., and Fervidibacillus halotolerans sp. nov., Isolated from Tidal Flat Sediments and Emendation of Misclassificed Taxa in the Genus Caldibacillus
- Sung&# , Mi&# , Hyun&# , Kae Kyoung Kwon
- J. Microbiol. 2023;61(2):175-187. Published online February 17, 2023
- DOI: https://doi.org/10.1007/s12275-023-00022-y
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- 2 Citations
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Abstract
- Two Gram-stain-positive, motile, endospore-forming, facultatively anaerobic strains, designated MEBiC13591T and MEBiC13594T, were isolated from tidal flat sediment of the Incheon City on the west coast of Korea. Growth of both novel strains was observed at pH 5–9 (optimum, pH 7–7.5), and in 0–8% NaCl (optimum, 2% for MEBiC13591T and 3% for MEBiC13594T). Strains MEBiC13591T and MEBiC13594T grew optimally at 50 °C, (37.5–56.1 °C) and 44 °C (20.7–50.7 °C), respectively. The main cellular fatty acids of strain MEBiC13591T were iso-C15: 0, anteiso-C15: 0, iso-C16: 0, iso-C17: 0 and anteiso-C17: 0, while those for strain MEBiC13594T were C14: 0, iso-C14: 0, iso-C15: 0, anteiso-C15: 0 and C16: 0. In both taxa, the major isoprenoid was MK-7. The genomic DNA G + C contents were 34.1 and 37.0 mol% for MEBiC13591T and MEBiC13594T, respectively. A 16S rRNA gene sequence analysis revealed that the novel strains showed high similarity with members of the genera Aeribacillus (95.0%) and Caldibacillus (93.5–94.5%); however, showed lower than 90% with Caldibacillus debilis TfT. Phylogenetic and Phylogenomic analysis revealed that two novel strains comprised distinct phyletic line with members formerly assigned to Caldibacillus. Based on genomic indices, such as AAI and ANI, members formerly affiliated with Caldibacillus and Bacillus as well as the novel strains should be classified into five independent genera. Based on the phenotypic, genomic and biochemical data, strains MEBiC13591T and MEBiC13594T represent two novel species in the novel genus, for which the names Fervidibacillus albus gen. nov., sp. nov. ( MEBiC13591T [= KCCM 43317T = KCTC 43181T = JCM 33662T = MCCC 1K04565T]), and Fervidibacillus halotolerans sp. nov. ( MEBiC13594T [= KCTC 43182T = JCM 34001T]) are proposed. Three additional genera Caldifermentibacillus, Palidibacillus, and Perspicuibacillus are also proposed by reclassification of the several species with valid names that formerly affiliated with the genera Caldibacillus.
Review
- COVID-19 vaccine development based on recombinant viral and bacterial vector systems: combinatorial effect of adaptive and trained immunity
- Mi-Hyun Lee , Bum-Joon Kim
- J. Microbiol. 2022;60(3):321-334. Published online February 14, 2022
- DOI: https://doi.org/10.1007/s12275-022-1621-2
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- 12 Citations
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Abstract
- Severe acute respiratory syndrome coronavirus 2 virus (SARSCoV- 2) infection, which causes coronavirus disease 2019 (COVID-19), has led to many cases and deaths worldwide. Therefore, a number of vaccine candidates have been developed to control the COVID-19 pandemic. Of these, to date, 21 vaccines have received emergency approval for human use in at least one country. However, the recent global emergence of SARS-CoV-2 variants has compromised the efficacy of the currently available vaccines. To protect against these variants, the use of vaccines that modulate T cell-mediated immune responses or innate immune cell memory function, termed trained immunity, is needed. The major advantage of a vaccine that uses bacteria or viral systems for the delivery of COVID-19 antigens is the ability to induce both T cell-mediated and humoral immune responses. In addition, such vaccine systems can also exert off-target effects via the vector itself, mediated partly through trained immunity; compared to other vaccine platforms, suggesting that this approach can provide better protection against even vaccine escape variants. This review presents the current status of the development of COVID-19 vaccines based on recombinant viral and bacterial delivery systems. We also discuss the current status of the use of licensed live vaccines for other infections, including BCG, oral polio and MMR vaccines, to prevent COVID-19 infections.
Journal Article
- Effects of rehydration on physiological and transcriptional responses of a water-stressed rhizobium
- Jie Zhu , Xin Jiang , Dawei Guan , Yaowei Kang , Li Li , Fengming Cao , Baisuo Zhao , Mingchao Ma , Ji Zhao , Jun Li
- J. Microbiol. 2022;60(1):31-46. Published online November 26, 2021
- DOI: https://doi.org/10.1007/s12275-022-1325-7
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- 5 Citations
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Abstract
- As a microsymbiont of soybean, Bradyrhizobium japonicum plays an important role in symbiotic nitrogen fixation and sustainable agriculture. However, the survival of B. japonicum cells under water-deplete (e.g., drought) and water-replete (e.g., flood) conditions is a major concern affecting their nitrogen-fixing ability by establishing the symbiotic relationship with the host. In this study, we isolated a water stress tolerant rhizobium from soybean root nodules and tested its survival under water-deplete conditions. The rhizobium was identified as Bradyrhizobium japonicum and named strain 5038. Interestingly, both plate counting and live/dead fluorescence staining assays indicate that a number of viable but non-culturable cells exist in the culture medium upon the rehydration process which could cause dilution stress. Bradyrhizobium japonicum 5038 cells increased production of exopolysaccharide (EPS) and trehalose when dehydrated, suggesting that protective responses were stimulated. As expected, cells reduced their production upon the subsequent rehydration. To examine differential gene expression of B. japonicum 5038 when exposed to water-deplete and subsequent waterreplete conditions, whole-genome transcriptional analysis was performed under 10% relative humidity (RH), and subsequent 100% RH, respectively. A total of 462 differentially expressed genes (DEGs, > 2.0-fold) were identified under the 10% RH condition, while 3,776 genes showed differential expression during the subsequent rehydration (100% RH) process. Genes involved in signal transduction, inorganic ion transport, energy production and metabolisms of carbohydrates, amino acids, and lipids were far more up-regulated than downregulated in the 10% RH condition. Notably, trehalose biosynthetic genes (otsAB, treS, and treYZ), genes ligD, oprB, and a sigma factor rpoH were significantly induced by 10% RH. Under the subsequent 100% RH condition, genes involved in transcription, translation, cell membrane regulation, replication and repair, and protein processing were highly up-regulated. Interestingly, most of 10%-RH inducible genes displayed rehydration-repressed, except three genes encoding heat shock (Hsp20) proteins. Therefore, this study provides molecular evidence for the switch of gene expression of B. japonicum cells when encountered the opposite water availability from water-deplete to water-replete conditions.
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