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Crabbé A, Jensen PØ, Bjarnsholt T, Coenye T. Antimicrobial Tolerance and Metabolic Adaptations in Microbial Biofilms. Trends Microbiol 2019; 27:850-863. [PMID: 31178124 DOI: 10.1016/j.tim.2019.05.003] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/25/2019] [Accepted: 05/07/2019] [Indexed: 01/04/2023]
Abstract
Active bacterial metabolism is a prerequisite for optimal activity of many classes of antibiotics. Hence, bacteria have developed strategies to reduce or modulate metabolic pathways to become tolerant. This review describes the tight relationship between metabolism and tolerance in bacterial biofilms, and how physicochemical properties of the microenvironment at the host-pathogen interface (such as oxygen and nutritional content) are key to this relationship. Understanding how metabolic adaptations lead to tolerance brings us to novel approaches to tackle antibiotic-tolerant biofilms. We describe the use of hyperbaric oxygen therapy, metabolism-stimulating metabolites, and alternative strategies to redirect bacterial metabolism towards an antibiotic-susceptible phenotype.
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Affiliation(s)
- Aurélie Crabbé
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | - Peter Østrup Jensen
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark; Institute for Inflammation Research, Center for Rheumatology and Spine Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Thomas Bjarnsholt
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium.
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102
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Pfiffer V, Sarenko O, Possling A, Hengge R. Genetic dissection of Escherichia coli's master diguanylate cyclase DgcE: Role of the N-terminal MASE1 domain and direct signal input from a GTPase partner system. PLoS Genet 2019; 15:e1008059. [PMID: 31022167 PMCID: PMC6510439 DOI: 10.1371/journal.pgen.1008059] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 05/10/2019] [Accepted: 02/28/2019] [Indexed: 11/18/2022] Open
Abstract
The ubiquitous second messenger c-di-GMP promotes bacterial biofilm formation by playing diverse roles in the underlying regulatory networks. This is reflected in the multiplicity of diguanylate cyclases (DGC) and phosphodiesterases (PDE) that synthesize and degrade c-di-GMP, respectively, in most bacterial species. One of the 12 DGCs of Escherichia coli, DgcE, serves as the top-level trigger for extracellular matrix production during macrocolony biofilm formation. Its multi-domain architecture–a N-terminal membrane-inserted MASE1 domain followed by three PAS, a GGDEF and a degenerate EAL domain–suggested complex signal integration and transmission through DgcE. Genetic dissection of DgcE revealed activating roles for the MASE1 domain and the dimerization-proficient PAS3 region, whereas the inhibitory EALdeg domain counteracts the formation of DgcE oligomers. The MASE1 domain is directly targeted by the GTPase RdcA (YjdA), a dimer or oligomer that together with its partner protein RdcB (YjcZ) activates DgcE, probably by aligning and promoting dimerization of the PAS3 and GGDEF domains. This activation and RdcA/DgcE interaction depend on GTP hydrolysis by RdcA, suggesting GTP as an inhibitor and the pronounced decrease of the cellular GTP pool during entry into stationary phase, which correlates with DgcE-dependent activation of matrix production, as a possible input signal sensed by RdcA. Furthermore, DgcE exhibits rapid, continuous and processive proteolytic turnover that also depends on the relatively disordered transmembrane MASE1 domain. Overall, our study reveals a novel GTP/c-di-GMP-connecting signaling pathway through the multi-domain DGC DgcE with a dual role for the previously uncharacterized MASE1 signaling domain. Biofilms represent a multicellular life form of bacteria, in which large numbers of cells live in communities surrounded and protected by a self-generated extracellular polymeric matrix. As biofilms tolerate antibiotics and host immune systems, they are causally associated with chronic infections. Biofilm formation is generally promoted by the ubiquitous bacterial second messenger c-di-GMP. DgcE, one of the 12 diguanylate cyclases that produce c-di-GMP in E. coli, was previously shown to specifically act as a top level trigger in the regulatory network that drives biofilm matrix production in this bacterium. However, signal input into DgcE itself, which is a large six-domain protein, had remained unknown. Here we demonstrate that DgcE activity is controlled by a novel type of dynamin-like GTPase that directly interacts with the N-terminal membrane-intrinsic MASE1 domain of DgcE. Our finding of a dual function of this MASE1 domain, which is essential for both activation and continuous proteolysis of DgcE, is the first characterization of this widespread bacterial signaling domain. Signal input via the dynamin-like GTPase system suggests that c-di-GMP production by DgcE might be stimulated by the decreasing cellular GTP level during entry into stationary phase, which is precisely the time when biofilm matrix production is turned on.
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Affiliation(s)
- Vanessa Pfiffer
- Institut für Biologie / Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Olga Sarenko
- Institut für Biologie / Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Alexandra Possling
- Institut für Biologie / Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Regine Hengge
- Institut für Biologie / Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
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103
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Xu H, Dauparas J, Das D, Lauga E, Wu Y. Self-organization of swimmers drives long-range fluid transport in bacterial colonies. Nat Commun 2019; 10:1792. [PMID: 30996269 PMCID: PMC6470179 DOI: 10.1038/s41467-019-09818-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 03/28/2019] [Indexed: 01/08/2023] Open
Abstract
Motile subpopulations in microbial communities are believed to be important for dispersal, quest for food, and material transport. Here, we show that motile cells in sessile colonies of peritrichously flagellated bacteria can self-organize into two adjacent, centimeter-scale motile rings surrounding the entire colony. The motile rings arise from spontaneous segregation of a homogeneous swimmer suspension that mimics a phase separation; the process is mediated by intercellular interactions and shear-induced depletion. As a result of this self-organization, cells drive fluid flows that circulate around the colony at a constant peak speed of ~30 µm s−1, providing a stable and high-speed avenue for directed material transport at the macroscopic scale. Our findings present a unique form of bacterial self-organization that influences population structure and material distribution in colonies. Motile and non-motile subpopulations often coexist in bacterial communities. Here, Xu et al. show that motile cells in colonies of common flagellated bacteria can self-organize into two adjacent motile rings, driving stable flows of fluid and materials around the colony.
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Affiliation(s)
- Haoran Xu
- Department of Physics and Shenzhen Research Institute, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People's Republic of China
| | - Justas Dauparas
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, CB3 0WA, UK
| | - Debasish Das
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, CB3 0WA, UK
| | - Eric Lauga
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, CB3 0WA, UK
| | - Yilin Wu
- Department of Physics and Shenzhen Research Institute, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People's Republic of China.
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104
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Brust FR, Boff L, da Silva Trentin D, Pedrotti Rozales F, Barth AL, Macedo AJ. Macrocolony of NDM-1 Producing Enterobacter hormaechei subsp. oharae Generates Subpopulations with Different Features Regarding the Response of Antimicrobial Agents and Biofilm Formation. Pathogens 2019; 8:pathogens8020049. [PMID: 31014001 PMCID: PMC6631906 DOI: 10.3390/pathogens8020049] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/08/2019] [Accepted: 04/11/2019] [Indexed: 11/16/2022] Open
Abstract
Enterobacter cloacae complex has been increasingly recognized as a nosocomial pathogen representing the third major Enterobacteriaceae species involved with infections. This study aims to evaluate virulence and antimicrobial susceptibility of subpopulations generated from macrocolonies of NDM-1 producing Enterobacter hormaechei clinical isolates. Biofilm was quantified using crystal violet method and fimbrial genes were investigated by PCR. Susceptibility of antimicrobials, alone and combined, was determined by minimum inhibitory concentration and checkerboard assays, respectively. Virulence and efficacy of antimicrobials were evaluated in Galleria mellonella larvae. Importantly, we verified that some subpopulations that originate from the same macrocolony present different biofilm production ability and distinct susceptibility to meropenem due to the loss of blaNDM-1 encoding plasmid. A more in-depth study was performed with the 798 macrocolony subpopulations. Type 3 fimbriae were straightly related with biofilm production; however, virulence in larvae was not statistically different among subpopulations. Triple combination with meropenem-rifampicin-polymyxin B showed in vitro synergistic effect against all subpopulations; while in vivo this treatment showed different efficacy rates for 798-1S and 798-4S subpopulations. The ability of multidrug resistant E. hormaechei isolates in generating bacterial subpopulations presenting different susceptible and virulence mechanisms are worrisome and may explain why these infections are hardly overcome.
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Affiliation(s)
- Flávia Roberta Brust
- Faculty of Pharmacy and Center of Biotechnology, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul CE 90610-000, Brazil.
| | - Luana Boff
- Faculty of Pharmacy and Center of Biotechnology, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul CE 90610-000, Brazil.
| | - Danielle da Silva Trentin
- Basic Health Sciences Department, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Rio Grande do Sul CE 90050-170, Brazil.
| | - Franciele Pedrotti Rozales
- Laboratory of Research in Bacterial Resistance, Center for Experimental Research, Clinical Hospital of Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul CE 90035-007, Brazil.
| | - Afonso Luís Barth
- Laboratory of Research in Bacterial Resistance, Center for Experimental Research, Clinical Hospital of Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul CE 90035-007, Brazil.
| | - Alexandre José Macedo
- Faculty of Pharmacy and Center of Biotechnology, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul CE 90610-000, Brazil.
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105
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Serra DO, Hengge R. A c-di-GMP-Based Switch Controls Local Heterogeneity of Extracellular Matrix Synthesis which Is Crucial for Integrity and Morphogenesis of Escherichia coli Macrocolony Biofilms. J Mol Biol 2019; 431:4775-4793. [PMID: 30954572 DOI: 10.1016/j.jmb.2019.04.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/26/2019] [Accepted: 04/01/2019] [Indexed: 12/14/2022]
Abstract
The extracellular matrix in macrocolony biofilms of Escherichia coli is arranged in a complex large-scale architecture, with homogenic matrix production close to the surface, whereas zones further below display pronounced local heterogeneity of matrix production, which results in distinct three-dimensional architectural structures. Combining genetics, cryosectioning and fluorescence microscopy of macrocolony biofilms, we demonstrate here in situ that this local matrix heterogeneity is generated by a c-di-GMP-dependent molecular switch characterized by several nested positive and negative feedback loops. In this switch, the trigger phosphodiesterase PdeR is the key component for establishing local heterogeneity in the activation of the transcription factor MlrA, which in turn activates expression of the major matrix regulator CsgD. Upon its release of direct inhibition by PdeR, the second switch component, the diguanylate cyclase DgcM, activates MlrA by direct interaction. Antagonistically acting PdeH and DgcE provide for a PdeR-sensed c-di-GMP input into this switch and-via their spatially differentially controlled expression-generate the long-range vertical asymmetry of the matrix architecture. Using flow cytometry, we show heterogeneity of CsgD expression to also occur in spatially unstructured planktonic cultures, where it is controlled by the same c-di-GMP circuitry as in macrocolony biofilms. Quantification by flow cytometry also showed CsgDON subpopulations with distinct CsgD expression levels and revealed an additional fine-tuning feedback within the PdeR/DgcM-mediated switch that depends on c-di-GMP synthesis by DgcM. Finally, local heterogeneity of matrix production was found to be crucial for the tissue-like elasticity that allows for large-scale wrinkling and folding of macrocolony biofilms.
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Affiliation(s)
- Diego O Serra
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Regine Hengge
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, 10115 Berlin, Germany.
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106
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Reichhardt C, Parsek MR. Confocal Laser Scanning Microscopy for Analysis of Pseudomonas aeruginosa Biofilm Architecture and Matrix Localization. Front Microbiol 2019; 10:677. [PMID: 31001240 PMCID: PMC6454187 DOI: 10.3389/fmicb.2019.00677] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 03/18/2019] [Indexed: 11/24/2022] Open
Abstract
Most microbes can produce surface-associated or suspended aggregates called biofilms, which are encased within a biopolymer-rich matrix. The biofilm matrix provides structural integrity to the aggregates and shields the resident cells against environmental stressors, including antibiotic treatment. Microscopy permits examination of biofilm structure in relation to the spatial localization of important biofilm matrix components. This review highlights microscopic approaches to investigate bacterial biofilm assembly, matrix composition, and localization using Pseudomonas aeruginosa as a model organism. Initial microscopic investigations provided information about the role key matrix components play in elaborating biofilm aggregate structures. Additionally, staining of matrix components using specific labels revealed distinct positioning of matrix components within the aggregates relative to the resident cells. In some cases, it was found that individual matrix components co-localize within aggregates. The methodologies for studying the biofilm matrix are continuing to develop as our studies reveal novel aspects of its composition and function. We additionally describe some outstanding questions and how microscopy might be used to identify the functional aspects of biofilm matrix components.
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Affiliation(s)
| | - Matthew R. Parsek
- Department of Microbiology, University of Washington, Seattle, WA, United States
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107
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Stenclova P, Freisinger S, Barth H, Kromka A, Mizaikoff B. Cyclic Changes in the Amide Bands Within Escherichia coli Biofilms Monitored Using Real-Time Infrared Attenuated Total Reflection Spectroscopy (IR-ATR). APPLIED SPECTROSCOPY 2019; 73:424-432. [PMID: 30654633 DOI: 10.1177/0003702819829081] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Contrary to the planktonic state of bacteria, their biofilm form represents severe complications in areas such as human medicine or food industry due to the increasing resistance against harsh conditions and treatment. In the present study, infrared attenuated total reflection (IR-ATR) spectroscopy has been applied as an analytic tool studying Escherichia coli ( E. coli) biofilm formation close to real time. We report on IR spectroscopic investigations on the biofilm formation via ATR waveguides probing the biofilm in the spectral window of 1800-900 cm-1 at dynamic flow conditions, which facilitated monitoring the growth dynamics during several days. Key IR bands are in the range 1700-1590 cm-1 (amide I), 1580-1490 cm-1 (amide II), and 1141-1006 cm-1 extracellular polymeric substances (EPS), which were evaluated as a function of time. Cyclic fluctuations of the amide I and amide II bands and a continuous increase of the EPS band were related to the starvation of bottom-layered bacteria caused by the nutrient gradient. Potential death of bacteria may then result in cannibalistic behavior known for E. coli colonies. Observing this behavior via IR spectroscopy allows revealing these cyclical changes in bottom-layered bacteria within the biofilm under continuous nutrient flow, in molecular detail, and during extended periods for the first time.
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Affiliation(s)
- Pavla Stenclova
- 1 Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Simon Freisinger
- 2 Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Holger Barth
- 2 Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Alexander Kromka
- 1 Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Boris Mizaikoff
- 3 Institute of Analytical and Bioanalytical Chemistry, Ulm University, Ulm, Germany
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108
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Sadiq FA, Flint S, Sakandar HA, He G. Molecular regulation of adhesion and biofilm formation in high and low biofilm producers of Bacillus licheniformis using RNA-Seq. BIOFOULING 2019; 35:143-158. [PMID: 30884970 DOI: 10.1080/08927014.2019.1575960] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 01/14/2019] [Accepted: 01/22/2019] [Indexed: 06/09/2023]
Abstract
RNA sequencing was used to reveal transcriptional changes during the motile-to-sessile switch in high and low biofilm-forming dairy strains of B. licheniformis isolated from Chinese milk powders. A significant part of the whole gene content was affected during this transition in both strains. In terms of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, seven metabolic pathways were significantly downregulated in the planktonic state compared to the biofilm state in both strains. Lipid and sugar metabolism seemed to play an important role in matrix production. Several genes involved in adhesion, matrix production and the matrix coating were either absent or less expressed in the biofilm state of the low biofilm producer compared to the high biofilm producer. Genes related to sporulation and the production of extracellular polymeric substances were concomitantly expressed in the biofilm state of both strains. These comprehensive insights will be helpful for future research into mechanisms and targets.
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Affiliation(s)
- Faizan Ahmed Sadiq
- a School of Food Science and Technology , Jiangnan University , Wuxi , PR China
- b College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
| | - Steve Flint
- c School of Food and Nutrition , Massey University , Private Bag 11 222 , Palmerston North , New Zealand
| | - Hafiz Arbab Sakandar
- a School of Food Science and Technology , Jiangnan University , Wuxi , PR China
- d Faculty of Biological Sciences , Quaid-i-Azam University , Islamabad , Pakistan
| | - GuoQing He
- b College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
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109
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de Vries HJ, Beyer F, Jarzembowska M, Lipińska J, van den Brink P, Zwijnenburg A, Timmers PHA, Stams AJM, Plugge CM. Isolation and characterization of Sphingomonadaceae from fouled membranes. NPJ Biofilms Microbiomes 2019; 5:6. [PMID: 30701078 PMCID: PMC6347639 DOI: 10.1038/s41522-018-0074-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 12/11/2018] [Indexed: 11/09/2022] Open
Abstract
Membrane filtration systems are widely applied for the production of clean drinking water. However, the accumulation of particles on synthetic membranes leads to fouling. Biological fouling (i.e., biofouling) of reverse osmosis and nanofiltration membranes is difficult to control by existing cleaning procedures. Improved strategies are therefore needed. The bacterial diversity on fouled membranes has been studied, especially to identify bacteria with specialized functions and to develop targeted approaches against these microbes. Previous studies have shown that Sphingomonadaceae are initial membrane colonizers that remain dominant while the biofilm develops. Here, we characterized 21 Sphingomonadaceae isolates, obtained from six different fouled membranes, to determine which physiological traits could contribute to colonization of membrane surfaces. Their growth conditions ranged from temperatures between 8 and 42 oC, salinity between 0.0 and 5.0% w/v NaCl, pH from 4 and 10, and all isolates were able to metabolize a wide range of substrates. The results presented here show that Sphingomonadaceae membrane isolates share many features that are uncommon for other members of the Sphingomonadaceae family: all membrane isolates are motile and their tolerance for different temperatures, salt concentrations, and pH is high. Although relative abundance is an indicator of fitness for a whole group, for the Sphingomonadaceae it does not reveal the specific physiological traits that are required for membrane colonization. This study, therefore, adds to more fundamental insights in membrane biofouling.
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Affiliation(s)
- Hendrik J. de Vries
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - Florian Beyer
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - Monika Jarzembowska
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Joanna Lipińska
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - Paula van den Brink
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - Arie Zwijnenburg
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - Peer H. A. Timmers
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - Alfons J. M. Stams
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Caroline M. Plugge
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
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110
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Chakraborty P, Kumar A. The extracellular matrix of mycobacterial biofilms: could we shorten the treatment of mycobacterial infections? MICROBIAL CELL 2019; 6:105-122. [PMID: 30740456 PMCID: PMC6364259 DOI: 10.15698/mic2019.02.667] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A number of non-tuberculous mycobacterium species are opportunistic pathogens and ubiquitously form biofilms. These infections are often recalcitrant to treatment and require therapy with multiple drugs for long duration. The biofilm resident bacteria also display phenotypic drug tolerance and thus it has been hypothesized that the drug unresponsiveness in vivo could be due to formation of biofilms inside the host. We have discussed the biofilms of several pathogenic non-tuberculous mycobacterium (NTM) species in context to the in vivo pathologies. Besides pathogenic NTMs, Mycobacterium smegmatis is often used as a model organism for understanding mycobacterial physiology and has been studied extensively for understanding the mycobacterial biofilms. A number of components of the mycobacterial cell wall such as glycopeptidolipids, short chain mycolic acids, monomeromycolyl diacylglycerol, etc. have been shown to play an important role in formation of pellicle biofilms. It shall be noted that these components impart a hydrophobic character to the mycobacterial cell surface that facilitates cell to cell interaction. However, these components are not necessarily the constituents of the extracellular matrix of mycobacterial biofilms. In the end, we have described the biofilms of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis. Three models of Mtb biofilm formation have been proposed to study the factors regulating biofilm formation, the physiology of the resident bacteria, and the nature of the biomaterial that holds these bacterial masses together. These models include pellicle biofilms formed at the liquid-air interface of cultures, leukocyte lysate-induced biofilms, and thiol reductive stressinduced biofilms. All the three models offer their own advantages in the study of Mtb biofilms. Interestingly, lipids (mainly keto-mycolic acids) are proposed to be the primary component of extracellular polymeric substance (EPS) in the pellicle biofilm, whereas the leukocyte lysate-induced and thiol reductive stress-induced biofilms possess polysaccharides as the primary component of EPS. Both models also contain extracellular DNA in the EPS. Interestingly, thiol reductive stressinduced Mtb biofilms are held together by cellulose and yet unidentified structural proteins. We believe that a better understanding of the EPS of Mtb biofilms and the physiology of the resident bacteria will facilitate the development of shorter regimen for TB treatment.
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Affiliation(s)
- Poushali Chakraborty
- Council of Scientific and Industrial Research, Institute of Microbial Technology, Chandigarh, India 160036
| | - Ashwani Kumar
- Council of Scientific and Industrial Research, Institute of Microbial Technology, Chandigarh, India 160036.,CSIR-Academy of Scientific & Innovative Research (AcSIR), Council of Scientific & Industrial Research, New Delhi-110001
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112
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Klotz M, Kretschmer M, Goetz A, Ezendam S, Lieleg O, Opitz M. Importance of the biofilm matrix for the erosion stability of Bacillus subtilis NCIB 3610 biofilms. RSC Adv 2019; 9:11521-11529. [PMID: 35520264 PMCID: PMC9063333 DOI: 10.1039/c9ra01955c] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 04/02/2019] [Indexed: 12/12/2022] Open
Abstract
Erosion of bacterial biofilms is dependent on the composition of the biofilm matrix and the surrounding chemical environment.
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Affiliation(s)
- M. Klotz
- Center for NanoScience
- Faculty of Physics
- Ludwig-Maximilians-Universität München
- Munich
- Germany
| | - M. Kretschmer
- Munich School of BioEngineering and Department of Mechanical Engineering
- Technische Universität München
- Garching
- Germany
| | - A. Goetz
- Center for NanoScience
- Faculty of Physics
- Ludwig-Maximilians-Universität München
- Munich
- Germany
| | - S. Ezendam
- Center for NanoScience
- Faculty of Physics
- Ludwig-Maximilians-Universität München
- Munich
- Germany
| | - O. Lieleg
- Munich School of BioEngineering and Department of Mechanical Engineering
- Technische Universität München
- Garching
- Germany
| | - M. Opitz
- Center for NanoScience
- Faculty of Physics
- Ludwig-Maximilians-Universität München
- Munich
- Germany
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113
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A Nonfimbrial Adhesin of Aggregatibacter actinomycetemcomitans Mediates Biofilm Biogenesis. Infect Immun 2018; 87:IAI.00704-18. [PMID: 30297525 DOI: 10.1128/iai.00704-18] [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: 09/13/2018] [Accepted: 10/03/2018] [Indexed: 11/20/2022] Open
Abstract
Periodontitis is an inflammatory disease caused by polymicrobial biofilms. The periodontal pathogen Aggregatibacter actinomycetemcomitans displays two proteinaceous surface structures, the fimbriae and the nonfimbrial extracellular matrix binding protein A (EmaA), as observed by electron microscopy. Fimbriae participate in biofilm biogenesis and the EmaA adhesins mediate collagen binding. However, in the absence of fimbriae, A. actinomycetemcomitans still retains the potential to form robust biofilms, suggesting that other surface macromolecules participate in biofilm development. Here, isogenic mutant strains lacking EmaA structures, but still expressing fimbriae, were observed to have reduced biofilm potential. In strains lacking both EmaA and fimbriae, biofilm mass was reduced by 80%. EmaA enhanced biofilm formation in different strains, independent of the fimbriation state or serotype. Confocal microscopy revealed differences in cell density within microcolonies between the EmaA positive and mutant strains. EmaA-mediated biofilm formation was found to be independent of the glycosylation state and the precise three-dimensional conformation of the protein, and thus this function is uncorrelated with collagen binding activity. The data suggest that EmaA is a multifunctional adhesin that utilizes different mechanisms to enhance bacterial binding to collagen and to enhance biofilm formation, both of which are important for A. actinomycetemcomitans colonization and subsequent infection.
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Helicobacter pylori Biofilm Involves a Multigene Stress-Biased Response, Including a Structural Role for Flagella. mBio 2018; 9:mBio.01973-18. [PMID: 30377283 PMCID: PMC6212823 DOI: 10.1128/mbio.01973-18] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Biofilms, communities of bacteria that are embedded in a hydrated matrix of extracellular polymeric substances, pose a substantial health risk and are key contributors to many chronic and recurrent infections. Chronicity and recalcitrant infections are also common features associated with the ulcer-causing human pathogen H. pylori. However, relatively little is known about the role of biofilms in H. pylori pathogenesis, as well as the biofilm structure itself and the genes associated with this mode of growth. In the present study, we found that H. pylori biofilm cells highly expressed genes related to cell envelope and stress response, as well as those encoding the flagellar apparatus. Flagellar filaments were seen in high abundance in the biofilm. Flagella are known to play a role in initial biofilm formation, but typically are downregulated after that state. H. pylori instead appears to have coopted these structures for nonmotility roles, including a role building a robust biofilm. Helicobacter pylori has an impressive ability to persist chronically in the human stomach. Similar characteristics are associated with biofilm formation in other bacteria. The H. pylori biofilm process, however, is poorly understood. To gain insight into this mode of growth, we carried out comparative transcriptomic analysis between H. pylori biofilm and planktonic cells, using the mouse-colonizing strain SS1. Optimal biofilm formation was obtained with a low concentration of serum and 3 days of growth, conditions that caused both biofilm and planktonic cells to be ∼80% coccoid. Transcriptome sequencing (RNA-seq) analysis found that 8.18% of genes were differentially expressed between biofilm and planktonic cell transcriptomes. Biofilm-downregulated genes included those involved in metabolism and translation, suggesting these cells have low metabolic activity. Biofilm-upregulated genes included those whose products were predicted to be at the cell envelope, involved in regulating a stress response, and surprisingly, genes related to formation of the flagellar apparatus. Scanning electron microscopy visualized flagella that appeared to be a component of the biofilm matrix, supported by the observation that an aflagellated mutant displayed a less robust biofilm with no apparent filaments. We observed flagella in the biofilm matrix of additional H. pylori strains, supporting that flagellar use is widespread. Our data thus support a model in which H. pylori biofilm involves a multigene stress-biased response and that flagella play an important role in H. pylori biofilm formation.
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115
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Erskine E, MacPhee CE, Stanley-Wall NR. Functional Amyloid and Other Protein Fibers in the Biofilm Matrix. J Mol Biol 2018; 430:3642-3656. [PMID: 30098341 PMCID: PMC6173796 DOI: 10.1016/j.jmb.2018.07.026] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 07/17/2018] [Accepted: 07/24/2018] [Indexed: 02/06/2023]
Abstract
Biofilms are ubiquitous in the natural and man-made environment. They are defined as microbes that are encapsulated in an extracellular, self-produced, biofilm matrix. Growing evidence from the genetic and biochemical analysis of single species biofilms has linked the presence of fibrous proteins to a functional biofilm matrix. Some of these fibers have been described as functional amyloid or amyloid-like fibers. Here we provide an overview of the biophysical and biological data for a wide range of protein fibers found in the biofilm matrix of Gram-positive and Gram-negative bacteria.
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Affiliation(s)
- Elliot Erskine
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Cait E MacPhee
- James Clerk Maxwell Building, School of Physics, University of Edinburgh, The Kings Buildings, Mayfield Road, Edinburgh, EH9 3JZ, UK.
| | - Nicola R Stanley-Wall
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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116
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Environmental conditions shape the biofilm of the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125. Microbiol Res 2018; 218:66-75. [PMID: 30454660 DOI: 10.1016/j.micres.2018.09.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 09/24/2018] [Accepted: 09/28/2018] [Indexed: 11/21/2022]
Abstract
Biofilms are the most widely distributed and successful microbial modes of life. The capacity of bacteria to colonize surfaces provides stability in the growth environment, allows the capturing of nutrients and affords protection from a range of environmental challenges and stress. Bacteria living in cold environments, like Antarctica, can be found as biofilms, even though the mechanisms of how this lifestyle is related to their environmental adaptation have been poorly investigated. In this paper, the biofilm of Pseudoalteromonas haloplanktis TAC125, one of the model organisms of cold-adapted bacteria, has been characterized in terms of biofilm typology and matrix composition. The characterization was performed on biofilms produced by the bacterium in response to different nutrient abundance and temperatures; in particular, this is the first report describing the structure of a biofilm formed at 0 °C. The results reported demonstrate that PhTAC125 produces biofilms in different amount and endowed with different physico-chemical properties, like hydrophobicity and roughness, by modulating the relative amount of the different macromolecules present in the biofilm matrix. The capability of PhTAC125 to adopt different biofilm structures in response to environment changes appears to be an interesting adaptation strategy and gives the first hints about the biofilm formation in cold environments.
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117
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Latif M, May EE. A Multiscale Agent-Based Model for the Investigation of E. coli K12 Metabolic Response During Biofilm Formation. Bull Math Biol 2018; 80:2917-2956. [PMID: 30218278 DOI: 10.1007/s11538-018-0494-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 08/24/2018] [Indexed: 12/14/2022]
Abstract
Bacterial biofilm formation is an organized collective response to biochemical cues that enables bacterial colonies to persist and withstand environmental insults. We developed a multiscale agent-based model that characterizes the intracellular, extracellular, and cellular scale interactions that modulate Escherichia coli MG1655 biofilm formation. Each bacterium's intracellular response and cellular state were represented as an outcome of interactions with the environment and neighboring bacteria. In the intracellular model, environment-driven gene expression and metabolism were captured using statistical regression and Michaelis-Menten kinetics, respectively. In the cellular model, growth, death, and type IV pili- and flagella-dependent movement were based on the bacteria's intracellular state. We implemented the extracellular model as a three-dimensional diffusion model used to describe glucose, oxygen, and autoinducer 2 gradients within the biofilm and bulk fluid. We validated the model by comparing simulation results to empirical quantitative biofilm profiles, gene expression, and metabolic concentrations. Using the model, we characterized and compared the temporal metabolic and gene expression profiles of sessile versus planktonic bacterial populations during biofilm formation and investigated correlations between gene expression and biofilm-associated metabolites and cellular scale phenotypes. Based on our in silico studies, planktonic bacteria had higher metabolite concentrations in the glycolysis and citric acid cycle pathways, with higher gene expression levels in flagella and lipopolysaccharide-associated genes. Conversely, sessile bacteria had higher metabolite concentrations in the autoinducer 2 pathway, with type IV pili, autoinducer 2 export, and cellular respiration genes upregulated in comparison with planktonic bacteria. Having demonstrated results consistent with in vitro static culture biofilm systems, our model enables examination of molecular phenomena within biofilms that are experimentally inaccessible and provides a framework for future exploration of how hypothesized molecular mechanisms impact bulk community behavior.
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Affiliation(s)
- Majid Latif
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Elebeoba E May
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA.
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118
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Reichhardt C, Cegelski L. The Congo red derivative FSB binds to curli amyloid fibers and specifically stains curliated E. coli. PLoS One 2018; 13:e0203226. [PMID: 30161215 PMCID: PMC6117054 DOI: 10.1371/journal.pone.0203226] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 08/16/2018] [Indexed: 02/04/2023] Open
Abstract
The Congo red derivative (E,E)-1-fluoro-2,5-bis(3-hydroxycarbonyl-4-hydroxy) styrylbenzene (FSB) specifically stains the functional amyloid curli in Escherichia coli biofilms. FSB binds to curli with similar affinity as Congo red, yet exhibits much greater fluorescence upon binding to curli as compared to Congo red and does not exhibit undesired binding to the cellulosic component of the biofilm. Thus, FSB presents a powerful tool to identify and visualize curli in E. coli biofilms and also enables new biophysical investigations of curli.
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Affiliation(s)
- Courtney Reichhardt
- Department of Chemistry, Stanford University, Stanford, California, United States of America
- * E-mail: (CR); (LC)
| | - Lynette Cegelski
- Department of Chemistry, Stanford University, Stanford, California, United States of America
- * E-mail: (CR); (LC)
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119
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Fuchs FM, Holland G, Moeller R, Laue M. Directed freeze-fracturing of Bacillus subtilis biofilms for conventional scanning electron microscopy. J Microbiol Methods 2018; 152:165-172. [PMID: 30125587 DOI: 10.1016/j.mimet.2018.08.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/13/2018] [Accepted: 08/14/2018] [Indexed: 10/28/2022]
Abstract
Biofilms have been intensively investigated over the past decades. Bacillus subtilis is able to form highly structured colony biofilms, and as one of the most studied Gram-positive model organisms, has helped to decipher the complex genetic regulation of biofilms. Several methods have been developed to analyze the architecture of biofilms. In this paper, we describe a method which allows the analysis of the internal structures of biofilms by scanning electron microscopy (SEM). The method uses a modified freeze-fracturing of chemically fixed biofilm to generate defined, well-preserved fractures at millimeter-scale which allows to analyze systematically the internal biofilm structure from macro- to nano-scale.
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Affiliation(s)
- Felix M Fuchs
- German Aerospace Center (DLR e.V.), Institute of Aerospace Medicine, Radiation Biology Department, Space Microbiology Research Group, Linder Hoehe, Cologne (Köln), Germany.
| | - Gudrun Holland
- Robert Koch Institute, Advanced Light and Electron Microscopy (ZBS 4), Berlin, Germany
| | - Ralf Moeller
- German Aerospace Center (DLR e.V.), Institute of Aerospace Medicine, Radiation Biology Department, Space Microbiology Research Group, Linder Hoehe, Cologne (Köln), Germany
| | - Michael Laue
- Robert Koch Institute, Advanced Light and Electron Microscopy (ZBS 4), Berlin, Germany
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120
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Klauck G, Serra DO, Possling A, Hengge R. Spatial organization of different sigma factor activities and c-di-GMP signalling within the three-dimensional landscape of a bacterial biofilm. Open Biol 2018; 8:180066. [PMID: 30135237 PMCID: PMC6119863 DOI: 10.1098/rsob.180066] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 07/18/2018] [Indexed: 12/25/2022] Open
Abstract
Bacterial biofilms are large aggregates of cells embedded in an extracellular matrix of self-produced polymers. In macrocolony biofilms of Escherichia coli, this matrix is generated in the upper biofilm layer only and shows a surprisingly complex supracellular architecture. Stratified matrix production follows the vertical nutrient gradient and requires the stationary phase σS (RpoS) subunit of RNA polymerase and the second messenger c-di-GMP. By visualizing global gene expression patterns with a newly designed fingerprint set of Gfp reporter fusions, our study reveals the spatial order of differential sigma factor activities, stringent control of ribosomal gene expression and c-di-GMP signalling in vertically cryosectioned macrocolony biofilms. Long-range physiological stratification shows a duplication of the growth-to-stationary phase pattern that integrates nutrient and oxygen gradients. In addition, distinct short-range heterogeneity occurs within specific biofilm strata and correlates with visually different zones of the refined matrix architecture. These results introduce a new conceptual framework for the control of biofilm formation and demonstrate that the intriguing extracellular matrix architecture, which determines the emergent physiological and biomechanical properties of biofilms, results from the spatial interplay of global gene regulation and microenvironmental conditions. Overall, mature bacterial macrocolony biofilms thus resemble the highly organized tissues of multicellular organisms.
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Affiliation(s)
- Gisela Klauck
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany
| | - Diego O Serra
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany
| | - Alexandra Possling
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany
| | - Regine Hengge
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany
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121
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Investigation of microorganisms involved in kefir biofilm formation. Antonie van Leeuwenhoek 2018; 111:2361-2370. [DOI: 10.1007/s10482-018-1125-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 07/06/2018] [Indexed: 11/26/2022]
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122
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Fulop T, Witkowski JM, Bourgade K, Khalil A, Zerif E, Larbi A, Hirokawa K, Pawelec G, Bocti C, Lacombe G, Dupuis G, Frost EH. Can an Infection Hypothesis Explain the Beta Amyloid Hypothesis of Alzheimer's Disease? Front Aging Neurosci 2018; 10:224. [PMID: 30087609 PMCID: PMC6066504 DOI: 10.3389/fnagi.2018.00224] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 07/02/2018] [Indexed: 12/19/2022] Open
Abstract
Alzheimer's disease (AD) is the most frequent type of dementia. The pathological hallmarks of the disease are extracellular senile plaques composed of beta-amyloid peptide (Aβ) and intracellular neurofibrillary tangles composed of pTau. These findings led to the "beta-amyloid hypothesis" that proposes that Aβ is the major cause of AD. Clinical trials targeting Aβ in the brain have mostly failed, whether they attempted to decrease Aβ production by BACE inhibitors or by antibodies. These failures suggest a need to find new hypotheses to explain AD pathogenesis and generate new targets for intervention to prevent and treat the disease. Many years ago, the "infection hypothesis" was proposed, but received little attention. However, the recent discovery that Aβ is an antimicrobial peptide (AMP) acting against bacteria, fungi, and viruses gives increased credence to an infection hypothesis in the etiology of AD. We and others have shown that microbial infection increases the synthesis of this AMP. Here, we propose that the production of Aβ as an AMP will be beneficial on first microbial challenge but will become progressively detrimental as the infection becomes chronic and reactivates from time to time. Furthermore, we propose that host measures to remove excess Aβ decrease over time due to microglial senescence and microbial biofilm formation. We propose that this biofilm aggregates with Aβ to form the plaques in the brain of AD patients. In this review, we will develop this connection between Infection - Aβ - AD and discuss future possible treatments based on this paradigm.
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Affiliation(s)
- Tamas Fulop
- Division of Geriatrics, Department of Medicine, Research Center on Aging, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Jacek M. Witkowski
- Department of Pathophysiology, Medical University of Gdańsk, Gdańsk, Poland
| | - Karine Bourgade
- Division of Geriatrics, Department of Medicine, Research Center on Aging, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Abdelouahed Khalil
- Division of Geriatrics, Department of Medicine, Research Center on Aging, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Echarki Zerif
- Division of Geriatrics, Department of Medicine, Research Center on Aging, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Anis Larbi
- Singapore Immunology Network, ASTAR, Biopolis, Singapore, Singapore
| | - Katsuiku Hirokawa
- Department of Pathology, Nitobe Memorial Nakano General Hospital, Tokyo, Japan
| | - Graham Pawelec
- Department of Internal Medicine II, Center for Medical Research, University of Tübingen, Tübingen, Germany
- Health Sciences North Research Institute, Greater Sudbury, ON, Canada
| | - Christian Bocti
- Division of Geriatrics, Department of Medicine, Research Center on Aging, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Guy Lacombe
- Division of Geriatrics, Department of Medicine, Research Center on Aging, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Gilles Dupuis
- Department of Biochemistry, Graduate Programme of Immunology, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Eric H. Frost
- Department of Microbiology and Infectious Diseases, University of Sherbrooke, Sherbrooke, QC, Canada
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123
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Van Gerven N, Van der Verren SE, Reiter DM, Remaut H. The Role of Functional Amyloids in Bacterial Virulence. J Mol Biol 2018; 430:3657-3684. [PMID: 30009771 PMCID: PMC6173799 DOI: 10.1016/j.jmb.2018.07.010] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/05/2018] [Accepted: 07/06/2018] [Indexed: 12/14/2022]
Abstract
Amyloid fibrils are best known as a product of human and animal protein misfolding disorders, where amyloid formation is associated with cytotoxicity and disease. It is now evident that for some proteins, the amyloid state constitutes the native structure and serves a functional role. These functional amyloids are proving widespread in bacteria and fungi, fulfilling diverse functions as structural components in biofilms or spore coats, as toxins and surface-active fibers, as epigenetic material, peptide reservoirs or adhesins mediating binding to and internalization into host cells. In this review, we will focus on the role of functional amyloids in bacterial pathogenesis. The role of functional amyloids as virulence factor is diverse but mostly indirect. Nevertheless, functional amyloid pathways deserve consideration for the acute and long-term effects of the infectious disease process and may form valid antimicrobial targets. Functional amyloids are widespread in bacteria, pathogenic and non-pathogenic. Bacterial biofilms most commonly function as structural support in the extracellular matrix of biofilms or spore coats, and in cell–cell and cell-surface adherence. The amyloid state can be the sole structured and functional state, or can be facultative, as a secondary state to folded monomeric subunits. Bacterial amyloids can enhance virulence by increasing persistence, cell adherence and invasion, intracellular survival, and pathogen spread by increased environmental survival. Bacterial amyloids may indirectly inflict disease by triggering inflammation, contact phase activation and possibly induce or aggravate human pathological aggregation disorders.
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Affiliation(s)
- Nani Van Gerven
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Sander E Van der Verren
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Dirk M Reiter
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Han Remaut
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium.
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124
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Fünfhaus A, Göbel J, Ebeling J, Knispel H, Garcia-Gonzalez E, Genersch E. Swarming motility and biofilm formation of Paenibacillus larvae, the etiological agent of American Foulbrood of honey bees (Apis mellifera). Sci Rep 2018; 8:8840. [PMID: 29892084 PMCID: PMC5995878 DOI: 10.1038/s41598-018-27193-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 05/29/2018] [Indexed: 12/19/2022] Open
Abstract
American Foulbrood is a worldwide distributed, fatal disease of the brood of the Western honey bee (Apis mellifera). The causative agent of this fatal brood disease is the Gram-positive, spore-forming bacterium Paenibacillus larvae, which can be classified into four different genotypes (ERIC I-IV), with ERIC I and II being the ones isolated from contemporary AFB outbreaks. P. larvae is a peritrichously flagellated bacterium and, hence, we hypothesized that P. larvae is capable of coordinated and cooperative multicellular behaviors like swarming motility and biofilm formation. In order to analyze these behaviors of P. larvae, we firstly established appropriate functional assays. Using these assays we demonstrated that P. larvae ERIC II, but not P. larvae ERIC I, was capable of swarming. Swarming motility was hampered in a P. larvae ERIC II-mutant lacking production of paenilarvin, an iturin-like lipopeptide exclusively expressed by this genotype. Both genotypes were able to form free floating biofilm aggregates loosely attached to the walls of the culture wells. Visualizing the biofilms by Congo red and thioflavin S staining suggested structural differences between the biofilms formed. Biofilm formation was shown to be independent from paenilarvin production because the paenilarvin deficient mutant was comparably able to form a biofilm.
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Affiliation(s)
- Anne Fünfhaus
- Institute for Bee Research, Department of Molecular Microbiology and Bee Diseases, Hohen Neuendorf, Germany
| | - Josefine Göbel
- Institute for Bee Research, Department of Molecular Microbiology and Bee Diseases, Hohen Neuendorf, Germany
| | - Julia Ebeling
- Institute for Bee Research, Department of Molecular Microbiology and Bee Diseases, Hohen Neuendorf, Germany
| | - Henriette Knispel
- Institute for Bee Research, Department of Molecular Microbiology and Bee Diseases, Hohen Neuendorf, Germany
| | - Eva Garcia-Gonzalez
- Institute for Bee Research, Department of Molecular Microbiology and Bee Diseases, Hohen Neuendorf, Germany
| | - Elke Genersch
- Institute for Bee Research, Department of Molecular Microbiology and Bee Diseases, Hohen Neuendorf, Germany.
- Freie Universität Berlin, Fachbereich Veterinärmedizin, Institut für Mikrobiologie und Tierseuchen, Berlin, Germany.
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125
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Inhibitory effects of Myricetin derivatives on curli-dependent biofilm formation in Escherichia coli. Sci Rep 2018; 8:8452. [PMID: 29855532 PMCID: PMC5981455 DOI: 10.1038/s41598-018-26748-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 05/18/2018] [Indexed: 01/09/2023] Open
Abstract
Biofilms are well-organised communities of microbes embedded in a self-produced extracellular matrix (e.g., curli amyloid fibers) and are associated with chronic infections. Therefore, development of anti-biofilm drugs is important to combat with these infections. Previously, we found that flavonol Myricetin inhibits curli-dependent biofilm formation by Escherichia coli (IC50 = 46.2 μM). In this study, we tested activities of seven Myricetin-derivatives to inhibit biofilm formation by E. coli K-12 in liquid culture. Among them, only Epigallocatechin gallate (EGCG), a major catechin in green tea, inhibited biofilm formation of K-12 (IC50 = 5.9 μM) more efficiently than Myricetin. Transmission electron microscopy and immunoblotting analyses demonstrated that EGCG prevented curli production by suppressing the expression of curli-related proteins. Quantitative RT-PCR analysis revealed that the transcripts of csgA, csgB, and csgD were significantly reduced in the presence of EGCG. Interestingly, the cellular level of RpoS, a stationary-phase specific alternative sigma factor, was reduced in the presence of EGCG, whereas the rpoS transcript was not affected. Antibiotic-chase experiments and genetic analyses revealed that EGCG accelerated RpoS degradation by ATP-dependent protease ClpXP in combination with its adaptor RssB. Collectively, these results provide significant insights into the development of drugs to treat chronic biofilm-associated infections.
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126
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Lipke PN. What We Do Not Know about Fungal Cell Adhesion Molecules. J Fungi (Basel) 2018; 4:jof4020059. [PMID: 29772751 PMCID: PMC6023273 DOI: 10.3390/jof4020059] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 04/27/2018] [Accepted: 05/10/2018] [Indexed: 12/16/2022] Open
Abstract
There has been extensive research on structure and function of fungal cell adhesion molecules, but the most of the work has been about adhesins in Candida albicans and Saccharomyces cerevisiae. These yeasts are members of a single ascomycete order, and adhesion molecules from the six other fungal phyla are only sparsely described in the literature. In these other phyla, most of the research is at the cellular level, rather than at the molecular level, so there has been little characterization of the adhesion molecules themselves. A catalog of known adhesins shows some common features: high Ser/Thr content, tandem repeats, N- and O-glycosylations, GPI anchors, dibasic sequence motifs, and potential amyloid-forming sequences. However, none of these features is universal. Known ligands include proteins and glycans on homologous cells and host cells. Existing and novel tools can exploit the availability of genome sequences to identify and characterize new fungal adhesins. These include bioinformatics tools and well-established yeast surface display models, which could be coupled with an adhesion substrate array. Thus, new knowledge could be exploited to answer key questions in fungal ecology, animal and plant pathogenesis, and roles of biofilms in infection and biomass turnover.
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Affiliation(s)
- Peter N Lipke
- Biology Department, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA.
- The Graduate Center, City University of New York, New York, NY 10016, USA.
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127
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Experimental Detection and Visualization of the Extracellular Matrix in Macrocolony Biofilms. Methods Mol Biol 2018; 1657:133-145. [PMID: 28889291 DOI: 10.1007/978-1-4939-7240-1_11] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
By adopting elaborate three-dimensional morphologies that vary according to their extracellular matrix composition, macrocolony biofilms offer a unique opportunity to interrogate about the roles of specific matrix components in shaping biofilm architecture. Here, we describe two methods optimized for Escherichia coli that profit from morphology and the high level of structural organization of macrocolonies to gain insight into the production and assembly of amyloid curli and cellulose-the two major biofilm matrix elements of E. coli-in biofilms. The first method, the macrocolony morphology assay, is based on the ability of curli and cellulose-either alone or in combination-to generate specific morphological and Congo Red-staining patterns in E. coli macrocolonies, which can then be used as a direct visual readout for the production of these matrix components. The second method involves thin sectioning of macrocolonies, which along with in situ staining of amyloid curli and cellulose and microscopic imaging allows gaining fine details of the spatial arrangement of both matrix elements inside macrocolonies. Beyond their current use with E. coli and related curli and cellulose-producing Enterobacteriaceae, both the methods offer the potential to be adapted to other bacterial species.
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128
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Cimdins A, Simm R. Semiquantitative Analysis of the Red, Dry, and Rough Colony Morphology of Salmonella enterica Serovar Typhimurium and Escherichia coli Using Congo Red. Methods Mol Biol 2018; 1657:225-241. [PMID: 28889298 DOI: 10.1007/978-1-4939-7240-1_18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The Congo Red (CR) assay is a standard biofilm test assessing the colony morphology of bacteria growing on agar plates supplemented with the diazo dye Congo Red. Biofilm forming Salmonella enterica serovar Typhimurium and Escherichia coli produce a red, dry, and rough (rdar) morphotype on CR-plates. The phenotype is characterized by staining of the extracellular matrix components curli (brown color) and cellulose (pink color) by CR. This method allows semiquantitative determination of the expression level of the individual matrix components and dissection of the regulatory networks controlling their production in response to c-di-GMP levels. Here, we describe the CR-assay and its variations and discuss the effect of deletion or overexpression of c-di-GMP turnover proteins on colony morphology.
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Affiliation(s)
- Annika Cimdins
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
- Institute of Hygiene, University of Münster, Mendelstrasse 7, 48149, Münster, Germany.
| | - Roger Simm
- Norwegian Veterinary Institute, Oslo, Norway
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
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129
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Herbst S, Lorkowski M, Sarenko O, Nguyen TKL, Jaenicke T, Hengge R. Transmembrane redox control and proteolysis of PdeC, a novel type of c-di-GMP phosphodiesterase. EMBO J 2018; 37:e97825. [PMID: 29514851 PMCID: PMC5897775 DOI: 10.15252/embj.201797825] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 01/31/2018] [Accepted: 02/08/2018] [Indexed: 12/17/2022] Open
Abstract
The nucleotide second messenger c-di-GMP nearly ubiquitously promotes bacterial biofilm formation, with enzymes that synthesize and degrade c-di-GMP being controlled by diverse N-terminal sensor domains. Here, we describe a novel class of widely occurring c-di-GMP phosphodiesterases (PDE) that feature a periplasmic "CSS domain" with two highly conserved cysteines that is flanked by two transmembrane regions (TM1 and TM2) and followed by a cytoplasmic EAL domain with PDE activity. Using PdeC, one of the five CSS domain PDEs of Escherichia coli K-12, we show that DsbA/DsbB-promoted disulfide bond formation in the CSS domain reduces PDE activity. By contrast, the free thiol form is enzymatically highly active, with the TM2 region promoting dimerization. Moreover, this form is processed by periplasmic proteases DegP and DegQ, yielding a highly active TM2 + EAL fragment that is slowly removed by further proteolysis. Similar redox control and proteolysis was also observed for a second CSS domain PDE, PdeB. At the physiological level, CSS domain PDEs modulate production and supracellular architecture of extracellular matrix polymers in the deeper layers of mature E. coli biofilms.
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Affiliation(s)
- Susanne Herbst
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Martin Lorkowski
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Olga Sarenko
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Thi Kim Loan Nguyen
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Tina Jaenicke
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Regine Hengge
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
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130
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Wermser C, Lopez D. Identification of Staphylococcus aureus genes involved in the formation of structured macrocolonies. MICROBIOLOGY-SGM 2018; 164:801-815. [PMID: 29638209 DOI: 10.1099/mic.0.000660] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The human pathogen Staphylococcus aureus causes difficult-to-eradicate biofilm-associated infections that generally become chronic. Understanding the genetic regulation of biofilm formation in S. aureus is central to a precise definition of the conditions and genes involved in development of chronic biofilm-associated infections. Biofilm-related genes have been detected by comparing mutants using the classical submerged biofilm formation assay, in which cells adhere to the bottom of a well containing culture medium. We recently developed an alternative biofilm formation model for S. aureus, based on macrocolony formation on agar plates, comparable to an assay used to study biofilm formation in a few other bacterial species. As organism features are the result of environmental conditions as well as of genes, we used a genome-wide collection of transposon-mapped mutants in this macrocolony assay to seek S. aureus developmental genes and pathways not identified by the classical biofilm formation assay. We identified routes related to glucose and purine metabolism and clarified their regulatory link to macrocolony formation. Our study demonstrates that formation of microbial communities must be correlated to specific growth conditions, and the role of metabolism must be considered in S. aureus biofilm formation and thus, in the development of chronic infections.
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Affiliation(s)
- Charlotte Wermser
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany.,Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
| | - Daniel Lopez
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany.,Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany.,National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid 28049, Spain
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131
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Cornell WC, Morgan CJ, Koyama L, Sakhtah H, Mansfield JH, Dietrich LEP. Paraffin Embedding and Thin Sectioning of Microbial Colony Biofilms for Microscopic Analysis. J Vis Exp 2018:57196. [PMID: 29630036 PMCID: PMC5933251 DOI: 10.3791/57196] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Sectioning via paraffin embedding is a broadly established technique in eukaryotic systems. Here we provide a method for the fixation, embedding, and sectioning of intact microbial colony biofilms using perfused paraffin wax. To adapt this method for use on colony biofilms, we developed techniques for maintaining each sample on its growth substrate and laminating it with an agar overlayer, and added lysine to the fixative solution. These optimizations improve sample retention and preservation of micromorphological features. Samples prepared in this manner are amenable to thin sectioning and imaging by light, fluorescence, and transmission electron microscopy. We have applied this technique to colony biofilms of Pseudomonas aeruginosa, Pseudomonas synxantha, Bacillus subtilis, and Vibrio cholerae. The high level of detail visible in samples generated by this method, combined with reporter strain engineering or the use of specific dyes, can provide exciting insights into the physiology and development of microbial communities.
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Affiliation(s)
| | | | - Leslie Koyama
- Department of Biological Sciences, Columbia University; Department of Biology, Barnard College, Columbia University
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132
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Nagar SD, Aggarwal B, Joon S, Bhatnagar R, Bhatnagar S. A Network Biology Approach to Decipher Stress Response in Bacteria Using Escherichia coli As a Model. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2018; 20:310-24. [PMID: 27195968 DOI: 10.1089/omi.2016.0028] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The development of drug-resistant pathogenic bacteria poses challenges to global health for their treatment and control. In this context, stress response enables bacterial populations to survive extreme perturbations in the environment but remains poorly understood. Specific modules are activated for unique stressors with few recognized global regulators. The phenomenon of cross-stress protection strongly suggests the presence of central proteins that control the diverse stress responses. In this work, Escherichia coli was used to model the bacterial stress response. A Protein-Protein Interaction Network was generated by integrating differentially expressed genes in eight stress conditions of pH, temperature, and antibiotics with relevant gene ontology terms. Topological analysis identified 24 central proteins. The well-documented role of 16 central proteins in stress indicates central control of the response, while the remaining eight proteins may have a novel role in stress response. Cluster analysis of the generated network implicated RNA binding, flagellar assembly, ABC transporters, and DNA repair as important processes during response to stress. Pathway analysis showed crosstalk of Two Component Systems with metabolic processes, oxidative phosphorylation, and ABC transporters. The results were further validated by analysis of an independent cross-stress protection dataset. This study also reports on the ways in which bacterial stress response can progress to biofilm formation. In conclusion, we suggest that drug targets or pathways disrupting bacterial stress responses can potentially be exploited to combat antibiotic tolerance and multidrug resistance in the future.
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Affiliation(s)
- Shashwat Deepali Nagar
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India
| | - Bhavye Aggarwal
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India
| | - Shikha Joon
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India .,2 Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University , New Delhi, India
| | - Rakesh Bhatnagar
- 2 Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University , New Delhi, India
| | - Sonika Bhatnagar
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India
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133
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Bacterial Biofilm Characterization and Microscopic Evaluation of the Antibacterial Properties of a Photocatalytic Coating Protecting Building Material. COATINGS 2018. [DOI: 10.3390/coatings8030093] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Use of photocatalytic paint-like coatings may be a way to protect building materials from microbial colonization. Numerous studies have shown the antimicrobial efficiency of TiO 2 photocatalysis on various microorganisms. However, few have focused on easy-to-apply solutions and on photocatalysis under low irradiance. This paper focuses on (a) the antibacterial properties of a semi-transparent coating formulated using TiO 2 particles and (b) the microscopic investigations of bacterial biofilm development on TiO 2 -coated building materials under accelerated growth conditions. Results showed significant antibacterial activity after few hours of testing. The efficiency seemed limited by the confinement of the TiO 2 particles inside the coating binder. However, a pre-irradiation with UV light can improve efficiency. In addition, a significant effect against the formation of a bacterial biofilm was also observed. The epifluorescence approach, in which fluorescence is produced by reflect rather than transmitted light, could be applied in further studies of microbial growth on coatings and building materials.
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134
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Avcıbaşı U, Demiroğlu H, Sakarya S, Ünak P, Tekin V, Ateş B. The effect of radiolabeled antibiotics on biofilm and microorganism within biofilm. J Radioanal Nucl Chem 2018. [DOI: 10.1007/s10967-018-5750-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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135
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Biofilm Formation by the Acidophile Bacterium Acidithiobacillus thiooxidans Involves c-di-GMP Pathway and Pel exopolysaccharide. Genes (Basel) 2018; 9:genes9020113. [PMID: 29466318 PMCID: PMC5852609 DOI: 10.3390/genes9020113] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 01/31/2018] [Accepted: 02/06/2018] [Indexed: 01/08/2023] Open
Abstract
Acidophile bacteria belonging to the Acidithiobacillus genus are pivotal players for the bioleaching of metallic values such as copper. Cell adherence to ores and biofilm formation, mediated by the production of extracellular polymeric substances, strongly favors bioleaching activity. In recent years, the second messenger cyclic diguanylate (c-di-GMP) has emerged as a central regulator for biofilm formation in bacteria. C-di-GMP pathways have been reported in different Acidithiobacillus species; however, c-di-GMP effectors and signal transduction networks are still largely uncharacterized in these extremophile species. Here we investigated Pel exopolysaccharide and its role in biofilm formation by sulfur-oxidizing species Acidithiobacillusthiooxidans. We identified 39 open reading frames (ORFs) encoding proteins involved in c-di-GMP metabolism and signal transduction, including the c-di-GMP effector protein PelD, a structural component of the biosynthesis apparatus for Pel exopolysaccharide production. We found that intracellular c-di-GMP concentrations and transcription levels of pel genes were higher in At. thiooxidans biofilm cells compared to planktonic ones. By developing an At. thiooxidans ΔpelD null-mutant strain we revealed that Pel exopolysaccharide is involved in biofilm structure and development. Further studies are still necessary to understand how Pel biosynthesis is regulated in Acidithiobacillus species, nevertheless these results represent the first characterization of a c-di-GMP effector protein involved in biofilm formation by acidophile species.
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136
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Autoinducer 2-Dependent Escherichia coli Biofilm Formation Is Enhanced in a Dual-Species Coculture. Appl Environ Microbiol 2018; 84:AEM.02638-17. [PMID: 29269492 PMCID: PMC5812939 DOI: 10.1128/aem.02638-17] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 12/12/2017] [Indexed: 12/21/2022] Open
Abstract
Biofilms in nature typically consist of multiple species, and microbial interactions are likely to have crucial effects on biofilm development, structure, and functions. The best-understood form of communication within bacterial communities involves the production, release, and detection of signal molecules (autoinducers), known as quorum sensing. Although autoinducers mainly promote intraspecies communication, autoinducer 2 (AI-2) is produced and detected by a variety of bacteria, thus principally allowing interspecies communication. Here we show the importance of AI-2-mediated signaling in the formation of mixed biofilms by Enterococcus faecalis and Escherichia coli. Our results demonstrate that AI-2 produced by E. faecalis promotes collective behaviors of E. coli at lower cell densities, enhancing autoaggregation of E. coli but also leading to chemotaxis-dependent coaggregation between the two species. Finally, we show that formation of such mixed dual-species biofilms increases the stress resistance of both E. coli and E. faecalis. IMPORTANCE The role of interspecies communication in the development of mixed microbial communities is becoming increasingly apparent, but specific examples of such communication remain limited. The universal signal molecule AI-2 is well known to regulate cell-density-dependent phenotypes of many bacterial species but, despite its potential for interspecies communication, the role of AI-2 in the establishment of multispecies communities is not well understood. In this study, we explore AI-2 signaling in a dual-species community containing two bacterial species that naturally cooccur in their mammalian hosts, i.e., Escherichia coli and Enterococcus faecalis. We show that active production of AI-2 by E. faecalis allows E. coli to perform collective behaviors at low cell densities. Additionally, AI-2- and chemotaxis-dependent coaggregation with E. faecalis creates nucleation zones for rapid growth of E. coli microcolonies in mixed biofilms and enhances the stress resistance of both species.
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137
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Thongsomboon W, Serra DO, Possling A, Hadjineophytou C, Hengge R, Cegelski L. Phosphoethanolamine cellulose: A naturally produced chemically modified cellulose. Science 2018; 359:334-338. [DOI: 10.1126/science.aao4096] [Citation(s) in RCA: 150] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 11/13/2017] [Indexed: 12/22/2022]
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138
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Troselj V, Cao P, Wall D. Cell-cell recognition and social networking in bacteria. Environ Microbiol 2017; 20:923-933. [PMID: 29194914 DOI: 10.1111/1462-2920.14005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 11/15/2017] [Accepted: 11/20/2017] [Indexed: 01/13/2023]
Abstract
The ability to recognize self and to recognize partnering cells allows microorganisms to build social networks that perform functions beyond the capabilities of the individual. In bacteria, recognition typically involves genetic determinants that provide cell surface receptors or diffusible signalling chemicals to identify proximal cells at the molecular level that can participate in cooperative processes. Social networks also rely on discriminating mechanisms to exclude competing cells from joining and exploiting their groups. In addition to their appropriate genotypes, cell-cell recognition also requires compatible phenotypes, which vary according to environmental cues or exposures as well as stochastic processes that lead to heterogeneity and potential disharmony in the population. Understanding how bacteria identify their social partners and how they synchronize their behaviours to conduct multicellular functions is an expanding field of research. Here, we review recent progress in the field and contrast the various strategies used in recognition and behavioural networking.
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Affiliation(s)
- Vera Troselj
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA
| | - Pengbo Cao
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA
| | - Daniel Wall
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA
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139
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Electron microscopic observations of prokaryotic surface appendages. J Microbiol 2017; 55:919-926. [DOI: 10.1007/s12275-017-7369-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 10/10/2017] [Accepted: 10/15/2017] [Indexed: 12/21/2022]
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140
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Amores GR, de Las Heras A, Sanches-Medeiros A, Elfick A, Silva-Rocha R. Systematic identification of novel regulatory interactions controlling biofilm formation in the bacterium Escherichia coli. Sci Rep 2017; 7:16768. [PMID: 29196655 PMCID: PMC5711951 DOI: 10.1038/s41598-017-17114-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/22/2017] [Indexed: 01/11/2023] Open
Abstract
Here, we investigated novel interactions of three global regulators of the network that controls biofilm formation in the model bacterium Escherichia coli using computational network analysis, an in vivo reporter assay and physiological validation experiments. We were able to map critical nodes that govern planktonic to biofilm transition and identify 8 new regulatory interactions for CRP, IHF or Fis responsible for the control of the promoters of rpoS, rpoE, flhD, fliA, csgD and yeaJ. Additionally, an in vivo promoter reporter assay and motility analysis revealed a key role for IHF as a repressor of cell motility through the control of FliA sigma factor expression. This investigation of first stage and mature biofilm formation indicates that biofilm structure is strongly affected by IHF and Fis, while CRP seems to provide a fine-tuning mechanism. Taken together, the analysis presented here shows the utility of combining computational and experimental approaches to generate a deeper understanding of the biofilm formation process in bacteria.
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Affiliation(s)
| | - Aitor de Las Heras
- Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, UK
- SynthSys Research Centre, University of Edinburgh, Edinburgh, UK
| | | | - Alistair Elfick
- Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, UK
- SynthSys Research Centre, University of Edinburgh, Edinburgh, UK
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141
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Hachicho N, Birnbaum A, Heipieper HJ. Osmotic stress in colony and planktonic cells of Pseudomonas putida mt-2 revealed significant differences in adaptive response mechanisms. AMB Express 2017; 7:62. [PMID: 28299749 PMCID: PMC5352697 DOI: 10.1186/s13568-017-0371-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 03/13/2017] [Indexed: 11/10/2022] Open
Abstract
Planktonic cells and those grown on surfaces (or as colony biofilm) are known to show significant differences regarding growth behavior, cell physiology, gene expression and stress tolerance. In order to compare stress behavior of different growth forms, shake cultures for planktonic growth and agar plate cultivation for colony growth, were carried out with the well investigated model organism, Pseudomonas putida mt-2. Cells were exposed to sodium chloride to cause osmotic stress as one main environmental stressor bacteria have to cope with when growing in soil. Planktonic cells were more tolerant with a complete inhibition of growth at 0.7 M NaCl, compared to 0.5 M for agar-grown cells. Cell surface hydrophobicity, measured as water contact angles, was significantly higher for agar-grown cells (92°) than for planktonic cells (40°), and increased in the presence of NaCl. Agar-grown cells also showed a significantly higher degree of saturation of membrane fatty acids that increased in the presence of NaCl. These results demonstrate that planktonic and colony grown bacteria show different responses when confronted with osmotic stress suggesting that the tolerance and adaptive mechanisms are dependent on the environmental conditions as well as the initial physiological state.
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142
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Hengge R. Trigger phosphodiesterases as a novel class of c-di-GMP effector proteins. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0498. [PMID: 27672149 PMCID: PMC5052742 DOI: 10.1098/rstb.2015.0498] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2016] [Indexed: 11/28/2022] Open
Abstract
The bacterial second messenger c-di-GMP controls bacterial biofilm formation, motility, cell cycle progression, development and virulence. It is synthesized by diguanylate cyclases (with GGDEF domains), degraded by specific phosphodiesterases (PDEs, with EAL of HD-GYP domains) and sensed by a wide variety of c-di-GMP-binding effectors that control diverse targets. c-di-GMP-binding effectors can be riboswitches as well as proteins with highly diverse structures and functions. The latter include ‘degenerate’ GGDEF/EAL domain proteins that are enzymatically inactive but still able to bind c-di-GMP. Surprisingly, two enzymatically active ‘trigger PDEs’, the Escherichia coli proteins PdeR and PdeL, have recently been added to this list of c-di-GMP-sensing effectors. Mechanistically, trigger PDEs are multifunctional. They directly and specifically interact with a macromolecular target (e.g. with a transcription factor or directly with a promoter region), whose activity they control by their binding and degradation of c-di-GMP—their PDE activity thus represents the c-di-GMP sensor or effector function. In this process, c-di-GMP serves as a regulatory ligand, but in contrast to classical allosteric control, this ligand is also degraded. The resulting kinetics and circuitry of control are ideally suited for trigger PDEs to serve as key components in regulatory switches. This article is part of the themed issue ‘The new bacteriology’.
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Affiliation(s)
- Regine Hengge
- Institute of Biology/Microbiology, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
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143
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Amyloid-Like β-Aggregates as Force-Sensitive Switches in Fungal Biofilms and Infections. Microbiol Mol Biol Rev 2017; 82:82/1/e00035-17. [PMID: 29187516 DOI: 10.1128/mmbr.00035-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cellular aggregation is an essential step in the formation of biofilms, which promote fungal survival and persistence in hosts. In many of the known yeast cell adhesion proteins, there are amino acid sequences predicted to form amyloid-like β-aggregates. These sequences mediate amyloid formation in vitro. In vivo, these sequences mediate a phase transition from a disordered state to a partially ordered state to create patches of adhesins on the cell surface. These β-aggregated protein patches are called adhesin nanodomains, and their presence greatly increases and strengthens cell-cell interactions in fungal cell aggregation. Nanodomain formation is slow (with molecular response in minutes and the consequences being evident for hours), and strong interactions lead to enhanced biofilm formation. Unique among functional amyloids, fungal adhesin β-aggregation can be triggered by the application of physical shear force, leading to cellular responses to flow-induced stress and the formation of robust biofilms that persist under flow. Bioinformatics analysis suggests that this phenomenon may be widespread. Analysis of fungal abscesses shows the presence of surface amyloids in situ, a finding which supports the idea that phase changes to an amyloid-like state occur in vivo. The amyloid-coated fungi bind the damage-associated molecular pattern receptor serum amyloid P component, and there may be a consequential modulation of innate immune responses to the fungi. Structural data now suggest mechanisms for the force-mediated induction of the phase change. We summarize and discuss evidence that the sequences function as triggers for protein aggregation and subsequent cellular aggregation, both in vitro and in vivo.
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144
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Vidakovic L, Singh PK, Hartmann R, Nadell CD, Drescher K. Dynamic biofilm architecture confers individual and collective mechanisms of viral protection. Nat Microbiol 2017; 3:26-31. [PMID: 29085075 PMCID: PMC5739289 DOI: 10.1038/s41564-017-0050-1] [Citation(s) in RCA: 167] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 09/29/2017] [Indexed: 01/21/2023]
Affiliation(s)
- Lucia Vidakovic
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Praveen K Singh
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Raimo Hartmann
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Carey D Nadell
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany. .,Department of Biological Sciences, Dartmouth College, Hanover, NH, USA.
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany. .,Department of Physics, Philipps University Marburg, Marburg, Germany.
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145
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Mamou G, Fiyaksel O, Sinai L, Ben-Yehuda S. Deficiency in Lipoteichoic Acid Synthesis Causes a Failure in Executing the Colony Developmental Program in Bacillus subtilis. Front Microbiol 2017; 8:1991. [PMID: 29114240 PMCID: PMC5660684 DOI: 10.3389/fmicb.2017.01991] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 09/27/2017] [Indexed: 01/18/2023] Open
Abstract
Colonies are an abundant form of bacterial multicellularity; however, relatively little is known about the initial stages of their construction. We have previously described that colony development of the soil bacterium Bacillus subtilis is a highly ordered process, typically initiating with the formation of extending cell chains arranged in a Y shape structure. Furthermore, we demonstrated that Y arm extension is a key for defining the size of the future colony. Here we conducted a genetic screen surveying for mutants deficient in these early developmental stages, and revealed LtaS, the major lipoteichoic acid (LTA) synthase, to be crucial for execution of these events. We found that the ltaS mutant fails to produce proper Y shape structures, forming extremely elongated chains of cells with no evidence of chain breakage, necessary for Y shape formation. Furthermore, we show that frequent cell death at the tips of the cell chains is a major cause in limiting arm extension. Collectively, these perturbations lead to the production of a small sized colony by the mutant. Thus, deficiency in LTA synthesis causes a mechanical failure in executing the colony developmental program.
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Affiliation(s)
- Gideon Mamou
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Osher Fiyaksel
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Lior Sinai
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Sigal Ben-Yehuda
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Hebrew University of Jerusalem, Jerusalem, Israel
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146
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More than Enzymes That Make or Break Cyclic Di-GMP-Local Signaling in the Interactome of GGDEF/EAL Domain Proteins of Escherichia coli. mBio 2017; 8:mBio.01639-17. [PMID: 29018125 PMCID: PMC5635695 DOI: 10.1128/mbio.01639-17] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The bacterial second messenger bis-(3'-5')-cyclic diguanosine monophosphate (c-di-GMP) ubiquitously promotes bacterial biofilm formation. Intracellular pools of c-di-GMP seem to be dynamically negotiated by diguanylate cyclases (DGCs, with GGDEF domains) and specific phosphodiesterases (PDEs, with EAL or HD-GYP domains). Most bacterial species possess multiple DGCs and PDEs, often with surprisingly distinct and specific output functions. One explanation for such specificity is "local" c-di-GMP signaling, which is believed to involve direct interactions between specific DGC/PDE pairs and c-di-GMP-binding effector/target systems. Here we present a systematic analysis of direct protein interactions among all 29 GGDEF/EAL domain proteins of Escherichia coli Since the effects of interactions depend on coexpression and stoichiometries, cellular levels of all GGDEF/EAL domain proteins were also quantified and found to vary dynamically along the growth cycle. Instead of detecting specific pairs of interacting DGCs and PDEs, we discovered a tightly interconnected protein network of a specific subset or "supermodule" of DGCs and PDEs with a coregulated core of five hyperconnected hub proteins. These include the DGC/PDE proteins representing the c-di-GMP switch that turns on biofilm matrix production in E. coli Mutants lacking these core hub proteins show drastic biofilm-related phenotypes but no changes in cellular c-di-GMP levels. Overall, our results provide the basis for a novel model of local c-di-GMP signaling in which a single strongly expressed master PDE, PdeH, dynamically eradicates global effects of several DGCs by strongly draining the global c-di-GMP pool and thereby restricting these DGCs to serving as local c-di-GMP sources that activate specific colocalized effector/target systems.IMPORTANCE c-di-GMP signaling in bacteria is believed to occur via changes in cellular c-di-GMP levels controlled by antagonistic and potentially interacting pairs of diguanylate cyclases (DGCs) and c-di-GMP phosphodiesterases (PDEs). Our systematic analysis of protein-protein interaction patterns of all 29 GGDEF/EAL domain proteins of E. coli, together with our measurements of cellular c-di-GMP levels, challenges both aspects of this current concept. Knocking out distinct DGCs and PDEs has drastic effects on E. coli biofilm formation without changing the cellular c-di-GMP level. In addition, rather than generally coming in interacting DGC/PDE pairs, a subset of DGCs and PDEs operates as central interaction hubs in a larger "supermodule," with other DGCs and PDEs behaving as "lonely players" without contacts to other c-di-GMP-related enzymes. On the basis of these data, we propose a novel concept of "local" c-di-GMP signaling in bacteria with multiple enzymes that make or break the second messenger c-di-GMP.
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147
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MacKenzie KD, Palmer MB, Köster WL, White AP. Examining the Link between Biofilm Formation and the Ability of Pathogenic Salmonella Strains to Colonize Multiple Host Species. Front Vet Sci 2017; 4:138. [PMID: 29159172 PMCID: PMC5581909 DOI: 10.3389/fvets.2017.00138] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Accepted: 08/09/2017] [Indexed: 12/11/2022] Open
Abstract
Salmonella are important pathogens worldwide and a predominant number of human infections are zoonotic in nature. The ability of strains to form biofilms, which is a multicellular behavior characterized by the aggregation of cells, is predicted to be a conserved strategy for increased persistence and survival. It may also contribute to the increasing number of infections caused by ingestion of contaminated fruits and vegetables. There is a correlation between biofilm formation and the ability of strains to colonize and replicate within the intestines of multiple host species. These strains predominantly cause localized gastroenteritis infections in humans. In contrast, there are salmonellae that cause systemic, disseminated infections in a select few host species; these “invasive” strains have a narrowed host range, and most are unable to form biofilms. This includes host-restricted Salmonella serovar Typhi, which are only able to infect humans, and atypical gastroenteritis strains associated with the opportunistic infection of immunocompromised patients. From the perspective of transmission, biofilm formation is advantageous for ensuring pathogen survival in the environment. However, from an infection point of view, biofilm formation may be an anti-virulence trait. We do not know if the capacity to form biofilms prevents a strain from accessing the systemic compartments within the host or if loss of the biofilm phenotype reflects a change in a strain’s interaction with the host. In this review, we examine the connections between biofilm formation, Salmonella disease states, degrees of host adaptation, and how this might relate to different transmission patterns. A better understanding of the dynamic lifecycle of Salmonella will allow us to reduce the burden of livestock and human infections caused by these important pathogens.
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Affiliation(s)
- Keith D MacKenzie
- Vaccine and Infectious Disease Organization-International Vaccine Centre, Saskatoon, SK, Canada.,Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Melissa B Palmer
- Vaccine and Infectious Disease Organization-International Vaccine Centre, Saskatoon, SK, Canada.,Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Wolfgang L Köster
- Vaccine and Infectious Disease Organization-International Vaccine Centre, Saskatoon, SK, Canada.,Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Aaron P White
- Vaccine and Infectious Disease Organization-International Vaccine Centre, Saskatoon, SK, Canada.,Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada
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148
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Bridier A, Piard JC, Pandin C, Labarthe S, Dubois-Brissonnet F, Briandet R. Spatial Organization Plasticity as an Adaptive Driver of Surface Microbial Communities. Front Microbiol 2017; 8:1364. [PMID: 28775718 PMCID: PMC5517491 DOI: 10.3389/fmicb.2017.01364] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/05/2017] [Indexed: 01/08/2023] Open
Abstract
Biofilms are dynamic habitats which constantly evolve in response to environmental fluctuations and thereby constitute remarkable survival strategies for microorganisms. The modulation of biofilm functional properties is largely governed by the active remodeling of their three-dimensional structure and involves an arsenal of microbial self-produced components and interconnected mechanisms. The production of matrix components, the spatial reorganization of ecological interactions, the generation of physiological heterogeneity, the regulation of motility, the production of actives enzymes are for instance some of the processes enabling such spatial organization plasticity. In this contribution, we discussed the foundations of architectural plasticity as an adaptive driver of biofilms through the review of the different microbial strategies involved. Moreover, the possibility to harness such characteristics to sculpt biofilm structure as an attractive approach to control their functional properties, whether beneficial or deleterious, is also discussed.
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Affiliation(s)
- Arnaud Bridier
- Antibiotics, Biocides, Residues and Resistance Unit, Fougères Laboratory, ANSESFougères, France
| | - Jean-Christophe Piard
- Micalis Institute, INRA, AgroParisTech, Université Paris-SaclayJouy-en-Josas, France
| | - Caroline Pandin
- Micalis Institute, INRA, AgroParisTech, Université Paris-SaclayJouy-en-Josas, France
| | - Simon Labarthe
- MaIAGE, INRA, Université Paris-SaclayJouy-en-Josas, France
| | | | - Romain Briandet
- Micalis Institute, INRA, AgroParisTech, Université Paris-SaclayJouy-en-Josas, France
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149
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Biofilm Formation Potential of Heat-Resistant Escherichia coli Dairy Isolates and the Complete Genome of Multidrug-Resistant, Heat-Resistant Strain FAM21845. Appl Environ Microbiol 2017; 83:AEM.00628-17. [PMID: 28550056 PMCID: PMC5514686 DOI: 10.1128/aem.00628-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/18/2017] [Indexed: 02/07/2023] Open
Abstract
We tested the biofilm formation potential of 30 heat-resistant and 6 heat-sensitive Escherichia coli dairy isolates. Production of curli and cellulose, static biofilm formation on polystyrene (PS) and stainless steel surfaces, biofilm formation under dynamic conditions (Bioflux), and initial adhesion rates (IAR) were evaluated. Biofilm formation varied greatly between strains, media, and assays. Our results highlight the importance of the experimental setup in determining biofilm formation under conditions of interest, as correlation between different assays was often not a given. The heat-resistant, multidrug-resistant (MDR) strain FAM21845 showed the strongest biofilm formation on PS and the highest IAR and was the only strain that formed significant biofilms on stainless steel under conditions relevant to the dairy industry, and it was therefore fully sequenced. Its chromosome is 4.9 Mb long, and it harbors a total of five plasmids (147.2, 54.2, 5.8, 2.5, and 1.9 kb). The strain carries a broad range of genes relevant to antimicrobial resistance and biofilm formation, including some on its two large conjugative plasmids, as demonstrated in plate mating assays.IMPORTANCE In biofilms, cells are embedded in an extracellular matrix that protects them from stresses, such as UV radiation, osmotic shock, desiccation, antibiotics, and predation. Biofilm formation is a major bacterial persistence factor of great concern in the clinic and the food industry. Many tested strains formed strong biofilms, and especially strains such as the heat-resistant, MDR strain FAM21845 may pose a serious issue for food production. Strong biofilm formation combined with diverse resistances (some encoded on conjugative plasmids) may allow for increased persistence, coselection, and possible transfer of these resistance factors. Horizontal gene transfer may conceivably occur in the food production setting or the gastrointestinal tract after consumption.
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150
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Abstract
Biofilms are communities of microbial cells that are encapsulated within a self-produced polymeric matrix. The matrix is critical to the success of biofilms in diverse habitats; however, many details of the composition, structure, and function remain enigmatic. Biofilms formed by the Gram-positive bacterium Bacillus subtilis depend on the production of the secreted film-forming protein BslA. Here, we show that a gradient of electron acceptor availability through the depth of the biofilm gives rise to two distinct functional roles for BslA and that these roles can be genetically separated through targeted amino acid substitutions. We establish that monomeric BslA is necessary and sufficient to give rise to complex biofilm architecture, whereas dimerization of BslA is required to render the community hydrophobic. Dimerization of BslA, mediated by disulfide bond formation, depends on two conserved cysteine residues located in the C-terminal region. Our findings demonstrate that bacteria have evolved multiple uses for limited elements in the matrix, allowing for alternative responses in a complex, changing environment.
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