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Knittel K, Miksch S, Moncada C, Silva-Solar S, Moye J, Amann R, Arnosti C. Distinct actors drive different mechanisms of biopolymer processing in polar marine coastal sediments. Environ Microbiol 2024; 26:e16687. [PMID: 39168162 DOI: 10.1111/1462-2920.16687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 07/24/2024] [Indexed: 08/23/2024]
Abstract
Heterotrophic bacteria in the ocean initiate biopolymer degradation using extracellular enzymes that yield low molecular weight hydrolysis products in the environment, or by using a selfish uptake mechanism that retains the hydrolysate for the enzyme-producing cell. The mechanism used affects the availability of hydrolysis products to other bacteria, and thus also potentially the composition and activity of the community. In marine systems, these two mechanisms of substrate processing have been studied in the water column, but to date, have not been investigated in sediments. In surface sediments from an Arctic fjord of Svalbard, we investigated mechanisms of biopolymer hydrolysis using four polysaccharides and mucin, a glycoprotein. Extracellular hydrolysis of all biopolymers was rapid. Moreover, rapid degradation of mucin suggests that it may be a key substrate for benthic microbes. Although selfish uptake is common in ocean waters, only a small fraction (0.5%-2%) of microbes adhering to sediments used this mechanism. Selfish uptake was carried out primarily by Planctomycetota and Verrucomicrobiota. The overall dominance of extracellular hydrolysis in sediments, however, suggests that the bulk of biopolymer processing is carried out by a benthic community relying on the sharing of enzymatic capabilities and scavenging of public goods.
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Affiliation(s)
- Katrin Knittel
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | | | - Chyrene Moncada
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | | | - Jannika Moye
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Rudolf Amann
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Carol Arnosti
- Department of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Bakalakos M, Ampadiotaki MM, Vlachos C, Sipsas N, Pneumaticos S, Vlamis J. Molecular Mechanisms of Biofilm Formation on Orthopaedic Implants: Review of the Literature. MAEDICA 2024; 19:129-136. [PMID: 38736937 PMCID: PMC11079743 DOI: 10.26574/maedica.2021.19.1.129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
Orthopaedic implant-associated infections (OIAIs) is one of the most catastrophic complications following joint arthroplasty or fracture fixation. Given the increasing number of orthopaedic implants which are used annually, periprosthetic infections emerge as a global problem. Their diagnosis and consequent therapeutic management remain challenging for clinicians. Biofilm formation is a complex and only partially understood process that has not been extensively studied. Understanding the underlying mechanisms involved in biofilm formation is crucial in the amelioration of both diagnosis and therapeutic management of OIAIs. We performed a literature review of the molecular mechanisms of biofilm formation and discussed the four most common and thoroughly researched microbes of biofilm-related OIAIs.
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Affiliation(s)
- Matthaios Bakalakos
- 3rd Orthopaedic Department, National and Kapodistrian University of Athens, KAT General Hospital, Athens, Greece
| | | | - Christos Vlachos
- 3rd Orthopaedic Department, National and Kapodistrian University of Athens, KAT General Hospital, Athens, Greece
| | - Nikolaos Sipsas
- Infectious Diseases, National and Kapodistrian University of Athens, Athens, Greece
| | - Spiros Pneumaticos
- 3rd Orthopaedic Department, National and Kapodistrian University of Athens, KAT General Hospital, Athens, Greece
| | - John Vlamis
- 3rd Orthopaedic Department, National and Kapodistrian University of Athens, KAT General Hospital, Athens, Greece
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McClure R, Garcia M, Couvillion S, Farris Y, Hofmockel KS. Removal of primary nutrient degraders reduces growth of soil microbial communities with genomic redundancy. Front Microbiol 2023; 13:1046661. [PMID: 36762098 PMCID: PMC9902710 DOI: 10.3389/fmicb.2022.1046661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 12/21/2022] [Indexed: 01/25/2023] Open
Abstract
Introduction Understanding how microorganisms within a soil community interact to support collective respiration and growth remains challenging. Here, we used a model substrate, chitin, and a synthetic Model Soil Consortium (MSC-2) to investigate how individual members of a microbial community contribute to decomposition and community growth. While MSC-2 can grow using chitin as the sole carbon source, we do not yet know how the growth kinetics or final biomass yields of MSC-2 vary when certain chitin degraders, or other important members, are absent. Methods To characterize specific roles within this synthetic community, we carried out experiments leaving out members of MSC-2 and measuring biomass yields and CO2 production. We chose two members to iteratively leave out (referred to by genus name): Streptomyces, as it is predicted via gene expression analysis to be a major chitin degrader in the community, and Rhodococcus as it is predicted via species co-abundance analysis to interact with several other members. Results Our results showed that when MSC-2 lacked Streptomyces, growth and respiration of the community was severely reduced. Removal of either Streptomyces or Rhodococcus led to major changes in abundance for several other species, pointing to a comprehensive shifting of the microbial community when important members are removed, as well as alterations in the metabolic profile, especially when Streptomyces was lacking. These results show that when keystone, chitin degrading members are removed, other members, even those with the potential to degrade chitin, do not fill the same metabolic niche to promote community growth. In addition, highly connected members may be removed with similar or even increased levels of growth and respiration. Discussion Our findings are critical to a better understanding of soil microbiology, specifically in how communities maintain activity when biotic or abiotic factors lead to changes in biodiversity in soil systems.
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Affiliation(s)
- Ryan McClure
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Marci Garcia
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Sneha Couvillion
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Yuliya Farris
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Kirsten S. Hofmockel
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
- Department of Agronomy, Iowa State University, Ames, IA, United States
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Wang X, Blumenfeld R, Feng XQ, Weitz DA. 'Phase transitions' in bacteria - From structural transitions in free living bacteria to phenotypic transitions in bacteria within biofilms. Phys Life Rev 2022; 43:98-138. [PMID: 36252408 DOI: 10.1016/j.plrev.2022.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 09/30/2022] [Indexed: 12/05/2022]
Abstract
Phase transitions are common in inanimate systems and have been studied extensively in natural sciences. Less explored are the rich transitions that take place at the micro- and nano-scales in biological systems. In conventional phase transitions, large-scale properties of the media change discontinuously in response to continuous changes in external conditions. Such changes play a significant role in the dynamic behaviours of organisms. In this review, we focus on some transitions in both free-living and biofilms of bacteria. Particular attention is paid to the transitions in the flagellar motors and filaments of free-living bacteria, in cellular gene expression during the biofilm growth, in the biofilm morphology transitions during biofilm expansion, and in the cell motion pattern transitions during the biofilm formation. We analyse the dynamic characteristics and biophysical mechanisms of these phase transition phenomena and point out the parallels between these transitions and conventional phase transitions. We also discuss the applications of some theoretical and numerical methods, established for conventional phase transitions in inanimate systems, in bacterial biofilms.
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Affiliation(s)
- Xiaoling Wang
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China; John A. Paulson School of Engineering and Applied Sciences, Harvard University, 9 Oxford St, Cambridge, MA, 02138, USA.
| | - Raphael Blumenfeld
- Gonville & Caius College, University of Cambridge, Trinity St., Cambridge CB2 1TA, UK
| | - Xi-Qiao Feng
- Institute of Biomechanics and Medical Engineering, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
| | - David A Weitz
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 9 Oxford St, Cambridge, MA, 02138, USA; Department of Physics, Harvard University, 9 Oxford St, Cambridge, MA, 02138, USA
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McClure R, Farris Y, Danczak R, Nelson W, Song HS, Kessell A, Lee JY, Couvillion S, Henry C, Jansson JK, Hofmockel KS. Interaction Networks Are Driven by Community-Responsive Phenotypes in a Chitin-Degrading Consortium of Soil Microbes. mSystems 2022; 7:e0037222. [PMID: 36154140 PMCID: PMC9599572 DOI: 10.1128/msystems.00372-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/24/2022] [Indexed: 12/24/2022] Open
Abstract
Soil microorganisms provide key ecological functions that often rely on metabolic interactions between individual populations of the soil microbiome. To better understand these interactions and community processes, we used chitin, a major carbon and nitrogen source in soil, as a test substrate to investigate microbial interactions during its decomposition. Chitin was applied to a model soil consortium that we developed, "model soil consortium-2" (MSC-2), consisting of eight members of diverse phyla and including both chitin degraders and nondegraders. A multiomics approach revealed how MSC-2 community-level processes during chitin decomposition differ from monocultures of the constituent species. Emergent properties of both species and the community were found, including changes in the chitin degradation potential of Streptomyces species and organization of all species into distinct roles in the chitin degradation process. The members of MSC-2 were further evaluated via metatranscriptomics and community metabolomics. Intriguingly, the most abundant members of MSC-2 were not those that were able to metabolize chitin itself, but rather those that were able to take full advantage of interspecies interactions to grow on chitin decomposition products. Using a model soil consortium greatly increased our knowledge of how carbon is decomposed and metabolized in a community setting, showing that niche size, rather than species metabolic capacity, can drive success and that certain species become active carbon degraders only in the context of their surrounding community. These conclusions fill important knowledge gaps that are key to our understanding of community interactions that support carbon and nitrogen cycling in soil. IMPORTANCE The soil microbiome performs many functions that are key to ecology, agriculture, and nutrient cycling. However, because of the complexity of this ecosystem we do not know the molecular details of the interactions between microbial species that lead to these important functions. Here, we use a representative but simplified model community of bacteria to understand the details of these interactions. We show that certain species act as primary degraders of carbon sources and that the most successful species are likely those that can take the most advantage of breakdown products, not necessarily the primary degraders. We also show that a species phenotype, including whether it is a primary degrader or not, is driven in large part by the membership of the community it resides in. These conclusions are critical to a better understanding of the soil microbial interaction network and how these interactions drive central soil microbiome functions.
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Affiliation(s)
- Ryan McClure
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Yuliya Farris
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Robert Danczak
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - William Nelson
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Hyun-Seob Song
- Department of Biological Systems Engineering, University of Nebraska—Lincoln, Lincoln, Nebraska, USA
- Department of Food Science and Technology, Nebraska Food for Health Center, University of Nebraska—Lincoln, Lincoln, Nebraska, USA
| | - Aimee Kessell
- Department of Biological Systems Engineering, University of Nebraska—Lincoln, Lincoln, Nebraska, USA
| | - Joon-Yong Lee
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Sneha Couvillion
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Christopher Henry
- Data Science and Learning Division, Argonne National Laboratory, Lemont, Illinois, USA
| | - Janet K. Jansson
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Kirsten S. Hofmockel
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
- Department of Agronomy, Iowa State University, Ames, Iowa, USA
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6
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Yurgel SN, Nadeem M, Cheema M. Microbial Consortium Associated with Crustacean Shells Composting. Microorganisms 2022; 10:1033. [PMID: 35630475 PMCID: PMC9145653 DOI: 10.3390/microorganisms10051033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/10/2022] [Accepted: 05/12/2022] [Indexed: 02/04/2023] Open
Abstract
Soil microbes play an essential role in the biodegradation of crustacean shells, which is the process of sustainable bioconversion to chitin derivatives ultimately resulting in the promotion of plant growth properties. While a number of microorganisms with chitinolytic properties have been characterized, little is known about the microbial taxa that participate in this process either by active chitin degradation or by facilitation of this activity through nutritional cooperation and composting with the chitinolytic microorganisms. In this study, we evaluated the transformation of the soil microbiome triggered by close approximation to the green crab shell surface. Our data indicate that the microbial community associated with green crab shell matter undergoes significant specialized changes, which was reflected in a decreased fungal and bacterial Shannon diversity and evenness and in a dramatic alteration in the community composition. The relative abundance of several bacterial and fungal genera including bacteria Flavobacterium, Clostridium, Pseudomonas, and Sanguibacter and fungi Mortierella, Mycochlamys, and Talaromyces were increased with approximation to the shell surface. Association with the shell triggered significant changes in microbial cooperation that incorporate microorganisms that were previously reported to be involved in chitin degradation as well as ones with no reported chitinolytic activity. Our study indicates that the biodegradation of crab shells in soil incorporates a consortium of microorganisms that might provide a more efficient way for bioconversion.
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Affiliation(s)
- Svetlana N. Yurgel
- USDA-ARS, Grain Legume Genetics and Physiology Research Unit, Prosser, WA 99350, USA
| | - Muhammad Nadeem
- School of Science and the Environment, Grenfell Campus, Memorial University of Newfoundland and Labrador, Corner Brook, NL A2H 5G4, Canada; (M.N.); (M.C.)
| | - Mumtaz Cheema
- School of Science and the Environment, Grenfell Campus, Memorial University of Newfoundland and Labrador, Corner Brook, NL A2H 5G4, Canada; (M.N.); (M.C.)
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Peplinski J, Malone MA, Fowler KJ, Potratz EJ, Pergams AG, Charmoy KL, Rasheed K, Avdieiev SS, Whelan CJ, Brown JS. Ecology of Fear: Spines, Armor and Noxious Chemicals Deter Predators in Cancer and in Nature. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.682504] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In nature, many multicellular and unicellular organisms use constitutive defenses such as armor, spines, and noxious chemicals to keep predators at bay. These defenses render the prey difficult and/or dangerous to subdue and handle, which confers a strong deterrent for predators. The distinct benefit of this mode of defense is that prey can defend in place and continue activities such as foraging even under imminent threat of predation. The same qualitative types of armor-like, spine-like, and noxious defenses have evolved independently and repeatedly in nature, and we present evidence that cancer is no exception. Cancer cells exist in environments inundated with predator-like immune cells, so the ability of cancer cells to defend in place while foraging and proliferating would clearly be advantageous. We argue that these defenses repeatedly evolve in cancers and may be among the most advanced and important adaptations of cancers. By drawing parallels between several taxa exhibiting armor-like, spine-like, and noxious defenses, we present an overview of different ways these defenses can appear and emphasize how phenotypes that appear vastly different can nevertheless have the same essential functions. This cross-taxa comparison reveals how cancer phenotypes can be interpreted as anti-predator defenses, which can facilitate therapy approaches which aim to give the predators (the immune system) the upper hand. This cross-taxa comparison is also informative for evolutionary ecology. Cancer provides an opportunity to observe how prey evolve in the context of a unique predatory threat (the immune system) and varied environments.
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Nutrient complexity triggers transitions between solitary and colonial growth in bacterial populations. ISME JOURNAL 2021; 15:2614-2626. [PMID: 33731836 PMCID: PMC8397785 DOI: 10.1038/s41396-021-00953-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/18/2021] [Accepted: 02/25/2021] [Indexed: 12/31/2022]
Abstract
Microbial populations often experience fluctuations in nutrient complexity in their natural environment such as between high molecular weight polysaccharides and simple monosaccharides. However, it is unclear if cells can adopt growth behaviors that allow individuals to optimally respond to differences in nutrient complexity. Here, we directly control nutrient complexity and use quantitative single-cell analysis to study the growth dynamics of individuals within populations of the aquatic bacterium Caulobacter crescentus. We show that cells form clonal microcolonies when growing on the polysaccharide xylan, which is abundant in nature and degraded using extracellular cell-linked enzymes; and disperse to solitary growth modes when the corresponding monosaccharide xylose becomes available or nutrients are exhausted. We find that the cellular density required to achieve maximal growth rates is four-fold higher on xylan than on xylose, indicating that aggregating is advantageous on polysaccharides. When collectives on xylan are transitioned to xylose, cells start dispersing, indicating that colony formation is no longer beneficial and solitary behaviors might serve to reduce intercellular competition. Our study demonstrates that cells can dynamically tune their behaviors when nutrient complexity fluctuates, elucidates the quantitative advantages of distinct growth behaviors for individual cells and indicates why collective growth modes are prevalent in microbial populations.
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9
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Ranjith K, Sharma S, Shivaji S. Microbes of the human eye: Microbiome, antimicrobial resistance and biofilm formation. Exp Eye Res 2021; 205:108476. [PMID: 33549582 DOI: 10.1016/j.exer.2021.108476] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/19/2021] [Accepted: 01/22/2021] [Indexed: 01/21/2023]
Abstract
BACKGROUND The review focuses on the bacteria associated with the human eye using the dual approach of detecting cultivable bacteria and the total microbiome using next generation sequencing. The purpose of this review was to highlight the connection between antimicrobial resistance and biofilm formation in ocular bacteria. METHODS Pubmed was used as the source to catalogue culturable bacteria and ocular microbiomes associated with the normal eyes and those with ocular diseases, to ascertain the emergence of anti-microbial resistance with special reference to biofilm formation. RESULTS This review highlights the genetic strategies used by microorganisms to evade the lethal effects of anti-microbial agents by tracing the connections between candidate genes and biofilm formation. CONCLUSION The eye has its own microbiome which needs to be extensively studied under different physiological conditions; data on eye microbiomes of people from different ethnicities, geographical regions etc. are also needed to understand how these microbiomes affect ocular health.
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Affiliation(s)
- Konduri Ranjith
- Jhaveri Microbiology Centre, Brien Holden Eye Research Centre, L. V. Prasad Eye Institute, Kallam Anji Reddy Campus, Hyderabad, Telangana, India.
| | - Savitri Sharma
- Jhaveri Microbiology Centre, Brien Holden Eye Research Centre, L. V. Prasad Eye Institute, Kallam Anji Reddy Campus, Hyderabad, Telangana, India.
| | - Sisinthy Shivaji
- Jhaveri Microbiology Centre, Brien Holden Eye Research Centre, L. V. Prasad Eye Institute, Kallam Anji Reddy Campus, Hyderabad, Telangana, India.
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10
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McClure R, Naylor D, Farris Y, Davison M, Fansler SJ, Hofmockel KS, Jansson JK. Development and Analysis of a Stable, Reduced Complexity Model Soil Microbiome. Front Microbiol 2020; 11:1987. [PMID: 32983014 PMCID: PMC7479069 DOI: 10.3389/fmicb.2020.01987] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/27/2020] [Indexed: 12/12/2022] Open
Abstract
The soil microbiome is central to the cycling of carbon and other nutrients and to the promotion of plant growth. Despite its importance, analysis of the soil microbiome is difficult due to its sheer complexity, with thousands of interacting species. Here, we reduced this complexity by developing model soil microbial consortia that are simpler and more amenable to experimental analysis but still represent important microbial functions of the native soil ecosystem. Samples were collected from an arid grassland soil and microbial communities (consisting mainly of bacterial species) were enriched on agar plates containing chitin as the main carbon source. Chitin was chosen because it is an abundant carbon and nitrogen polymer in soil that often requires the coordinated action of several microorganisms for complete metabolic degradation. Several soil consortia were derived that had tractable richness (30–50 OTUs) with diverse phyla representative of the native soil, including Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, and Verrucomicrobia. The resulting consortia could be stored as glycerol or lyophilized stocks at −80°C and revived while retaining community composition, greatly increasing their use as tools for the research community at large. One of the consortia that was particularly stable was chosen as a model soil consortium (MSC-1) for further analysis. MSC-1 species interactions were studied using both pairwise co-cultivation in liquid media and during growth in soil under several perturbations. Co-abundance analyses highlighted interspecies interactions and helped to define keystone species, including Mycobacterium, Rhodococcus, and Rhizobiales taxa. These experiments demonstrate the success of an approach based on naturally enriching a community of interacting species that can be stored, revived, and shared. The knowledge gained from querying these communities and their interactions will enable better understanding of the soil microbiome and the roles these interactions play in this environment.
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Affiliation(s)
- Ryan McClure
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Dan Naylor
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Yuliya Farris
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Michelle Davison
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Sarah J Fansler
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Kirsten S Hofmockel
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States.,Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA, United States
| | - Janet K Jansson
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
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The Physiological and Pathological Implications of the Formation of Hydrogels, with a Specific Focus on Amyloid Polypeptides. Biomolecules 2017; 7:biom7040070. [PMID: 28937634 PMCID: PMC5745453 DOI: 10.3390/biom7040070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 08/30/2017] [Accepted: 09/18/2017] [Indexed: 02/07/2023] Open
Abstract
Hydrogels are water-swollen and viscoelastic three-dimensional cross-linked polymeric network originating from monomer polymerisation. Hydrogel-forming polypeptides are widely found in nature and, at a cellular and organismal level, they provide a wide range of functions for the organism making them. Amyloid structures, arising from polypeptide aggregation, can be damaging or beneficial to different types of organisms. Although the best-known amyloids are those associated with human pathologies, this underlying structure is commonly used by higher eukaryotes to maintain normal cellular activities, and also by microbial communities to promote their survival and growth. Amyloidogenesis occurs by nucleation-dependent polymerisation, which includes several species (monomers, nuclei, oligomers, and fibrils). Oligomers of pathological amyloids are considered the toxic species through cellular membrane perturbation, with the fibrils thought to represent a protective sink for toxic species. However, both functional and disease-associated amyloids use fibril cross-linking to form hydrogels. The properties of amyloid hydrogels can be exploited by organisms to fulfil specific physiological functions. Non-physiological hydrogelation by pathological amyloids may provide additional toxic mechanism(s), outside of membrane toxicity by oligomers, such as physical changes to the intracellular and extracellular environments, with wide-spread consequences for many structural and dynamic processes, and overall effects on cell survival.
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12
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Guilhen C, Forestier C, Balestrino D. Biofilm dispersal: multiple elaborate strategies for dissemination of bacteria with unique properties. Mol Microbiol 2017; 105:188-210. [PMID: 28422332 DOI: 10.1111/mmi.13698] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2017] [Indexed: 01/22/2023]
Abstract
In most environments, microorganisms evolve in a sessile mode of growth, designated as biofilm, which is characterized by cells embedded in a self-produced extracellular matrix. Although a biofilm is commonly described as a "cozy house" where resident bacteria are protected from aggression, bacteria are able to break their biofilm bonds and escape to colonize new environments. This regulated process is observed in a wide variety of species; it is referred to as biofilm dispersal, and is triggered in response to various environmental and biological signals. The first part of this review reports the main regulatory mechanisms and effectors involved in biofilm dispersal. There is some evidence that dispersal is a necessary step between the persistence of bacteria inside biofilm and their dissemination. In the second part, an overview of the main methods used so far to study the dispersal process and to harvest dispersed bacteria was provided. Then focus was on the properties of the biofilm-dispersed bacteria and the fundamental role of the dispersal process in pathogen dissemination within a host organism. In light of the current body of knowledge, it was suggested that dispersal acts as a potent means of disseminating bacteria with enhanced colonization properties in the surrounding environment.
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Affiliation(s)
- Cyril Guilhen
- Laboratoire Microorganismes : Génome et Environnement, UMR CNRS 6023, Université Clermont Auvergne, Clermont Ferrand, F-63001, France
| | - Christiane Forestier
- Laboratoire Microorganismes : Génome et Environnement, UMR CNRS 6023, Université Clermont Auvergne, Clermont Ferrand, F-63001, France
| | - Damien Balestrino
- Laboratoire Microorganismes : Génome et Environnement, UMR CNRS 6023, Université Clermont Auvergne, Clermont Ferrand, F-63001, France
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13
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Qi Z, Chen L, Zhang W. Comparison of Transcriptional Heterogeneity of Eight Genes between Batch Desulfovibrio vulgaris Biofilm and Planktonic Culture at a Single-Cell Level. Front Microbiol 2016; 7:597. [PMID: 27199927 PMCID: PMC4847118 DOI: 10.3389/fmicb.2016.00597] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 04/11/2016] [Indexed: 11/13/2022] Open
Abstract
Sulfate-reducing bacteria (SRB) biofilm formed on metal surfaces can change the physicochemical properties of metals and cause metal corrosion. To enhance understanding of differential gene expression in Desulfovibrio vulgaris under planktonic and biofilm growth modes, a single-cell based RT-qPCR approach was applied to determine gene expression levels of 8 selected target genes in four sets of the 31 individual cells isolated from each growth condition (i.e., biofilm formed on a mild steel (SS) and planktonic cultures, exponential and stationary phases). The results showed obvious gene-expression heterogeneity for the target genes among D. vulgaris single cells of both biofilm and planktonic cultures. In addition, an increased gene-expression heterogeneity in the D. vulgaris biofilm when compared with the planktonic culture was also observed for seven out of eight selected genes at exponential phase, and six out of eight selected genes at stationary phase, respectively, which may be contributing to the increased complexity in terms of structures and morphology in the biofilm. Moreover, the results showed up-regulation of DVU0281 gene encoding exopolysaccharide biosynthesis protein, and down-regulation of genes involved in energy metabolism (i.e., DVU0434 and DVU0588), stress responses (i.e., DVU2410) and response regulator (i.e., DVU3062) in the D. vulgaris biofilm cells. Finally, the gene (DVU2571) involved in iron transportation was found down-regulated, and two genes (DVU1340 and DVU1397) involved in ferric uptake repressor and iron storage were up-regulated in D. vulgaris biofilm, suggesting their possible roles in maintaining normal metabolism of the D. vulgaris biofilm under environments of high concentration of iron. This study showed that the single-cell based analysis could be a useful approach in deciphering metabolism of microbial biofilms.
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Affiliation(s)
- Zhenhua Qi
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin UniversityTianjin, China; Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin UniversityTianjin, China; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and EngineeringTianjin, China
| | - Lei Chen
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin UniversityTianjin, China; Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin UniversityTianjin, China; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and EngineeringTianjin, China
| | - Weiwen Zhang
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin UniversityTianjin, China; Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin UniversityTianjin, China; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and EngineeringTianjin, China
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14
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Abstract
Bacteria have traditionally been studied as single-cell organisms. In laboratory settings, aerobic bacteria are usually cultured in aerated flasks, where the cells are considered essentially homogenous. However, in many natural environments, bacteria and other microorganisms grow in mixed communities, often associated with surfaces. Biofilms are comprised of surface-associated microorganisms, their extracellular matrix material, and environmental chemicals that have adsorbed to the bacteria or their matrix material. While this definition of a biofilm is fairly simple, biofilms are complex and dynamic. Our understanding of the activities of individual biofilm cells and whole biofilm systems has developed rapidly, due in part to advances in molecular, analytical, and imaging tools and the miniaturization of tools designed to characterize biofilms at the enzyme level, cellular level, and systems level.
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15
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Li XY, Pietschke C, Fraune S, Altrock PM, Bosch TCG, Traulsen A. Which games are growing bacterial populations playing? J R Soc Interface 2016; 12:20150121. [PMID: 26236827 PMCID: PMC4528578 DOI: 10.1098/rsif.2015.0121] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Microbial communities display complex population dynamics, both in frequency and absolute density. Evolutionary game theory provides a natural approach to analyse and model this complexity by studying the detailed interactions among players, including competition and conflict, cooperation and coexistence. Classic evolutionary game theory models typically assume constant population size, which often does not hold for microbial populations. Here, we explicitly take into account population growth with frequency-dependent growth parameters, as observed in our experimental system. We study the in vitro population dynamics of the two commensal bacteria (Curvibacter sp. (AEP1.3) and Duganella sp. (C1.2)) that synergistically protect the metazoan host Hydra vulgaris (AEP) from fungal infection. The frequency-dependent, nonlinear growth rates observed in our experiments indicate that the interactions among bacteria in co-culture are beyond the simple case of direct competition or, equivalently, pairwise games. This is in agreement with the synergistic effect of anti-fungal activity observed in vivo. Our analysis provides new insight into the minimal degree of complexity needed to appropriately understand and predict coexistence or extinction events in this kind of microbial community dynamics. Our approach extends the understanding of microbial communities and points to novel experiments.
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Affiliation(s)
- Xiang-Yi Li
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, August-Thienemannstraße 2, 24306 Plön, Germany
| | - Cleo Pietschke
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, August-Thienemannstraße 2, 24306 Plön, Germany
- Zoological Institute, Christian-Albrechts-University Kiel, Olshausenstraße 40, 24098 Kiel, Germany
| | - Sebastian Fraune
- Zoological Institute, Christian-Albrechts-University Kiel, Olshausenstraße 40, 24098 Kiel, Germany
| | - Philipp M. Altrock
- Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02138, USA
| | - Thomas C. G. Bosch
- Zoological Institute, Christian-Albrechts-University Kiel, Olshausenstraße 40, 24098 Kiel, Germany
| | - Arne Traulsen
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, August-Thienemannstraße 2, 24306 Plön, Germany
- e-mail:
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16
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Abstract
The dense aggregation of cells on a surface, as seen in biofilms, inevitably results in both environmental and cellular heterogeneity. For example, nutrient gradients can trigger cells to differentiate into various phenotypic states. Not only do cells adapt physiologically to the local environmental conditions, but they also differentiate into cell types that interact with each other. This allows for task differentiation and, hence, the division of labor. In this article, we focus on cell differentiation and the division of labor in three bacterial species: Myxococcus xanthus, Bacillus subtilis, and Pseudomonas aeruginosa. During biofilm formation each of these species differentiates into distinct cell types, in some cases leading to cooperative interactions. The division of labor and the cooperative interactions between cell types are assumed to yield an emergent ecological benefit. Yet in most cases the ecological benefits have yet to be elucidated. A notable exception is M. xanthus, in which cell differentiation within fruiting bodies facilitates the dispersal of spores. We argue that the ecological benefits of the division of labor might best be understood when we consider the dynamic nature of both biofilm formation and degradation.
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17
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Mayali X, Stewart B, Mabery S, Weber PK. Temporal succession in carbon incorporation from macromolecules by particle-attached bacteria in marine microcosms. ENVIRONMENTAL MICROBIOLOGY REPORTS 2016; 8:68-75. [PMID: 26525158 DOI: 10.1111/1758-2229.12352] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 09/25/2015] [Accepted: 10/27/2015] [Indexed: 05/26/2023]
Abstract
We investigated bacterial carbon assimilation from stable isotope-labelled macromolecular substrates (proteins; lipids; and two types of polysaccharides, starch and cellobiose) while attached to killed diatom detrital particles during laboratory microcosms incubated for 17 days. Using Chip-SIP (secondary ion mass spectrometry analysis of RNA microarrays), we identified generalist operational taxonomic units (OTUs) from the Gammaproteobacteria, belonging to the genera Colwellia, Glaciecola, Pseudoalteromonas and Rheinheimera, and from the Bacteroidetes, genera Owenweeksia and Maribacter, that incorporated the four tested substrates throughout the incubation period. Many of these OTUs exhibited the highest isotope incorporation relative to the others, indicating that they were likely the most active. Additional OTUs from the Gammaproteobacteria, Bacteroidetes and Alphaproteobacteria exhibited generally (but not always) lower activity and did not incorporate all tested substrates at all times, showing species succession in organic carbon incorporation. We also found evidence to suggest that both generalist and specialist OTUs changed their relative substrate incorporation over time, presumably in response to changing substrate availability as the particles aged. This pattern was demonstrated by temporal succession from relatively higher starch incorporation early in the incubations, eventually switching to higher cellobiose incorporation after 2 weeks.
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Affiliation(s)
- Xavier Mayali
- Physical and Life Science Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94550, USA
| | - Benjamin Stewart
- Physical and Life Science Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94550, USA
| | - Shalini Mabery
- Physical and Life Science Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94550, USA
| | - Peter K Weber
- Physical and Life Science Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94550, USA
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18
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Emerenini BO, Hense BA, Kuttler C, Eberl HJ. A Mathematical Model of Quorum Sensing Induced Biofilm Detachment. PLoS One 2015; 10:e0132385. [PMID: 26197231 PMCID: PMC4511412 DOI: 10.1371/journal.pone.0132385] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 06/12/2015] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Cell dispersal (or detachment) is part of the developmental cycle of microbial biofilms. It can be externally or internally induced, and manifests itself in discrete sloughing events, whereby many cells disperse in an instance, or in continuous slower dispersal of single cells. One suggested trigger of cell dispersal is quorum sensing, a cell-cell communication mechanism used to coordinate gene expression and behavior in groups based on population densities. METHOD To better understand the interplay of colony growth and cell dispersal, we develop a dynamic, spatially extended mathematical model that includes biofilm growth, production of quorum sensing molecules, cell dispersal triggered by quorum sensing molecules, and re-attachment of cells. This is a highly nonlinear system of diffusion-reaction equations that we study in computer simulations. RESULTS Our results show that quorum sensing induced cell dispersal can be an efficient mechanism for bacteria to control the size of a biofilm colony, and at the same time enhance its downstream colonization potential. In fact we find that over the lifetime of a biofilm colony the majority of cells produced are lost into the aqueous phase, supporting the notion of biofilms as cell nurseries. We find that a single quorum sensing based mechanism can explain both, discrete dispersal events and continuous shedding of cells from a colony. Moreover, quorum sensing induced cell dispersal affects the structure and architecture of the biofilm, for example it might lead to the formation of hollow inner regions in a biofilm colony.
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Affiliation(s)
| | - Burkhard A. Hense
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Christina Kuttler
- Zentrum Mathematik, Technische Universität München, Neuherberg, Germany
| | - Hermann J. Eberl
- Dept. Mathematics and Statistics, University of Guelph, Guelph, ON, Canada
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19
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Lewis AM, Matzdorf SS, Endres JL, Windham IH, Bayles KW, Rice KC. Examination of the Staphylococcus aureus nitric oxide reductase (saNOR) reveals its contribution to modulating intracellular NO levels and cellular respiration. Mol Microbiol 2015; 96:651-69. [PMID: 25651868 DOI: 10.1111/mmi.12962] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2015] [Indexed: 12/21/2022]
Abstract
Staphylococcus aureus nitrosative stress resistance is due in part to flavohemoprotein (Hmp). Although hmp is present in all sequenced S. aureus genomes, 37% of analyzed strains also contain nor, encoding a predicted quinol-type nitric oxide (NO) reductase (saNOR). DAF-FM staining of NO-challenged wild-type, nor, hmp and nor hmp mutant biofilms suggested that Hmp may have a greater contribution to intracellular NO detoxification relative to saNOR. However, saNOR still had a significant impact on intracellular NO levels and complemented NO detoxification in a nor hmp mutant. When grown as NO-challenged static (low-oxygen) cultures, hmp and nor hmp mutants both experienced a delay in growth initiation, whereas the nor mutant's ability to initiate growth was comparable with the wild-type strain. However, saNOR contributed to cell respiration in this assay once growth had resumed, as determined by membrane potential and respiratory activity assays. Expression of nor was upregulated during low-oxygen growth and dependent on SrrAB, a two-component system that regulates expression of respiration and nitrosative stress resistance genes. High-level nor promoter activity was also detectable in a cell subpopulation near the biofilm substratum. These results suggest that saNOR contributes to NO-dependent respiration during nitrosative stress, possibly conferring an advantage to nor+ strains in vivo.
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Affiliation(s)
- A M Lewis
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL, 32611-0700, USA
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20
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Mielich-Süss B, Lopez D. Molecular mechanisms involved in Bacillus subtilis biofilm formation. Environ Microbiol 2015; 17:555-65. [PMID: 24909922 PMCID: PMC4188541 DOI: 10.1111/1462-2920.12527] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 06/01/2014] [Indexed: 02/02/2023]
Abstract
Biofilms are the predominant lifestyle of bacteria in natural environments, and they severely impact our societies in many different fashions. Therefore, biofilm formation is a topic of growing interest in microbiology, and different bacterial models are currently studied to better understand the molecular strategies that bacteria undergo to build biofilms. Among those, biofilms of the soil-dwelling bacterium Bacillus subtilis are commonly used for this purpose. Bacillus subtilis biofilms show remarkable architectural features that are a consequence of sophisticated programmes of cellular specialization and cell-cell communication within the community. Many laboratories are trying to unravel the biological role of the morphological features of biofilms, as well as exploring the molecular basis underlying cellular differentiation. In this review, we present a general perspective of the current state of knowledge of biofilm formation in B. subtilis and thereby placing a special emphasis on summarizing the most recent discoveries in the field.
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Affiliation(s)
| | - Daniel Lopez
- Research Centre for Infectious Diseases (ZINF). University of Würzburg, Germany
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21
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Yan Z, Jingmei Y, Dingyu D, Yi X. [Progress in study of oral biofilm dispersal-inducing agents]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2014; 32:625-630. [PMID: 25665436 PMCID: PMC7030709 DOI: 10.7518/hxkq.2014.06.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 09/15/2014] [Indexed: 06/04/2023]
Abstract
Communities of bacteria wrapped in self-generated extracellular polymeric matrix and attached to a solid surface are known as biofilm. Biofilm formation and development can be divided into three stages: adhesion of cells to a surface, reproduction of the cells, and dispersion of cells. The procedure, which surface-attached biofilm disperses bacterial cells into the environment to colonize new sites, is defined as biofilm dispersal. Biofilm dispersal is an essential stage of biofilm life cycle. It plays an important role in the transmission of bacteria. For many pathogenic bacteria, biofilm dispersal can transform bacteria in biofilm into planktonic state and promote the spread of infection. The formation of biofilm may increase the resistance of bacteria to antimicrobial agent and host defence response compared with planktonic cells. In the oral cavity, oral microorganism can attach to the surface of oral tissue and prosthesis to form biofilm. Dental caries and periodontal disease are oral chronic infections diseases of the oral tissue. The occurrence of them has a close relationship with biofilm. The mechanism of dispersal is a hot topic in recent years. Some agents which promote dispersal might be a therapeutic potential against biofilm infections. The clinical implication of dispersal agents and potential application are promising. This article reviews the dispersal-inducing agents of oral biofilms.
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22
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Beier S, Bertilsson S. Bacterial chitin degradation-mechanisms and ecophysiological strategies. Front Microbiol 2013; 4:149. [PMID: 23785358 PMCID: PMC3682446 DOI: 10.3389/fmicb.2013.00149] [Citation(s) in RCA: 233] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 05/28/2013] [Indexed: 11/13/2022] Open
Abstract
Chitin is one the most abundant polymers in nature and interacts with both carbon and nitrogen cycles. Processes controlling chitin degradation are summarized in reviews published some 20 years ago, but the recent use of culture-independent molecular methods has led to a revised understanding of the ecology and biochemistry of this process and the organisms involved. This review summarizes different mechanisms and the principal steps involved in chitin degradation at a molecular level while also discussing the coupling of community composition to measured chitin hydrolysis activities and substrate uptake. Ecological consequences are then highlighted and discussed with a focus on the cross feeding associated with the different habitats that arise because of the need for extracellular hydrolysis of the chitin polymer prior to metabolic use. Principal environmental drivers of chitin degradation are identified which are likely to influence both community composition of chitin degrading bacteria and measured chitin hydrolysis activities.
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Affiliation(s)
- Sara Beier
- Department of Ecology and Genetics, Limnology, Uppsala University Uppsala, Sweden ; Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, UPMC Paris 06, UMR 7621 Banyuls sur mer, France ; Laboratoire d'Océanographie Microbienne, Observatoire Océanologique Centre National de la Recherche Scientifique, UMR 7621 Banyuls sur mer, France
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23
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Esiobu N, Green M, Echeverry A, Bonilla TD, Stinson CM, Hartz A, Rogerson A, McCorquodale DS. High numbers of Staphylococcus aureus at three bathing beaches in South Florida. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2012; 23:46-57. [PMID: 22924435 DOI: 10.1080/09603123.2012.699027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
While the value of Staphylococcus aureus as an indicator for non-enteric diseases is unclear, understanding its prevalence in recreational beaches would prove useful, given its pathogenic potential. Staphylococcus aureus levels were evaluated in sand and seawater at three beaches during one year. To elucidate possible S. aureus sources or colonization trends, distribution in sand was analyzed at Hollywood Beach. Staphylococcus aureus levels fluctuated throughout the study with highest average densities detected in dry sand (3.46 × 10⁵ CFU/g, Hobie Beach), particularly at beaches with high human density. Patchy distribution marked hotspots of human use and/or possible bacterial re-growth. Data from a brief epidemiological survey indicated a very slight association between beach usage and skin conditions; suggesting high S. aureus levels in sand may not necessarily constitute major health risks. Because the possibility of disease transmission exists, particularly to children and immuno-compromised beach-goers, periodic surveying of highly frequented beaches seems warranted.
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Affiliation(s)
- Nwadiuto Esiobu
- Biological Sciences, Florida Atlantic University, 3200 College Ave, Davie, FL 33314, USA.
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24
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Mitchell AC, Peterson L, Reardon CL, Reed SB, Culley DE, Romine MR, Geesey GG. Role of outer membrane c-type cytochromes MtrC and OmcA in Shewanella oneidensis MR-1 cell production, accumulation, and detachment during respiration on hematite. GEOBIOLOGY 2012; 10:355-370. [PMID: 22360295 DOI: 10.1111/j.1472-4669.2012.00321.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The iron-reducing bacterium Shewanella oneidensis MR-1 has the capacity to contribute to iron cycling over the long term by respiring on crystalline iron oxides such as hematite when poorly crystalline phases are depleted. The ability of outer membrane cytochromes OmcA and MtrC of MR-1 to bind to and transfer electrons to hematite has led to the suggestion that they function as terminal reductases when this mineral is used as a respiratory substrate. Differences in their redox behavior and hematite-binding properties, however, indicate that they play different roles in the electron transfer reaction. Here, we investigated how these differences in cytochrome behavior with respect to hematite affected biofilm development when the mineral served as terminal electron acceptor (TEA). Upon attachment to hematite, cells of the wild-type (WT) strain as well as those of a ΔomcA mutant but not those of a ΔmtrC mutant replicated and accumulated on the mineral surface. The results indicate that MtrC but not OmcA is required for growth when this mineral serves as TEA. While an OmcA deficiency did not impede cell replication and accumulation on hematite prior to achievement of a maximum surface cell density comparable to that established by WT cells, OmcA was required for efficient electron transfer and cell attachment to hematite once maximum surface cell density was achieved. OmcA may therefore play a role in overcoming barriers to electron transfer and cell attachment to hematite imposed by reductive dissolution of the mineral surface from cell respiration associated with achievement of high surface cell densities.
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Affiliation(s)
- A C Mitchell
- Department of Microbiology and Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
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25
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Mohammed RL, Echeverry A, Stinson CM, Green M, Bonilla TD, Hartz A, McCorquodale DS, Rogerson A, Esiobu N. Survival trends of Staphylococcus aureus, Pseudomonas aeruginosa, and Clostridium perfringens in a sandy South Florida beach. MARINE POLLUTION BULLETIN 2012; 64:1201-1209. [PMID: 22516512 DOI: 10.1016/j.marpolbul.2012.03.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Revised: 02/20/2012] [Accepted: 03/08/2012] [Indexed: 05/31/2023]
Abstract
The search for alternative indicators of disease-risk from non-enteric pathogens at the beach revealed high densities of targeted bacteria. To explain the high numbers of potential non-enteric pathogens, Staphylococcus aureus and Pseudomonas aeruginosa, in beach sand, we investigated factors affecting their survival and distribution, as well as those of a potential fecal indicator, Clostridium perfringens. Results indicated greater S. aureus and P. aeruginosa survival and proliferation in sterile beach sand, than seawater, with diminished numbers upon exposure to natural micro-predators. C. perfringens remained relatively consistent with initial numbers. Intermediate sand particles (850 μm-2 mm) constituted the major micro-niche; creating implications for beach classification programs. Colonization of sterile sand boxes at the beach by S. aureus and P. aeruginosa confirmed the filtering action (>100×) of beach sand. The use of these potential pathogens in periodic sanitary evaluation of beach sand quality is indicated, regardless of the factors influencing their abundance.
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Affiliation(s)
- R L Mohammed
- Department of Biological Sciences, Charles E. Schmidt College of Science, Florida Atlantic University, 3200 College Ave., Davie, FL 33314, USA
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26
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Should we stay or should we go: mechanisms and ecological consequences for biofilm dispersal. Nat Rev Microbiol 2011; 10:39-50. [PMID: 22120588 DOI: 10.1038/nrmicro2695] [Citation(s) in RCA: 521] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In most environments, bacteria reside primarily in biofilms, which are social consortia of cells that are embedded in an extracellular matrix and undergo developmental programmes resulting in a predictable biofilm 'life cycle'. Recent research on many different bacterial species has now shown that the final stage in this life cycle includes the production and release of differentiated dispersal cells. The formation of these cells and their eventual dispersal is initiated through diverse and remarkably sophisticated mechanisms, suggesting that there are strong evolutionary pressures for dispersal from an otherwise largely sessile biofilm. The evolutionary aspect of biofilm dispersal is now being explored through the integration of molecular microbiology with eukaryotic ecological and evolutionary theory, which provides a broad conceptual framework for the diversity of specific mechanisms underlying biofilm dispersal. Here, we review recent progress in this emerging field and suggest that the merging of detailed molecular mechanisms with ecological theory will significantly advance our understanding of biofilm biology and ecology.
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27
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Jagmann N, von Rekowski KS, Philipp B. Interactions of bacteria with different mechanisms for chitin degradation result in the formation of a mixed-species biofilm. FEMS Microbiol Lett 2011; 326:69-75. [PMID: 22092834 DOI: 10.1111/j.1574-6968.2011.02435.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 09/20/2011] [Accepted: 10/06/2011] [Indexed: 11/28/2022] Open
Abstract
In this study, interactions between bacteria possessing either released or cell-associated enzymes for polymer degradation were investigated. For this, a co-culture of Aeromonas hydrophila strain AH-1N as an enzyme-releasing bacterium and of Flavobacterium sp. strain 4D9 as a bacterium with cell-associated enzymes was set up with chitin embedded into agarose beads to account for natural conditions, under which polymers are usually embedded in organic aggregates. In single cultures, strain AH-1N grew with embedded chitin, while strain 4D9 did not. In co-cultures, strain 4D9 grew and outcompeted strain AH-1N in the biofilm fraction. Experiments with cell-free culture supernatants containing the chitinolytic enzymes of strain AH-1N revealed that growth of strain 4D9 in the co-culture was based on intercepting N-acetylglucosamine from chitin degradation. For this, strain 4D9 had to actively integrate into the biofilm of strain AH-1N. This study shows that bacteria using different chitin degradation mechanisms can coexist by formation of a mixed-species biofilm.
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Affiliation(s)
- Nina Jagmann
- Fachbereich Biologie, Mikrobielle Ökologie, Universität Konstanz, Konstanz, Germany
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28
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Biofilms in chronic rhinosinusitis: systematic review and suggestions for future research. The Journal of Laryngology & Otology 2011; 125:331-7. [PMID: 21310099 DOI: 10.1017/s0022215111000016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND A biofilm is a community of micro-organisms encased within a self-produced, extracellular, polymeric substance. The role of biofilms as a major pathological aetiology in chronic rhinosinusitis would help explain the clinical manifestation of the disease. OBJECTIVES To examine the current evidence, and to discuss possible future research directions, in relation to biofilms and chronic rhinosinusitis. STUDY DESIGN Systematic literature review. EVALUATION METHOD Two assessors independently undertook critical appraisal of the studies identified by the literature search. Significant findings were incorporated into this review. The primary outcome assessed was the presence of biofilm in human mucosal biopsy samples taken from patients with chronic rhinosinusitis, and from healthy controls. RESULTS We identified 11 studies examining biofilm formation in human mucosal biopsy samples taken from patients with chronic rhinosinusitis. CONCLUSION It is unlikely that biofilms occur in every case of chronic rhinosinusitis; consequently, the significance of 'biofilm detection' in some series should be considered carefully. Several authors have argued strongly for the use of confocal scanning laser microscopy with fluorescent in situ hybridisation probes as the 'gold standard' for biofilm imaging. This imaging modality should be combined with further investigation of the microbiology of chronic rhinosinusitis, and of the efficacy of traditional culture techniques used for pathogen identification.
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29
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Abstract
Extracellular enzymes initiate microbial remineralization of organic matter by hydrolyzing substrates to sizes sufficiently small to be transported across cell membranes. As much of marine primary productivity is processed by heterotrophic microbes, the substrate specificities of extracellular enzymes, the rates at which they function in seawater and sediments, and factors controlling their production, distribution, and active lifetimes, are central to carbon cycling in marine systems. In this review, these topics are considered from biochemical, microbial/molecular biological, and geochemical perspectives. Our understanding of the capabilities and limitations of heterotrophic microbial communities has been greatly advanced in recent years, in part through genetic and genomic approaches. New methods to measure enzyme activities in the field are needed to keep pace with these advances and to pursue intriguing evidence that patterns of enzyme activities in different environments are linked to differences in microbial community composition that may profoundly affect the marine carbon cycle.
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Affiliation(s)
- Carol Arnosti
- Department of Marine Sciences, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina 27599-3300, USA.
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30
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Kaplan JB. Biofilm dispersal: mechanisms, clinical implications, and potential therapeutic uses. J Dent Res 2010; 89:205-18. [PMID: 20139339 DOI: 10.1177/0022034509359403] [Citation(s) in RCA: 479] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Like all sessile organisms, surface-attached communities of bacteria known as biofilms must release and disperse cells into the environment to colonize new sites. For many pathogenic bacteria, biofilm dispersal plays an important role in the transmission of bacteria from environmental reservoirs to human hosts, in horizontal and vertical cross-host transmission, and in the exacerbation and spread of infection within a host. The molecular mechanisms of bacterial biofilm dispersal are only beginning to be elucidated. Biofilm dispersal is a promising area of research that may lead to the development of novel agents that inhibit biofilm formation or promote biofilm cell detachment. Such agents may be useful for the prevention and treatment of biofilms in a variety of industrial and clinical settings. This review describes the current status of research on biofilm dispersal, with an emphasis on studies aimed to characterize dispersal mechanisms, and to identify environmental cues and inter- and intracellular signals that regulate the dispersal process. The clinical implications of biofilm dispersal and the potential therapeutic applications of some of the most recent findings will also be discussed.
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Affiliation(s)
- J B Kaplan
- Department of Oral Biology, New Jersey Dental School, Newark, NJ 07103, USA.
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31
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Hartz A, Cuvelier M, Nowosielski K, Bonilla TD, Green M, Esiobu N, McCorquodale DS, Rogerson A. Survival potential of Escherichia coli and Enterococci in subtropical beach sand: implications for water quality managers. JOURNAL OF ENVIRONMENTAL QUALITY 2008; 37:898-905. [PMID: 18453412 DOI: 10.2134/jeq2007.0312] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Fecal bacteria have traditionally been used as indicator organisms to monitor the quality of recreational waters. Recent work has questioned the robustness of traditional indicators, particularly at seawater bathing beaches. For example, a study of Florida beaches found unexpectedly high abundances of Escherichia coli, fecal coliforms, and enterococci in beach sand. The aim of the present study was to explain these abundances by assessing the survival of E. coli and enterococci in beach sand relative to seawater. We used a combination of quantitative laboratory mesocosm experiments and field observations. Results suggested that E. coli and enterococci exhibited increased survivability and growth in sand relative to seawater. Because fecal bacteria are capable of replicating in sand, at least under controlled laboratory conditions, the results suggest that sand may be an important reservoir of metabolically active fecal organisms. Experiments with "natural" mesocosms (i.e., unsterilized sand or water rich in micropredators and native bacteria) failed to show the same increases in fecal indicators as was found in sterile sand. It is postulated that this was due to predation and competition with indigenous bacteria in these "natural" systems. Nonetheless, high populations of indicators were maintained and recovered from sand over the duration of the experiment as opposed to the die-off noted in water. Indicator bacteria may wash out of sand into shoreline waters during weather and tidal events, thereby decreasing the effectiveness of these indicators as predictors of health risk and complicating the interpretations for water quality managers.
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Affiliation(s)
- A Hartz
- Oceanographic Center of Nova Southeastern University, 8000 N. Ocean Drive, Dania Beach, FL 33004, USA
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32
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Abstract
Biofilms contain bacterial cells that are in a wide range of physiological states. Within a biofilm population, cells with diverse genotypes and phenotypes that express distinct metabolic pathways, stress responses and other specific biological activities are juxtaposed. The mechanisms that contribute to this genetic and physiological heterogeneity include microscale chemical gradients, adaptation to local environmental conditions, stochastic gene expression and the genotypic variation that occurs through mutation and selection. Here, we discuss the processes that generate chemical gradients in biofilms, the genetic and physiological responses of the bacteria as they adapt to these gradients and the techniques that can be used to visualize and measure the microscale physiological heterogeneities of bacteria in biofilms.
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33
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Ziervogel K, Arnosti C. Polysaccharide hydrolysis in aggregates and free enzyme activity in aggregate-free seawater from the north-eastern Gulf of Mexico. Environ Microbiol 2007; 10:289-99. [PMID: 18093165 DOI: 10.1111/j.1462-2920.2007.01451.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Marine snow aggregates represent hotspots of carbon remineralization in the ocean. Various aspects of bacterial dynamics have been investigated on marine snow. To date, extracellular enzymatic activities in aggregates have been measured using small substrate proxies that do not adequately reflect the complexity of biomacromolecules such as polysaccharides, proteins and lipids. To address this issue, we used six structurally distinct, fluorescently labelled polysaccharides to measure enzymatic hydrolysis on aggregates formed with a roller table and in aggregate-free (ambient) seawater from two near-coast sites, north-eastern Gulf of Mexico. A single polysaccharide was incubated in aggregates and ambient seawater. Changes in polysaccharide molecular weight were monitored over time to measure the course of enzymatic hydrolysis. All six polysaccharides were hydrolysed in aggregates, indicating a broad range of enzyme activities in aggregate-associated bacteria. Four substrates were also hydrolysed in ambient waters. Epifluorescence microscopy revealed that nearly all of the bacteria present in original waters were incorporated into aggregates. Therefore hydrolytic activities in ambient waters were presumably due to enzymes spatially disconnected from cells and aggregates. Our results show substantial enzymatic activity in cell/aggregate-free seawater, suggesting a significant role of free enzymes in hydrolytic activity in waters from the north-eastern Gulf of Mexico.
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Affiliation(s)
- Kai Ziervogel
- University of North Carolina-Chapel Hill, Department of Marine Sciences, Chapel Hill, NC 27599, USA.
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34
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Hall-Stoodley L, Costerton JW, Stoodley P. Bacterial biofilms: from the natural environment to infectious diseases. Nat Rev Microbiol 2004; 2:95-108. [PMID: 15040259 DOI: 10.1038/nrmicro821] [Citation(s) in RCA: 4208] [Impact Index Per Article: 210.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Biofilms--matrix-enclosed microbial accretions that adhere to biological or non-biological surfaces--represent a significant and incompletely understood mode of growth for bacteria. Biofilm formation appears early in the fossil record (approximately 3.25 billion years ago) and is common throughout a diverse range of organisms in both the Archaea and Bacteria lineages, including the 'living fossils' in the most deeply dividing branches of the phylogenetic tree. It is evident that biofilm formation is an ancient and integral component of the prokaryotic life cycle, and is a key factor for survival in diverse environments. Recent advances show that biofilms are structurally complex, dynamic systems with attributes of both primordial multicellular organisms and multifaceted ecosystems. Biofilm formation represents a protected mode of growth that allows cells to survive in hostile environments and also disperse to colonize new niches. The implications of these survival and propagative mechanisms in the context of both the natural environment and infectious diseases are discussed in this review.
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Affiliation(s)
- Luanne Hall-Stoodley
- Department of Veterinary Molecular Microbiology, Departments of Microbiology and Civil Engineering, Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
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35
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Dynamics of microbial communities on marine snow aggregates: colonization, growth, detachment, and grazing mortality of attached bacteria. Appl Environ Microbiol 2003. [PMID: 12788697 DOI: 10.1128/aem.69.6.3036‐3047.2003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We studied the dynamics of microbial communities attached to model aggregates (4-mm-diameter agar spheres) and the component processes of colonization, detachment, growth, and grazing mortality. Agar spheres incubated in raw seawater were rapidly colonized by bacteria, followed by flagellates and ciliates. Colonization can be described as a diffusion process, and encounter volume rates were estimated at about 0.01 and 0.1 cm(3) h(-1) for bacteria and flagellates, respectively. After initial colonization, the abundances of flagellates and ciliates remained approximately constant at 10(3) to 10(4) and approximately 10(2) cells sphere(-1), respectively, whereas bacterial populations increased at a declining rate to >10(7) cells sphere(-1). Attached microorganisms initially detached at high specific rates of approximately 10(-2) min(-1), but the bacteria gradually became irreversibly attached to the spheres. Bacterial growth (0 to 2 day(-1)) was density dependent and declined hyperbolically when cell density exceeded a threshold. Bacterivorous flagellates grazed on the sphere surface at an average saturated rate of 15 bacteria flagellate(-1) h(-1). At low bacterial densities, the flagellate surface clearance rate was approximately 5 x 10(-7) cm(2) min(-1), but it declined hyperbolically with increasing bacterial density. Using the experimentally estimated process rates and integrating the component processes in a simple model reproduces the main features of the observed microbial population dynamics. Differences between observed and predicted population dynamics suggest, however, that other factors, e.g., antagonistic interactions between bacteria, are of importance in shaping marine snow microbial communities.
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36
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Grossart HP, Kiørboe T, Tang K, Ploug H. Bacterial colonization of particles: growth and interactions. Appl Environ Microbiol 2003; 69:3500-9. [PMID: 12788756 PMCID: PMC161515 DOI: 10.1128/aem.69.6.3500-3509.2003] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Marine particles in the ocean are exposed to diverse bacterial communities, and colonization and growth of attached bacteria are important processes in the degradation and transformation of the particles. In an earlier study, we showed that the initial colonization of model particles by individual bacterial strains isolated from marine aggregates was a function of attachment and detachment. In the present study, we have investigated how this colonization process was further affected by growth and interspecific interactions among the bacteria. Long-term incubation experiments showed that growth dominated over attachment and detachment after a few hours in controlling the bacterial population density on agar particles. In the absence of grazing mortality, this growth led to an equilibrium population density consistent with the theoretical limit due to oxygen diffusion. Interspecific interaction experiments showed that the presence of some bacterial strains ("residents") on the agar particles either increased or decreased the colonization rate of other strains ("newcomers"). Comparison between an antibiotic-producing strain and its antibiotic-free mutant showed no inhibitory effect on the newcomers due to antibiotic production. On the contrary, hydrolytic activity of the antibiotic-producing strain appeared to benefit the newcomers and enhance their colonization rate. These results show that growth- and species-specific interactions have to be taken into account to adequately describe bacterial colonization of marine particles. Changes in colonization pattern due to such small-scale processes may have profound effects on the transformation and fluxes of particulate matter in the ocean.
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Affiliation(s)
- Hans-Peter Grossart
- Institute of Chemistry and Biology of the Marine Environment, University of Oldenburg, 26111 Oldenburg, Germany.
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37
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Kiørboe T, Tang K, Grossart HP, Ploug H. Dynamics of microbial communities on marine snow aggregates: colonization, growth, detachment, and grazing mortality of attached bacteria. Appl Environ Microbiol 2003; 69:3036-47. [PMID: 12788697 PMCID: PMC161531 DOI: 10.1128/aem.69.6.3036-3047.2003] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2002] [Accepted: 02/28/2003] [Indexed: 11/20/2022] Open
Abstract
We studied the dynamics of microbial communities attached to model aggregates (4-mm-diameter agar spheres) and the component processes of colonization, detachment, growth, and grazing mortality. Agar spheres incubated in raw seawater were rapidly colonized by bacteria, followed by flagellates and ciliates. Colonization can be described as a diffusion process, and encounter volume rates were estimated at about 0.01 and 0.1 cm(3) h(-1) for bacteria and flagellates, respectively. After initial colonization, the abundances of flagellates and ciliates remained approximately constant at 10(3) to 10(4) and approximately 10(2) cells sphere(-1), respectively, whereas bacterial populations increased at a declining rate to >10(7) cells sphere(-1). Attached microorganisms initially detached at high specific rates of approximately 10(-2) min(-1), but the bacteria gradually became irreversibly attached to the spheres. Bacterial growth (0 to 2 day(-1)) was density dependent and declined hyperbolically when cell density exceeded a threshold. Bacterivorous flagellates grazed on the sphere surface at an average saturated rate of 15 bacteria flagellate(-1) h(-1). At low bacterial densities, the flagellate surface clearance rate was approximately 5 x 10(-7) cm(2) min(-1), but it declined hyperbolically with increasing bacterial density. Using the experimentally estimated process rates and integrating the component processes in a simple model reproduces the main features of the observed microbial population dynamics. Differences between observed and predicted population dynamics suggest, however, that other factors, e.g., antagonistic interactions between bacteria, are of importance in shaping marine snow microbial communities.
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Affiliation(s)
- Thomas Kiørboe
- Danish Institute for Fisheries Research, DK-2920 Charlottenlund, Denmark.
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38
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Kiørboe T, Grossart HP, Ploug H, Tang K. Mechanisms and rates of bacterial colonization of sinking aggregates. Appl Environ Microbiol 2002; 68:3996-4006. [PMID: 12147501 PMCID: PMC124032 DOI: 10.1128/aem.68.8.3996-4006.2002] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2002] [Accepted: 05/23/2002] [Indexed: 11/20/2022] Open
Abstract
Quantifying the rate at which bacteria colonize aggregates is a key to understanding microbial turnover of aggregates. We used encounter models based on random walk and advection-diffusion considerations to predict colonization rates from the bacteria's motility patterns (swimming speed, tumbling frequency, and turn angles) and the hydrodynamic environment (stationary versus sinking aggregates). We then experimentally tested the models with 10 strains of bacteria isolated from marine particles: two strains were nonmotile; the rest were swimming at 20 to 60 microm s(-1) with different tumbling frequency (0 to 2 s(-1)). The rates at which these bacteria colonized artificial aggregates (stationary and sinking) largely agreed with model predictions. We report several findings. (i) Motile bacteria rapidly colonize aggregates, whereas nonmotile bacteria do not. (ii) Flow enhances colonization rates. (iii) Tumbling strains colonize aggregates enriched with organic substrates faster than unenriched aggregates, while a nontumbling strain did not. (iv) Once on the aggregates, the bacteria may detach and typical residence time is about 3 h. Thus, there is a rapid exchange between attached and free bacteria. (v) With the motility patterns observed, freely swimming bacteria will encounter an aggregate in <1 day at typical upper-ocean aggregate concentrations. This is faster than even starving bacteria burn up their reserves, and bacteria may therefore rely solely on aggregates for food. (vi) The net result of colonization and detachment leads to a predicted equilibrium abundance of attached bacteria as a function of aggregate size, which is markedly different from field observations. This discrepancy suggests that inter- and intraspecific interactions among bacteria and between bacteria and their predators may be more important than colonization in governing the population dynamics of bacteria on natural aggregates.
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Affiliation(s)
- Thomas Kiørboe
- Danish Institute for Fisheries Research, DK-2920 Charlottenlund, Denmark.
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39
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Abstract
Sophisticated molecular and microscopic methods used to study biofilm formation are rapidly broadening our understanding of surface-attached microbial communities in a wide variety of organisms. Regulatory mechanisms involved in the attachment and subsequent development of mature biofilms are being elucidated. Common themes are beginning to emerge, providing promise for the development of sophisticated control strategies.
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Affiliation(s)
- Luanne Hall-Stoodley
- Center for Biofilm Engineering, Department of Microbiology and Civil Engineering, 366 EPS Building, Montana State University, Bozeman, MT 59717, USA
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40
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Jackson DW, Suzuki K, Oakford L, Simecka JW, Hart ME, Romeo T. Biofilm formation and dispersal under the influence of the global regulator CsrA of Escherichia coli. J Bacteriol 2002; 184:290-301. [PMID: 11741870 PMCID: PMC134780 DOI: 10.1128/jb.184.1.290-301.2002] [Citation(s) in RCA: 320] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The predominant mode of growth of bacteria in the environment is within sessile, matrix-enclosed communities known as biofilms. Biofilms often complicate chronic and difficult-to-treat infections by protecting bacteria from the immune system, decreasing antibiotic efficacy, and dispersing planktonic cells to distant body sites. While the biology of bacterial biofilms has become a major focus of microbial research, the regulatory mechanisms of biofilm development remain poorly defined and those of dispersal are unknown. Here we establish that the RNA binding global regulatory protein CsrA (carbon storage regulator) of Escherichia coli K-12 serves as both a repressor of biofilm formation and an activator of biofilm dispersal under a variety of culture conditions. Ectopic expression of the E. coli K-12 csrA gene repressed biofilm formation by related bacterial pathogens. A csrA knockout mutation enhanced biofilm formation in E. coli strains that were defective for extracellular, surface, or regulatory factors previously implicated in biofilm formation. In contrast, this csrA mutation did not affect biofilm formation by a glgA (glycogen synthase) knockout mutant. Complementation studies with glg genes provided further genetic evidence that the effects of CsrA on biofilm formation are mediated largely through the regulation of intracellular glycogen biosynthesis and catabolism. Finally, the expression of a chromosomally encoded csrA'-'lacZ translational fusion was dynamically regulated during biofilm formation in a pattern consistent with its role as a repressor. We propose that global regulation of central carbon flux by CsrA is an extremely important feature of E. coli biofilm development.
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Affiliation(s)
- Debra W Jackson
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas 76107-2699, USA
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41
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Stoodley P, Wilson S, Hall-Stoodley L, Boyle JD, Lappin-Scott HM, Costerton JW. Growth and detachment of cell clusters from mature mixed-species biofilms. Appl Environ Microbiol 2001; 67:5608-13. [PMID: 11722913 PMCID: PMC93350 DOI: 10.1128/aem.67.12.5608-5613.2001] [Citation(s) in RCA: 209] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Detachment from biofilms is an important consideration in the dissemination of infection and the contamination of industrial systems but is the least-studied biofilm process. By using digital time-lapse microscopy and biofilm flow cells, we visualized localized growth and detachment of discrete cell clusters in mature mixed-species biofilms growing under steady conditions in turbulent flow in situ. The detaching biomass ranged from single cells to an aggregate with a diameter of approximately 500 microm. Direct evidence of local cell cluster detachment from the biofilms was supported by microscopic examination of filtered effluent. Single cells and small clusters detached more frequently, but larger aggregates contained a disproportionately high fraction of total detached biomass. These results have significance in the establishment of an infectious dose and public health risk assessment.
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Affiliation(s)
- P Stoodley
- Civil Engineering, Montana State University-Bozeman, Bozeman, Montana 59717-3980, USA.
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42
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Baty AM, Diwu Z, Dunham G, Eastburn CC, Geesey GG, Goodman AE, Suci PA, Techkarnjanaruk S. Characterization of extracellular chitinolytic activity in biofilms. Methods Enzymol 2001; 336:279-301. [PMID: 11398405 DOI: 10.1016/s0076-6879(01)36596-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Extracellular enzymes produced by bacterial biofilms tend to become an integral, permanent part of the biofilm/substratum system. Thus, characterizing extracellular enzyme activity is an essential component of understanding biofilm ecology. Methods have been presented for characterizing three aspects of extracellular enzyme activity in biofilms: promoter activity of the structural gene, local catalytic activity, and kinetics of collective substrate degradation. The abundance of intracellular transcript derived from a structural gene is only indirectly related to the magnitude of catalytic activity of the corresponding enzyme. This relationship may be particularly tenuous in the case of extracellular enzymes, which must be transported out of the cell in order to become active. Fluorogenic substrates that allow direct detection of an increasingly greater variety of enzyme activities are becoming available. There are technical problems, originating from surface roughness and intrinsic fluorescence, associated with microscopic examination of biofilms on natural materials. Thin films provide one option for acquiring data about biofilms colonizing relevant materials.
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Affiliation(s)
- A M Baty
- W. L. Gore & Associates, Inc., Flagstaff, Arizona 86002, USA
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43
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Abstract
Population level studies demonstrate that bacterial colonization of surfaces and subsequent biofilm architecture are controlled by a variety of factors that include the hydrodynamics, surface chemistry and genotype of the cell. New molecular tools now extend our ability to investigate among bacterial cells within a surface-associated population subtle phenotypic differences that do not involve changes in genotype. Such resolution has led to new discoveries in relationships between bacterial cells and their environment.
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Affiliation(s)
- G G Geesey
- Department of Microbiology and Center for Biofilm Engineering, PO Box 173520, Montana State University, Bozeman, Montana 59717-3520, USA.
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44
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Baty AM, Eastburn CC, Diwu Z, Techkarnjanaruk S, Goodman AE, Geesey GG. Differentiation of chitinase-active and non-chitinase-active subpopulations of a marine bacterium during chitin degradation. Appl Environ Microbiol 2000; 66:3566-73. [PMID: 10919822 PMCID: PMC92186 DOI: 10.1128/aem.66.8.3566-3573.2000] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability of marine bacteria to adhere to detrital particulate organic matter and rapidly switch on metabolic genes in an effort to reproduce is an important response for bacterial survival in the pelagic marine environment. The goal of this investigation was to evaluate the relationship between chitinolytic gene expression and extracellular chitinase activity in individual cells of the marine bacterium Pseudoalteromonas sp. strain S91 attached to solid chitin. A green fluorescent protein reporter gene under the control of the chiA promoter was used to evaluate chiA gene expression, and a precipitating enzyme-linked fluorescent probe, ELF-97-N-acetyl-beta-D-glucosaminide, was used to evaluate extracellular chitinase activity among cells in the bacterial population. Evaluation of chiA expression and ELF-97 crystal location at the single-cell level revealed two physiologically distinct subpopulations of S91 on the chitin surface: one that was chitinase active and remained associated with the surface and another that was non-chitinase active and released daughter cells into the bulk aqueous phase. It is hypothesized that the surface-associated, non-chitinase-active population is utilizing chitin degradation products that were released by the adjacent chitinase-active population for cell replication and dissemination into the bulk aqueous phase.
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Affiliation(s)
- A M Baty
- Department of Microbiology, Montana State University, Bozeman 59717, USA
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