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Loeffler M, Hilbig J, Velasco L, Weiss J. Usage of in situ exopolysaccharide-forming lactic acid bacteria in food production: Meat products-A new field of application? Compr Rev Food Sci Food Saf 2020; 19:2932-2954. [PMID: 33337046 DOI: 10.1111/1541-4337.12615] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 07/02/2020] [Accepted: 07/15/2020] [Indexed: 12/01/2022]
Abstract
In the meat industry, hydrocolloids and phosphates are used to improve the quality attributes of meat products. However, latest research results revealed that the usage of exopolysaccharide (EPS)-forming lactic acid bacteria (LAB), which are able to produce EPS in situ during processing could be an interesting alternative. The current review aims to give a better understanding of bacterial EPS production in food matrices with a special focus on meat products. This includes an introduction to microbial EPS production (homopolysaccharides as well as heteropolysaccharides) and an overview of parameters affecting EPS formation and yield depending on LAB used. This is followed by a summary of methods to detect and characterize EPS to facilitate a rational selection of starter cultures and fermentation conditions based on desired structure-function relationships in different food matrices. The mechanism of action of in situ generated EPS is then highlighted with an emphasis on different meat products. In the process, this review also highlights food additives currently used in meat production that could in the future be replaced by in situ EPS-forming LAB.
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Affiliation(s)
- Myriam Loeffler
- Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, Stuttgart, Germany
| | - Jonas Hilbig
- Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, Stuttgart, Germany
| | - Lina Velasco
- Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, Stuttgart, Germany
| | - Jochen Weiss
- Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, Stuttgart, Germany
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2
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König D, Dagenais P, Senk A, Djonov V, Aegerter CM, Jaźwińska A. Distribution and Restoration of Serotonin-Immunoreactive Paraneuronal Cells During Caudal Fin Regeneration in Zebrafish. Front Mol Neurosci 2019; 12:227. [PMID: 31616250 PMCID: PMC6763699 DOI: 10.3389/fnmol.2019.00227] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 09/04/2019] [Indexed: 12/22/2022] Open
Abstract
Aquatic vertebrates possess diverse types of sensory cells in their skin to detect stimuli in the water. In the adult zebrafish, a common model organism, the presence of such cells in fins has only rarely been studied. Here, we identified scattered serotonin (5-HT)-positive cells in the epidermis of the caudal fin. These cells were distinct from keratinocytes as revealed by their low immunoreactivity for cytokeratin and desmosome markers. Instead, they were detected by Calretinin (Calbindin-2) and Synaptic vesicle glycoprotein 2 (SV2) antibodies, indicating a calcium-regulated neurosecretory activity. Consistently, electron microscopy revealed abundant secretory organelles in desmosome-negative cells in the fin epidermis. Based on the markers, 5-HT, Calretinin and SV2, we referred to these cells as HCS-cells. We found that HCS-cells were spread throughout the entire caudal fin at an average density of 140 cells per mm2 on each fin surface. These cells were strongly enriched at ray bifurcations in wild type fins, as well as in elongated fins of another longfin mutant fish. To determine whether hydrodynamics play a role in the distribution of HCS-cells, we used an interdisciplinary approach and performed kinematic analysis. Measurements of particle velocity with a fin model revealed differences in fluid velocities between bifurcated rods and adjacent non-bifurcated regions. Therefore the accumulation of HCS-cells near bone bifurcations may be a biological adaptation for sensing of water parameters. The significance of this HCS-cell pattern is reinforced by the fact, that it is reestablished in the regenerated fin after amputation. Regeneration of HCS-cells was not impaired by the chemical inhibition of serotonin synthesis, suggesting that this neurotransmitter is not essential for the restorative process. In conclusion, our study identified a specific population of solitary paraneurons in the zebrafish fin, whose distribution correlates with fluid dynamics.
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Affiliation(s)
- Désirée König
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Paule Dagenais
- Physik-Institut, University of Zurich, Zurich, Switzerland
| | - Anita Senk
- Institute of Anatomy, University of Bern, Bern, Switzerland
| | | | | | - Anna Jaźwińska
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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Hrubanova K, Krzyzanek V, Nebesarova J, Ruzicka F, Pilat Z, Samek O. Monitoring Candida parapsilosis and Staphylococcus epidermidis Biofilms by a Combination of Scanning Electron Microscopy and Raman Spectroscopy. SENSORS 2018; 18:s18124089. [PMID: 30469521 PMCID: PMC6308600 DOI: 10.3390/s18124089] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 11/16/2018] [Accepted: 11/20/2018] [Indexed: 02/03/2023]
Abstract
The biofilm-forming microbial species Candida parapsilosis and Staphylococcus epidermidis have been recently linked to serious infections associated with implanted medical devices. We studied microbial biofilms by high resolution scanning electron microscopy (SEM), which allowed us to visualize the biofilm structure, including the distribution of cells inside the extracellular matrix and the areas of surface adhesion. We compared classical SEM (chemically fixed samples) with cryogenic SEM, which employs physical sample preparation based on plunging the sample into various liquid cryogens, as well as high-pressure freezing (HPF). For imaging the biofilm interior, we applied the freeze-fracture technique. In this study, we show that the different means of sample preparation have a fundamental influence on the observed biofilm structure. We complemented the SEM observations with Raman spectroscopic analysis, which allowed us to assess the time-dependent chemical composition changes of the biofilm in vivo. We identified the individual spectral peaks of the biomolecules present in the biofilm and we employed principal component analysis (PCA) to follow the temporal development of the chemical composition.
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Affiliation(s)
- Kamila Hrubanova
- Institute of Scientific Instruments of the Czech Academy of Sciences, CZ-61264 Brno, Czech Republic.
| | - Vladislav Krzyzanek
- Institute of Scientific Instruments of the Czech Academy of Sciences, CZ-61264 Brno, Czech Republic.
| | - Jana Nebesarova
- Biology Centre of the Czech Academy of Sciences, CZ-37005 Ceske Budejovice, Czech Republic.
| | - Filip Ruzicka
- Department of Microbiology, Faculty of Medicine, Masaryk University and St. Anne's Faculty Hospital, CZ-65691 Brno, Czech Republic.
| | - Zdenek Pilat
- Institute of Scientific Instruments of the Czech Academy of Sciences, CZ-61264 Brno, Czech Republic.
| | - Ota Samek
- Institute of Scientific Instruments of the Czech Academy of Sciences, CZ-61264 Brno, Czech Republic.
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Hrubanova K, Nebesarova J, Ruzicka F, Krzyzanek V. The innovation of cryo-SEM freeze-fracturing methodology demonstrated on high pressure frozen biofilm. Micron 2018; 110:28-35. [PMID: 29715620 DOI: 10.1016/j.micron.2018.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/18/2018] [Accepted: 04/19/2018] [Indexed: 11/30/2022]
Abstract
In this study we present an innovative method for the preparation of fully hydrated samples of microbial biofilms of cultures Staphylococcus epidermidis, Candida parapsilosis and Candida albicans. Cryo-scanning electron microscopy (cryo-SEM) and high-pressure freezing (HPF) rank among cutting edge techniques in the electron microscopy of hydrated samples such as biofilms. However, the combination of these techniques is not always easily applicable. Therefore, we present a method of combining high-pressure freezing using EM PACT2 (Leica Microsystems), which fixes hydrated samples on small sapphire discs, with a high resolution SEM equipped with the widely used cryo-preparation system ALTO 2500 (Gatan). Using a holder developed in house, a freeze-fracturing technique was applied to image and investigate microbial cultures cultivated on the sapphire discs. In our experiments, we focused on the ultrastructure of the extracellular matrix produced during cultivation and the relationships among microbial cells in the biofilm. The main goal of our investigations was the detailed visualization of areas of the biofilm where the microbial cells adhere to the substrate/surface. We show the feasibility of this technique, which is clearly demonstrated in experiments with various freeze-etching times.
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Affiliation(s)
- Kamila Hrubanova
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Jana Nebesarova
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice, Czech Republic; Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Filip Ruzicka
- Department of Microbiology, Faculty of Medicine, Masaryk University and St. Anne's Faculty Hospital, Brno, Czech Republic
| | - Vladislav Krzyzanek
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic.
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5
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Hynninen A, Külaviir M, Kirsimäe K. Air-drying is sufficient pre-treatment for in situ visualization of microbes on minerals with scanning electron microscopy. J Microbiol Methods 2018; 146:77-82. [PMID: 29428739 DOI: 10.1016/j.mimet.2018.02.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 01/26/2018] [Accepted: 02/07/2018] [Indexed: 11/29/2022]
Abstract
Scanning electron microscopy (SEM) is a powerful tool for observing microbe-mineral interactions in situ. Despite its wide usage in geomicrobiology there is no consensus on how the samples should be handled before visualizing in SEM. We compared response of artificial laboratory-grown bacterial community and natural in situ microbes on terrestrial basalt to different sample pre-treatment methods with the aim to preserve microbe-mineral interaction interface. Air-drying was the only method that maintained the location of loosely attached bacteria on a mineral surface, whereas chemical fixation and drying dislocated the cells. On the contrary, chemical fixation preserved the cellular morphology while air-drying caused the collapse of most of the laboratory-grown cells. Natural microbial communities on dry terrestrial basalt were composed of desiccation resistant microbes which remained attached to the surface and partially maintained their morphology regardless of the sample pre-treatment method. None of the tested methods allowed visualization of microbe-mineral interface in a biofilm. We suggest air-drying as a main sample pre-treatment method for visualizing microbes on mineral surfaces when loss of morphology is secondary to potentially dislocated cells and to potential chemical changes in the sample caused by the chemical fixation reagents.
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Affiliation(s)
- Anu Hynninen
- Department of Geology, University of Tartu, Tartu, Estonia; Department of Geography and Geology, University of Turku, Turku, Finland.
| | | | - Kalle Kirsimäe
- Department of Geology, University of Tartu, Tartu, Estonia
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Abstract
Volume is an essential characteristic of a cell, and this review describes the main methods of its measurement that have been used in the past several decades. The discussed methods include various implementations of light scattering, estimates based on one or two cell dimensions, surface scanning, fluorescence confocal and transmission slice-by-slice imaging, intracellular volume markers, displacement of extracellular solution, quantitative phase imaging, radioactive methods, and some others. Suitability of these methods to some typical samples and applications is discussed. © 2017 International Society for Advancement of Cytometry.
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Affiliation(s)
- Michael A Model
- Department of Biological Sciences, Kent State University, Kent, Ohio
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7
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Braun S, Morono Y, Littmann S, Kuypers M, Aslan H, Dong M, Jørgensen BB, Lomstein BA. Size and Carbon Content of Sub-seafloor Microbial Cells at Landsort Deep, Baltic Sea. Front Microbiol 2016; 7:1375. [PMID: 27630628 PMCID: PMC5005352 DOI: 10.3389/fmicb.2016.01375] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/19/2016] [Indexed: 11/13/2022] Open
Abstract
The discovery of a microbial ecosystem in ocean sediments has evoked interest in life under extreme energy limitation and its role in global element cycling. However, fundamental parameters such as the size and the amount of biomass of sub-seafloor microbial cells are poorly constrained. Here we determined the volume and the carbon content of microbial cells from a marine sediment drill core retrieved by the Integrated Ocean Drilling Program (IODP), Expedition 347, at Landsort Deep, Baltic Sea. To determine their shape and volume, cells were separated from the sediment matrix by multi-layer density centrifugation and visualized via epifluorescence microscopy (FM) and scanning electron microscopy (SEM). Total cell-carbon was calculated from amino acid-carbon, which was analyzed by high-performance liquid chromatography (HPLC) after cells had been purified by fluorescence-activated cell sorting (FACS). The majority of microbial cells in the sediment have coccoid or slightly elongated morphology. From the sediment surface to the deepest investigated sample (~60 m below the seafloor), the cell volume of both coccoid and elongated cells decreased by an order of magnitude from ~0.05 to 0.005 μm3. The cell-specific carbon content was 19–31 fg C cell−1, which is at the lower end of previous estimates that were used for global estimates of microbial biomass. The cell-specific carbon density increased with sediment depth from about 200 to 1000 fg C μm−3, suggesting that cells decrease their water content and grow small cell sizes as adaptation to the long-term subsistence at very low energy availability in the deep biosphere. We present for the first time depth-related data on the cell volume and carbon content of sedimentary microbial cells buried down to 60 m below the seafloor. Our data enable estimates of volume- and biomass-specific cellular rates of energy metabolism in the deep biosphere and will improve global estimates of microbial biomass.
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Affiliation(s)
- Stefan Braun
- Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Yuki Morono
- Geomicrobiology Group, Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology Kochi, Japan
| | - Sten Littmann
- Biogeochemistry Group, Max Planck Institute for Marine Microbiology Bremen, Germany
| | - Marcel Kuypers
- Biogeochemistry Group, Max Planck Institute for Marine Microbiology Bremen, Germany
| | - Hüsnü Aslan
- Interdisciplinary Nanoscience Center, Aarhus University Aarhus, Denmark
| | - Mingdong Dong
- Interdisciplinary Nanoscience Center, Aarhus University Aarhus, Denmark
| | - Bo B Jørgensen
- Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Bente Aa Lomstein
- Center for Geomicrobiology, Department of Bioscience, Aarhus UniversityAarhus, Denmark; Section for Microbiology, Department of Bioscience, Aarhus UniversityAarhus, Denmark
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8
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van der Pol E, Coumans FAW, Grootemaat AE, Gardiner C, Sargent IL, Harrison P, Sturk A, van Leeuwen TG, Nieuwland R. Particle size distribution of exosomes and microvesicles determined by transmission electron microscopy, flow cytometry, nanoparticle tracking analysis, and resistive pulse sensing. J Thromb Haemost 2014; 12:1182-92. [PMID: 24818656 DOI: 10.1111/jth.12602] [Citation(s) in RCA: 620] [Impact Index Per Article: 62.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 04/25/2014] [Indexed: 11/30/2022]
Abstract
BACKGROUND Enumeration of extracellular vesicles has clinical potential as a biomarker for disease. In biological samples, the smallest and largest vesicles typically differ 25-fold in size, 300,000-fold in concentration, 20,000-fold in volume, and 10,000,000-fold in scattered light. Because of this heterogeneity, the currently employed techniques detect concentrations ranging from 10(4) to 10(12) vesicles mL(-1) . OBJECTIVES To investigate whether the large variation in the detected concentration of vesicles is caused by the minimum detectable vesicle size of five widely used techniques. METHODS The size and concentration of vesicles and reference beads were measured with transmission electron microscopy (TEM), a conventional flow cytometer, a flow cytometer dedicated to detecting submicrometer particles, nanoparticle tracking analysis (NTA), and resistive pulse sensing (RPS). RESULTS Each technique gave a different size distribution and a different concentration for the same vesicle sample. CONCLUSION Differences between the detected vesicle concentrations are primarily caused by differences between the minimum detectable vesicle sizes. The minimum detectable vesicle sizes were 70-90 nm for NTA, 70-100 nm for RPS, 150-190 nm for dedicated flow cytometry, and 270-600 nm for conventional flow cytometry. TEM could detect the smallest vesicles present, albeit after adhesion on a surface. Dedicated flow cytometry was most accurate in determining the size of reference beads, but is expected to be less accurate on vesicles, owing to heterogeneity of the refractive index of vesicles. Nevertheless, dedicated flow cytometry is relatively fast and allows multiplex fluorescence detection, making it most applicable to clinical research.
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Affiliation(s)
- E van der Pol
- Laboratory of Experimental Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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9
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Joens MS, Huynh C, Kasuboski JM, Ferranti D, Sigal YJ, Zeitvogel F, Obst M, Burkhardt CJ, Curran KP, Chalasani SH, Stern LA, Goetze B, Fitzpatrick JAJ. Helium Ion Microscopy (HIM) for the imaging of biological samples at sub-nanometer resolution. Sci Rep 2013; 3:3514. [PMID: 24343236 PMCID: PMC3865489 DOI: 10.1038/srep03514] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 11/26/2013] [Indexed: 11/08/2022] Open
Abstract
Scanning Electron Microscopy (SEM) has long been the standard in imaging the sub-micrometer surface ultrastructure of both hard and soft materials. In the case of biological samples, it has provided great insights into their physical architecture. However, three of the fundamental challenges in the SEM imaging of soft materials are that of limited imaging resolution at high magnification, charging caused by the insulating properties of most biological samples and the loss of subtle surface features by heavy metal coating. These challenges have recently been overcome with the development of the Helium Ion Microscope (HIM), which boasts advances in charge reduction, minimized sample damage, high surface contrast without the need for metal coating, increased depth of field, and 5 angstrom imaging resolution. We demonstrate the advantages of HIM for imaging biological surfaces as well as compare and contrast the effects of sample preparation techniques and their consequences on sub-nanometer ultrastructure.
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Affiliation(s)
- Matthew S. Joens
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Chuong Huynh
- Ion Microscopy Innovation Center, Carl Zeiss Microscopy LLC, One Corporation Way, Peabody, MA 01960, USA
| | - James M. Kasuboski
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - David Ferranti
- Ion Microscopy Innovation Center, Carl Zeiss Microscopy LLC, One Corporation Way, Peabody, MA 01960, USA
| | - Yury J. Sigal
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Fabian Zeitvogel
- Center for Applied Geosciences, University Tübingen, Hoelderlinstr. 12, 72074 Tuebingen, Germany
| | - Martin Obst
- Center for Applied Geosciences, University Tübingen, Hoelderlinstr. 12, 72074 Tuebingen, Germany
| | - Claus J. Burkhardt
- NMI Natural and Medical Sciences Institute, Markwiesenstr. 55, 72770 Reutlingen, Germany
| | - Kevin P. Curran
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Sreekanth H. Chalasani
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Lewis A. Stern
- Ion Microscopy Innovation Center, Carl Zeiss Microscopy LLC, One Corporation Way, Peabody, MA 01960, USA
| | - Bernhard Goetze
- Ion Microscopy Innovation Center, Carl Zeiss Microscopy LLC, One Corporation Way, Peabody, MA 01960, USA
| | - James A. J. Fitzpatrick
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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McTee MR, Gibbons SM, Feris K, Gordon NS, Gannon JE, Ramsey PW. Heavy metal tolerance genes alter cellular thermodynamics in Pseudomonas putida and river Pseudomonas spp. and influence amebal predation. FEMS Microbiol Lett 2013; 347:97-106. [PMID: 23895438 DOI: 10.1111/1574-6968.12226] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/18/2013] [Accepted: 07/24/2013] [Indexed: 11/27/2022] Open
Abstract
Predation rates were measured for two Acanthamoeba castellanii strains feeding on metal-tolerant and metal-sensitive strains of Pseudomonas putida and compared with cellular thermodynamic data. Predation rates by A. castellanii strain ATCC 30010 correlated with cell volume of the prey. To explore whether this observation could be environmentally relevant, pseudomonad species were isolated from a pristine and a metal-contaminated river and were paired based on phylogenetic and physiological relatedness. Then, cellular thermodynamics and predation rates were measured on the most similar pseudomonad pair. Under cadmium stress, the strain from contaminated river sediments, Pseudomonas sp. CF150, exited metabolic dormancy faster than its pair from pristine sediments, Pseudomonas sp. N9, but consumed available resources less efficiently (more energy was lost as heat). Predation rates by both strains of ameba were greater on Pseudomonas sp. CF150 than on Pseudomonas sp. N9 at the highest cadmium concentration.
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Affiliation(s)
- Michael R McTee
- Microbial Ecology, Division of Biological Sciences, University of Montana, Missoula, MT, USA; MPG Ranch, Florence, MT, USA
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Imaging hydrated microbial extracellular polymers: comparative analysis by electron microscopy. Appl Environ Microbiol 2010; 77:1254-62. [PMID: 21169451 DOI: 10.1128/aem.02001-10] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microbe-mineral and -metal interactions represent a major intersection between the biosphere and geosphere but require high-resolution imaging and analytical tools for investigation of microscale associations. Electron microscopy has been used extensively for geomicrobial investigations, and although used bona fide, the traditional methods of sample preparation do not preserve the native morphology of microbiological components, especially extracellular polymers. Herein, we present a direct comparative analysis of microbial interactions by conventional electron microscopy approaches with imaging at room temperature and a suite of cryogenic electron microscopy methods providing imaging in the close-to-natural hydrated state. In situ, we observed an irreversible transformation of the hydrated bacterial extracellular polymers during the traditional dehydration-based sample preparation that resulted in their collapse into filamentous structures. Dehydration-induced polymer collapse can lead to inaccurate spatial relationships and hence could subsequently affect conclusions regarding the nature of interactions between microbial extracellular polymers and their environment.
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12
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Use of microcalorimetry to determine the costs and benefits to Pseudomonas putida strain KT2440 of harboring cadmium efflux genes. Appl Environ Microbiol 2010; 77:108-13. [PMID: 21057015 DOI: 10.1128/aem.01187-10] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel microcalorimetric approach was used to analyze the responses of a metal-tolerant soil bacterium (Pseudomonas putida strain KT2440) to metal resistance gene deletions in cadmium-amended media. As hypothesized, under cadmium stress, the wild-type strain benefited from the resistance genes by entering the exponential growth phase earlier than two knockout strains. In the absence of cadmium, strain KT1, carrying a deletion in the main component (czcA1) of a Cd/Zn chemiosmotic efflux transporter (CzcCBA1), grew more efficiently than the wild type and released ∼700 kJ (per mole of biomass carbon) less heat than the wild-type strain, showing the energetic cost of maintaining CzcCBA1 in the absence of cadmium. A second mutant strain (KT4) carrying a different gene deletion, ΔcadA2, which encodes the main Cd/Pb efflux transporter (a P-type ATPase), did not survive beyond moderate cadmium concentrations and exhibited a decreased growth yield in the absence of cadmium. Therefore, CadA2 plays an essential role in cadmium resistance and perhaps serves an additional function. The results of this study provide direct evidence that heavy metal cation efflux mechanisms facilitate shorter lag phases in the presence of metals and that the maintenance and expression of tolerance genes carry quantifiable energetic costs and benefits.
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Portell X, Ginovart M, Carbó R, Vives-Rego J. Differences in stationary-phase cells of a commercial Saccharomyces cerevisiae wine yeast grown in aerobic and microaerophilic batch cultures assessed by electric particle analysis, light diffraction and flow cytometry. J Ind Microbiol Biotechnol 2010; 38:141-51. [PMID: 20820858 DOI: 10.1007/s10295-010-0839-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 07/26/2010] [Indexed: 11/30/2022]
Abstract
We applied electric particle analysis, light diffraction and flow cytometry to obtain information on the morphological changes during the stationary phase of Saccharomyces cerevisiae. The reported analyses of S. cerevisiae populations were obtained under two different conditions, aerobic and microaerophilic, at 27°C. The samples analysed were taken at between 20 and 50 h from the beginning of culture. To assist in the interpretation of the observed distributions a complexity index was used. The aerobically grown culture reached significantly greater cell density. Under these conditions, the cell density experienced a much lower reduction (3%) compared with the microaerophilic conditions (30%). Under aerobic conditions, the mean cell size determined by both electric particle analysis and light diffraction was lower and remained similar throughout the experiment. Under microaerophilic conditions, the mean cell size determined by electric particle analysis decreased slightly as the culture progressed through the stationary phase. Forward and side scatter distributions revealed two cell subpopulations under both growth conditions. However, in the aerobic growing culture the two subpopulations were more separated and hence easier to distinguish. The distributions obtained with the three experimental techniques were analysed using the complexity index. This analysis suggested that a complexity index is a good descriptor of the changes that take place in a yeast population in the stationary phase, and that it aids in the discussion and understanding of the implications of these distributions obtained by these experimental techniques.
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Affiliation(s)
- X Portell
- Department of Agri-Food Engineering and Biotechnology, Universitat Politècnica de Catalunya, Campus Baix Llobregat, Esteve Terradas 8, 08860, Castelldefels, Barcelona, Spain.
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14
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Lee S, Fuhrman JA. Relationships between Biovolume and Biomass of Naturally Derived Marine Bacterioplankton. Appl Environ Microbiol 2010; 53:1298-303. [PMID: 16347362 PMCID: PMC203858 DOI: 10.1128/aem.53.6.1298-1303.1987] [Citation(s) in RCA: 327] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microscopic estimation of bacterial biomass requires determination of both biovolume and biovolume-to-biomass conversion. Both steps have uncertainty when applied to the very small bacteria typically found in natural seawater. In the present study, natural bacterioplankton assemblages were freshly collected, passed through 0.6-mum-pore-size Nuclepore filters to remove larger particulate materials, and diluted for growth in 0.22-mum-pore-size Millipore filter-sterilized unenriched seawater. This provided cells comparable in size and morphology to those in natural seawater, but the cultures were free of the interfering particulate detritus naturally present. Cells were collected on glass-fiber GF/F filters, and biovolumes were corrected for cells passing these filters; C and N were measured with a CHN analyzer. Our criteria for size measurement by epifluorescence photomicrography were confirmed with fluorescent microspheres of known diameters. Surprisingly, in six cultures with average per-cell biovolumes ranging from 0.036 to 0.073 mum, the average per-cell carbon biomass was relatively constant at 20 +/- 0.08 fg of C (mean +/- standard error of the mean). The biovolume-to-biomass conversion factor averaged 0.38 +/- 0.05 g of C cm, which is about three times higher than the value previously estimated from Escherichia coli, and decreased with increasing cell volume. The C:N ratio was 3.7 +/- 0.2. We conclude that natural marine bacterial biomass and production may be higher than was previously thought and that variations in bacterial size may not reflect variations in biomass per cell.
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Affiliation(s)
- S Lee
- Marine Sciences Research Center, State University of New York, Stony Brook, New York 11794
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Nagata T. Carbon and nitrogen content of natural planktonic bacteria. Appl Environ Microbiol 2010; 52:28-32. [PMID: 16347114 PMCID: PMC203387 DOI: 10.1128/aem.52.1.28-32.1986] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A method of estimating carbon and nitrogen content per unit of natural bacterial cell volume was developed. This method is based on the difference in the retentiveness of bacteria between two kinds of glass fiber filter, GF/C and GF/F (Whatman, Inc., Clifton, N.J.). Biovolume and biomass (carbon and nitrogen content) of bacteria which passed through the GF/C but not the GF/F filter were estimated with an epifluorescence microscopy and a CHN analyzer, respectively. From seasonal determinations of natural planktonic bacteria in epilimnetic waters of a mesotrophic lake, the conversion factors of 106 fg of C/mum and 25 fg of N/mum were derived as average values. By using these values, the contribution of bacteria to the biomass of lake plankton is discussed.
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Affiliation(s)
- T Nagata
- Otsu Hydrobiological Station, Kyoto University, Shimosakamoto, Otsu, Shiga-ken 520-01, Japan
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16
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Kogure K, Koike I. Particle counter determination of bacterial biomass in seawater. Appl Environ Microbiol 2010; 53:274-7. [PMID: 16347275 PMCID: PMC203651 DOI: 10.1128/aem.53.2.274-277.1987] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The applicability of the Elzone particle counter to the determination of marine bacterial biomass was investigated. The biomass of bacterial pure cultures and a mixed natural population were followed by using the particle counter, a CHN analyzer, and an ATP analyzer. The particle counter showed the precise size distribution of number and volume of submicron-size particles in seawater. For the pure cultured bacterial strains, the conversion factor from volume to carbon is 0.209 mg of C per mm, and for natural bacterial cells of >0.6 mum in diameter, it is 0.184 mg of C per mm. It is recommended that 0.2 be used as the conversion factor for both pure cultured marine bacterial cells and natural bacteria from coastal and near-shore marine environments.
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Affiliation(s)
- K Kogure
- Ocean Research Institute, University of Tokyo, Minamidai, Nakano, Tokyo 164, Japan
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17
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Abstract
The biomass of bacterial populations in aquatic ecosystems is often estimated by measuring bacterial biovolume and converting this into biomass in terms of carbon. A reliable conversion factor relating the measured bacterial biovolume to bacterial carbon content is essential for this approach. Based on direct measurements of bacterial cell carbon content, cell number, and biovolume, I have derived an average conversion factor of 5.6 x 10 g of C mum. This conversion factor is 3.4 to 6.6 times higher than most theoretically derived factors currently in use. Both bacterial biomass and bacterial production in aquatic ecosystems may thus have been seriously underestimated.
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Affiliation(s)
- G Bratbak
- Department of Microbiology and Plant Physiology, University of Bergen, Allegaten 70, N-5000 Bergen, Norway
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18
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FRY J, DAVIES A. An assessment of methods for measuring volumes of planktonic bacteria, with particular reference to television image analysis. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1985.tb01435.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Solé A, Gaju N, Esteve I. The biomass dynamics of cyanobacteria in an annual cycle determined by confocal laser scanning microscopy. SCANNING 2003; 25:1-7. [PMID: 12627891 DOI: 10.1002/sca.4950250102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We recently published a method for estimating cyanobacteria biomass in delta microbial mats from the Ebro river using confocal laser scanning microscopy (CLSM). The present paper uses this method for identifying different groups of cyanobacteria and for determining their biomass dynamics. Microcoleus chthonoplastes and the Lyngbya-Oscillatoria were the most important contributors to the cyanobacterial biomass throughout the study. Biomass values ranged from 1.29 to 6.55 mgC/cm2 sediment for Microcoleus chthonoplastes, and from 128 microgC/cm2 to 3.16 mgC/cm2 sediment for Lyngbya-Oscillatoria. This technique is useful for determining biomass and for studying filamentous cyanobacteria as well as ramified eukaryotic cells. Confocal serial sections through the samples can be obtained. Two-dimensional images from the samples can be used to calculate the biomass of individual cells.
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Affiliation(s)
- A Solé
- Department of Genetics and Microbiology, Autonomous University of Barcelona, Barcelona, Spain.
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20
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Direct determination of carbon and nitrogen contents of natural bacterial assemblages in marine environments. Appl Environ Microbiol 1998; 64:3352-8. [PMID: 9726882 PMCID: PMC106732 DOI: 10.1128/aem.64.9.3352-3358.1998] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In order to better estimate bacterial biomass in marine environments, we developed a novel technique for direct measurement of carbon and nitrogen contents of natural bacterial assemblages. Bacterial cells were separated from phytoplankton and detritus with glass fiber and membrane filters (pore size, 0.8 &mgr;m) and then concentrated by tangential flow filtration. The concentrate was used for the determination of amounts of organic carbon and nitrogen by a high-temperature catalytic oxidation method, and after it was stained with 4',6-diamidino-2-phenylindole, cell abundance was determined by epifluorescence microscopy. We found that the average contents of carbon and nitrogen for oceanic bacterial assemblages were 12.4 +/- 6.3 and 2.1 +/- 1.1 fg cell-1 (mean +/- standard deviation; n = 6), respectively. Corresponding values for coastal bacterial assemblages were 30.2 +/- 12.3 fg of C cell-1 and 5.8 +/- 1.5 fg of N cell-1 (n = 5), significantly higher than those for oceanic bacteria (two-tailed Student's t test; P < 0.03). There was no significant difference (P > 0.2) in the bacterial C:N ratio (atom atom-1) between oceanic (6.8 +/- 1.2) and coastal (5.9 +/- 1.1) assemblages. Our estimates support the previous proposition that bacteria contribute substantially to total biomass in marine environments, but they also suggest that the use of a single conversion factor for diverse marine environments can lead to large errors in assessing the role of bacteria in food webs and biogeochemical cycles. The use of a factor, 20 fg of C cell-1, which has been widely adopted in recent studies may result in the overestimation (by as much as 330%) of bacterial biomass in open oceans and in the underestimation (by as much as 40%) of bacterial biomass in coastal environments.
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21
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22
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Hedal M, Norland S, Bratback G, Riemann B. Determination of bacterial cell number and cell volume by means of flow cytometry, transmission electron microscopy, and epifluorescence microscopy. J Microbiol Methods 1994. [DOI: 10.1016/0167-7012(94)90050-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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23
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Massana R, Pedrós-Alió C. Role of Anaerobic Ciliates in Planktonic Food Webs: Abundance, Feeding, and Impact on Bacteria in the Field. Appl Environ Microbiol 1994; 60:1325-34. [PMID: 16349239 PMCID: PMC201477 DOI: 10.1128/aem.60.4.1325-1334.1994] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We studied the dynamics of two populations of anaerobic ciliates,
Plagiopyla
sp. and
Metopus
sp., and of their potential prey, heterotrophic and phototrophic purple bacteria, in Lake Cisó throughout a 1-year cycle. The abundance of both ciliates was very low (less than 2 individuals per ml). During mixing,
Plagiopyla
ciliates exhibited high clearance rates (about 100 nl ciliate
-1
h
-1
), its integrated abundance increased with a net doubling time of 47 days, and its potential doubling times, as calculated from the number of bacteria consumed, ranged between 5 and 8 days. During stratification, the activity of
Plagiopyla
ciliates was reduced and the population decreased; this was related to the higher amounts of sulfide present. The impact of predation by the
Plagiopyla
population on bacterioplankton was found to be insignificant, less than 0.1% of bacterial biomass consumed per day. Thus, anaerobic ciliates cannot control the bacterioplankton in Lake Cisó because of both the low abundance over the period studied and the low feeding rates during certain periods. A review of available field studies suggests that this conclusion can be extrapolated to most other anoxic systems.
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Affiliation(s)
- R Massana
- Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas, Passeig Joan de Borbó s/n, E-08039 Barcelona, Spain
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24
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Sime-Ngande T, Bourdier G, Amblard C, Pinel-Alloul B. Short-term variations in specific biovolumes of different bacterial forms in aquatic ecosystems. MICROBIAL ECOLOGY 1991; 21:211-226. [PMID: 24194212 DOI: 10.1007/bf02539155] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/1990] [Revised: 02/05/1991] [Indexed: 06/02/2023]
Abstract
Short-term and spatial fluctuations in specific biovolumes (volume x cell(-1)) of different morphological categories of planktonic bacteria were estimated microscopically. Samples were taken from two lakes occurring in two different climatic systems: Lake Aydat (France) and Lake Cromwell (Canada). The study was done in summer, using 24-hour cycles of sampling.Due to their large size, the specific volume of filamentous bacteria constituted, on average, the major part (>70%) of the total specific volume of all bacterial forms considered. Greatest variations in specific biovolumes were recorded for filamentous bacteria (coefficients of variation ranged from 16 to 109%). These variations were more pronounced in the oxygenated and microaerophilic strata (DOC ≈1.5 mg liter(-1)). Fluctuations in cell volume were high (coefficients of variation =12-80%) for coccal bacteria, whereas no marked fluctuations were found for the rod and vibrio bacteria (coefficients of variation =4-10%).Evidence of diel patterns of cell volume of filamentous bacteria is provided. These cells displayed their maximum size during the day until early night, indicating cell division was occurring at night. Homogeneous circadian patterns were not provided by specific volume variations of coccal, rod, and vibrio bacteria.Statistical relationships between bacterial specific biovolumes and the biotic and abiotic parameters considered are discussed.
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Affiliation(s)
- T Sime-Ngande
- Laboratoire de Zoologie et Protistologie, Université Blaise Pascal de Clermont-Ferrand II, U. A. CNRS 138, 63177, Aubière Cedex, France
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25
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26
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Gaju NÃ, Guerrero R, Pedrós-Alió C. Measurement of cell volume of phototrophic bacteria in pure cultures and natural samples: phase contrast, epifluorescence and particle sizing. FEMS Microbiol Lett 1989. [DOI: 10.1111/j.1574-6968.1989.tb03383.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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27
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Choi JW, Stoecker DK. Effects of Fixation on Cell Volume of Marine Planktonic Protozoa. Appl Environ Microbiol 1989; 55:1761-5. [PMID: 16347970 PMCID: PMC202947 DOI: 10.1128/aem.55.7.1761-1765.1989] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effects of fixation on the cell volume of marine heterotrophic nanoflagellates and planktonic ciliates were investigated. Decreases in cell volume depended on the combination of the protozoan taxa and the particular fixative. For a particular fixative and protozoan species, degree of shrinkage was independent of physiological state. The volume of fixed cells was found to be approximately 20 to 55% lower than the cell volume of live organisms. For the heterotrophic microflagellates, the fixatives ranked, in order of decreasing effect on cell volume, as glutaraldehyde, formaldehyde, acid Lugol's solution, and modified van der Veer solution. With oligotrichous ciliates and a tintinnid ciliate, formaldehyde caused less shrinkage than glutaraldehyde or acid Lugol's solution. With the aldehyde fixatives, the microflagellates were found to shrink more than the ciliates. Differential effects of fixation on cell volumes may result in an underestimation of the biomass of certain protozoan taxa in natural samples.
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Affiliation(s)
- J W Choi
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
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28
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Abstract
Ciliates were collected from a freshwater sulfuretum, Lake Cisó, which is part of a gypsum karstic area whose main feature is Lake Banyoles (Girona, Spain). Chromatium, Lamprocystis and Chlorobium are the major phototrophic sulfur bacteria in Lake Cisó. Blooms of a photosynthetic cryptomonad (up to 5 X 10(5) ind ml-1) were found at the metalimnion. The community of ciliates could be divided in three groups: aerobic, cosmopolitan, genera such as Stentor and Vorticella, in the epilimnion; a large population (up to 10(4) ind ml-1) of Coleps, adapted to low concentrations of both oxygen and sulfide, together with a few individuals of the equally sulfide-tolerant genus Paramecium, in the metalimnion, and anaerobic, true sulfide-loving genera such as Plagiopyla and Metopus, in the hypolimnion, where sulfide concentration was between 0.6 and 1.2 mM.
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29
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Guerrero R, Mas J, Pedr�s-Ali� C. Buoyant density changes due to intracellular content of sulfur in Chromatium warmingii and Chromatium vinosum. Arch Microbiol 1984. [DOI: 10.1007/bf00410733] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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30
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Paul JH, Jeffrey WH. Measurement of diameters of estuarine bacteria and particulates in natural water samples by use of a submicron particle analyzer. Curr Microbiol 1984. [DOI: 10.1007/bf01576040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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