1
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Egas RA, Sahonero-Canavesi DX, Bale NJ, Koenen M, Yildiz Ç, Villanueva L, Sousa DZ, Sánchez-Andrea I. Acetic acid stress response of the acidophilic sulfate reducer Acididesulfobacillus acetoxydans. Environ Microbiol 2024; 26:e16565. [PMID: 38356112 DOI: 10.1111/1462-2920.16565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 12/12/2023] [Indexed: 02/16/2024]
Abstract
Acid mine drainage (AMD) waters are a severe environmental threat, due to their high metal content and low pH (pH <3). Current technologies treating AMD utilize neutrophilic sulfate-reducing microorganisms (SRMs), but acidophilic SRM could offer advantages. As AMDs are low in organics these processes require electron donor addition, which is often incompletely oxidized into organic acids (e.g., acetic acid). At low pH, acetic acid is undissociated and toxic to microorganisms. We investigated the stress response of the acetotrophic Acididesulfobacillus acetoxydans to acetic acid. A. acetoxydans was cultivated in bioreactors at pH 5.0 (optimum). For stress experiments, triplicate reactors were spiked until 7.5 mM of acetic acid and compared with (non-spiked) triplicate reactors for physiological, transcriptomic, and membrane lipid changes. After acetic acid spiking, the optical density initially dropped, followed by an adaptation phase during which growth resumed at a lower growth rate. Transcriptome analysis revealed a downregulation of genes involved in glutamate and aspartate synthesis following spiking. Membrane lipid analysis revealed a decrease in iso and anteiso fatty acid relative abundance; and an increase of acetyl-CoA as a fatty acid precursor. These adaptations allow A. acetoxydans to detoxify acetic acid, creating milder conditions for other microorganisms in AMD environments.
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Affiliation(s)
- Reinier A Egas
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Diana X Sahonero-Canavesi
- Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research (NIOZ), Texel, Den Burg, The Netherlands
| | - Nicole J Bale
- Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research (NIOZ), Texel, Den Burg, The Netherlands
| | - Michel Koenen
- Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research (NIOZ), Texel, Den Burg, The Netherlands
| | - Çağlar Yildiz
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Laura Villanueva
- Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research (NIOZ), Texel, Den Burg, The Netherlands
- Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands
| | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
- Centre for Living Technologies, Alliance TU/e, WUR, UU, UMC Utrecht, Utrecht, The Netherlands
| | - Irene Sánchez-Andrea
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
- Environmental Sciences and Sustainability Department, Science & Technology School, IE University, Segovia, Spain
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2
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Han J, Aljahdali N, Zhao S, Tang H, Harbottle H, Hoffmann M, Frye JG, Foley SL. Infection biology of Salmonella enterica. EcoSal Plus 2024:eesp00012023. [PMID: 38415623 DOI: 10.1128/ecosalplus.esp-0001-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 07/31/2023] [Indexed: 02/29/2024]
Abstract
Salmonella enterica is the leading cause of bacterial foodborne illness in the USA, with an estimated 95% of salmonellosis cases due to the consumption of contaminated food products. Salmonella can cause several different disease syndromes, with the most common being gastroenteritis, followed by bacteremia and typhoid fever. Among the over 2,600 currently identified serotypes/serovars, some are mostly host-restricted and host-adapted, while the majority of serotypes can infect a broader range of host species and are associated with causing both livestock and human disease. Salmonella serotypes and strains within serovars can vary considerably in the severity of disease that may result from infection, with some serovars that are more highly associated with invasive disease in humans, while others predominantly cause mild gastroenteritis. These observed clinical differences may be caused by the genetic make-up and diversity of the serovars. Salmonella virulence systems are very complex containing several virulence-associated genes with different functions that contribute to its pathogenicity. The different clinical syndromes are associated with unique groups of virulence genes, and strains often differ in the array of virulence traits they display. On the chromosome, virulence genes are often clustered in regions known as Salmonella pathogenicity islands (SPIs), which are scattered throughout different Salmonella genomes and encode factors essential for adhesion, invasion, survival, and replication within the host. Plasmids can also carry various genes that contribute to Salmonella pathogenicity. For example, strains from several serovars associated with significant human disease, including Choleraesuis, Dublin, Enteritidis, Newport, and Typhimurium, can carry virulence plasmids with genes contributing to attachment, immune system evasion, and other roles. The goal of this comprehensive review is to provide key information on the Salmonella virulence, including the contributions of genes encoded in SPIs and plasmids during Salmonella pathogenesis.
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Affiliation(s)
- Jing Han
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
| | - Nesreen Aljahdali
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
- Biological Science Department, College of Science, King Abdul-Aziz University, Jeddah, Saudi Arabia
| | - Shaohua Zhao
- Center for Veterinary Medicine, U.S. Food and Drug Administration, Rockville, Maryland, USA
| | - Hailin Tang
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
| | - Heather Harbottle
- Center for Veterinary Medicine, U.S. Food and Drug Administration, Rockville, Maryland, USA
| | - Maria Hoffmann
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, Maryland, USA
| | - Jonathan G Frye
- Agricutlutral Research Service, U.S. Department of Agriculture, Athens, Georgia, USA
| | - Steven L Foley
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
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3
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Zhang YQ, Song XY, Liu F. XanFur, a novel Fur protein induced by H 2O 2, positively regulated by the global transcriptional regulator Clp and required for the full virulence of Xanthomonas oryzae pv. oryzae in rice. Microbiol Spectr 2023; 11:e0118723. [PMID: 37831462 PMCID: PMC10714925 DOI: 10.1128/spectrum.01187-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 08/07/2023] [Indexed: 10/14/2023] Open
Abstract
IMPORTANCE Although Xanthomonas oryzae pv. oryzae (Xoo) has been found to be a bacterial pathogen causing bacterial leaf blight in rice for many years, the molecular mechanisms of the rice-Xoo interaction has not been fully understood. In this study, we found that XanFur of Xoo is a novel ferric uptake regulator (Fur) protein conserved among major pathogenic Xanthomonas species. XanFur is required for the virulence of Xoo in rice, and likely involved in regulating the virulence determinants of Xoo. The expression of xanfur is induced by H2O2, and positively regulated by the global transcriptional regulator Clp. Our results reveal the function and regulation of the novel virulence-related Fur protein XanFur in Xoo, providing new insights into the interaction mechanisms of rice-Xoo.
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Affiliation(s)
- Yu-Qiang Zhang
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, Shandong, China
| | - Xiao-Yan Song
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, Shandong, China
| | - Fengquan Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
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4
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Martínez de la Escalera G, Kruk C, Segura AM, Piccini C. Effect of hydrological modification on the potential toxicity of Microcystis aeruginosa complex in Salto Grande reservoir, Uruguay. HARMFUL ALGAE 2023; 123:102403. [PMID: 36894214 DOI: 10.1016/j.hal.2023.102403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 02/02/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
It is widely known that the environmental conditions caused by the construction of reservoirs favor the proliferation of toxic cyanobacteria and the formation of blooms due to the high residence time of the water, low turbidity, temperature regimes, among others. Microcystin-producing cyanobacteria such as those from the Microcystis aeruginosa complex (MAC) are the most frequently found organisms in reservoirs worldwide, being the role of the environment on microcystin production poorly understood. Here, we addressed the community dynamics and potential toxicity of MAC cyanobacteria in a subtropical reservoir (Salto Grande) located in the low Uruguay river. Samples were taken from five different sites (upstream, inside the reservoir and downstream) during contrasting seasons (summer and winter) to analyze: (i) the MAC community structure by amplicon sequencing of the phycocyanin gene spacer, (ii) the genotype diversity of microcystin-producing MAC by high resolution melting analysis of the mcyJ gene, and (iii) the abundance and mcy transcription activity of the microcystin-producing (toxic) fraction. We found that MAC diversity decreased from summer to winter but, despite the observed changes in MAC community structure, the abundance of toxic organisms and the transcription of mcy genes were always higher inside the reservoir, regardless of the season. Two different genotypes of toxic MAC were detected inside the reservoir, one associated with low water temperature (15 °C) and one thriving at high water temperature (31 °C). These findings indicate that the environmental conditions inside the reservoir reduce community diversity while promoting the proliferation of toxic genotypes that actively transcribe mcy genes, whose relative abundance will depend on the water temperature.
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Affiliation(s)
| | - Carla Kruk
- Facultad de Ciencias, IECA, Universidad de la República, Uruguay; Departamento de Modelización Estadística de Datos e Inteligencia Artificial (MEDIA), CURE-Rocha, Universidad de la República, Uruguay
| | - Angel M Segura
- Departamento de Modelización Estadística de Datos e Inteligencia Artificial (MEDIA), CURE-Rocha, Universidad de la República, Uruguay
| | - Claudia Piccini
- Departamento de Microbiología, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montvideo, Uruguay.
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5
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Huang M, Liu M, Liu J, Wang M, Jia R, Zhu D, Chen S, Zhao X, Yang Q, Wu Y, Zhang S, Gao Q, Huang J, Ou X, Mao S, Tian B, Sun D, Cheng A. Evaluation of the immunoprotection efficacy of Riemerella anatipestifer fur-deficient mutant as an attenuated vaccine. Poult Sci 2022; 102:102450. [PMID: 36621099 PMCID: PMC9841290 DOI: 10.1016/j.psj.2022.102450] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/10/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Riemerella anatipestifer (R. anatipestifer, RA) is an infectious pathogen that causes septicemia and polyserositis in ducks. Our previous studies showed that RA CH-1 ∆fur was significantly attenuated in ducklings, which highlights the potential of this strain as a live attenuated vaccine. In this study, it was shown that infection with 109 CFU of the fur mutant did not cause any clinical symptoms or significant histological lesions in 3-day-old ducklings and that the bacteria were readily cleared by the host within 3 d. Compared with the nonvaccinated group, the group inoculated with the mutant strain RA CH-1 ∆fur exhibited protection of ducklings against a high-dose (2.28 × 1010 CFU) challenge with the wild-type strain RA CH-1. Moreover, the average body weights and body weight gains of the Δfur-inoculated group were not significantly affected by the challenge. Further analysis revealed that RA CH-1 ∆fur elicited higher IgY titers and that the serum antibody levels persisted for at least 49 d after immunization. Overall, our study showed that RA CH-1 ∆fur is a safe and effective vaccine candidate that is expected to play an important role in RA CH-1 infection prevention in the duck industry.
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Affiliation(s)
- Mi Huang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Mafeng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Jiajun Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Renyong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Dekang Zhu
- Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Xinxin Zhao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Shaqiu Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Qun Gao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Juan Huang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Xumin Ou
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Sai Mao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Bin Tian
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Di Sun
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China; Research Centre of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China.
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6
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Ferrous Iron Uptake Is Required for Salmonella to Persist within Vacuoles of Host Cells. Infect Immun 2022; 90:e0014922. [PMID: 35536027 DOI: 10.1128/iai.00149-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Iron is an essential oligoelement that incorporates into proteins as a biocatalyst or electron carrier. The intracellular pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) takes iron as free reduced ferrous cation or as oxidized ferric cation complexed to siderophores or ferrichromes. Deficiencies in ferrous or ferric iron uptake attenuate S. Typhimurium virulence, but how the uptake systems are used in the intracellular environment remains poorly understood. Here, using S. Typhimurium mutants deficient in multiple iron uptake systems, we show that SitABCD and FeoABC, involved in ferrous iron uptake, are central for this pathogen to persist within vacuoles of fibroblasts. Assays at the protein level showed that components of these two uptake systems, SitD and FeoB, are produced at high levels by intravacuolar bacteria. Despite not being essential for viability inside the vacuole, intracellular bacteria also upregulate transporters involved in ferric iron uptake such as IroN, FepA, and CirA. In addition, an unprecedented cleavage at the N-terminal region of FepA was observed as a distinctive feature of nonproliferating intravacuolar bacteria. Collectively, our findings indicate that SitABCD and FeoABC contribute to S. Typhimurium virulence by promoting iron acquisition within the vacuolar compartment.
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7
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Abstract
Iron limitation is a universal strategy of host immunity during bacterial infection. However, the mechanisms by which pathogens antagonize host nutritional immunity have not been fully elucidated. Here, we identified a requirement for the UMPylator YdiU for this process in Salmonella. The expression of YdiU was dramatically induced by the metal starvation signal. The intracellular iron content was much lower in the ΔydiU strain than in wild-type Salmonella, and the ΔydiU strain exhibited severe growth defect under metal deficiency environments. Genome-wide expression analyses revealed significantly decreased expression of iron uptake genes in ΔydiU strain compared with the wild-type strain. Interestingly, YdiU did not affect the expression level of the major iron uptake regulator Fur but directly UMPylated Fur on its H118 residue in vivo and in vitro. UMPylation destroyed the Fur dimer, promoted Fur aggregation, and eliminated the DNA-binding activity of Fur, thus abolishing the ability of Fur to inhibit iron uptake. Restricting Fur to the deUMPylated state dramatically eliminates Salmonella iron uptake in iron deficiency environments. In parallel, YdiU facilitates Salmonella survival within host cells by regulating the iron uptake pathway.
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8
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Ding Y, Yi Z, Fang Y, He S, Li Y, He K, Zhao H, Jin Y. Multi-Omics Reveal the Efficient Phosphate-Solubilizing Mechanism of Bacteria on Rocky Soil. Front Microbiol 2021; 12:761972. [PMID: 34956124 PMCID: PMC8696128 DOI: 10.3389/fmicb.2021.761972] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/22/2021] [Indexed: 12/13/2022] Open
Abstract
Phosphate-solubilizing bacteria (PSB) can alleviate available phosphorus (AP)-deficiency without causing environmental pollution like chemical phosphate fertilizers. However, the research and application of PSB on the barren rocky soil is very rare. We screened six PSB from sweetpotato rhizosphere rocky soil. Among them, Ochrobactrum haematophilum FP12 showed the highest P-solubilizing ability of 1,085.00 mg/L at 7 days, which was higher than that of the most reported PSB. The assembled genome of PSB FP12 was 4.92 Mb with P-solubilizing and plant growth-promoting genes. In an AP-deficient environment, according to transcriptome and metabolomics analysis, PSB FP12 upregulated genes involved in gluconic acid synthesis and the tricarboxylic acid cycle, and increased the concentration of gluconic acid and malic acid, which would result in the enhanced P-solubilizing ability. Moreover, a series of experiments in the laboratory and field confirmed the efficient role of the screened PSB on significantly increasing AP in the barren rocky soil and promoting sweetpotato yield. So, in this study, we screened highly efficient PSB, especially suitable for the barren rocky soil, and explored the P-solubilizing mechanism. The research will reduce the demand for chemical phosphate fertilizers and promote the environment-friendly agricultural development.
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Affiliation(s)
- Yanqiang Ding
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Zhuolin Yi
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Yang Fang
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Sulan He
- Sweetpotato Institute, Nanchong Academy of Agricultural Sciences, Nanchong, China
| | - Yuming Li
- Sweetpotato Institute, Nanchong Academy of Agricultural Sciences, Nanchong, China
| | - Kaize He
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Hai Zhao
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Yanling Jin
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
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9
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Debnath N, Thakur M, Khushboo, Negi NP, Gautam V, Kumar Yadav A, Kumar D. Insight of oral vaccines as an alternative approach to health and disease management: An innovative intuition and challenges. Biotechnol Bioeng 2021; 119:327-346. [PMID: 34755343 DOI: 10.1002/bit.27987] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/06/2021] [Accepted: 11/03/2021] [Indexed: 12/11/2022]
Abstract
Vaccination is the most suitable and persuasive healthcare program for the prohibition of various deadly diseases. However, the higher production cost and purification strategies are out of reach for the developing nations. In this scenario, development of edible vaccine turns out to be the most promising alternative for remodeling the pharmaceutical industry with reduced production and purification costs. Generally, oral route of vaccination is mostly preferred due to its safety, compliance, low manufacturing cost and most importantly the ability to induce immunity in both systemic and mucosal sites. Genetically modified microorganisms and plants could efficiently be used as vehicles for edible vaccines. Edible vaccines are supposed to reduce the risk associated with traditional vaccines. Currently, oral vaccines are available in the market for several viral and bacterial diseases like cholera, hepatitis B, malaria, rabies etc. Herein, the review focuses on the breakthrough events in the area of edible vaccines associated with dietary microbes and plants for better control over diseases.
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Affiliation(s)
- Nabendu Debnath
- Centre for Molecular Biology, Central University of Jammu, Samba, Jammu & Kashmir (UT), India
| | - Mony Thakur
- Department of Microbiology, Central University of Haryana, Mahendergarh, Haryana, India
| | - Khushboo
- Department of Biotechnology, Central University of Haryana, Mahendergarh, Haryana, India
| | - Neelam P Negi
- Department of Biotechnology, University Institute of Biotechnology, Chandigarh University, Mohali, Punjab, India
| | - Vibhav Gautam
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Ashok Kumar Yadav
- Centre for Molecular Biology, Central University of Jammu, Samba, Jammu & Kashmir (UT), India
| | - Deepak Kumar
- Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India
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10
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Bai H, Zhou D, Zhang X, Cao Y, Xiao X, Zhang Y, Yu Y. The responses of Salmonella enterica serovar Typhimurium to vanillin in apple juice through global transcriptomics. Int J Food Microbiol 2021; 347:109189. [PMID: 33838479 DOI: 10.1016/j.ijfoodmicro.2021.109189] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 03/09/2021] [Accepted: 03/24/2021] [Indexed: 11/29/2022]
Abstract
Salmonella enterica serovar Typhimurium can survive some extreme environment in food processing, and vanillin generally recognized as safe is bactericidal to pathogens. Thus, we need to explore the responses of S. Typhimurium to vanillin in order to apply this antimicrobial agent in food processing. In this study, we exposed S. Typhimurium to commercial apple juice with/without vanillin (3.2 mg/mL) at 45 °C for 75 min to determine the survival rate. Subsequently, the 10-min cultures were selected for transcriptomic analysis. Using high-throughput RNA sequencing, genes related to vanillin resistance and their expression changes of S. Typhimurium were identified. The survival curve showed that S. Typhimurium treated with vanillin were inactivated by 5.5 log after 75 min, while the control group only decreased by 2.3 log. Such a discrepancy showed the significant antibacterial effect of vanillin on S. Typhimurium. As a result, 265 differentially expressed genes (DEGs) were found when coping with vanillin, among which, 225 showed up-regulation and 40 DEGs were down-regulated. Treated with vanillin, S. Typhimurium significantly up-regulated genes involved in cell membrane, acid tolerance response (ATR) and oxidative stress response, cold shock cross-protection, DNA repair, virulence factors and some key regulators. Firstly, membrane-related genes, including outer membrane (bamE, mepS, ygdI, lolB), inner membrane (yaiY, yicS) and other proteins (yciC, yjcH), were significantly up-regulated because of the damaged cell membrane. Then, up-regulated proteins associated with arginine synthesis (ArgABCDIG) and inward transportation (ArtI, ArtJ, ArtP and HisP), participated in ATR to pump out the protons inside the cell in this scenario. Next, superoxide stress response triggered by vanillin was found to have a significant up-regulation as well, which was controlled by SoxRS regulon. Besides, NADH-associated (nuoA, nuoB, nuoK, nadE, fre and STM3021), thioredoxin (trxA, trxC, tpx and bcp) and glutaredoxin (grxC and grxD) DEGs led to the increase of the oxidative stress response. Cold shock proteins such as CspA and CspC showed an up-regulation, suggesting it might play a role in cross-protecting S. Typhimurium from vanillin stress. Furthermore, DEGs in DNA repair and virulence factors, including flagellar assembly, adhesins and type III secretion system were up-regulated. Some regulators like fur, rpoE and csrA played a pivotal role in response to the stress caused by vanillin. Therefore, this study sounds an alarm for the risks caused by stress tolerance of S. Typhimurium in food industry.
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Affiliation(s)
- Hong Bai
- School of Food Science and Engineering, South China University of Technology, Guangzhou City, Guangdong Province 510640, China
| | - Donggen Zhou
- Ningbo International Travel Healthcare Center, No.336 LiutingStreet, Haishu District, Ningbo City, Zhejiang Province 315012, China
| | - Xiaowei Zhang
- School of Food Science and Engineering, South China University of Technology, Guangzhou City, Guangdong Province 510640, China
| | - Yifang Cao
- School of Food Science and Engineering, South China University of Technology, Guangzhou City, Guangdong Province 510640, China
| | - Xinglong Xiao
- School of Food Science and Engineering, South China University of Technology, Guangzhou City, Guangdong Province 510640, China.
| | - Yan Zhang
- School of Food Science and Engineering, South China University of Technology, Guangzhou City, Guangdong Province 510640, China
| | - Yigang Yu
- School of Food Science and Engineering, South China University of Technology, Guangzhou City, Guangdong Province 510640, China.
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11
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Impact of the Resistance Responses to Stress Conditions Encountered in Food and Food Processing Environments on the Virulence and Growth Fitness of Non-Typhoidal Salmonellae. Foods 2021; 10:foods10030617. [PMID: 33799446 PMCID: PMC8001757 DOI: 10.3390/foods10030617] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 02/24/2021] [Accepted: 03/10/2021] [Indexed: 01/22/2023] Open
Abstract
The success of Salmonella as a foodborne pathogen can probably be attributed to two major features: its remarkable genetic diversity and its extraordinary ability to adapt. Salmonella cells can survive in harsh environments, successfully compete for nutrients, and cause disease once inside the host. Furthermore, they are capable of rapidly reprogramming their metabolism, evolving in a short time from a stress-resistance mode to a growth or virulent mode, or even to express stress resistance and virulence factors at the same time if needed, thanks to a complex and fine-tuned regulatory network. It is nevertheless generally acknowledged that the development of stress resistance usually has a fitness cost for bacterial cells and that induction of stress resistance responses to certain agents can trigger changes in Salmonella virulence. In this review, we summarize and discuss current knowledge concerning the effects that the development of resistance responses to stress conditions encountered in food and food processing environments (including acid, osmotic and oxidative stress, starvation, modified atmospheres, detergents and disinfectants, chilling, heat, and non-thermal technologies) exerts on different aspects of the physiology of non-typhoidal Salmonellae, with special emphasis on virulence and growth fitness.
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12
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Jaworska K, Ludwiczak M, Murawska E, Raczkowska A, Brzostek K. The Regulator OmpR in Yersinia enterocolitica Participates in Iron Homeostasis by Modulating Fur Level and Affecting the Expression of Genes Involved in Iron Uptake. Int J Mol Sci 2021; 22:ijms22031475. [PMID: 33540627 PMCID: PMC7867234 DOI: 10.3390/ijms22031475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 01/29/2021] [Accepted: 01/29/2021] [Indexed: 12/02/2022] Open
Abstract
In this study, we found that the loss of OmpR, the response regulator of the two-component EnvZ/OmpR system, increases the cellular level of Fur, the master regulator of iron homeostasis in Y. enterocolitica. Furthermore, we demonstrated that transcription of the fur gene from the YePfur promoter is subject to negative OmpR-dependent regulation. Four putative OmpR-binding sites (OBSs) were indicated by in silico analysis of the fur promoter region, and their removal affected OmpR-dependent fur expression. Moreover, OmpR binds specifically to the predicted OBSs which exhibit a distinct hierarchy of binding affinity. Finally, the data demonstrate that OmpR, by direct binding to the promoters of the fecA, fepA and feoA genes, involved in the iron transport and being under Fur repressor activity, modulates their expression. It seems that the negative effect of OmpR on fecA and fepA transcription is sufficient to counteract the indirect, positive effect of OmpR resulting from decreasing the Fur repressor level. The expression of feoA was positively regulated by OmpR and this mode of action seems to be direct and indirect. Together, the expression of fecA, fepA and feoA in Y. enterocolitica has been proposed to be under a complex mode of regulation involving OmpR and Fur regulators.
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13
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Sousa Gerós A, Simmons A, Drakesmith H, Aulicino A, Frost JN. The battle for iron in enteric infections. Immunology 2020; 161:186-199. [PMID: 32639029 PMCID: PMC7576875 DOI: 10.1111/imm.13236] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/01/2020] [Indexed: 02/06/2023] Open
Abstract
Iron is an essential element for almost all living organisms, but can be extremely toxic in high concentrations. All organisms must therefore employ homeostatic mechanisms to finely regulate iron uptake, usage and storage in the face of dynamic environmental conditions. The critical step in mammalian systemic iron homeostasis is the fine regulation of dietary iron absorption. However, as the gastrointestinal system is also home to >1014 bacteria, all of which engage in their own programmes of iron homeostasis, the gut represents an anatomical location where the inter-kingdom fight for iron is never-ending. Here, we explore the molecular mechanisms of, and interactions between, host and bacterial iron homeostasis in the gastrointestinal tract. We first detail how mammalian systemic and cellular iron homeostasis influences gastrointestinal iron availability. We then focus on two important human pathogens, Salmonella and Clostridia; despite their differences, they exemplify how a bacterial pathogen must navigate and exploit this web of iron homeostasis interactions to avoid host nutritional immunity and replicate successfully. We then reciprocally explore how iron availability interacts with the gastrointestinal microbiota, and the consequences of this on mammalian physiology and pathogen iron acquisition. Finally, we address how understanding the battle for iron in the gastrointestinal tract might inform clinical practice and inspire new treatments for important diseases.
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Affiliation(s)
- Ana Sousa Gerós
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
- Translational Gastroenterology UnitJohn Radcliffe HospitalOxfordUK
| | - Alison Simmons
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
- Translational Gastroenterology UnitJohn Radcliffe HospitalOxfordUK
| | - Hal Drakesmith
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
| | - Anna Aulicino
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
- Translational Gastroenterology UnitJohn Radcliffe HospitalOxfordUK
| | - Joe N. Frost
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
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14
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Sarjit A, Ravensdale JT, Coorey R, Fegan N, Dykes GA. Salmonella survival after exposure to heat in a model meat juice system. Food Microbiol 2020; 94:103628. [PMID: 33279093 DOI: 10.1016/j.fm.2020.103628] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 08/06/2020] [Accepted: 08/15/2020] [Indexed: 12/21/2022]
Abstract
The effect of heat against eleven Salmonella strains in model meat juices was examined. Juices from beef, lamb and goat were made from either the fatty layer (FL), muscle (M) or a mixture of both (FLM). The pH of each FLM sample was altered to match the pH of PBS and vice versa to determine the pH effect on the survival of Salmonella against the effect of heat. Salmonella were exposed to either gradual heating to 70 °C in FLM, M and FL or heat shock at 70 °C for 5 min in FLM. Fat, fatty acid profile and iron content of the juices were determined. Gradual heat treatment significantly (p ≤ 0.05) reduced Salmonella as compared to the untreated controls (~1.92-7.61 log CFU ml-1) while heat shock significantly (p ≤ 0.05) reduced Salmonella as compared to the untreated controls (~5.80-7.36 log CFU ml-1). Survival of Salmonella was higher in lamb juices than other juices. The fat content in lamb FL (3.25%) was significantly higher (p ≤ 0.05) than beef (1.30%) and goat FL (1.42%). Iron content in lamb FLM (~127 mg kg-1) was significantly (p ≤ 0.05) lower than beef (~233 mg kg-1) and goat FLM (~210 mg kg-1). The omega 6 and linoleic acid content in goat FLM (~36.0% and ~34.4%) was significantly higher (p ≤ 0.05) than beef (~29.1% and ~27.1%). Fat, fatty acids and iron may differentially protect Salmonella against the effect of heat in these juices.
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Affiliation(s)
- Amreeta Sarjit
- School of Public Health, Curtin University, Bentley, Western Australia, Australia; CSIRO Agriculture and Food, Brisbane, Queensland, Australia
| | - Joshua T Ravensdale
- School of Public Health, Curtin University, Bentley, Western Australia, Australia
| | - Ranil Coorey
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Narelle Fegan
- CSIRO Agriculture and Food, Brisbane, Queensland, Australia
| | - Gary A Dykes
- School of Public Health, Curtin University, Bentley, Western Australia, Australia.
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15
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Chen XK, Li XY, Ha YF, Lin JQ, Liu XM, Pang X, Lin JQ, Chen LX. Ferric Uptake Regulator Provides a New Strategy for Acidophile Adaptation to Acidic Ecosystems. Appl Environ Microbiol 2020; 86:e00268-20. [PMID: 32245756 PMCID: PMC7237784 DOI: 10.1128/aem.00268-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 03/16/2020] [Indexed: 12/25/2022] Open
Abstract
Acidophiles play a dominant role in driving elemental cycling in natural acid mine drainage (AMD) habitats and exhibit important application value in bioleaching and bioremediation. Acidity is an inevitable environmental stress and a key factor that affects the survival of acidophiles in their acidified natural habitats; however, the regulatory strategies applied by acidophilic bacteria to withstand low pH are unclear. We identified the significance of the ferric uptake regulator (Fur) in acidophiles adapting to acidic environments and discovered that Fur is ubiquitous as well as highly conserved in acidophilic bacteria. Mutagenesis of the fur gene of Acidithiobacillus caldus, a prototypical acidophilic sulfur-oxidizing bacterium found in AMD, revealed that Fur is required for the acid resistance of this acidophilic bacterium. Phenotypic characterization, transcriptome sequencing (RNA-seq), mutagenesis, and biochemical assays indicated that the Acidithiobacillus caldus ferric uptake regulator (AcFur) is involved in extreme acid resistance by regulating the expression of several key genes of certain cellular activities, such as iron transport, biofilm formation, sulfur metabolism, chemotaxis, and flagellar biosynthesis. Finally, a Fur-dependent acid resistance regulatory strategy in A. caldus was proposed to illustrate the ecological behavior of acidophilic bacteria under low pH. This study provides new insights into the adaptation strategies of acidophiles to AMD ecosystems and will promote the design and development of engineered biological systems for the environmental adaptation of acidophiles.IMPORTANCE This study advances our understanding of the acid tolerance mechanism of A. caldus, identifies the key fur gene responsible for acid resistance, and elucidates the correlation between fur and acid resistance, thus contributing to an understanding of the ecological behavior of acidophilic bacteria. These findings provide new insights into the acid resistance process in Acidithiobacillus species, thereby promoting the study of the environmental adaptation of acidophilic bacteria and the design of engineered biological systems.
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Affiliation(s)
- Xian-Ke Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Xiao-Yan Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Yi-Fan Ha
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Jian-Qiang Lin
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Xiang-Mei Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Xin Pang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Jian-Qun Lin
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Lin-Xu Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
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16
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Milojevic T, Weckwerth W. Molecular Mechanisms of Microbial Survivability in Outer Space: A Systems Biology Approach. Front Microbiol 2020; 11:923. [PMID: 32499769 PMCID: PMC7242639 DOI: 10.3389/fmicb.2020.00923] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 04/20/2020] [Indexed: 01/08/2023] Open
Abstract
Since the dawn of space exploration, the survivability of terrestrial life in outer space conditions has attracted enormous attention. Space technology has enabled the development of advanced space exposure facilities to investigate in situ responses of microbial life to the stress conditions of space during interplanetary transfer. Significant progress has been made toward the understanding of the effects of space environmental factors, e.g., microgravity, vacuum and radiation, on microorganisms exposed to real and simulated space conditions. Of extreme importance is not only knowledge of survival potential of space-exposed microorganisms, but also the determination of mechanisms of survival and adaptation of predominant species to the extreme space environment, i.e., revealing the molecular machinery, which elicit microbial survivability and adaptation. Advanced technologies in -omics research have permitted genome-scale studies of molecular alterations of space-exposed microorganisms. A variety of reports show that microorganisms grown in the space environment exhibited global alterations in metabolic functions and gene expression at the transcriptional and translational levels. Proteomic, metabolomic and especially metabolic modeling approaches as essential instruments of space microbiology, synthetic biology and metabolic engineering are rather underrepresented. Here we summarized the molecular space-induced alterations of exposed microorganisms in terms of understanding the molecular mechanisms of microbial survival and adaptation to drastic outer space environment.
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Affiliation(s)
- Tetyana Milojevic
- Extremophiles/Space Biochemistry Group, Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
| | - Wolfram Weckwerth
- Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria
- Vienna Metabolomics Center, University of Vienna, Vienna, Austria
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17
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18
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Liu CJ, Lin CT, Chiang JD, Lin CY, Tay YX, Fan LC, Peng KN, Lin CH, Peng HL. RcsB regulation of the YfdX-mediated acid stress response in Klebsiella pneumoniae CG43S3. PLoS One 2019; 14:e0212909. [PMID: 30818355 PMCID: PMC6394985 DOI: 10.1371/journal.pone.0212909] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 02/12/2019] [Indexed: 12/31/2022] Open
Abstract
In Klebsiella pneumoniae CG43S3, deletion of the response regulator gene rcsB reduced the capsular polysaccharide amount and survival on exposure to acid stress. A comparison of the pH 4.4-induced proteomes between CG43S3 and CG43S3ΔrcsB revealed numerous differentially expressed proteins and one of them, YfdX, which has recently been reported as a periplasmic protein, was absent in CG43S3ΔrcsB. Acid survival analysis was then conducted to determine its role in the acid stress response. Deletion of yfdX increased the sensitivity of K. pneumoniae CG43S3 to a pH of 2.5, and transforming the mutant with a plasmid carrying yfdX restored the acid resistance (AR) levels. In addition, the effect of yfdX deletion was cross-complemented by the expression of the periplasmic chaperone HdeA. Furthermore, the purified recombinant protein YfdX reduced the acid-induced protein aggregation, suggesting that YfdX as well as HdeA functions as a chaperone. The following promoter activity measurement revealed that rcsB deletion reduced the expression of yfdX after the bacteria were subjected to pH 4.4 adaptation. Western blot analysis also revealed that YfdX production was inhibited by rcsB deletion and only the plasmid expressing RcsB or the nonphosphorylated form of RcsB, RcsBD56A, could restore the YfdX production, and the RcsB-mediated complementation was no longer observed when the sensor kinase RcsD gene was deleted. In conclusion, this is the first study demonstrating that YfdX may be involved in the acid stress response as a periplasmic chaperone and that RcsB positively regulates the acid stress response partly through activation of yfdX expression. Moreover, the phosphorylation status of RcsB may affect the YfdX expression under acidic conditions.
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Affiliation(s)
- Chia-Jui Liu
- Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
| | - Ching-Ting Lin
- School of Chinese Medicine, China Medical University, Taichung, Taiwan, Republic of China
| | - Jo-Di Chiang
- Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
| | - Chen-Yi Lin
- Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
| | - Yen-Xi Tay
- Institute of Molecular Medicine and Biological Technology, School of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
| | - Li-Cheng Fan
- Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
| | - Kuan-Nan Peng
- Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
| | - Chih-Huan Lin
- Institute of Molecular Medicine and Biological Technology, School of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
| | - Hwei-Ling Peng
- Department of Biological Science and Technology, School of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
- Institute of Molecular Medicine and Biological Technology, School of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
- * E-mail:
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19
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Mutz YDS, Rosario DKA, Paschoalin VMF, Conte-Junior CA. Salmonella enterica: A hidden risk for dry-cured meat consumption? Crit Rev Food Sci Nutr 2019; 60:976-990. [DOI: 10.1080/10408398.2018.1555132] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Yhan da Silva Mutz
- Chemistry Institute, Federal University of Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil
- Department of Food Technology, Federal Fluminense University, Vital Brazil Filho, Niterói, RJ, Brazil
| | - Denes Kaic Alves Rosario
- Chemistry Institute, Federal University of Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil
- Department of Food Technology, Federal Fluminense University, Vital Brazil Filho, Niterói, RJ, Brazil
| | | | - Carlos Adam Conte-Junior
- Chemistry Institute, Federal University of Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil
- Department of Food Technology, Federal Fluminense University, Vital Brazil Filho, Niterói, RJ, Brazil
- National Institute of Health Quality Control, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
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20
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Sarvan S, Butcher J, Stintzi A, Couture JF. Variation on a theme: investigating the structural repertoires used by ferric uptake regulators to control gene expression. Biometals 2018; 31:681-704. [DOI: 10.1007/s10534-018-0120-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 06/12/2018] [Indexed: 11/29/2022]
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21
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Biological and regulatory roles of acid-induced small RNA RyeC in Salmonella Typhimurium. Biochimie 2018; 150:48-56. [PMID: 29730297 DOI: 10.1016/j.biochi.2018.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 05/01/2018] [Indexed: 12/23/2022]
Abstract
Salmonella Typhimurium is an enteric pathogen that has evolved masterful strategies to enable survival under stress conditions both within and outside a host. The acid tolerance response (ATR) is one such mechanism that enhances the viability of acid adapted bacteria to lethal pH levels. While numerous studies exist on the protein coding components of this response, there is very little data on the roles of small RNAs (sRNAs). These non-coding RNA molecules have recently been shown to play roles as regulators of bacterial stress response and virulence pathways. They function through complementary base pairing interactions with target mRNAs and affect their translation and/or stability. There are also a few that directly bind to proteins by mimicking their respective targets. Here, we identify several sRNAs expressed during the ATR of S. Typhimurium and characterize one highly induced candidate, RyeC. Further, we identify ptsI as a trans-encoded target that is directly regulated by this sRNA. From a functional perspective, over-expression of RyeC in Salmonella produced a general attenuation of several in vitro phenotypes including acid survival, motility, adhesion and invasion of epithelial cell lines as well as replication within macrophages. Together, this study highlights the diverse roles played by sRNAs in acid tolerance and virulence of S. Typhimurium.
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22
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Clark-Curtiss JE, Curtiss R. Salmonella Vaccines: Conduits for Protective Antigens. THE JOURNAL OF IMMUNOLOGY 2018; 200:39-48. [PMID: 29255088 DOI: 10.4049/jimmunol.1600608] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 11/06/2017] [Indexed: 11/19/2022]
Abstract
Vaccines afford a better and more cost-effective approach to combatting infectious diseases than continued reliance on antibiotics or antiviral or antiparasite drugs in the current era of increasing incidences of diseases caused by drug-resistant pathogens. Recombinant attenuated Salmonella vaccines (RASVs) have been significantly improved to exhibit the same or better attributes than wild-type parental strains to colonize internal lymphoid tissues and persist there to serve as factories to continuously synthesize and deliver rAgs. Encoded by codon-optimized pathogen genes, Ags are selected to induce protective immunity to infection by that pathogen. After immunization through a mucosal surface, the RASV attributes maximize their abilities to elicit mucosal and systemic Ab responses and cell-mediated immune responses. This article summarizes many of the numerous innovative technologies and discoveries that have resulted in RASV platforms that will enable development of safe efficacious RASVs to protect animals and humans against a diversity of infectious disease agents.
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Affiliation(s)
- Josephine E Clark-Curtiss
- Division of Infectious Diseases and Global Medicine, Department of Medicine, College of Medicine, University of Florida, Gainesville, FL 32610.,Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611
| | - Roy Curtiss
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611; and .,Department of Comparative, Diagnostic and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611
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23
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Bae YM, Yoon JH, Kim JY, Lee SY. Identifying the mechanism ofEscherichia coliO157:H7 survival by the addition of salt in the treatment with organic acids. J Appl Microbiol 2017; 124:241-253. [DOI: 10.1111/jam.13613] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/30/2017] [Accepted: 08/03/2017] [Indexed: 11/29/2022]
Affiliation(s)
- Y.-M. Bae
- Department of Food Science and Technology; Chung-Ang University; Anseong-si Gyeonggi-do Korea
| | - J.-H. Yoon
- Department of Food Science and Technology; Chung-Ang University; Anseong-si Gyeonggi-do Korea
| | - J.-Y. Kim
- Department of Food Science and Technology; Chung-Ang University; Anseong-si Gyeonggi-do Korea
| | - S.-Y. Lee
- Department of Food Science and Technology; Chung-Ang University; Anseong-si Gyeonggi-do Korea
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24
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The Campylobacter jejuni Ferric Uptake Regulator Promotes Acid Survival and Cross-Protection against Oxidative Stress. Infect Immun 2016; 84:1287-1300. [PMID: 26883589 DOI: 10.1128/iai.01377-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 02/05/2016] [Indexed: 12/29/2022] Open
Abstract
Campylobacter jejuni is a prevalent cause of bacterial gastroenteritis in humans worldwide. The mechanisms by which C. jejuni survives stomach acidity remain undefined. In the present study, we demonstrated that the C. jejuni ferric uptake regulator (Fur) plays an important role in C. jejuni acid survival and acid-induced cross-protection against oxidative stress. A C. jejuni Δfur mutant was more sensitive to acid than the wild-type strain. Profiling of the acid stimulon of the C. jejuni Δfur mutant allowed us to uncover Fur-regulated genes under acidic conditions. In particular, Fur was found to upregulate genes involved in flagellar and cell envelope biogenesis upon acid stress, and mutants with deletions of these genes were found to be defective in surviving acid stress. Interestingly, prior acid exposure of C. jejuni cross-protected against oxidative stress in a catalase (KatA)- and Fur-dependent manner. Western blotting and reverse transcription-quantitative PCR revealed increased expression of KatA upon acid stress. Electrophoretic mobility shift assays (EMSAs) demonstrated that the binding affinity between Fur and the katA promoter is reduced in vitro under conditions of low pH, rationalizing the higher levels of expression of katA under acidic conditions. Strikingly, the Δfur mutant exhibited reduced virulence in both human epithelial cells and the Galleria mellonella infection model. Altogether, this is the first study showing that, in addition to its role in iron metabolism, Fur is an important regulator of C. jejuni acid responses and this function cross-protects against oxidative stress. Moreover, our results clearly demonstrate Fur's important role in C. jejuni pathogenesis.
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Hu YH, Sun L. The global regulatory effect of Edwardsiella tarda Fur on iron acquisition, stress resistance, and host infection: A proteomics-based interpretation. J Proteomics 2016; 140:100-10. [PMID: 27102497 DOI: 10.1016/j.jprot.2016.04.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/27/2016] [Accepted: 04/07/2016] [Indexed: 02/01/2023]
Abstract
UNLABELLED Ferric uptake regulator (Fur) is an important transcriptional regulator of Gram-negative bacteria. Edwardsiella tarda is a severe fish bacterial pathogen with a broad host range that includes humans. In this study, we examined the regulatory function of Fur in E. tarda via a proteomic approach. Compared to the wild type TX01, the fur mutant TX01Δfur exhibited (i) retarded growth, (ii) enhanced siderophore production, (iii) increased acid tolerance, which is in contrast to observations in other bacterial species, (iv) decreased survival against oxidative stress and host serum, (v) impaired ability to inhibit host immune response, (vi) attenuated tissue infectivity and overall virulence. The deficiency of TX01Δfur was rescued by introduction of an exogenous fur gene. iTRAQ-based comparative proteomic analysis of TX01Δfur and TX01 identified 89 differentially expressed proteins that cover a wide range of functional categories including those affected by fur mutation. In addition, 16 proteins were identified for the first time to be regulated by Fur in Gram-negative bacteria. These results provide the first protein-based interpretation of the global impact of Fur on the physiology and infectivity of E. tarda. SIGNIFICANCE This study demonstrates that in E. tarda, Fur controls multiple aspects of bacterial life, including growth, metabolism, iron acquisition, stress response, and host infection. In line with these observations, proteomics analysis identified a large amount of proteins affected in expression by Fur, which are involved in bacterial physiology and infectivity. Hence, these results link for the first time the pleiotropic effect of Fur with global protein expression and shed new light on the function and regulatory mechanism of Fur in pathogenic bacteria.
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Affiliation(s)
- Yong-Hua Hu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Li Sun
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
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Fingermann M, Hozbor D. Acid tolerance response of Bordetella bronchiseptica in avirulent phase. Microbiol Res 2015; 181:52-60. [DOI: 10.1016/j.micres.2015.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 08/26/2015] [Accepted: 09/01/2015] [Indexed: 01/06/2023]
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Ryan D, Pati NB, Ojha UK, Padhi C, Ray S, Jaiswal S, Singh GP, Mannala GK, Schultze T, Chakraborty T, Suar M. Global transcriptome and mutagenic analyses of the acid tolerance response of Salmonella enterica serovar Typhimurium. Appl Environ Microbiol 2015; 81:8054-65. [PMID: 26386064 PMCID: PMC4651094 DOI: 10.1128/aem.02172-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 09/01/2015] [Indexed: 01/18/2023] Open
Abstract
Salmonella enterica serovar Typhimurium (S. Typhimurium) is one of the leading causative agents of food-borne bacterial gastroenteritis. Swift invasion through the intestinal tract and successful establishment in systemic organs are associated with the adaptability of S. Typhimurium to different stress environments. Low-pH stress serves as one of the first lines of defense in mammalian hosts, which S. Typhimurium must efficiently overcome to establish an infection. Therefore, a better understanding of the molecular mechanisms underlying the adaptability of S. Typhimurium to acid stress is highly relevant. In this study, we have performed a transcriptome analysis of S. Typhimurium under the acid tolerance response (ATR) and found a large number of genes (∼47%) to be differentially expressed (more than 1.5-fold or less than -1.5-fold; P < 0.01). Functional annotation revealed differentially expressed genes to be associated with regulation, metabolism, transport and binding, pathogenesis, and motility. Additionally, our knockout analysis of a subset of differentially regulated genes facilitated the identification of proteins that contribute to S. Typhimurium ATR and virulence. Mutants lacking genes encoding the K(+) binding and transport protein KdpA, hypothetical protein YciG, the flagellar hook cap protein FlgD, and the nitrate reductase subunit NarZ were significantly deficient in their ATRs and displayed varied in vitro virulence characteristics. This study offers greater insight into the transcriptome changes of S. Typhimurium under the ATR and provides a framework for further research on the subject.
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Affiliation(s)
- Daniel Ryan
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | - Niladri Bhusan Pati
- Institute of Medical Microbiology, German Centre of Infection Research, Site Giessen-Marburg-Langen, Justus-Liebig-University Giessen, Giessen, Germany
| | - Urmesh K Ojha
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | | | - Shilpa Ray
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | - Sangeeta Jaiswal
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | - Gajinder P Singh
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | - Gopala K Mannala
- Institute of Medical Microbiology, German Centre of Infection Research, Site Giessen-Marburg-Langen, Justus-Liebig-University Giessen, Giessen, Germany
| | - Tilman Schultze
- Institute of Medical Microbiology, German Centre of Infection Research, Site Giessen-Marburg-Langen, Justus-Liebig-University Giessen, Giessen, Germany
| | - Trinad Chakraborty
- Institute of Medical Microbiology, German Centre of Infection Research, Site Giessen-Marburg-Langen, Justus-Liebig-University Giessen, Giessen, Germany
| | - Mrutyunjay Suar
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
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Lin IYC, Van TTH, Smooker PM. Live-Attenuated Bacterial Vectors: Tools for Vaccine and Therapeutic Agent Delivery. Vaccines (Basel) 2015; 3:940-72. [PMID: 26569321 PMCID: PMC4693226 DOI: 10.3390/vaccines3040940] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 10/30/2015] [Accepted: 10/30/2015] [Indexed: 12/14/2022] Open
Abstract
Genetically attenuated microorganisms, including pathogenic and commensal bacteria, can be engineered to carry and deliver heterologous antigens to elicit host immunity against both the vector as well as the pathogen from which the donor gene is derived. These live attenuated bacterial vectors have been given much attention due to their capacity to induce a broad range of immune responses including localized mucosal, as well as systemic humoral and/or cell-mediated immunity. In addition, the unique tumor-homing characteristics of these bacterial vectors has also been exploited for alternative anti-tumor vaccines and therapies. In such approach, tumor-associated antigen, immunostimulatory molecules, anti-tumor drugs, or nucleotides (DNA or RNA) are delivered. Different potential vectors are appropriate for specific applications, depending on their pathogenic routes. In this review, we survey and summarize the main features of the different types of live bacterial vectors and discussed the clinical applications in the field of vaccinology. In addition, different approaches for using live attenuated bacterial vectors for anti-cancer therapy is discussed, and some promising pre-clinical and clinical studies in this field are outlined.
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Affiliation(s)
- Ivan Y C Lin
- School of Applied Sciences, RMIT University, Plenty Road, Bundoora VIC-3083, Australia.
| | - Thi Thu Hao Van
- School of Applied Sciences, RMIT University, Plenty Road, Bundoora VIC-3083, Australia.
| | - Peter M Smooker
- School of Applied Sciences, RMIT University, Plenty Road, Bundoora VIC-3083, Australia.
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Kaushik MS, Singh P, Tiwari B, Mishra AK. Ferric Uptake Regulator (FUR) protein: properties and implications in cyanobacteria. ANN MICROBIOL 2015. [DOI: 10.1007/s13213-015-1134-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Brenneman KE, Gonzales A, Roland KL, Curtiss R. Use of Ensure® nutrition shakes as an alternative formulation method for live recombinant Attenuated Salmonella Typhi vaccines. BMC Microbiol 2015; 15:76. [PMID: 25879849 PMCID: PMC4391280 DOI: 10.1186/s12866-015-0409-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/12/2015] [Indexed: 11/12/2022] Open
Abstract
Background To be effective, orally administered live Salmonella vaccines must first survive their encounter with the low pH environment of the stomach. To enhance survival, an antacid is often given to neutralize the acidic environment of the stomach just prior to or concomitant with administration of the vaccine. One drawback of this approach, from the perspective of the clinical trial volunteer, is that the taste of a bicarbonate-based acid neutralization system can be unpleasant. Thus, we explored an alternative method that would be at least as effective as bicarbonate and with a potentially more acceptable taste. Because ingestion of protein can rapidly buffer stomach pH, we examined the possibility that the protein-rich Ensure® Nutrition shakes would be effective alternatives to bicarbonate. Results We tested one Salmonella enterica serovar Typhimurium and three Salmonella Typhi vaccine strains and found that all strains survived equally well when incubated in either Ensure® or bicarbonate. In a low gastric pH mouse model, Ensure® worked as well or better than bicarbonate to enhance survival through the intestinal tract, although neither agent enhanced the survival of the S. Typhi test strain possessing a rpoS mutation. Conclusions Our data show that a protein-rich drink such as Ensure® Nutrition shakes can serve as an alternative to bicarbonate for reducing gastric pH prior to administration of a live Salmonella vaccine.
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Affiliation(s)
- Karen E Brenneman
- The Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA. .,Present address - 23andMe, Inc, 1390 Shorebird Way, Mountain View, CA, 94043, USA.
| | - Amanda Gonzales
- The Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA.
| | - Kenneth L Roland
- The Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA.
| | - Roy Curtiss
- The Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA. .,School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA.
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Liu L, Si L, Meng X, Luo L. Comparative transcriptomic analysis reveals novel genes and regulatory mechanisms of Tetragenococcus halophilus in response to salt stress. J Ind Microbiol Biotechnol 2015; 42:601-16. [PMID: 25563971 DOI: 10.1007/s10295-014-1579-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 12/25/2014] [Indexed: 11/29/2022]
Abstract
Tetragenococcus halophilus, a moderately halophilic Gram-positive bacterium, was isolated from Chinese style soy sauce. This species is a valuable resource for investigating salt tolerance mechanisms and improving salinity resistance in microorganisms. RNA-seq was used to sequence T. halophilus samples treated with 0 M (T1), 1 M (T2), and 3.5 M NaCl (T3). Comparative transcriptomic analyses of the different treatments were performed using gene ontology and Kyoto encyclopedia of genes and genome. The comparison of T1 and T2 by RNA-seq revealed that genes involved in transcription, translation, membrane system, and division were highly up-regulated under optimum salt condition. The comparison of T2 and T3 showed that genes related to heat shock proteins or the ATP-binding cassette transport systems were significantly up-regulated under maximum-salt condition. In addition, a considerable proportion of the significantly differently expressed genes identified in this study are novel. These data provide a crucial resource that may determine specific responses to salt stress in T. halophilus.
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Affiliation(s)
- Licui Liu
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China
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Lund P, Tramonti A, De Biase D. Coping with low pH: molecular strategies in neutralophilic bacteria. FEMS Microbiol Rev 2014; 38:1091-125. [PMID: 24898062 DOI: 10.1111/1574-6976.12076] [Citation(s) in RCA: 272] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 02/26/2014] [Accepted: 03/14/2014] [Indexed: 12/31/2022] Open
Abstract
As part of their life cycle, neutralophilic bacteria are often exposed to varying environmental stresses, among which fluctuations in pH are the most frequent. In particular, acid environments can be encountered in many situations from fermented food to the gastric compartment of the animal host. Herein, we review the current knowledge of the molecular mechanisms adopted by a range of Gram-positive and Gram-negative bacteria, mostly those affecting human health, for coping with acid stress. Because organic and inorganic acids have deleterious effects on the activity of the biological macromolecules to the point of significantly reducing growth and even threatening their viability, it is not unexpected that neutralophilic bacteria have evolved a number of different protective mechanisms, which provide them with an advantage in otherwise life-threatening conditions. The overall logic of these is to protect the cell from the deleterious effects of a harmful level of protons. Among the most favoured mechanisms are the pumping out of protons, production of ammonia and proton-consuming decarboxylation reactions, as well as modifications of the lipid content in the membrane. Several examples are provided to describe mechanisms adopted to sense the external acidic pH. Particular attention is paid to Escherichia coli extreme acid resistance mechanisms, the activity of which ensure survival and may be directly linked to virulence.
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Affiliation(s)
- Peter Lund
- School of Biosciences, University of Birmingham, Birmingham, UK
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Evaluation of protective efficacy of live attenuated Salmonella enterica serovar Gallinarum vaccine strains against fowl typhoid in chickens. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:1267-76. [PMID: 24990908 DOI: 10.1128/cvi.00310-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Salmonella enterica serovar Gallinarum is the etiological agent of fowl typhoid, which constitutes a considerable economic problem for poultry growers in developing countries. The vaccination of chickens seems to be the most effective strategy to control the disease in those areas. We constructed S. Gallinarum strains with a deletion of the global regulatory gene fur and evaluated their virulence and protective efficacy in Rhode Island Red chicks and Brown Leghorn layers. The fur deletion mutant was avirulent and, when delivered orally to chicks, elicited excellent protection against lethal S. Gallinarum challenge. It was not as effective when given orally to older birds, although it was highly immunogenic when delivered by intramuscular injection. We also examined the effect of a pmi mutant and a combination of fur deletions with mutations in the pmi and rfaH genes, which affect O-antigen synthesis, and ansB, whose product inhibits host T-cell responses. The S. Gallinarum Δpmi mutant was only partially attenuated, and the ΔansB mutant was fully virulent. The Δfur Δpmi and Δfur ΔansB double mutants were attenuated but not protective when delivered orally to the chicks. However, a Δpmi Δfur strain was highly immunogenic when administered intramuscularly. All together, our results show that the fur gene is essential for the virulence of S. Gallinarum, and the fur mutant is effective as a live recombinant vaccine against fowl typhoid.
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The iron-sensing fur regulator controls expression timing and levels of salmonella pathogenicity island 2 genes in the course of environmental acidification. Infect Immun 2014; 82:2203-10. [PMID: 24643535 DOI: 10.1128/iai.01625-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In order to survive inside macrophages, Salmonella produces a series of proteins encoded by genes within Salmonella pathogenicity island 2 (SPI-2). In the present study, we report that Fur, a central regulator of iron utilization, negatively controls the expression of SPI-2 genes. Time course analysis of SPI-2 expression after the entry of Salmonella into macrophages revealed that SPI-2 genes are induced earlier and at higher levels in the absence of the Fur regulator. It was hypothesized that Fur repressed the SPI-2 expression that was activated during acidification of the phagosome. Indeed, as pH was lowered from pH 7.0 to pH 5.5, the lack of Fur enabled SPI-2 gene expression to be induced at higher pH and to be expressed at higher levels. Fur controlled SPI-2 genes via repression of the SsrB response regulator, a primary activator of SPI-2 expression. Fur repressed ssrB expression both inside macrophages and under acidic conditions, which we ascribe to the direct binding of Fur to the ssrB promoter. Our study suggests that Salmonella could employ iron inside the phagosome to precisely control the timing and levels of SPI-2 expression inside macrophages.
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Fillat MF. The FUR (ferric uptake regulator) superfamily: diversity and versatility of key transcriptional regulators. Arch Biochem Biophys 2014; 546:41-52. [PMID: 24513162 DOI: 10.1016/j.abb.2014.01.029] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/27/2014] [Accepted: 01/31/2014] [Indexed: 11/17/2022]
Abstract
Control of metal homeostasis is essential for life in all kingdoms. In most prokaryotic organisms the FUR (ferric uptake regulator) family of transcriptional regulators is involved in the regulation of iron and zinc metabolism through control by Fur and Zur proteins. A third member of this family, the peroxide-stress response PerR, is present in most Gram-positives, establishing a tight functional interaction with the global regulator Fur. These proteins play a pivotal role for microbial survival under adverse conditions and in the expression of virulence in most pathogens. In this paper we present the current state of the art in the knowledge of the FUR family, including those members only present in more reduced numbers of bacteria, namely Mur, Nur and Irr. The huge amount of work done in the two last decades shows that FUR proteins present considerable diversity in their regulatory mechanisms and interesting structural differences. However, much work needs to be done to obtain a more complete picture of this family, especially in connection with the roles of some members as gas and redox sensors as well as to fully characterize their participation in bacterial adaptative responses.
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Affiliation(s)
- María F Fillat
- Department of Biochemistry and Molecular and Cell Biology, Institute for Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Pedro Cerbuna, 12, 50009 Zaragoza, Spain.
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Evolutionary potential, cross-stress behavior and the genetic basis of acquired stress resistance in Escherichia coli. Mol Syst Biol 2013; 9:643. [PMID: 23385483 PMCID: PMC3588905 DOI: 10.1038/msb.2012.76] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 12/08/2012] [Indexed: 12/20/2022] Open
Abstract
Escherichia coli cells were evolved over 500 generations and profiled in four abiotic stressors to observe several cases of emerging cross-stress behavior whereby adaptation to one stressful environment provided fitness advantage when exposed to a second stressor. ![]()
Cross-stress dependencies were found to be ubiquitous, highly interconnected and can emerge within short timeframes. Several targets were implicated in adaptation and cross-stress protection, including genes related to iron transport and flagella. Adaptation in a first stress can lead to higher fitness to a second stress when compared with cells adapted only in the latter environment. Adaptation to any specific stress and the growth media was found to be generally independent.
Bacterial populations have a remarkable capacity to cope with extreme environmental fluctuations in their natural environments. In certain cases, adaptation to one stressful environment provides a fitness advantage when cells are exposed to a second stressor, a phenomenon that has been coined as cross-stress protection. A tantalizing question in bacterial physiology is how the cross-stress behavior emerges during evolutionary adaptation and what the genetic basis of acquired stress resistance is. To address these questions, we evolved Escherichia coli cells over 500 generations in five environments that include four abiotic stressors. Through growth profiling and competition assays, we identified several cases of positive and negative cross-stress behavior that span all strain–stress combinations. Resequencing the genomes of the evolved strains resulted in the identification of several mutations and gene amplifications, whose fitness effect was further assessed by mutation reversal and competition assays. Transcriptional profiling of all strains under a specific stress, NaCl-induced osmotic stress, and integration with resequencing data further elucidated the regulatory responses and genes that are involved in this phenomenon. Our results suggest that cross-stress dependencies are ubiquitous, highly interconnected, and can emerge within short timeframes. The high adaptive potential that we observed argues that bacterial populations occupy a genotypic space that enables a high phenotypic plasticity during adaptation in fluctuating environments.
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Brenneman KE, Willingham C, Kong W, Curtiss R, Roland KL. Low-pH rescue of acid-sensitive Salmonella enterica Serovar Typhi Strains by a Rhamnose-regulated arginine decarboxylase system. J Bacteriol 2013; 195:3062-72. [PMID: 23645603 PMCID: PMC3697538 DOI: 10.1128/jb.00104-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 04/29/2013] [Indexed: 12/17/2022] Open
Abstract
For Salmonella, transient exposure to gastric pH prepares invading bacteria for the stresses of host-cell interactions. To resist the effects of low pH, wild-type Salmonella enterica uses the acid tolerance response and the arginine decarboxylase acid resistance system. However, arginine decarboxylase is typically repressed under routine culture conditions, and for many live attenuated Salmonella vaccine strains, the acid tolerance response is unable to provide the necessary protection. The objective of this study was to enhance survival of Salmonella enterica serovar Typhi vaccine strains at pHs 3.0 and 2.5 to compensate for the defects in the acid tolerance response imposed by mutations in rpoS, phoPQ, and fur. We placed the arginine decarboxylase system (adiA and adiC) under the control of the ParaBAD or PrhaBAD promoter to provide inducible acid resistance when cells are grown under routine culture conditions. The rhamnose-regulated promoter PrhaBAD was less sensitive to the presence of its cognate sugar than the arabinose-regulated promoter ParaBAD and provided tighter control over adiA expression. Increased survival at low pH was only observed when adiA and adiC were coregulated by rhamnose and depended on the presence of rhamnose in the culture medium and arginine in the challenge medium. Rhamnose-regulated acid resistance significantly improved the survival of ΔaroD and ΔphoPQ mutants at pHs 3 and 2.5 but only modestly improved the survival of a fur mutant. The construction of the rhamnose-regulated arginine decarboxylase system allowed us to render S. Typhi acid resistant (to pH 2.5) on demand, with survival levels approximately equivalent to that of the native arginine decarboxylase system.
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Affiliation(s)
| | | | - Wei Kong
- The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Roy Curtiss
- The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Kenneth L. Roland
- The Biodesign Institute, Arizona State University, Tempe, Arizona, USA
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Leclerc JM, Dozois CM, Daigle F. Role of the Salmonella enterica serovar Typhi Fur regulator and small RNAs RfrA and RfrB in iron homeostasis and interaction with host cells. Microbiology (Reading) 2013; 159:591-602. [DOI: 10.1099/mic.0.064329-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Jean-Mathieu Leclerc
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
| | - Charles M. Dozois
- INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, QC H7V 1B7, Canada
| | - France Daigle
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
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Vishwakarma V, Pati NB, Chandel HS, Sahoo SS, Saha B, Suar M. Evaluation of Salmonella enterica serovar Typhimurium TTSS-2 deficient fur mutant as safe live-attenuated vaccine candidate for immunocompromised mice. PLoS One 2012; 7:e52043. [PMID: 23284865 PMCID: PMC3524104 DOI: 10.1371/journal.pone.0052043] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 11/08/2012] [Indexed: 01/14/2023] Open
Abstract
Salmonella enterica serovar Typhimurium has been extensively exploited as live attenuated vaccines (LAV) which generally confers better protection than killed or subunit vaccines. However, many LAV are limited by their inherent ability to access systemic organs in many of the vaccinated hosts, especially those which are immunocompromised. We evaluated the efficacy of a live-attenuated SPI2-deficient (ΔssaV) S. Typhimurium vaccine candidate (MT13) that additionally devoids the ferric uptake regulator (fur). We used specific pathogen free (SPF) streptomycin-pretreated mouse colitis model that included healthy C57BL/6 and immunocompromised iNos−/−, IL10−/− and CD40L−/− in the background of C57BL/6 mice to assess the efficacy of developed vaccine candidate. In our study, the S. Typhimurium MT13 strain was established as a safe vaccine candidate to be administered in immunocompromised mice as it was found to be systemically attenuated without conferring significant pathological signs and growth defect within the host. In bacterial challenge experiment, the MT13-vaccinated C57BL/6 mice were protected from subsequent wild-type S. Typhimurium infection by inducing proficient mucosal immunity. The MT13 strain elicited efficient O-antigen specific mucosal secretory IgA associated protective response which was comparable with its parental ssaV mutant. Vaccination with MT13 also showed proficient T-cell activation in host mice; which has direct relation with pathogen clearance from host tissues. Collectively, these data implicate the possible application of SPI-2 deficient fur mutant (MT13) as a novel live attenuated vaccine strain with adept immunogenicity and improved safety, even in immunocompromised hosts. Further, this vaccine candidate can be employed to express heterologous antigens targeted against several other diseases, especially related to enterocolitic pathogens.
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Affiliation(s)
| | | | | | | | - Bhaskar Saha
- National Centre for Cell Sciences, Ganeshkhind, Pune, India
| | - Mrutyunjay Suar
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
- * E-mail:
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Darcan C, Aydin E. fur (-) mutation increases the survival time of Escherichia coli under photooxidative stress in aquatic environments. ACTA BIOLOGICA HUNGARICA 2012; 63:399-409. [PMID: 22963920 DOI: 10.1556/abiol.63.2012.3.10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We investigated the survival of the wild type Escherichia coli (QC771) and fur- mutant strain (QC1732) under photooxidative stress in different water sources. The survival of fur- mutant and wild type E. coli was seen as a significant decrease in the visible light samples in the presence of methylene blue (MB). The fur-E. coli strain lived longer than the wild type E. coli strain on exposure to MB and visible light, which generates singlet oxygen, in both lake water (48-h) and pure water (16-h). It is interesting to note that the survival of both wild type and the fur- mutant strain was more protected at 24 °C than at other temperatures. The Fur protein does not have any relation to the entry of E. coli into the viable but nonculturable state (VBNC) under photooxidative stress. This is the first study which shows that fur- mutation increases the resistance of E. coli to photooxidative stress in aquatic environments, and the Fur protein does not have any relation to the entry of E. coli into the VBNC state.
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Affiliation(s)
- C Darcan
- Department of Biology, Faculty of Arts and Sciences, Dumlupinar University, 43100 Kütahya, Turkey.
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Acid stress response and protein induction in Campylobacter jejuni isolates with different acid tolerance. BMC Microbiol 2012; 12:174. [PMID: 22889088 PMCID: PMC3528441 DOI: 10.1186/1471-2180-12-174] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 07/20/2012] [Indexed: 11/23/2022] Open
Abstract
Background During the transmission route from poultry to the human host, the major foodborne pathogen C. jejuni may experience many types of stresses, including low pH caused by different acids. However, not all strains are equally sensitive to the stresses. The aim of this study was to investigate the response to acid stress of three sequenced C. jejuni strains with different acid tolerances using HCl and acetic acid. Results Two-dimensional gel electrophoresis was used for proteomic analysis and proteins were radioactively labelled with methionine to identify proteins only related to acid exposure. To allow added radioactive methionine to be incorporated into induced proteins, a modified chemically defined broth was developed with the minimal amount of methionine necessary for satisfactory growth of all strains. Protein spots were analyzed using image software and identification was done with MALDI-TOF-TOF. The most acid-sensitive isolate was C. jejuni 327, followed by NCTC 11168 and isolate 305 as the most tolerant. Overall, induction of five proteins was observed within the pI range investigated: 19 kDa periplasmic protein (p19), thioredoxin-disulfide (TrxB), a hypothetical protein Cj0706 (Cj0706), molybdenum cofactor biosynthesis protein (MogA), and bacterioferritin (Dps). Strain and acid type dependent differences in the level of response were observed. For strain NCTC 11168, the induced proteins and the regulator fur were analysed at the transcriptomic level using qRT-PCR. In this transcriptomic analysis, only up-regulation of trxB and p19 was observed. Conclusions A defined medium that supports the growth of a range of Campylobacter strains and suitable for proteomic analysis was developed. Mainly proteins normally involved in iron control and oxidative stress defence were induced during acid stress of C. jejuni. Both strain and acid type affected sensitivity and response.
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Silverman JM, Brunet YR, Cascales E, Mougous JD. Structure and regulation of the type VI secretion system. Annu Rev Microbiol 2012; 66:453-72. [PMID: 22746332 DOI: 10.1146/annurev-micro-121809-151619] [Citation(s) in RCA: 269] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The type VI secretion system (T6SS) is a complex and widespread gram-negative bacterial export pathway with the capacity to translocate protein effectors into a diversity of target cell types. Current structural models of the T6SS indicate that the apparatus is composed of at least two complexes, a dynamic bacteriophage-like structure and a cell-envelope-spanning membrane-associated assembly. How these complexes interact to promote effector secretion and cell targeting remains a major question in the field. As a contact-dependent pathway with specific cellular targets, the T6SS is subject to tight regulation. Thus, the identification of regulatory elements that control T6S expression continues to shape our understanding of the environmental circumstances relevant to its function. This review discusses recent progress toward characterizing T6S structure and regulation.
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Affiliation(s)
- Julie M Silverman
- Department of Microbiology, University of Washington, Seattle, 98195, USA
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Álvarez-Ordóñez A, Prieto M, Bernardo A, Hill C, López M. The Acid Tolerance Response of Salmonella spp.: An adaptive strategy to survive in stressful environments prevailing in foods and the host. Food Res Int 2012. [DOI: 10.1016/j.foodres.2011.04.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Toledo H, Villafaena C, Valenzuela M, López-Solís R. Arginine 66 residue of Fur is required for the regulatory function of this protein in the acid adaptation mechanism of Helicobacter pylori. Helicobacter 2012; 17:16-22. [PMID: 22221611 DOI: 10.1111/j.1523-5378.2011.00893.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND Helicobacter pylori colonizes the gastric mucosa and must survive the acid pH of that environment. Like other enteric bacterial pathogens, including Salmonella enterica, H. pylori develops an acid tolerance response that is dependent on the function of the transcriptional regulator protein Fur. OBJECTIVE To explore by site-directed mutagenesis whether two particular amino acid residues in the amino acid sequence of the H. pylori Fur protein, arginine 66 and histidine 99, are involved in the acid response mechanism in this bacterium. MATERIALS AND METHODS Complementation assays in Escherichia coli H1780 (fur null mutant) both with plasmids carrying the H. pylori fur gene bearing substitution mutations R66A or H99A or R66A/H99A and with the H. pylori Fur-R66A mutant were conducted. Wild-type and mutated Fur proteins from H. pylori were assayed by using the fiu::lacZ reporter gene in the E. coli H1780 heterologous system at various pH and iron concentrations. RESULTS Both bacterial growth and repression of the reporter gene were impaired under acid conditions in E. coli H1780 complemented with pUC19-fur-R66A. Also, in the H. pylori Fur-R66 strain bacterial growth and speA gene expression were impaired under acid conditions. CONCLUSIONS Arginine 66 but not histidine 99 in H. pylori Fur is required for the regulatory function of the Fur protein in the acid adaptation mechanism of the bacterium.
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Affiliation(s)
- Héctor Toledo
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Avenida Independencia 1027, Casilla 70086, Santiago-7, Chile.
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Pinto F, van Elburg KA, Pacheco CC, Lopo M, Noirel J, Montagud A, Urchueguía JF, Wright PC, Tamagnini P. Construction of a chassis for hydrogen production: physiological and molecular characterization of a Synechocystis sp. PCC 6803 mutant lacking a functional bidirectional hydrogenase. MICROBIOLOGY-SGM 2011; 158:448-464. [PMID: 22096147 DOI: 10.1099/mic.0.052282-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cyanobacteria are photosynthetic prokaryotes that are promising 'low-cost' microbial cell factories due to their simple nutritional requirements and metabolic plasticity, and the availability of tools for their genetic manipulation. The unicellular non-nitrogen-fixing Synechocystis sp. PCC 6803 is the best studied cyanobacterial strain and its genome was the first to be sequenced. The vast amount of physiological and molecular data available, together with a relatively small genome, makes Synechocystis suitable for computational metabolic modelling and to be used as a photoautotrophic chassis in synthetic biology applications. To prepare it for the introduction of a synthetic hydrogen producing device, a Synechocystis sp. PCC 6803 deletion mutant lacking an active bidirectional hydrogenase (ΔhoxYH) was produced and characterized at different levels: physiological, proteomic and transcriptional. The results showed that, under conditions favouring hydrogenase activity, 17 of the 210 identified proteins had significant differential fold changes in comparisons of the mutant with the wild-type. Most of these proteins are related to the redox and energy state of the cell. Transcriptional studies revealed that only six genes encoding those proteins exhibited significant differences in transcript levels. Moreover, the mutant exhibits similar growth behaviour compared with the wild-type, reflecting Synechocystis plasticity and metabolic adaptability. Overall, this study reveals that the Synechocystis ΔhoxYH mutant is robust and can be used as a photoautotrophic chassis for the integration of synthetic constructs, i.e. molecular constructs assembled from well characterized biological and/or synthetic parts (e.g. promoters, regulators, coding regions, terminators) designed for a specific purpose.
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Affiliation(s)
- Filipe Pinto
- Faculdade de Ciências, Departamento de Biologia, Universidade do Porto, Rua do Campo Alegre, Edifício FC4, 4169-007 Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Karin A van Elburg
- Biological and Environmental Systems Group, ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Mapping Street, Sheffield S1 3JD, UK
| | - Catarina C Pacheco
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Miguel Lopo
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Josselin Noirel
- Biological and Environmental Systems Group, ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Mapping Street, Sheffield S1 3JD, UK
| | - Arnau Montagud
- Instituto Universitario de Matemática Pura y Aplicada, Universidad Politécnica de Valencia, Camí de Vera, E-46071 Valencia, Spain
| | - Javier F Urchueguía
- Instituto Universitario de Matemática Pura y Aplicada, Universidad Politécnica de Valencia, Camí de Vera, E-46071 Valencia, Spain
| | - Phillip C Wright
- Biological and Environmental Systems Group, ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Mapping Street, Sheffield S1 3JD, UK
| | - Paula Tamagnini
- Faculdade de Ciências, Departamento de Biologia, Universidade do Porto, Rua do Campo Alegre, Edifício FC4, 4169-007 Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
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Álvarez-Ordóñez A, Begley M, Prieto M, Messens W, López M, Bernardo A, Hill C. Salmonella spp. survival strategies within the host gastrointestinal tract. MICROBIOLOGY-SGM 2011; 157:3268-3281. [PMID: 22016569 DOI: 10.1099/mic.0.050351-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Human salmonellosis infections are usually acquired via the food chain as a result of the ability of Salmonella serovars to colonize and persist within the gastrointestinal tract of their hosts. In addition, after food ingestion and in order to cause foodborne disease in humans, Salmonella must be able to resist several deleterious stress conditions which are part of the host defence against infections. This review gives an overview of the main defensive mechanisms involved in the Salmonella response to the extreme acid conditions of the stomach, and the elevated concentrations of bile salts, osmolytes and commensal bacterial metabolites, and the low oxygen tension conditions of the mammalian and avian gastrointestinal tracts.
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Affiliation(s)
- Avelino Álvarez-Ordóñez
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.,Department of Microbiology, University College Cork, Cork, Ireland
| | - Máire Begley
- Department of Microbiology, University College Cork, Cork, Ireland
| | - Miguel Prieto
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, León, Spain
| | - Winy Messens
- Biological Hazards (BIOHAZ) Unit, European Food Safety Authority (EFSA), Largo N. Palli 5/A, I-43121 Parma, Italy
| | - Mercedes López
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, León, Spain
| | - Ana Bernardo
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, León, Spain
| | - Colin Hill
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.,Department of Microbiology, University College Cork, Cork, Ireland
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Valenzuela M, Albar JP, Paradela A, Toledo H. Helicobacter pylori exhibits a fur-dependent acid tolerance response. Helicobacter 2011; 16:189-99. [PMID: 21585604 DOI: 10.1111/j.1523-5378.2011.00824.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Helicobacter pylori colonizes the acid environment of the gastric mucosa. Like other enteric bacterial pathogens, including Salmonella enterica, which must survive a brief exposure to that environment, H. pylori displays a rapid response to subtle changes in pH, which confers an increased ability to survive at more extreme acidic pH. This two-step acid tolerance response (ATR) requires de novo protein synthesis and is dependent on the function of the global regulatory protein Fur. OBJECTIVE We have explored the physiological bases of the ATR in H. pylori. MATERIALS AND METHODS Proteomic analysis of phenotypes of H. pylori and fur mutant strains show that subtle pH changes elicit significant changes in the pattern of proteins synthesized. RESULTS A loss-of-function mutation in the fur gene, obtained by insertion of an antibiotic resistance cassette, indicated that Fur regulates the expression of a fraction of H. pylori proteins. CONCLUSION A subset of proteins is involved in the ATR and confer a negative ATR phenotype.
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Affiliation(s)
- Manuel Valenzuela
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Casilla 70086, Santiago-7, Chile
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Choi SS, Chivers PT, Berg DE. Point mutations in Helicobacter pylori's fur regulatory gene that alter resistance to metronidazole, a prodrug activated by chemical reduction. PLoS One 2011; 6:e18236. [PMID: 21464913 PMCID: PMC3064673 DOI: 10.1371/journal.pone.0018236] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Accepted: 02/23/2011] [Indexed: 02/08/2023] Open
Abstract
Background Helicobacter pylori's Fur regulatory protein controls transcription of dozens of genes in response to iron availability, acidity and oxidative stress, and affects the vigor of infection and severity of disease. It is unusual among Fur family proteins in being active both when iron-loaded and iron-free. Metholodolgy/Principal Findings We tested if H. pylori fur mutations could affect resistance to metronidazole (Mtz), an anti-H. pylori prodrug rendered bactericidal by chemical reduction. Point mutations were made by PCR in DNA containing fur and a downstream chloramphenicol resistance gene, and were placed in the H. pylori chromosome by transformation of a fur-deletion (Δfur) strain. Several substitutions affecting H. pylori Fur's ∼10 residue N terminal arm, which has no counterpart in prototype (E. coli-type) Fur proteins, increased Mtz resistance, as did mutations affecting the region between DNA binding and dimerization domains. Three types of mutations decreased resistance more than did Δfur: substitutions affecting the N-terminal arm; substitutions affecting the metal binding pocket; and nonsense mutations that resulted in a truncated Fur protein with no C-terminal dimerization domain. Most metal binding pocket mutations were obtained only in fur genes with additional inactivating mutations, and thus seemed deleterious or lethal because they. Conclusions/Significance These results establish that H. pylori Fur's distinctive N terminal arm is functional, and more generally illustrate that point mutations can confer informative phenotypes, distinct from those conferred by null mutations. We propose that fur mutations can affect Mtz susceptibility by altering the balance among Fur's several competing activities, and thereby the expression of genes that control cellular redox potential or elimination of bactericidal Mtz activation products. Further analyses of selected mutants should provide insights into Fur interactions with other cellular components, metabolic circuitry, and how H. pylori thrives in its special gastric niche.
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Affiliation(s)
- Sung Sook Choi
- Department of Molecular Microbiology, Washington University Medical School, St Louis, Missouri, United States of America
| | - Peter T. Chivers
- Department of Biochemistry and Molecular Biophysics, Washington University Medical School, St Louis, Missouri, United States of America
| | - Douglas E. Berg
- Department of Molecular Microbiology, Washington University Medical School, St Louis, Missouri, United States of America
- * E-mail:
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Vajrala N, Sayavedra-Soto LA, Bottomley PJ, Arp DJ. Role of a Fur homolog in iron metabolism in Nitrosomonas europaea. BMC Microbiol 2011; 11:37. [PMID: 21338516 PMCID: PMC3050691 DOI: 10.1186/1471-2180-11-37] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 02/21/2011] [Indexed: 11/24/2022] Open
Abstract
Background In response to environmental iron concentrations, many bacteria coordinately regulate transcription of genes involved in iron acquisition via the ferric uptake regulation (Fur) system. The genome of Nitrosomonas europaea, an ammonia-oxidizing bacterium, carries three genes (NE0616, NE0730 and NE1722) encoding proteins belonging to Fur family. Results Of the three N. europaea fur homologs, only the Fur homolog encoded by gene NE0616 complemented the Escherichia coli H1780 fur mutant. A N. europaea fur:kanP mutant strain was created by insertion of kanamycin-resistance cassette in the promoter region of NE0616 fur homolog. The total cellular iron contents of the fur:kanP mutant strain increased by 1.5-fold compared to wild type when grown in Fe-replete media. Relative to the wild type, the fur:kanP mutant exhibited increased sensitivity to iron at or above 500 μM concentrations. Unlike the wild type, the fur:kanP mutant was capable of utilizing iron-bound ferrioxamine without any lag phase and showed over expression of several outer membrane TonB-dependent receptor proteins irrespective of Fe availability. Conclusions Our studies have clearly indicated a role in Fe regulation by the Fur protein encoded by N. europaea NE0616 gene. Additional studies are required to fully delineate role of this fur homolog.
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Affiliation(s)
- Neeraja Vajrala
- Department of Botany and Plant Pathology, 2082 Cordley, Oregon State University, Corvallis, OR 97331, USA
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