1
|
Zhang T, Cai R, Sun C. Light and polyphosphate kinase 2 cooperatively regulate the production of zero-valent sulfur in a deep-sea bacterium. mSystems 2025:e0047325. [PMID: 40377319 DOI: 10.1128/msystems.00473-25] [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: 04/01/2025] [Accepted: 04/21/2025] [Indexed: 05/18/2025] Open
Abstract
It is well established that different wavelengths of light exist in various deep-sea environments, and many deep-sea microorganisms have evolved specialized mechanisms for sensing and utilizing light energy. Our previous research found that blue light promotes zero-valent sulfur (ZVS) production in Erythrobacter flavus 21-3, a bacterium isolated from a deep-sea cold seep. Given that long-wavelength light is more prevalent in deep-sea environments, the present study investigates the mechanism by which E. flavus 21-3 senses infrared light (wavelength 940 nm) and regulates ZVS production. We found that the bacteriophytochrome BPHP-15570 is responsible for sensing infrared light, which induces autophosphorylation of BPHP-15570, activating the diguanylate cyclase DGC-0450 for c-di-GMP biosynthesis. Subsequently, the PilZ domain-containing protein mPilZ-1753 binds to c-di-GMP, triggering a well-established ZVS production pathway involving thiosulfate dehydrogenase (TsdA) and two homologs of thiosulfohydrolases (SoxB). Notably, polyphosphate kinase 2 (PPK2) is recruited to compete for GTP, the direct precursor of c-di-GMP biosynthesis. This competition downregulates ZVS production as well as other important metabolic processes. This negative regulatory pathway helps the bacterium avoid excessive ZVS accumulation, which could be toxic to bacterial growth. Overall, E. flavus 21-3 has evolved a sophisticated regulatory pathway to sense both blue and infrared light, triggering ZVS production. Our study provides a valuable model for understanding light utilization and its coupling with sulfur cycling in deep-sea environments.IMPORTANCEIt is widely believed that deep-sea ecosystems operate independently of light, relying primarily on chemical energy. However, the discovery of non-photosynthetic bacteria in various deep-sea environments that can sense and utilize light has challenged this assumption. In a recent study, we found that blue light significantly promotes the production of zero-valent sulfur (ZVS) in the deep-sea bacterium Erythrobacter flavus 21-3. Given that long-wavelength light is more prevalent in deep-sea environments, we investigated whether infrared light also plays a role in regulating ZVS production in E. flavus 21-3. Our results indicate that infrared light does promote ZVS formation in this bacterium. We identified PPK2 as a negative regulator, maintaining intracellular ZVS at safe levels to prevent toxicity due to excessive accumulation. Overall, our study offers a valuable model for exploring how light is utilized and its interaction with microbial sulfur cycling in the extreme conditions of the deep sea.
Collapse
Affiliation(s)
- Tianhang Zhang
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology & Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, China
- College of Earth Science, University of Chinese Academy of Sciences, Beijing, China
- Center of Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Ruining Cai
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology & Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, China
- Center of Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Chaomin Sun
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology & Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, China
- College of Earth Science, University of Chinese Academy of Sciences, Beijing, China
- Center of Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| |
Collapse
|
2
|
Lu Z, Zhang J, Li J, Feng L, Wang Y, Zhu J. Biofilm formation of Pseudomonas fluorescens induced by a novel diguanylate cyclase modulated c-di-GMP promotes spoilage of large yellow croaker (Larimichthys crocea). Food Res Int 2025; 208:116231. [PMID: 40263799 DOI: 10.1016/j.foodres.2025.116231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2024] [Revised: 02/12/2025] [Accepted: 03/11/2025] [Indexed: 04/24/2025]
Abstract
Pseudomonas as major agents cause the microbial spoilage in aerobically stored seafoods due to the strong biofilm forming ability, resulting in significant economic losses. C-di-GMP regulates the transition to biofilm states in numerous bacteria, however, its function in biofilm and spoilage of Pseudomonas fluorescens has still been scarce. Here, in a fish spoiler P. fluorescens PF07 strain, 26 proteins of diguanylate cyclase (DGC) containing a GGDEF domain were characterized, and both intracellular c-di-GMP and biofilm formation consistently decreased in the constructed 12 deletion mutants of DGC domain. Compared to wild type (WT) strain, both swimming and swarming in these mutants remarkably enhanced, while the secretion of siderophore, protease activity, and the production of total volatile basic nitrogen (TVB-N) were decreased in several mutants, indicating the different modulating effects among these DGC mutants. Furthermore, correlation analysis of these six phenotypes, PF07_04309 exhibited the most significant alteration, which was identified a novel functional DGC enzyme. Moreover, the GGAAA mutation of PF07_04309 induced the down-regulation of Psl and Alg operons and increased flagellar related gene, resulting in forming the sparser and thinner biofilms. Two mutants of 04309 induced by low c-di-GMP significantly declined the accumulation of TVB-N, thiobarbituric acid, extracellular protease activity and spoilage flavor compounds, especially methylamine and carbon disulfide, in the fillets of large yellow croaker stored at 4 °C. Thus, our results indicated that a novel DGC 04309 modulated the polysaccharide secretion, flagellar, and iron carrier by synthesis of c-di-GMP, positively regulating the spoilage potential of P. fluorescens, which expanded the original insights of DGC and c-di-GMP function on microbial food spoilage.
Collapse
Affiliation(s)
- Zhong Lu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, China
| | - Jun Zhang
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, China
| | - Jiashi Li
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, China
| | - Lifang Feng
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, China
| | - Yanbo Wang
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| | - Junli Zhu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, China.
| |
Collapse
|
3
|
Shen T, Cao C, Zhu R, Chen J, Wang F, Wang Y. Identification of a TonB-Dependent Siderophore Receptor as a Novel Anti-Biofilm Target and Virtual Screening for Its Inhibitor in Pseudomonas fluorescens PF08. Foods 2025; 14:531. [PMID: 39942124 PMCID: PMC11816823 DOI: 10.3390/foods14030531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2024] [Revised: 01/23/2025] [Accepted: 01/28/2025] [Indexed: 02/16/2025] Open
Abstract
Pseudomonas fluorescens is a vital food spoilage bacterium that commonly spoils foods in the biofilm state. Uncovering the targets responsible for biofilm formation and disrupting their function is a promising way to control bacterial biofilms and food spoilage. In this work, using the combination of qRT-PCR and construction of the gene deletion strain, Δtdsr, TonB-dependent siderophore receptor D7M10_RS23410 was, for the first time, proven to play an essential part in the biofilm development of P. fluorescens. By utilizing structure-based virtual screening technology, a natural compound, adenosine monophosphate (AMP), with the highest binding activity to D7M10_RS23410, was obtained as an effective biofilm inhibitor. AMP significantly decreased the cell autoaggregation and biofilm biomass at sub-MIC concentrations (2.5, 1.25, and 0.625 mg/mL), mainly through inhibiting the generation of extracellular polymeric substances (EPS) in the biofilm matrix and promoting the cell motility. Furthermore, AMP was found to form hydrogen bonds with specific amino acid residues and stretched the protein structure of D7M10_RS23410, and this structural alteration undoubtedly interfered with the functionality of the D7M10_RS23410 protein.
Collapse
Affiliation(s)
- Taizhi Shen
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Changrong Cao
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Ruiyu Zhu
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Jian Chen
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Feifei Wang
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Yanbo Wang
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
| |
Collapse
|
4
|
Zhang T, Zhang S, Wang Y, Peng Z, Xin B, Zhong C. Tandem GGDEF-EAL Domain Proteins Pleiotropically Modulate c-di-GMP Metabolism Enrolled in Bacterial Cellulose Biosynthesis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2025; 73:1982-1993. [PMID: 39794331 DOI: 10.1021/acs.jafc.4c07301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2025]
Abstract
Cyclic diguanosine monophosphate (c-di-GMP) is a crucial secondary messenger that regulates bacterial cellulose (BC) synthesis. It is synthesized by diguanylate cyclase (DGC) containing a Gly-Gly-Asp/Glu-Glu-Phe (GGDEF) domain and degraded by phosphodiesterase (PDE) with a Glu-Ala-Leu (EAL) domain. In this work, a systematic analysis of ten GGDEF-EAL tandem domain proteins from Komagataeibacter xylinus CGMCC 2955 assessed their c-di-GMP metabolic functions and effects on BC titer and structure. Of these, five proteins exhibited DGC activity, and five exhibited PDE activity in vitro. GE03 was identified as a bifunctional protein. Most mutant strains deficient in GGDEF-EAL protein showed changes in BC metabolism, motility, and c-di-GMP levels. The combined knockout of identified PDE proteins increased the BC titer by 48.1% compared to the wild type. Overall, our findings advance our understanding of c-di-GMP signaling and its role in BC synthesis, introducing novel concepts and effective strategies for enhancing industrial BC production.
Collapse
Affiliation(s)
- Tianzhen Zhang
- Key Laboratory of Industrial Fermentation Microbiology (Ministry of Education), Tianjin University of Science & Technology, Tianjin 300457, People's Republic of China
- Haihe Laboratory of Synthetic Biology, Tianjin 300051, People's Republic of China
| | - Shiqi Zhang
- Key Laboratory of Industrial Fermentation Microbiology (Ministry of Education), Tianjin University of Science & Technology, Tianjin 300457, People's Republic of China
- Haihe Laboratory of Synthetic Biology, Tianjin 300051, People's Republic of China
| | - Yan Wang
- Key Laboratory of Industrial Fermentation Microbiology (Ministry of Education), Tianjin University of Science & Technology, Tianjin 300457, People's Republic of China
- Haihe Laboratory of Synthetic Biology, Tianjin 300051, People's Republic of China
| | - Zhaojun Peng
- Key Laboratory of Industrial Fermentation Microbiology (Ministry of Education), Tianjin University of Science & Technology, Tianjin 300457, People's Republic of China
- Haihe Laboratory of Synthetic Biology, Tianjin 300051, People's Republic of China
| | - Bo Xin
- Key Laboratory of Industrial Fermentation Microbiology (Ministry of Education), Tianjin University of Science & Technology, Tianjin 300457, People's Republic of China
- Haihe Laboratory of Synthetic Biology, Tianjin 300051, People's Republic of China
| | - Cheng Zhong
- Key Laboratory of Industrial Fermentation Microbiology (Ministry of Education), Tianjin University of Science & Technology, Tianjin 300457, People's Republic of China
- Haihe Laboratory of Synthetic Biology, Tianjin 300051, People's Republic of China
| |
Collapse
|
5
|
Cen C, Wang X, Li H, Chen J, Wang Y. An inhibitor of the adaptability of Pseudomonas fluorescens in a high-salt environment. Phenomenon and mechanism of inhibition. Int J Food Microbiol 2024; 412:110553. [PMID: 38181519 DOI: 10.1016/j.ijfoodmicro.2023.110553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/13/2023] [Accepted: 12/21/2023] [Indexed: 01/07/2024]
Abstract
Pseudomonas fluorescens is a spoilage bacterium in food that has the ability to maintain growth and reproduction in high-salt environments. It acts as a defence mechanism through the exclusion of ions and the formation of biofilms. Hence, disrupting this defence mechanism may be a good way to control food spoilage. In this study, a specific flavonoid small molecule baicalin was found, which was able to dismantle the defence mechanism of the bacteria at a lower concentration (400 μM) of treatment. In synergy with salt, baicalin showed a significant inhibitory effect on the growth, c-di-gmp synthetics and biofilm formation of Pseudomonas fluorescens Pf08. Through transcriptomics, we also found that baicalein interfered with bacterial transport and polysaccharide production functions. Through molecular docking and QPCR, we found that baicalin is able to binding with the RpoS protein through hydrogen bonding and thus interfere with its function.
Collapse
Affiliation(s)
- Congnan Cen
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, PR China; Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, PR China
| | - Xinxuan Wang
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, PR China
| | - Huan Li
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, PR China
| | - Jian Chen
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, PR China
| | - Yanbo Wang
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, PR China; Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, PR China.
| |
Collapse
|
6
|
The HD-GYP domain protein of Shewanella putrefaciens YZ08 regulates biofilm formation and spoilage activities. Food Res Int 2022; 157:111466. [DOI: 10.1016/j.foodres.2022.111466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 05/28/2022] [Accepted: 06/01/2022] [Indexed: 11/22/2022]
|
7
|
Yi Z, Xie J. Genomic Analysis of Two Representative Strains of Shewanella putrefaciens Isolated from Bigeye Tuna: Biofilm and Spoilage-Associated Behavior. Foods 2022; 11:foods11091261. [PMID: 35563985 PMCID: PMC9100107 DOI: 10.3390/foods11091261] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 04/22/2022] [Accepted: 04/26/2022] [Indexed: 01/27/2023] Open
Abstract
Shewanella putrefaciens can cause the spoilage of seafood and shorten its shelf life. In this study, both strains of S. putrefaciens (YZ08 and YZ-J) isolated from spoiled bigeye tuna were subjected to in-depth phenotypic and genotypic characterization to better understand their roles in seafood spoilage. The complete genome sequences of strains YZ08 and YZ-J were reported. Unique genes of the two S. putrefaciens strains were identified by pan-genomic analysis. In vitro experiments revealed that YZ08 and YZ-J could adapt to various environmental stresses, including cold-shock temperature, pH, NaCl, and nutrient stresses. YZ08 was better at adapting to NaCl stress, and its genome possessed more NaCl stress-related genes compared with the YZ-J strain. YZ-J was a higher biofilm and exopolysaccharide producer than YZ08 at 4 and 30 °C, while YZ08 showed greater motility and enhanced capacity for biogenic amine metabolism, trimethylamine metabolism, and sulfur metabolism compared with YZ-J at both temperatures. That YZ08 produced low biofilm and exopolysaccharide contents and displayed high motility may be associated with the presence of more a greater number of genes encoding chemotaxis-related proteins (cheX) and low expression of the bpfA operon. This study provided novel molecular targets for the development of new antiseptic antisepsis strategies.
Collapse
Affiliation(s)
- Zhengkai Yi
- College of Food Science & Technology, Shanghai Ocean University, Shanghai 201306, China;
- Shanghai Professional Technology Service Platform on Cold Chain Equipment Performance and Energy Saving Evaluation, Shanghai 201306, China
- National Experimental Teaching Demonstration Center for Food Science and Engineering, Shanghai 201306, China
| | - Jing Xie
- College of Food Science & Technology, Shanghai Ocean University, Shanghai 201306, China;
- Shanghai Professional Technology Service Platform on Cold Chain Equipment Performance and Energy Saving Evaluation, Shanghai 201306, China
- National Experimental Teaching Demonstration Center for Food Science and Engineering, Shanghai 201306, China
- Shanghai Engineering Research Center of Aquatic Product Processing & Preservation, Shanghai 201306, China
- Correspondence: ; Tel.: +86-02161900391
| |
Collapse
|
8
|
Sung JS, Bong JH, Lee SJ, Jung J, Kang MJ, Lee M, Shim WB, Jose J, Pyun JC. One-step immunoassay for food allergens based on screened mimotopes from autodisplayed F V-antibody library. Biosens Bioelectron 2022; 202:113976. [PMID: 35042130 DOI: 10.1016/j.bios.2022.113976] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/21/2021] [Accepted: 01/06/2022] [Indexed: 02/07/2023]
Abstract
One-step immunoassay detects a target analyte simply by mixing a sample with a reagent solution without any washing steps. Herein, we present a one-step immunoassay that uses a peptide mimicking a target analyte (mimotope). The key idea of this strategy is that the mimotopes are screened from an autodisplayed FV-antibody library using monoclonal antibodies against target analytes. The monoclonal antibodies are bound to fluorescence-labeled mimotopes, which are quantitatively released into the solution when the target analytes are bound to the monoclonal antibodies. Thus, the target analyte is detected without any washing steps. For the mimotope screening, an FV-antibody library was exhibited on the outer membrane of E. coli with a diversity of >106 clones/library using autodisplay technology. The targeted clones were screened from the autodisplayed FV-antibody library using magnetic beads with immobilized monoclonal antibodies against food allergens. The analysis of binding properties of a control strain with mutant FV -antibodies composed of only CDR1 and CDR2 demonstrated that the CDR3 regions of the screened FV-antibodies showed binding affinity to food allergens. The CDR3 regions were synthesized into peptides as mimotopes for the corresponding food allergens (mackerel, peanuts, and pig fat). One-step immunoassays for food allergens were demonstrated using mimotopes against mackerel, peanut, and pig fat without any washing steps in solution without immobilization of antibodies to a solid support.
Collapse
Affiliation(s)
- Jeong Soo Sung
- Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, South Korea
| | - Ji-Hong Bong
- Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, South Korea
| | - Soo Jeong Lee
- Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, South Korea
| | - Jaeyong Jung
- Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, South Korea
| | - Min-Jung Kang
- Korea Institute of Science and Technology (KIST), Seoul, South Korea
| | - Misu Lee
- Institute for New Drug Development, College of Life Science and Bioengineering, Incheon National University, Incheon, 22012, Republic of Korea
| | - Won-Bo Shim
- Department of Food Science and Technology & Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, Gyeongnam, 52828, South Korea
| | - Joachim Jose
- Institute of Pharmaceutical and Medical Chemistry, Westfälischen Wilhelms-Universität Münster, Muenster, Germany
| | - Jae-Chul Pyun
- Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, South Korea.
| |
Collapse
|
9
|
Wang Y, Wang Y, Chen J, Koseki S, Yang Q, Yu H, Fu L. Screening and preservation application of quorum sensing inhibitors of Pseudomonas fluorescens and Shewanella baltica in seafood products. Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2021.111749] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|
10
|
Identification of a Diguanylate Cyclase That Facilitates Biofilm Formation on Electrodes by Shewanella oneidensis MR-1. Appl Environ Microbiol 2021; 87:AEM.00201-21. [PMID: 33637573 DOI: 10.1128/aem.00201-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 02/19/2021] [Indexed: 12/29/2022] Open
Abstract
In many bacteria, cyclic diguanosine monophosphate (c-di-GMP), synthesized by diguanylate cyclase (DGC), serves as a second messenger involved in the regulation of biofilm formation. Although studies have suggested that c-di-GMP also regulates the formation of electrochemically active biofilms (EABFs) by Shewanella oneidensis MR-1, DGCs involved in this process remained to be identified. Here, we report that the SO_1646 gene, hereafter named dgcS, is upregulated under medium flow conditions in electrochemical flow cells (EFCs), and its product (DgcS) functions as a major DGC in MR-1. In vitro assays demonstrated that purified DgcS catalyzed the synthesis of c-di-GMP from GTP. Comparisons of intracellular c-di-GMP levels in the wild-type strain and a dgcS deletion mutant (ΔdgcS mutant) showed that production of c-di-GMP was markedly reduced in the ΔdgcS mutant when cells were grown in batch cultures and on electrodes in EFCs. Cultivation of the ΔdgcS mutant in EFCs also revealed that the loss of DgcS resulted in impaired biofilm formation and decreased current generation. These findings demonstrate that MR-1 uses DgcS to synthesize c-di-GMP under medium flow conditions, thereby activating biofilm formation on electrodes.IMPORTANCE Bioelectrochemical systems (BESs) have attracted wide attention owing to their utility in sustainable biotechnology processes, such as microbial fuel cells and electrofermentation systems. In BESs, electrochemically active bacteria (EAB) form biofilms on electrode surfaces, thereby serving as effective catalysts for the interconversion between chemical and electric energy. It is therefore important to understand mechanisms for the formation of biofilm by EAB grown on electrodes. Here, we show that a model EAB, S. oneidensis MR-1, expresses DgcS as a major DGC, thereby activating the formation of biofilms on electrodes via c-di-GMP-dependent signal transduction cascades. The findings presented herein provide the molecular basis for improving electrochemical interactions between EAB and electrodes in BESs. The results also offer molecular insights into how Shewanella regulates biofilm formation on solid surfaces in the natural environment.
Collapse
|
11
|
Bao X, Wang F, Yang R, Zhang Y, Fu L, Wang Y. Ornithine Decarboxylation System of Shewanella baltica Regulates Putrescine Production and Acid Resistance. J Food Prot 2021; 84:303-309. [PMID: 33003195 DOI: 10.4315/jfp-20-227] [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: 06/08/2020] [Accepted: 09/30/2020] [Indexed: 01/18/2023]
Abstract
ABSTRACT Shewanella baltica, one of the dominant spoilers of seafoods, can synthesize putrescine from ornithine under acidic conditions, which could result in food spoilage and health problems. We identified three regulatory enzymes (SpeC, SpeF, and PotE) in the ornithine decarboxylation (ODC) pathway of S. baltica by searching the NCBI database and exploring their functional roles through gene knock-out technology. The ornithine decarboxylase SpeC is an auxiliary adjustor of the ODC system, whereas the ornithine-putrescine transporter SpeE and ornithine decarboxylase SpeF participate in the production of extracellular putrescine. Exogenous addition of ornithine and putrescine promotes the extracellular secretion of putrescine by upregulating the expression of speF and potE. The putrescine biosynthesis and alkalization of cytoplasm is enhanced at weak acidic pH compared with neutral pH, especially at pH 6.0. The maximum upregulation of ODC genes and the optimum decarboxylation activity of SpeF are achieved in a weak acidic environment (pH 6.0), suggesting that the ODC pathway plays an important role in putrescine production and the cytoplasmic acid counteraction of S. baltica. This study contributes to a wider understanding of spoilage mechanisms in food systems and provides theoretical support for developing novel seafood preservation methods. HIGHLIGHTS
Collapse
Affiliation(s)
- Xingyue Bao
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, People's Republic of China
| | - Feifei Wang
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, People's Republic of China
| | - Rendi Yang
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, People's Republic of China
| | - Yan Zhang
- Hebei Food Inspection and Research Institute, Shijiazhuang 050091, People's Republic of China
| | - Linglin Fu
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, People's Republic of China
| | - Yanbo Wang
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, People's Republic of China
| |
Collapse
|
12
|
Mukherjee M, Zaiden N, Teng A, Hu Y, Cao B. Shewanella biofilm development and engineering for environmental and bioenergy applications. Curr Opin Chem Biol 2020; 59:84-92. [PMID: 32750675 DOI: 10.1016/j.cbpa.2020.05.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 05/10/2020] [Accepted: 05/12/2020] [Indexed: 12/31/2022]
Abstract
The genus Shewanella comprises about 70 species of Gram-negative, facultative anaerobic bacteria inhabiting various environments, which have shown great potential in various biotechnological applications ranging from environmental bioremediation, metal(loid) recovery and material synthesis to bioenergy generation. Most environmental and energy applications of Shewanella involve the biofilm mode of growth on surfaces of solid minerals or electrodes. In this article, we first provide an overview of Shewanella biofilm biology with the focus on biofilm dynamics, biofilm matrix, and key signalling systems involved in Shewanella biofilm development. Then we review strategies recently exploited to engineer Shewanella biofilms to improve biofilm-mediated bioprocesses.
Collapse
Affiliation(s)
- Manisha Mukherjee
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore
| | - Norazean Zaiden
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551, Singapore; Interdisciplinary Graduate Programme, Graduate College, Nanyang Technological University, 637335, Singapore
| | - Aloysius Teng
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551, Singapore; Interdisciplinary Graduate Programme, Graduate College, Nanyang Technological University, 637335, Singapore
| | - Yidan Hu
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551, Singapore; Interdisciplinary Graduate Programme, Graduate College, Nanyang Technological University, 637335, Singapore
| | - Bin Cao
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore.
| |
Collapse
|