Journal of Microbiology

Journal Articles

Rhizosphere Microbial Community and Metabolites of Susceptible and Resistant Tobacco Cultivars to Bacterial Wilt: Wan Zhao , Yanyan Li , Chunlei Yang , Yong Yang , Yun Hu; J. Microbiol. 2023;61(4):389-402. Published online March 7, 2023; DOI: https://doi.org/10.1007/s12275-023-00012-0

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Abstract: Soil-borne diseases are closely related to rhizosphere microecosystem. While, plant species and genotypes are important factors affected rhizosphere microecosystem. In this study, the rhizosphere soil microbial community and metabolites of susceptible and resistant tobacco cultivars were investigated. The results showed that there were significant differences in the rhizosphere microbial community and metabolites between susceptible cultivar Yunyan87 and resistant cultivar Fandi3. Furthermore, the rhizosphere soil of Fandi3 showed a higher microbial diversity than that of Yunyan87. The abundance of R. solanacearum was much higher in the rhizosphere soil of Yunyan87 than in the rhizosphere soil of Fandi3, resulting in a higher disease incidence and index. While the abundance of beneficial bacteria in the rhizosphere soil of Fandi3 were higher than that of Yunyan87. Additionally, there were significant differences in metabolites between Yunyan87 and Fandi3 cultivars, and 4-hydroxybenzaldehyde, 3-hydroxy-4-methoxybenzoic acid, vamillic aldehyde, benzoic acid, 4-hydroxybenzyl alcohol, p-hydroxybenzoic acid and phthalic acid were notably high in Yunyan87. Redundancy analysis (RDA) indicated that the rhizosphere microbial community of Fandi3 and Yunyan87 were highly correlated with various environmental factors and metabolites. Overall, susceptible and resistant tobacco cultivars had different impact on rhizosphere microbial community and metabolites. The results expand our understanding of the roles of tobacco cultivars in plant-micro-ecosystem interactions, and provide a basis for the control of tobacco bacterial wilt.

Impact of small RNA RaoN on nitrosative-oxidative stress resistance and virulence of Salmonella enterica serovar Typhimurium: Sinyeon Kim , Yong Heon Lee; J. Microbiol. 2020;58(6):499-506. Published online April 11, 2020; DOI: https://doi.org/10.1007/s12275-020-0027-2

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Abstract: RaoN is a Salmonella-specific small RNA that is encoded in the cspH-envE intergenic region on Salmonella pathogenicity island-11. We previously reported that RaoN is induced under conditions of acid and oxidative stress combined with nutrient limitation, contributing to the intramacrophage growth of Salmonella enterica serovar Typhimurium. However, the role of RaoN in nitrosative stress response and virulence has not yet been elucidated. Here we show that the raoN mutant strain has increased susceptibility to nitrosative stress by using a nitric oxide generating acidified nitrite. Extending previous research on the role of RaoN in oxidative stress resistance, we found that NADPH oxidase inhibition restores the growth of the raoN mutant in LPS-treated J774A.1 macrophages. Flow cytometry analysis further revealed that the inactivation of raoN leads to an increase in the intracellular level of reactive oxygen species (ROS) in Salmonella-infected macrophages, suggesting that RaoN is involved in the inhibition of NADPH oxidase-mediated ROS production by mechanisms not yet resolved. Moreover, we evaluated the effect of raoN mutation on the virulence in murine systemic infection and determined that the raoN mutant is less virulent than the wild-type strain following oral inoculation. In
conclusion
, small regulatory RNA RaoN controls nitrosativeoxidative stress resistance and is required for virulence of Salmonella in mice.

Retracted Publication

NOTE] Identification of the Vibrio vulnificus htpG Gene and Its Influence on Cold Shock Recovery: Slae Choi , Kyungku Jang , Seulah Choi , Hee-jee Yun , Dong-Hyun Kang; J. Microbiol. 2012;50(4):707-711. Published online August 25, 2012; DOI: https://doi.org/10.1007/s12275-012-2294-z

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Abstract: An htpG gene encoding the heat shock protein HtpG was identified and cloned from Vibrio vulnificus. The deduced amino acid sequence of HtpG from V. vulnificus exhibited 71 and 85% identity to those reported from Escherichia coli and V. cholera, respectively. Functions of HtpG were assessed by the construction of an isogenic mutant whose htpG gene was deleted and by evaluating its phenotype changes during and after cold shock. The results demonstrated that recovery of the wild type from cold shock was significantly faster (p<0.05) than that of the htpG mutant, and indicated that the chaperone protein HtpG contributes to cold shock recovery, rather than cold shock tolerance, of V. vulnificus.

Research Support, Non-U.S. Gov'ts

Protection Against Helicobacter pylori Infection by a Trivalent Fusion Vaccine Based on a Fragment of Urease B-UreB414: Li Wang Wang , Xiao-Fei Liu , Shi Yun , Xiao-Peng Yuan , Xu-Hu Mao , Chao Wu , Wei-Jun Zhang , Kai-Yun Liu , Gang Guo , Dong-Shui Lu , Wen-De Tong , Ai-Dong Wen , Quan-Ming Zou; J. Microbiol. 2010;48(2):223-228. Published online May 1, 2010; DOI: https://doi.org/10.1007/s12275-009-0233-4

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Abstract: A multivalent fusion vaccine is a promising option for protection against Helicobacter pylori infection. In this study, UreB414 was identified as an antigenic fragment of urease B subunit (UreB) and it induced an antibody inhibiting urease activity. Immunization with UreB414 partially protected mice from H. pylori infection. Furthermore, a trivalent fusion vaccine was constructed by genetically linking heat shock protein A (HspA), H. pylori adhesin A (HpaA), and UreB414, resulting in recombinant HspA-HpaA-UreB414 (rHHU). Its protective effect against H. pylori infection was tested in BALB/c mice. Oral administration of rHHU significantly protected mice from H. pylori infection, which was associated with H. pylori-specific antibody production and Th1/Th2-type immune responses. The results show that a trivalent fusion vaccine efficiently combats H. pylori infection, and that an antigenic fragment of the protein can be used instead of the whole protein to construct a multivalent vaccine.

Heat Shock Causes Oxidative Stress and Induces a Variety of Cell Rescue Proteins in Saccharomyces cerevisiae KNU5377: Il-Sup Kim , Hye-Youn Moon , Hae-Sun Yun , Ingnyol Jin; J. Microbiol. 2006;44(5):492-501.; DOI: https://doi.org/2449 [pii]

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Abstract: In this study, we attempted to characterize the physiological response to oxidative stress by heat shock in Saccharomyces cerevisiae KNU5377 (KNU5377) that ferments at a temperature of 40°C. The KNU5377 strain evidenced a very similar growth rate at 40°C as was recorded under normal conditions. Unlike the laboratory strains of S. cerevisiae, the cell viability of KNU5377 was affected slightly under 2 hours of heat stress conditions at 43°C. KNU5377 evidenced a time-dependent increase in hydroperoxide levels, carbonyl contents, and malondialdehyde (MDA), which increased in the expression of a variety of cell rescue proteins containing Hsp104p, Ssap, Hsp30p, Sod1p, catalase, glutathione reductase, G6PDH, thioredoxin, thioredoxin peroxidase (Tsa1p), Adhp, Aldp, trehalose and glycogen at high temperature. Pma1/2p, Hsp90p and H+-ATPase expression levels were reduced as the result of exposure to heat shock. With regard to cellular fatty acid composition, levels of unsaturated fatty acids (USFAs) were increased significantly at high temperatures (43°C), and this was particularly true of oleic acid (C18:1). The results of this study indicated that oxidative stress as the result of heat shock may induce a more profound stimulation of trehalose, antioxidant enzymes, and heat shock proteins, as well as an increase in the USFAs ratios. This might contribute to cellular protective functions for the maintenance of cellular homeostasis, and may also contribute to membrane fluidity.

Synthesis and Requirement of Escherichia coli Heat Shock Proteins GroEL and DnaK for Survival under Phenol Stress Conditions: Jeon, Taeck Joong , Lee, Kil Jae; J. Microbiol. 1998;36(1):26-33.

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Abstract: Exposure of Escherichia coli strain MC4100 to various concentrations of phenol at temperatures higher than 20℃ led to induction of stress proteins such as GroEL and DnaK, as analyzed by SDS-PAGE and Western blotting methods. The optimum range of phenol concentration for the induction of GroEL and DnaK was slightly different at each temperature of bacterial growth and phenol treatment. The level of GroEL increased as the temperatures of growth and phenol treatment were increased from 30℃ to 40℃. The level of induced FroEL was maximal in the wild type cells which had been grown and treated by 2000㎍/㎖ phenol at 40℃. In contrast to GroEL, the level of DnaK decreased as the temperatures of growth and phenol treatment were increased from 25℃ to 40℃. Dnak was maximally induced in the cells grown and exposed to 1000㎍/㎖ phenol at 25℃. In rpoH mutant cells KY1601, GroEL was not additionally induced by phenol treatment and DnaK was not even detectable under normal and phenol stress conditions. Viability of cells under the same conditions of phenol treatment showed that the phenol resistance in much more induced in wild type cells than rpoH mutant cells. These results suggest that the induction of GroEL and DnaK is required for the enhanced viability of cells under conditions of phenol stress.

Stress-shock Response of a Methylotrophic Bacterium Methylovorus sp. strain SS1 DSM 11726: Jong H. Park , Si W. Kim , Eungbin Kim , Young T. Ro , Young M. Kim; J. Microbiol. 2001;39(3):162-167.

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Abstract: Methylovorus sp. strain SS1 DSM 11726 was found to grow continuously when it was transferred from 30 C to 40 C and 43 C. A shift in growth temperature from 30 C to 45 C, 47 C and 50 C reduced the viability of the cell population by more than 10^2 , 10^3 and 10^5 folds, respectively, after 1 h cultivation. Cells transferred to 47 C and 50 C after preincubation for 15 min at 43 C, however, exhibited 10-fold increase in viability. It was found that incubation for 15 min at 40 C of Methylovorus sp. strain SS1 grown at 30 C was sufficient to accelerate the synthesis of a specific subset of proteins. The major heat shock proteins had apparent molecular masses of 90, 70, 66, 60, and 58 kDa. The 60 and 58 kDa proteins were found to cross-react with the antiserum raised against GroEL protein. The heat shock response persisted for over 1 h. The shock proteins were stable for 90 min in the cell. Exposure of the cells to methanol induced proteins identical to the heat shock proteins. Addition of ethanol induced a unique protein with a molecular mass of about 40 kDa in addition to the heat-induced proteins. The proteins induced in paraquat-treated cells were different from the heat shock proteins, except the 70 and 60 kDa proteins.

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