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Cate JD, Sullivan YZ, King MD. Inhibition of Microbial Growth and Biofilm Formation in Pure and Mixed Bacterial Samples. Microorganisms 2024; 12:1500. [PMID: 39065268 PMCID: PMC11278618 DOI: 10.3390/microorganisms12071500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 07/08/2024] [Accepted: 07/11/2024] [Indexed: 07/28/2024] Open
Abstract
Hydraulic fracturing, or fracking, requires large amounts of water to extract fossil fuel from rock formations. As a result of hydraulic fracturing, the briny wastewater, often termed back-produced fracturing or fracking water (FW), is pumped into holding ponds. One of the biggest challenges with produced water management is controlling microbial activity that could reduce the pond water's reusable layer and pose a significant environmental hazard. This study focuses on the characterization of back-produced water that has been hydraulically fractured using chemical and biological analysis and the development of a high-throughput screening method to evaluate and predict the antimicrobial effect of four naturally and commercially available acidic inhibitors (edetic acid, boric acid, tannic acid, and lactic acid) on the growth of the FW microbiome. Liquid cultures and biofilms of two laboratory model strains, the vegetative Escherichia coli MG1655, and the spore-forming Bacillus atrophaeus (also known as Bacillus globigii, BG) bacteria, were used as reference microorganisms. Planktonic bacteria in FW were more sensitive to antimicrobials than sessile bacteria in biofilms. Spore-forming BG bacteria exhibited more sensitivity to acidic inhibitors than the vegetative E. coli cells. Organic acids were the most effective bacterial growth inhibitors in liquid culture and biofilm.
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Affiliation(s)
| | | | - Maria D. King
- Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA; (J.D.C.); (Y.Z.S.)
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2
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Chen H, Wang X, Li C, Xu X, Wang G. Characterization of individual spores of two biological insecticides, Bacillus thuringiensis and Lysinibacillus sphaericus, in response to glutaraldehyde using single-cell optical approaches. Arch Microbiol 2024; 206:227. [PMID: 38642141 DOI: 10.1007/s00203-024-03941-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 03/22/2024] [Accepted: 03/23/2024] [Indexed: 04/22/2024]
Abstract
Bacillus thuringiensis (Bt) and Lysinibacillus sphaericus (Ls) are the most widely used microbial insecticides. Both encounter unfavorable environmental factors and pesticides in the field. Here, the responses of Bt and Ls spores to glutaraldehyde were characterized using Raman spectroscopy and differential interference contrast imaging at the single-cell level. Bt spores were more sensitive to glutaraldehyde than Ls spores under prolonged exposure: <1.0% of Bt spores were viable after 10 min of 0.5% (v/v) glutaraldehyde treatment, compared to ~ 20% of Ls spores. The Raman spectra of glutaraldehyde-treated Bt and Ls spores were almost identical to those of untreated spores; however, the germination process of individual spores was significantly altered. The time to onset of germination, the period of rapid Ca2+-2,6-pyridinedicarboxylic acid (CaDPA) release, and the period of cortex hydrolysis of treated Bt spores were significantly longer than those of untreated spores, with dodecylamine germination being particularly affected. Similarly, the germination of treated Ls spores was significantly prolonged, although the prolongation was less than that of Bt spores. Although the interiors of Bt and Ls spores were undamaged and CaDPA did not leak, proteins and structures involved in spore germination could be severely damaged, resulting in slower and significantly prolonged germination. This study provides insights into the impact of glutaraldehyde on bacterial spores at the single cell level and the variability in spore response to glutaraldehyde across species and populations.
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Affiliation(s)
- Huanjun Chen
- Institute of Eco-Environmental Research, Guangxi Academy of Sciences, 98 Daling Road, Nanning, Guangxi, 530007, China
| | - Xiaochun Wang
- Institute of Eco-Environmental Research, Guangxi Academy of Sciences, 98 Daling Road, Nanning, Guangxi, 530007, China
| | - Cuimei Li
- Institute of Eco-Environmental Research, Guangxi Academy of Sciences, 98 Daling Road, Nanning, Guangxi, 530007, China
| | - Xiaoling Xu
- Agriculture and Food Engineering College, Baise University, Baise, Guangxi, 533000, China
| | - Guiwen Wang
- Institute of Eco-Environmental Research, Guangxi Academy of Sciences, 98 Daling Road, Nanning, Guangxi, 530007, China.
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3
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Guerrero M. GG. Sporulation, Structure Assembly, and Germination in the Soil Bacterium Bacillus thuringiensis: Survival and Success in the Environment and the Insect Host. MICROBIOLOGY RESEARCH 2023. [DOI: 10.3390/microbiolres14020035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a rod-shaped, Gram-positive soil bacterium that belongs to the phylum Firmicutes and the genus Bacillus. It is a spore-forming bacterium. During sporulation, it produces a wide range of crystalline proteins that are toxic to different orders of insects. Sporulation, structure assembly, and germination are essential stages in the cell cycle of B. thuringiensis. The majority of studies on these issues have focused on the model organism Bacillus subtilis, followed by Bacillus cereus and Bacillus anthracis. The machinery for sporulation and germination extrapolated to B. thuringiensis. However, in the light of recent findings concerning the role of the sporulation proteins (SPoVS), the germination receptors (Gr), and the cortical enzymes in Bt, the theory strengthened that conservation in sporulation, structure assembly, and germination programs drive the survival and success of B. thuringiensis in the environment and the insect host. In the present minireview, the latter pinpointed and reviewed.
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Affiliation(s)
- Gloria G. Guerrero M.
- Unidad Académica de Ciencias Biológicas, Laboratorio de Immunobiología, Universidad Autónoma de Zacatecas, Av. Preparatoria S/N, Col. Agronomicas, Zacatecas 98066, Mexico
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4
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Kruse S, Schenk M, Pierre F, Morlock GE. Bacillus subtilis spores in probiotic feed quantified via bacterial metabolite using planar chromatography. Anal Chim Acta 2022; 1221:340124. [DOI: 10.1016/j.aca.2022.340124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 05/15/2022] [Accepted: 06/23/2022] [Indexed: 11/01/2022]
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5
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Wu WJ, Chang J. Effect of oxygen on the germination and culturability of Bacillus atrophaeus spores. Int Microbiol 2022; 25:353-363. [PMID: 34993648 PMCID: PMC9132810 DOI: 10.1007/s10123-021-00229-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 11/15/2021] [Accepted: 12/14/2021] [Indexed: 11/23/2022]
Abstract
The effect of oxygen on the germination and culturability of aerobic Bacillus atrophaeus spores was investigated in this study. Under oxic or anoxic conditions, various nutritional and non-nutritional germinants were utilized to induce germination. Tb3+-dipicolinic acid fluorescence assay and phase-contrast microscopy were used to track the germination process. The final germination level, germination half time, and germination speed were used to define germination kinetics. Colony-forming unit enumeration was used to assess the culturability of germinated spores germinated with or without oxygen. The results show that in the absence of oxygen, the final germination level was unaffected, germination half time decreased by up to 35.0%, germination speed increased by up to 27.4%, and culturability decreased by up to 95.1%. It is suggested that oxygen affects some germinant receptor-dependent germination pathways, implying that biomolecules engaged in these pathways may be oxygen-sensitive. Furthermore, spores that have completed the germination process in either anoxic or oxic conditions may have different culturability. This research contributed to a better understanding of the fundamental mechanism of germination.
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Affiliation(s)
- Wen Jie Wu
- Department of Radiation Physics, The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer (IBMC), Chinese Academy of Sciences, Hangzhou, 310022, Zhejiang, China. .,Zhejiang Key Laboratory of Radiation Oncology, Hangzhou, 310022, Zhejiang, China.
| | - Jinhui Chang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China
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6
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Malyshev D, Dahlberg T, Wiklund K, Andersson PO, Henriksson S, Andersson M. Mode of Action of Disinfection Chemicals on the Bacterial Spore Structure and Their Raman Spectra. Anal Chem 2021; 93:3146-3153. [PMID: 33523636 PMCID: PMC7893628 DOI: 10.1021/acs.analchem.0c04519] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
Contamination of
toxic spore-forming bacteria is problematic since
spores can survive a plethora of disinfection chemicals and it is
hard to rapidly detect if the disinfection chemical has inactivated
the spores. Thus, robust decontamination strategies and reliable detection
methods to identify dead from viable spores are critical. In this
work, we investigate the chemical changes of Bacillus
thuringiensis spores treated with sporicidal agents
such as chlorine dioxide, peracetic acid, and sodium hypochlorite
using laser tweezers Raman spectroscopy. We also image treated spores
using SEM and TEM to verify if we can correlate structural changes
in the spores with changes to their Raman spectra. We found that over
30 min, chlorine dioxide did not change the Raman spectrum or the
spore structure, peracetic acid showed a time-dependent decrease in
the characteristic DNA/DPA peaks and ∼20% of the spores were
degraded and collapsed, and spores treated with sodium hypochlorite
showed an abrupt drop in DNA and DPA peaks within 20 min and some
structural damage to the exosporium. Structural changes appeared in
spores after 10 min, compared to the inactivation time of the spores,
which is less than a minute. We conclude that vibrational spectroscopy
provides powerful means to detect changes in spores but it might be
problematic to identify if spores are live or dead after a decontamination
procedure.
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Affiliation(s)
| | | | | | - Per Ola Andersson
- Swedish Defence Research Agency (FOI), Umeå, 906 21 Sweden.,Department of Engineering Sciences, Uppsala University, Box 35 751 03, Uppsala, Sweden
| | - Sara Henriksson
- Umeå Core Facility for Electron Microscopy, Umeå University, Umeå, 901 87 Sweden
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Kakagianni M, Chatzitzika C, Koutsoumanis KP, Valdramidis VP. The impact of high power ultrasound for controlling spoilage by Alicyclobacillus acidoterrestris: A population and a single spore assessment. INNOV FOOD SCI EMERG 2020. [DOI: 10.1016/j.ifset.2020.102405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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8
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Schottroff F, Pyatkovskyy T, Reineke K, Setlow P, Sastry SK, Jaeger H. Mechanisms of enhanced bacterial endospore inactivation during sterilization by ohmic heating. Bioelectrochemistry 2019; 130:107338. [PMID: 31377394 DOI: 10.1016/j.bioelechem.2019.107338] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 07/24/2019] [Accepted: 07/24/2019] [Indexed: 02/06/2023]
Abstract
During ohmic heating, the electric field may additionally inactivate bacterial endospores. However, the exact mechanism of action is unclear. Thus, a mechanistic study was carried out, investigating the possible target of electric fields inside the spore. Bacillus subtilis spores were heated by conventional and ohmic heating in a capillary system under almost identical thermal conditions. Wild-type (PS533) spores were used, as well as isogenic mutants lacking certain components known for their contribution to spores' heat resistance: small-acid soluble proteins (SASP) protecting DNA (PS578); the coat covering the spore (PS3328); and the spore germination enzyme SleB (FB122(+)). Treatment-dependent release of the spore core's depot of dipicolinic acid (DPA) was further evaluated. Up to 2.4 log10 additional inactivation of PS533 could be achieved by ohmic heating, compared to conventional heating. The difference varied for the mutants, with a decreasing difference indicating a decreased effect of the electric field and vice versa. In particular, mutant spores lacking SASPs showed a behavior more similar to thermal inactivation alone. The combination of heat and electric field was shown to be necessary for enhanced spore inactivation. Thus, it is hypothesized that either the heat treatment makes the spore susceptible to the electric field, or vice versa.
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Affiliation(s)
- Felix Schottroff
- Institute of Food Technology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria; Department of Food, Agricultural and Biological Engineering, Ohio State University, Columbus, OH, USA.
| | - Taras Pyatkovskyy
- Department of Food, Agricultural and Biological Engineering, Ohio State University, Columbus, OH, USA
| | | | - Peter Setlow
- Department of Molecular Biology and Biophysics, UCONN Health, Farmington, CT, USA
| | - Sudhir K Sastry
- Department of Food, Agricultural and Biological Engineering, Ohio State University, Columbus, OH, USA
| | - Henry Jaeger
- Institute of Food Technology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
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10
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Lopes RP, Mota MJ, Gomes AM, Delgadillo I, Saraiva JA. Application of High Pressure with Homogenization, Temperature, Carbon Dioxide, and Cold Plasma for the Inactivation of Bacterial Spores: A Review. Compr Rev Food Sci Food Saf 2018; 17:532-555. [PMID: 33350128 DOI: 10.1111/1541-4337.12311] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 08/29/2017] [Accepted: 09/01/2017] [Indexed: 12/18/2022]
Abstract
Formation of highly resistant spores is a concern for the safety of low-acid foods as they are a perfect vehicle for food spoilage and/or human infection. For spore inactivation, the strategy usually applied in the food industry is the intensification of traditional preservation methods to sterilization levels, which is often accompanied by decreases of nutritional and sensory properties. In order to overcome these unwanted side effects in food products, novel and emerging sterilization technologies are being developed, such as pressure-assisted thermal sterilization, high-pressure carbon dioxide, high-pressure homogenization, and cold plasma. In this review, the application of these emergent technologies is discussed, in order to understand the effects on bacterial spores and their inactivation and thus ensure food safety of low-acid foods. In general, the application of these novel technologies for inactivating spores is showing promising results. However, it is important to note that each technique has specific features that can be more suitable for a particular type of product. Thus, the most appropriate sterilization method for each product (and target microorganisms) should be assessed and carefully selected.
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Affiliation(s)
- Rita P Lopes
- QOPNA, Chemistry Dept., Univ. of Aveiro, Campus Univ. de Santiago, 3810-193 Aveiro, Portugal
| | - Maria J Mota
- QOPNA, Chemistry Dept., Univ. of Aveiro, Campus Univ. de Santiago, 3810-193 Aveiro, Portugal
| | - Ana M Gomes
- Escola Superior de Biotecnologia, Univ. Católica Portuguesa, 4200-072 Porto, Portugal
| | - Ivonne Delgadillo
- QOPNA, Chemistry Dept., Univ. of Aveiro, Campus Univ. de Santiago, 3810-193 Aveiro, Portugal
| | - Jorge A Saraiva
- QOPNA, Chemistry Dept., Univ. of Aveiro, Campus Univ. de Santiago, 3810-193 Aveiro, Portugal
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11
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Kakagianni M, Aguirre JS, Lianou A, Koutsoumanis KP. Effect of storage temperature on the lag time of Geobacillus stearothermophilus individual spores. Food Microbiol 2017. [PMID: 28648296 DOI: 10.1016/j.fm.2017.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The lag times (λ) of Geobacillus stearothermophilus single spores were studied at different storage temperatures ranging from 45 to 59 °C using the Bioscreen C method. A significant variability of λ was observed among individual spores at all temperatures tested. The storage temperature affected both the position and the spread of the λ distributions. The minimum mean value of λ (i.e. 10.87 h) was observed at 55 °C, while moving away from this temperature resulted in an increase for both the mean and standard deviation of λ. A Cardinal Model with Inflection (CMI) was fitted to the reverse mean λ, and the estimated values for the cardinal parameters Tmin, Tmax, Topt and the optimum mean λ of G. stearothermophilus were found to be 38.1, 64.2, 53.6 °C and 10.3 h, respectively. To interpret the observations, a probabilistic growth model for G. stearothermophilus individual spores, taking into account λ variability, was developed. The model describes the growth of a population, initially consisting of N0 spores, over time as the sum of cells in each of the N0 imminent subpopulations originating from a single spore. Growth simulations for different initial contamination levels showed that for low N0 the number of cells in the population at any time is highly variable. An increase in N0 to levels exceeding 100 spores results in a significant decrease of the above variability and a shorter λ of the population. Considering that the number of G. stearothermophilus surviving spores in the final product is usually very low, the data provided in this work can be used to evaluate the probability distribution of the time-to-spoilage and enable decision-making based on the "acceptable level of risk".
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Affiliation(s)
- Myrsini Kakagianni
- Laboratory of Food Microbiology and Hygiene, Department of Food Science and Technology, School of Agriculture, Faculty of Agriculture, Forestry and Natural Environment, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Juan S Aguirre
- Laboratorio de Microbiología y Probioticos, INTA, Universidad de Chile, Avenida El Líbano 5524, Macul, Santiago, Chile
| | - Alexandra Lianou
- Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science and Human Nutrition, School of Food, Biotechnology and Development, Agricultural University of Athens, Iera Odos 75, Athens 11855, Greece
| | - Konstantinos P Koutsoumanis
- Laboratory of Food Microbiology and Hygiene, Department of Food Science and Technology, School of Agriculture, Faculty of Agriculture, Forestry and Natural Environment, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
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12
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Piktel E, Pogoda K, Savage PB, Bucki R. The search for new sporicidal agents for medical use: where are we? Future Microbiol 2017; 12:735-737. [PMID: 28593804 DOI: 10.2217/fmb-2017-0069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Ewelina Piktel
- Department of Microbiological & Nanobiomedical Engineering, Medical University of Białystok, Białystok, Poland
| | - Katarzyna Pogoda
- Institute of Nuclear Physics, Polish Academy of Sciences, PL31342 Kraków, Poland
| | - Paul B Savage
- Department of Chemistry & Biochemistry, Brigham Young University, Provo, UT 84604, USA
| | - Robert Bucki
- Department of Microbiological & Nanobiomedical Engineering, Medical University of Białystok, Białystok, Poland
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13
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Changes in Bacillus Spore Small Molecules, rRNA, Germination, and Outgrowth after Extended Sublethal Exposure to Various Temperatures: Evidence that Protein Synthesis Is Not Essential for Spore Germination. J Bacteriol 2016; 198:3254-3264. [PMID: 27645383 DOI: 10.1128/jb.00583-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 09/08/2016] [Indexed: 11/20/2022] Open
Abstract
rRNAs of dormant spores of Bacillus subtilis were >95% degraded during extended incubation at 50°C, as reported previously (E. Segev, Y. Smith, and S. Ben-Yehuda, Cell 148:139-114, 2012, doi:http://dx.doi.org/10.1016/j.cell.2011.11.059), and this was also true of spores of Bacillus megaterium Incubation of spores of these two species for ∼20 h at 75 to 80°C also resulted in the degradation of all or the great majority of the 23S and 16S rRNAs, although this rRNA degradation was slower than nonenzymatic hydrolysis of purified rRNAs at these temperatures. This rRNA degradation at high temperature generated almost exclusively oligonucleotides with minimal levels of mononucleotides. RNase Y, suggested to be involved in rRNA hydrolysis during B. subtilis spore incubation at 50°C, did not play a role in B. subtilis spore rRNA breakdown at 80°C. Twenty hours of incubation of Bacillus spores at 70°C also decreased the already minimal levels of ATP in dormant spores 10- to 30-fold, to ≤0.01% of the total free adenine nucleotide levels. Spores depleted of rRNA were viable and germinated relatively normally, often even faster than starting spores. Their return to vegetative growth was also similar to that of untreated spores for B. megaterium spores and slower for heat-treated B. subtilis spores; accumulation of rRNA took place only after completion of spore germination. These findings thus strongly suggest that protein synthesis is not essential for Bacillus spore germination.IMPORTANCE A recent report (L. Sinai, A. Rosenberg, Y. Smith, E. Segev, and S. Ben-Yehuda, Mol Cell 57:3486-3495, 2015, doi:http://dx.doi.org/10.1016/j.molcel.2014.12.019) suggested that protein synthesis is essential for early steps in the germination of dormant spores of Bacillus subtilis If true, this would be a paradigm shift in our understanding of spore germination. We now show that essentially all of the rRNA can be eliminated from spores of Bacillus megaterium or B. subtilis, and these rRNA-depleted spores are viable and germinate as well as or better than spores with normal rRNA levels. Thus, protein synthesis is not required in the process of spore germination.
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Effects of High-Pressure Treatment on Spores of Clostridium Species. Appl Environ Microbiol 2016; 82:5287-97. [PMID: 27316969 PMCID: PMC4988188 DOI: 10.1128/aem.01363-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/15/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED This work analyzes the high-pressure (HP) germination of spores of the food-borne pathogen Clostridium perfringens (with inner membrane [IM] germinant receptors [GRs]) and the opportunistic pathogen Clostridium difficile (with no IM GRs), which has growing implications as an emerging food safety threat. In contrast to those of spores of Bacillus species, mechanisms of HP germination of clostridial spores have not been well studied. HP treatments trigger Bacillus spore germination through spores' IM GRs at ∼150 MPa or through SpoVA channels for release of spores' dipicolinic acid (DPA) at ≥400 MPa, and DPA-less spores have lower wet heat resistance than dormant spores. We found that C. difficile spores exhibited no germination events upon 150-MPa treatment and were not heat sensitized. In contrast, 150-MPa-treated unactivated C. perfringens spores released DPA and became heat sensitive, although most spores did not complete germination by fully rehydrating the spore core, but this treatment of heat-activated spores led to almost complete germination and greater heat sensitization. Spores of both clostridial organisms released DPA during 550-MPa treatment, but C. difficile spores did not complete germination and remained heat resistant. Heat-activated 550-MPa-HP-treated C. perfringens spores germinated almost completely and became heat sensitive. However, unactivated 550-MPa-treated C. perfringens spores did not germinate completely and were less heat sensitive than spores that completed germination. Since C. difficile and C. perfringens spores use different mechanisms for sensing germinants, our results may allow refinement of HP methods for their inactivation in foods and other applications and may guide the development of commercially sterile low-acid foods. IMPORTANCE Spores of various clostridial organisms cause human disease, sometimes due to food contamination by spores. Because of these spores' resistance to normal decontamination regimens, there is continued interest in ways to kill spores without compromising food quality. High hydrostatic pressure (HP) under appropriate conditions can inactivate bacterial spores. With growing use of HP for food pasteurization, advancement of HP for commercial production of sterile low-acid foods requires understanding of mechanisms of spores' interactions with HP. While much is known about HP germination and inactivation of spores of Bacillus species, how HP germinates and inactivates clostridial spores is less well understood. In this work we have tried to remedy this information deficit by examining germination of spores of Clostridium difficile and Clostridium perfringens by several HP and temperature levels. The results may give insight that could facilitate more efficient methods for spore eradication in food sterilization or pasteurization, biodecontamination, and health care.
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15
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Wells-Bennik MH, Eijlander RT, den Besten HM, Berendsen EM, Warda AK, Krawczyk AO, Nierop Groot MN, Xiao Y, Zwietering MH, Kuipers OP, Abee T. Bacterial Spores in Food: Survival, Emergence, and Outgrowth. Annu Rev Food Sci Technol 2016; 7:457-82. [DOI: 10.1146/annurev-food-041715-033144] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marjon H.J. Wells-Bennik
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- NIZO Food Research, 6718 ZB Ede, The Netherlands;
| | - Robyn T. Eijlander
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- NIZO Food Research, 6718 ZB Ede, The Netherlands;
| | - Heidy M.W. den Besten
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Erwin M. Berendsen
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- NIZO Food Research, 6718 ZB Ede, The Netherlands;
- Molecular Genetics Department, University of Groningen, 9700 AB Groningen, The Netherlands
| | - Alicja K. Warda
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Wageningen UR Food & Biobased Research, 6700 AA Wageningen, The Netherlands
| | - Antonina O. Krawczyk
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Molecular Genetics Department, University of Groningen, 9700 AB Groningen, The Netherlands
| | - Masja N. Nierop Groot
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Wageningen UR Food & Biobased Research, 6700 AA Wageningen, The Netherlands
| | - Yinghua Xiao
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Marcel H. Zwietering
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Oscar P. Kuipers
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Molecular Genetics Department, University of Groningen, 9700 AB Groningen, The Netherlands
| | - Tjakko Abee
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
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16
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Redding B, Schwab M, Pan YL. Raman Spectroscopy of Optically Trapped Single Biological Micro-Particles. SENSORS 2015; 15:19021-46. [PMID: 26247952 PMCID: PMC4570358 DOI: 10.3390/s150819021] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 06/30/2015] [Accepted: 07/27/2015] [Indexed: 12/20/2022]
Abstract
The combination of optical trapping with Raman spectroscopy provides a powerful method for the study, characterization, and identification of biological micro-particles. In essence, optical trapping helps to overcome the limitation imposed by the relative inefficiency of the Raman scattering process. This allows Raman spectroscopy to be applied to individual biological particles in air and in liquid, providing the potential for particle identification with high specificity, longitudinal studies of changes in particle composition, and characterization of the heterogeneity of individual particles in a population. In this review, we introduce the techniques used to integrate Raman spectroscopy with optical trapping in order to study individual biological particles in liquid and air. We then provide an overview of some of the most promising applications of this technique, highlighting the unique types of measurements enabled by the combination of Raman spectroscopy with optical trapping. Finally, we present a brief discussion of future research directions in the field.
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Affiliation(s)
- Brandon Redding
- U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783, USA.
| | - Mark Schwab
- U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783, USA.
| | - Yong-le Pan
- U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783, USA.
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17
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Huser T, Chan J. Raman spectroscopy for physiological investigations of tissues and cells. Adv Drug Deliv Rev 2015; 89:57-70. [PMID: 26144996 DOI: 10.1016/j.addr.2015.06.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 06/08/2015] [Accepted: 06/26/2015] [Indexed: 12/29/2022]
Abstract
Raman micro-spectroscopy provides a convenient non-destructive and location-specific means of probing cellular physiology and tissue physiology at sub-micron length scales. By probing the vibrational signature of molecules and molecular groups, the distribution and metabolic products of small molecules that cannot be labeled with fluorescent dyes can be analyzed. This method works well for molecular concentrations in the micro-molar range and has been demonstrated as a valuable tool for monitoring drug-cell interactions. If the small molecule of interest does not contain groups that would allow for a discrimination against cytoplasmic background signals, "labeling" of the molecule by isotope substitution or by incorporating other unique small groups, e.g. alkynes provides a stable signal even for time-lapse imaging such compounds in living cells. In this review we highlight recent progress in assessing the physiology of cells and tissue by Raman spectroscopy and imaging.
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Meaney CA, Cartman ST, McClure PJ, Minton NP. Optimal spore germination in Clostridium botulinum ATCC 3502 requires the presence of functional copies of SleB and YpeB, but not CwlJ. Anaerobe 2015; 34:86-93. [PMID: 25937262 DOI: 10.1016/j.anaerobe.2015.04.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/10/2015] [Accepted: 04/28/2015] [Indexed: 10/23/2022]
Abstract
Germination, the process by which dormant endospores return to vegetative growth, is a critical process in the life cycle of the notorious pathogen Clostridium botulinum. Crucial is the degradation by hydrolytic enzymes of an inner peptidoglycan spore layer termed the cortex. Two mechanistically different systems of cortex lysis exist in spores of Clostridium species. C. botulinum ATCC 3502 harbours the Bacillus-like system of SleB, CwlJ and YpeB cortex lytic enzymes (CLEs). Through the construction of insertional gene knockout mutants in the sleB, cwlJ and ypeB genes of C. botulinum ATCC 3502 and the production of spores of each mutant strain, the effect on germination was assessed. This study demonstrates a reduced germination efficiency in spores carrying mutations in either sleB or ypeB with an approximate 2-fold reduction in heat resistant colony forming units (CFU/OD600) when plated on rich media. This reduction could be restored to wild-type levels by removing the spore coat and plating on media supplemented with lysozyme. It was observed that cwlJ spores displayed a similar germination efficiency as wild-type spores (P > 0.05). An optimal germinant commixture was identified to include a combination of l-alanine with sodium bicarbonate as it resulted in a 32% drop in OD600, while the additional incorporation of l-lactate resulted in a 57% decrease. Studies of the germination efficiency of spores prepared from all three CLE mutants was performed by monitoring the associated decrease in optical density but a germination defect was not observed in any of the CLE mutant strains. This was likely due to the lack of specificity of this particular assay. Taken together, these data indicate that functional copies of SleB and YpeB, but not CwlJ are required for the optimal germination of the spores of C. botulinum ATCC 3502.
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Affiliation(s)
- Carolyn A Meaney
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Stephen T Cartman
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | | | - Nigel P Minton
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK.
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Location and stoichiometry of the protease CspB and the cortex-lytic enzyme SleC in Clostridium perfringens spores. Food Microbiol 2015; 50:83-7. [PMID: 25998819 DOI: 10.1016/j.fm.2015.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 11/22/2022]
Abstract
The protease CspB and the cortex-lytic enzyme SleC are essential for peptoglycan cortex hydrolysis during germination of spores of the Clostridium perfringens food poisoning isolate SM101. In this study, Western blot analyses were used to demonstrate that CspB and SleC are present exclusively in the C. perfringens SM101 spore coat layer fraction and absent in the lysate from decoated spores and from the purified inner spore membrane. These results indicate why decoating treatments greatly reduce both germination and apparent viability of C. perfringens spores in the absence of an exogenous lytic enzyme. In addition, quantitative Western blot analyses showed that there are approximately 2000 and 130,000 molecules of CspB and pro-SleC, respectively, per C. perfringens SM101 spore, consistent with CspB's role in acting catalytically on pro-SleC to convert this zymogen to the active enzyme.
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20
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Slow leakage of Ca-dipicolinic acid from individual bacillus spores during initiation of spore germination. J Bacteriol 2015; 197:1095-103. [PMID: 25583976 DOI: 10.1128/jb.02490-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When exposed to nutrient or nonnutrient germinants, individual Bacillus spores can return to life through germination followed by outgrowth. Laser tweezers, Raman spectroscopy, and either differential interference contrast or phase-contrast microscopy were used to analyze the slow dipicolinic acid (DPA) leakage (normally ∼20% of spore DPA) from individual spores that takes place prior to the lag time, Tlag, when spores begin rapid release of remaining DPA. Major conclusions from this work with Bacillus subtilis spores were as follows: (i) slow DPA leakage from wild-type spores germinating with nutrients did not begin immediately after nutrient exposure but only at a later heterogeneous time T1; (ii) the period of slow DPA leakage (ΔTleakage = Tlag - T1) was heterogeneous among individual spores, although the amount of DPA released in this period was relatively constant; (iii) increases in germination temperature significantly decreased T1 times but increased values of ΔTleakage; (iv) upon germination with l-valine for 10 min followed by addition of d-alanine to block further germination, all germinated spores had T1 times of less than 10 min, suggesting that T1 is the time when spores become committed to germinate; (v) elevated levels of SpoVA proteins involved in DPA movement in spore germination decreased T1 and Tlag times but not the amount of DPA released in ΔTleakage; (vi) lack of the cortex-lytic enzyme CwlJ increased DPA leakage during germination due to longer ΔTleakage times in which more DPA was released; and (vii) there was slow DPA leakage early in germination of B. subtilis spores by the nonnutrients CaDPA and dodecylamine and in nutrient germination of Bacillus cereus and Bacillus megaterium spores. Overall, these findings have identified and characterized a new early event in Bacillus spore germination.
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21
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Angle-resolved light scattering of individual rod-shaped bacteria based on Fourier transform light scattering. Sci Rep 2014; 4:5090. [PMID: 24867385 PMCID: PMC4035574 DOI: 10.1038/srep05090] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/16/2014] [Indexed: 12/02/2022] Open
Abstract
Two-dimensional angle-resolved light scattering maps of individual rod-shaped bacteria are measured at the single-cell level. Using quantitative phase imaging and Fourier transform light scattering techniques, the light scattering patterns of individual bacteria in four rod-shaped species (Bacillus subtilis, Lactobacillus casei, Synechococcus elongatus, and Escherichia coli) are measured with unprecedented sensitivity in a broad angular range from −70° to 70°. The measured light scattering patterns are analyzed along the two principal axes of rod-shaped bacteria in order to systematically investigate the species-specific characteristics of anisotropic light scattering. In addition, the cellular dry mass of individual bacteria is calculated and used to demonstrate that the cell-to-cell variations in light scattering within bacterial species is related to the cellular dry mass and growth.
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23
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Analysis of the loss in heat and acid resistance during germination of spores of Bacillus species. J Bacteriol 2014; 196:1733-40. [PMID: 24563034 DOI: 10.1128/jb.01555-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A major event in the nutrient germination of spores of Bacillus species is release of the spores' large depot of dipicolinic acid (DPA). This event is preceded by both commitment, in which spores continue through germination even if germinants are removed, and loss of spore heat resistance. The latter event is puzzling, since spore heat resistance is due largely to core water content, which does not change until DPA is released during germination. We now find that for spores of two Bacillus species, the early loss in heat resistance during germination is most likely due to release of committed spores' DPA at temperatures not lethal for dormant spores. Loss in spore acid resistance during germination also paralleled commitment and was also associated with the release of DPA from committed spores at acid concentrations not lethal for dormant spores. These observations plus previous findings that DPA release during germination is preceded by a significant release of spore core cations suggest that there is a significant change in spore inner membrane permeability at commitment. Presumably, this altered membrane cannot retain DPA during heat or acid treatments innocuous for dormant spores, resulting in DPA-less spores that are rapidly killed.
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Abstract
Spores of Bacillus species can remain in their dormant and resistant states for years, but exposure to agents such as specific nutrients can cause spores' return to life within minutes in the process of germination. This process requires a number of spore-specific proteins, most of which are in or associated with the inner spore membrane (IM). These proteins include the (i) germinant receptors (GRs) that respond to nutrient germinants, (ii) GerD protein, which is essential for GR-dependent germination, (iii) SpoVA proteins that form a channel in spores' IM through which the spore core's huge depot of dipicolinic acid is released during germination, and (iv) cortex-lytic enzymes (CLEs) that degrade the large peptidoglycan cortex layer, allowing the spore core to take up much water and swell, thus completing spore germination. While much has been learned about nutrient germination, major questions remain unanswered, including the following. (i) How do nutrient germinants penetrate through spores' outer layers to access GRs in the IM? (ii) What happens during the highly variable and often long lag period between the exposure of spores to nutrient germinants and the commitment of spores to germinate? (iii) What do GRs and GerD do, and how do these proteins interact? (iv) What is the structure of the SpoVA channel in spores' IM, and how is this channel gated? (v) What is the precise state of the spore IM, which has a number of novel properties even though its lipid composition is very similar to that of growing cells? (vi) How is CLE activity regulated such that these enzymes act only when germination has been initiated? (vii) And finally, how does the germination of spores of clostridia compare with that of spores of bacilli?
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25
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Monitoring rates and heterogeneity of high-pressure germination of bacillus spores by phase-contrast microscopy of individual spores. Appl Environ Microbiol 2013; 80:345-53. [PMID: 24162576 DOI: 10.1128/aem.03043-13] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Germination of Bacillus spores with a high pressure (HP) of ∼150 MPa is via activation of spores' germinant receptors (GRs). The HP germination of multiple individual Bacillus subtilis spores in a diamond anvil cell (DAC) was monitored with phase-contrast microscopy. Major conclusions were that (i) >95% of wild-type spores germinated in 40 min in a DAC at ∼150 MPa and 37°C but individual spores' germination kinetics were heterogeneous; (ii) individual spores' HP germination kinetic parameters were similar to those of nutrient-triggered germination with a variable lag time (Tlag) prior to a period of the rapid release (ΔTrelease) of the spores' dipicolinic acid in a 1:1 chelate with Ca(2+) (CaDPA); (iii) spore germination at 50 MPa had longer average Tlag values than that at ∼150 MPa, but the ΔTrelease values at the two pressures were identical and HPs of <10 MPa did not induce germination; (iv) B. subtilis spores that lacked the cortex-lytic enzyme CwlJ and that were germinated with an HP of 150 MPa exhibited average ΔTrelease values ∼15-fold longer than those for wild-type spores, but the two types of spores exhibited similar average Tlag values; and (v) the germination of wild-type spores given a ≥30-s 140-MPa HP pulse followed by a constant pressure of 1 MPa was the same as that of spores exposed to a constant pressure of 140 MPa that was continued for ≥35 min; (vi) however, after short 150-MPa HP pulses and incubation at 0.1 MPa (ambient pressure), spore germination stopped 5 to 10 min after the HP was released. These results suggest that an HP of ∼150 MPa for ≤30 s is sufficient to fully activate spores' GRs, which remain activated at 1 MPa but can deactivate at ambient pressure.
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26
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Setlow P. Summer meeting 2013 - when the sleepers wake: the germination of spores of Bacillus
species. J Appl Microbiol 2013; 115:1251-68. [DOI: 10.1111/jam.12343] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/08/2013] [Accepted: 09/09/2013] [Indexed: 11/27/2022]
Affiliation(s)
- P. Setlow
- Department of Molecular, Microbial and Structural Biology; University of Connecticut Health Center; Farmington CT USA
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27
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Zhou T, Dong Z, Setlow P, Li YQ. Kinetics of germination of individual spores of Geobacillus stearothermophilus as measured by raman spectroscopy and differential interference contrast microscopy. PLoS One 2013; 8:e74987. [PMID: 24058645 PMCID: PMC3772816 DOI: 10.1371/journal.pone.0074987] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 08/07/2013] [Indexed: 11/19/2022] Open
Abstract
Geobacillus stearothermophilus is a gram-positive, thermophilic bacterium, spores of which are very heat resistant. Raman spectroscopy and differential interference contrast microscopy were used to monitor the kinetics of germination of individual spores of G. stearothermophilus at different temperatures, and major conclusions from this work were as follows. 1) The CaDPA level of individual G. stearothermophilus spores was similar to that of Bacillus spores. However, the Raman spectra of protein amide bands suggested there are differences in protein structure in spores of G. stearothermophilus and Bacillus species. 2) During nutrient germination of G. stearothermophilus spores, CaDPA was released beginning after a lag time (Tlag) between addition of nutrient germinants and initiation of CaDPA release. CaDPA release was complete at Trelease, and ΔTrelease (Trelease – Tlag) was 1–2 min. 3) Activation by heat or sodium nitrite was essential for efficient nutrient germination of G. stearothermophilus spores, primarily by decreasing Tlag values. 4) Values of Tlag and Trelease were heterogeneous among individual spores, but ΔTrelease values were relatively constant. 5) Temperature had major effects on nutrient germination of G. stearothermophilus spores, as at temperatures below 65°C, average Tlag values increased significantly. 6) G. stearothermophilus spore germination with exogenous CaDPA or dodecylamine was fastest at 65°C, with longer Tlag values at lower temperatures. 7) Decoating of G. stearothermophilus spores slowed nutrient germination slightly and CaDPA germination significantly, but increased dodecylamine germination markedly. These results indicate that the dynamics and heterogeneity of the germination of individual G. stearothermophilus spores are generally similar to that of Bacillus species.
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Affiliation(s)
- Tingting Zhou
- Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Department of Physics, East Carolina University, Greenville, North Carolina, United States of America
| | - Zhiyang Dong
- Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Peter Setlow
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Yong-qing Li
- Department of Physics, East Carolina University, Greenville, North Carolina, United States of America
- * E-mail:
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28
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Setlow B, Yu J, Li YQ, Setlow P. Analysis of the germination kinetics of individual Bacillus subtilis
spores treated with hydrogen peroxide or sodium hypochlorite. Lett Appl Microbiol 2013; 57:259-65. [DOI: 10.1111/lam.12113] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/04/2013] [Accepted: 06/04/2013] [Indexed: 11/28/2022]
Affiliation(s)
- B. Setlow
- Department of Molecular; Microbial and Structural Biology; University of Connecticut Health Center; Farmington CT USA
| | - J. Yu
- Department of Physics; East Carolina University; Greeneville NC USA
| | - Y.-Q. Li
- Department of Physics; East Carolina University; Greeneville NC USA
| | - P. Setlow
- Department of Molecular; Microbial and Structural Biology; University of Connecticut Health Center; Farmington CT USA
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29
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Activity and regulation of various forms of CwlJ, SleB, and YpeB proteins in degrading cortex peptidoglycan of spores of Bacillus species in vitro and during spore germination. J Bacteriol 2013; 195:2530-40. [PMID: 23543708 DOI: 10.1128/jb.00259-13] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Germination of Bacillus spores requires degradation of a modified layer of peptidoglycan (PG) termed the spore cortex by two redundant cortex-lytic enzymes (CLEs), CwlJ and SleB, plus SleB's partner protein, YpeB. In this study, in vitro and in vivo analyses have been used to clarify the roles of individual SleB and YpeB domains in PG degradation. Purified mature Bacillus cereus SleB without its signal sequence (SleB(M)) and the SleB C-terminal catalytic domain (SleB(C)) efficiently triggered germination of decoated Bacillus megaterium and Bacillus subtilis spores lacking endogenous CLEs; previously, SleB's N-terminal domain (SleB(N)) was shown to bind PG but have no enzymatic activity. YpeB lacking its putative membrane anchoring sequence (YpeB(M)) or its N- and C-terminal domains (YpeB(N) and YpeB(C)) alone did not exhibit degradative activity, but YpeB(N) inhibited SleB(M) and SleB(C) activity in vitro. The severe germination defect of B. subtilis cwlJ sleB or cwlJ sleB ypeB spores was complemented by ectopic expression of full-length sleB [sleB(FL)] and ypeB [ypeB(FL)], but normal levels of SleB(FL) in spores required normal spore levels of YpeB(FL) and vice versa. sleB(FL) or ypeB(FL) alone, sleB(FL) plus ypeB(C) or ypeB(N), and sleB(C) or sleB(N) plus ypeB(FL) did not complement the cortex degradation defect in cwlJ sleB ypeB spores. In addition, ectopic expression of sleB(FL) or cwlJ(FL) with a Glu-to-Gln mutation in a predicted active-site residue failed to restore the germination of cwlJ sleB spores, supporting the role of this invariant glutamate as the key catalytic residue in SleB and CwlJ.
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Expression level of Bacillus subtilis germinant receptors determines the average rate but not the heterogeneity of spore germination. J Bacteriol 2013; 195:1735-40. [PMID: 23396907 DOI: 10.1128/jb.02212-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Germination of Bacillus subtilis spores can be triggered by the binding of specific nutrients, called germinants, to germinant receptors (GRs) in the spore's inner membrane. This interaction eventually initiates, with variable time delays, the release of dipicolinic acid and cations from the spore core--a key step in spore germination. The kinetics of this process are highly heterogeneous for individual spores. In this work, we sought to investigate how the germination heterogeneity was controlled. In particular, we tested whether the rates of germination were determined by GR levels, which vary from spore to spore due to stochastic gene expression. Both the expression levels of GRs and the germination rate were measured in single spores, and the experimental results were compared to theoretical predictions. Our results indicated that the variation in the expression levels of GRs was not the primary factor that controls spore germination heterogeneity. Two alternative hypotheses are discussed in light of this experimental discovery.
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Perez-Valdespino A, Ghosh S, Cammett EP, Kong L, Li YQ, Setlow P. Isolation and characterization of Bacillus subtilis spores that are superdormant for germination with dodecylamine or Ca2+ -dipicolinic acid. J Appl Microbiol 2013; 114:1109-19. [PMID: 23289722 DOI: 10.1111/jam.12125] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 12/24/2012] [Accepted: 12/28/2012] [Indexed: 11/30/2022]
Abstract
AIMS To isolate and characterize spores superdormant (SD) for germination with either Ca(2+)-dipicolinic acid (CaDPA) or dodecylamine. METHODS AND RESULTS Bacillus subtilis spores were germinated three times with either CaDPA or dodecylamine and germinated spores removed after each germination treatment, yielding 0.9% (CaDPA-SD spores) or 0.4% (dodecylamine-SD spores) of initial dormant spores. Compared to dormant spores, CaDPA-SD spores germinated poorly with CaDPA and better with dodecylamine and nutrient germinants, although release of DPA from individual CaDPA-SD spores was slow during nutrient germination, and this germination was strongly inhibited by TbCl3. The CaDPA-SD spores were sensitive to hypochlorite and had elevated levels of nutrient germinant receptors (GRs) relative to levels in dormant spores. Dodecylamine-SD spores' germination with dodecylamine and nutrients was similar to that of dormant spores, their germination with Ca-DPA was slower than that of dormant spores, and these SD spores' GR levels were lower than in dormant spores. However, dodecylamine-SD spores were not sensitive to hypochlorite, and the nutrient germination of these SD spores was only partially inhibited by TbCl3 . CONCLUSIONS CaDPA-SD spores appear to have a coat defect and accompanying low levels of the cortex-lytic enzyme CwlJ. The defect in dodecylamine-SD spores, however, is not clear. SIGNIFICANCE AND IMPACT OF THE STUDY The results suggest that triggering germination by non-GR-dependent germinants is a potential strategy for efficient spore inactivation.
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Affiliation(s)
- A Perez-Valdespino
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, CT 06030-3305, USA
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Chan JW. Recent advances in laser tweezers Raman spectroscopy (LTRS) for label-free analysis of single cells. JOURNAL OF BIOPHOTONICS 2013; 6:36-48. [PMID: 23175434 DOI: 10.1002/jbio.201200143] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 10/15/2012] [Accepted: 10/28/2012] [Indexed: 05/19/2023]
Abstract
Laser tweezers Raman spectroscopy (LTRS), a technique that integrates optical tweezers with confocal Raman spectroscopy, is a variation of micro-Raman spectroscopy that enables the manipulation and biochemical analysis of single biological particles in suspension. This article provides an overview of the LTRS method, with an emphasis on highlighting recent advances over the past several years in the development of the technology and several new biological and biomedical applications that have been demonstrated. A perspective on the future developments of this powerful cytometric technology will also be presented.
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Affiliation(s)
- James W Chan
- Department of Pathology and Laboratory Medicine, University of California, Davis, Sacramento, CA 95817, USA.
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33
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Butzin XY, Troiano AJ, Coleman WH, Griffiths KK, Doona CJ, Feeherry FE, Wang G, Li YQ, Setlow P. Analysis of the effects of a gerP mutation on the germination of spores of Bacillus subtilis. J Bacteriol 2012; 194:5749-58. [PMID: 22904285 PMCID: PMC3486119 DOI: 10.1128/jb.01276-12] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 08/08/2012] [Indexed: 12/28/2022] Open
Abstract
As previously reported, gerP Bacillus subtilis spores were defective in nutrient germination triggered via various germinant receptors (GRs), and the defect was eliminated by severe spore coat defects. The gerP spores' GR-dependent germination had a longer lag time between addition of germinants and initiation of rapid release of spores' dipicolinic acid (DPA), but times for release of >90% of DPA from individual spores were identical for wild-type and gerP spores. The gerP spores were also defective in GR-independent germination by DPA with its associated Ca(2+) divalent cation (CaDPA) but germinated better than wild-type spores with the GR-independent germinant dodecylamine. The gerP spores exhibited no increased sensitivity to hypochlorite, suggesting that these spores have no significant coat defect. Overexpression of GRs in gerP spores did lead to faster germination via the overexpressed GR, but this was still slower than germination of comparable gerP(+) spores. Unlike wild-type spores, for which maximal nutrient germinant concentrations were between 500 μM and 2 mM for l-alanine and ≤10 mM for l-valine, rates of gerP spore germination increased up to between 200 mM and 1 M l-alanine and 100 mM l-valine, and at 1 M l-alanine, the rates of germination of wild-type and gerP spores with or without all alanine racemases were almost identical. A high pressure of 150 MPa that triggers spore germination by activating GRs also triggered germination of wild-type and gerP spores identically. All these results support the suggestion that GerP proteins facilitate access of nutrient germinants to their cognate GRs in spores' inner membrane.
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Affiliation(s)
- Xuan Yi Butzin
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Anthony J. Troiano
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - William H. Coleman
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Keren K. Griffiths
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Christopher J. Doona
- U.S. Army—Natick Soldier RD&E Center, Warfighter Directorate, Natick, Massachusetts, USA
| | - Florence E. Feeherry
- U.S. Army—Natick Soldier RD&E Center, Warfighter Directorate, Natick, Massachusetts, USA
| | - Guiwen Wang
- Department of Physics, East Carolina University, Greenville, North Carolina, USA
| | - Yong-qing Li
- Department of Physics, East Carolina University, Greenville, North Carolina, USA
| | - Peter Setlow
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
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Wang G, Paredes-Sabja D, Sarker M, Green C, Setlow P, Li YQ. Effects of wet heat treatment on the germination of individual spores of Clostridium perfringens. J Appl Microbiol 2012; 113:824-36. [DOI: 10.1111/j.1365-2672.2012.05387.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 07/01/2012] [Accepted: 07/03/2012] [Indexed: 11/30/2022]
Affiliation(s)
- G. Wang
- Department of Physics; East Carolina University; Greenville; NC; USA
| | | | - M.R. Sarker
- Departments of Biomedical Sciences and Microbiology; Oregon State University; Corvallis; OR; USA
| | - C. Green
- Department of Molecular, Microbial and Structural Biology; University of Connecticut Health Center; Farmington; CT; USA
| | - P. Setlow
- Department of Molecular, Microbial and Structural Biology; University of Connecticut Health Center; Farmington; CT; USA
| | - Y-q. Li
- Department of Physics; East Carolina University; Greenville; NC; USA
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35
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MENG LJ, LIN MM, NIU LY, LIU JX, WANG HJ, YAO HL. Raman Spectroscopic Analysis of Single Red Blood Cells in Vivo Rat. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2012. [DOI: 10.3724/sp.j.1096.2011.01394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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36
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Role of a SpoVA protein in dipicolinic acid uptake into developing spores of Bacillus subtilis. J Bacteriol 2012; 194:1875-84. [PMID: 22328679 DOI: 10.1128/jb.00062-12] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The proteins encoded by the spoVA operon, including SpoVAD, are essential for the uptake of the 1:1 chelate of pyridine-2,6-dicarboxylic acid (DPA(2,6)) and Ca(2+) into developing spores of the bacterium Bacillus subtilis. The crystal structure of B. subtilis SpoVAD has been determined recently, and a structural homology search revealed that SpoVAD shares significant structural similarity but not sequence homology to a group of enzymes that bind to and/or act on small aromatic molecules. We find that molecular docking placed DPA(2,6) exclusively in a highly conserved potential substrate-binding pocket in SpoVAD that is similar to that in the structurally homologous enzymes. We further demonstrate that SpoVAD binds both DPA(2,6) and Ca(2+)-DPA(2,6) with a similar affinity, while exhibiting markedly weaker binding to other DPA isomers. Importantly, mutations of conserved amino acid residues in the putative DPA(2,6)-binding pocket in SpoVAD essentially abolish its DPA(2,6)-binding capacity. Moreover, replacement of the wild-type spoVAD gene in B. subtilis with any of these spoVAD gene variants effectively eliminated DPA(2,6) uptake into developing spores in sporulation, although the variant proteins were still located in the spore inner membrane. Our results provide direct evidence that SpoVA proteins, in particular SpoVAD, are directly involved in DPA(2,6) movement into developing B. subtilis spores.
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Zhang P, Kong L, Wang G, Scotland M, Ghosh S, Setlow B, Setlow P, Li YQ. Analysis of the slow germination of multiple individual superdormant Bacillus subtilis spores using multifocus Raman microspectroscopy and differential interference contrast microscopy. J Appl Microbiol 2012; 112:526-36. [DOI: 10.1111/j.1365-2672.2011.05230.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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38
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Cheng HW, Huan SY, Yu RQ. Nanoparticle-based substrates for surface-enhanced Raman scattering detection of bacterial spores. Analyst 2012; 137:3601-8. [DOI: 10.1039/c2an35448a] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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39
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Effects of cortex peptidoglycan structure and cortex hydrolysis on the kinetics of Ca(2+)-dipicolinic acid release during Bacillus subtilis spore germination. J Bacteriol 2011; 194:646-52. [PMID: 22123250 DOI: 10.1128/jb.06452-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The kinetic parameters of the release of Ca(2+)-dipicolinic acid (CaDPA) during germination of spore populations and multiple individual spores of Bacillus subtilis strains with major alterations in the structure of the spore peptidoglycan (PG) cortex or lacking one or both of the two redundant enzymes involved in cortex hydrolysis (cortex-lytic enzymes [CLEs]) were determined. The lack of the CLE CwlJ greatly slowed CaDPA release with a germinant receptor (GR)-dependent germinant, l-valine, or a non-GR-dependent germinant, dodecylamine. The absence of the cortex-specific PG modification muramic acid-δ-lactam also increased the time needed for full CaDPA release during germination with both types of germinants. In contrast, increased cortex PG cross-linking was associated with faster times for initiation of CaDPA release with both l-valine and dodecylamine but not with faster CaDPA release once this release had been initiated. These data suggest that the precise structure of the spore cortex plays a significant role in determining the timing and the rate of CaDPA release during B. subtilis spore germination and, further, that this effect is independent of effects of GRs.
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Cheng HW, Chen YY, Lin XX, Huan SY, Wu HL, Shen GL, Yu RQ. Surface-enhanced Raman spectroscopic detection of Bacillus subtilis spores using gold nanoparticle based substrates. Anal Chim Acta 2011; 707:155-63. [PMID: 22027133 DOI: 10.1016/j.aca.2011.09.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2011] [Revised: 09/03/2011] [Accepted: 09/08/2011] [Indexed: 11/24/2022]
Abstract
The detection of bacterial spores requires the capability of highly sensitive and biocompatible probes. This report describes the findings of an investigation of surface-enhanced Raman spectroscopic (SERS) detection of Bacillus subtilis spores using gold-nanoparticle (Au NP) based substrates as the spectroscopic probe. The SERS substrates are shown to be highly sensitive for the detection of B. subtilis spores, which release calcium dipicolinate (CaDPA) as a biomarker. The SERS bands of CaDPA released from the spores by extraction using nitric acid provide the diagnostic signal for the detection, exhibiting a limit of detection (LOD) of 1.5×10(9) spores L(-1) (or 2.5×10(-14) M). The LOD for the Au NP based substrates is quite comparable with that reported for Ag nanoparticle based substrates for the detection of spores, though the surface adsorption equilibrium constant is found to be smaller by a factor of 1-2 orders of magnitude than the Ag nanoparticle based substrates. The results have also revealed the viability of SERS detection of CaDPA released from the spores under ambient conditions without extraction using any reagents, showing a significant reduction of the diagnostic peak width for the detection. These findings have demonstrated the viability of Au NP based SERS substrates for direct use with high resolution and sensitivity as a biocompatible probe for the detection of bacterial spores.
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Affiliation(s)
- Han-Wen Cheng
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
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41
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Wang G, Zhang P, Paredes-Sabja D, Green C, Setlow P, Sarker M, Li YQ. Analysis of the germination of individual Clostridium perfringens spores and its heterogeneity. J Appl Microbiol 2011; 111:1212-23. [DOI: 10.1111/j.1365-2672.2011.05135.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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42
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Ashton L, Lau K, Winder CL, Goodacre R. Raman spectroscopy: lighting up the future of microbial identification. Future Microbiol 2011; 6:991-7. [DOI: 10.2217/fmb.11.89] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Over the last decade Raman spectroscopy has become established as a physicochemical technique for the rapid identification of microbes. This powerful analytical method generates a spectroscopic fingerprint from the microbial sample, which provides quantitative and qualitative information that can be used to characterize, discriminate and identify microorganisms, in both bacteria slurry and at the single-cell level. Recent developments in Raman spectroscopy have dramatically increased in recent years due to the enhancement of the signal by techniques including tip-enhanced Raman spectroscopy and coherent anti-Stokes Raman spectroscopy and due to the availability of user-friendly instrumentation and software. The result of this has been reduced cost and rapid collection time, and it has allowed the nonspecialist access to this physical sciences approach for biological applications. In this article, we will briefly explain the technique of Raman spectroscopy and discuss enhancement techniques, including the recent application of tip-enhanced Raman spectroscopy to microbiology, as well as the move towards rapid microbial identification with Raman spectroscopy. Furthermore, recent studies have combined Raman spectroscopy with microfluidic devices, giving greater control of sample conditions, which will no doubt have an important impact in the future development of Raman spectroscopy for microbial identification.
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Affiliation(s)
| | - Katherine Lau
- Spectroscopy Products Division, Renishaw plc, Old Town, Wotton-Under-Edge, Gloucestershire, GL12 7DW, UK
| | - Catherine L Winder
- School of Chemistry, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
- Manchester Centre for Integrative Systems Biology, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Royston Goodacre
- School of Chemistry, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
- Manchester Centre for Integrative Systems Biology, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
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43
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Kinnunen M, Kauppila A, Karmenyan A, Myllylä R. Effect of the size and shape of a red blood cell on elastic light scattering properties at the single-cell level. BIOMEDICAL OPTICS EXPRESS 2011; 2:1803-14. [PMID: 21750759 PMCID: PMC3130568 DOI: 10.1364/boe.2.001803] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 05/26/2011] [Accepted: 05/31/2011] [Indexed: 05/06/2023]
Abstract
We demonstrate the use of a double-beam optical tweezers system to stabilize red blood cell (RBC) orientation in the optical tweezers during measurements of elastic light scattering from the trapped cells in an angle range of 5-30 degrees. Another laser (He-Ne) was used to illuminate the cell and elastic light scattering distribution from the single cell was measured with a goniometer and a photomultiplier tube. Moreover, CCD camera images of RBCs with and without laser illumination are presented as complementary information. Light scattering from a RBC was measured in different fixed orientations. Light scattering from cells was also measured when the length of the cell was changed in two different orientations. Light scattering measurements from spherical and crenate RBCs are described and the results are compared with other cell orientations. Analysis shows that the measured elastic light scattering distributions reveal changes in the RBC's orientation and shape. The effect of stretching on the changes in scattering is larger in the case of face-on incidence of He-Ne laser light than in rim-on incidence. The scattering patterns from RBCs in different orientations as well as from a spherical RBC were compared with numerical results found in literature. Good correlation was found.
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Affiliation(s)
- Matti Kinnunen
- Optoelectronics and Measurement Techniques Laboratory, University of Oulu, Finland
| | - Antti Kauppila
- Optoelectronics and Measurement Techniques Laboratory, University of Oulu, Finland
| | - Artashes Karmenyan
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Risto Myllylä
- Optoelectronics and Measurement Techniques Laboratory, University of Oulu, Finland
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44
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Quantitative analysis of spatial-temporal correlations during germination of spores of Bacillus Species. J Bacteriol 2011; 193:3765-72. [PMID: 21622756 DOI: 10.1128/jb.05154-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Bacteria of Bacillus species sporulate upon starvation, and the resultant dormant spores germinate when the environment appears likely to allow the resumption of vegetative growth. Normally, the rates of germination of individual spores in populations are very heterogeneous, and the current work has investigated whether spore-to-spore communication enhances the synchronicity of germination. In order to do this work, time-lapse optical images of thousands of individual spores were captured during germination, and an image analysis algorithm was developed to do the following: (i) measure the positions and germination rates of many thousands of individual spores and (ii) compute pairwise correlations of their germination. This analysis showed that an individual spore's germination rate was dependent on its distance from other spores, especially at short distances. Thus, spores that were within a few micrometers exhibited an increased synchronicity in germination, suggesting that there is a mechanism for short-range communication between such spores during germination. However, two molecules known to be germinants that are released during germination, l-alanine and the 1:1 chelate of Ca²⁺ and dipicolinic acid, did not mediate spore-to-spore communication during germination.
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45
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Monitoring the wet-heat inactivation dynamics of single spores of Bacillus species by using Raman tweezers, differential interference contrast microscopy, and nucleic acid dye fluorescence microscopy. Appl Environ Microbiol 2011; 77:4754-69. [PMID: 21602365 DOI: 10.1128/aem.00194-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dynamic processes during wet-heat treatment of individual spores of Bacillus cereus, Bacillus megaterium, and Bacillus subtilis at 80 to 90°C were investigated using dual-trap Raman spectroscopy, differential interference contrast (DIC) microscopy, and nucleic acid stain (SYTO 16) fluorescence microscopy. During spore wet-heat treatment, while the spores' 1:1 chelate of Ca(2+) with dipicolinic acid (CaDPA) was released rapidly at a highly variable time T(lag), the levels of spore nucleic acids remained nearly unchanged, and the T(lag) times for individual spores from the same preparation were increased somewhat as spore levels of CaDPA increased. The brightness of the spores' DIC image decreased by ~50% in parallel with CaDPA release, and there was no spore cortex hydrolysis observed. The lateral diameters of the spores' DIC image and SYTO 16 fluorescence image also decreased in parallel with CaDPA release. The SYTO 16 fluorescence intensity began to increase during wet-heat treatment at a time before T(lag) and reached maximum at a time slightly later than T(release). However, the fluorescence intensities of wet-heat-inactivated spores were ~15-fold lower than those of nutrient-germinated spores, and this low SYTO 16 fluorescence intensity may be due in part to the low permeability of the dormant spores' inner membranes to SYTO 16 and in part to nucleic acid denaturation during the wet-heat treatment.
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46
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Characterization of bacterial spore germination using phase-contrast and fluorescence microscopy, Raman spectroscopy and optical tweezers. Nat Protoc 2011; 6:625-39. [PMID: 21527920 DOI: 10.1038/nprot.2011.307] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This protocol describes a method combining phase-contrast and fluorescence microscopy, Raman spectroscopy and optical tweezers to characterize the germination of single bacterial spores. The characterization consists of the following steps: (i) loading heat-activated dormant spores into a temperature-controlled microscope sample holder containing a germinant solution plus a nucleic acid stain; (ii) capturing a single spore with optical tweezers; (iii) simultaneously measuring phase-contrast images, Raman spectra and fluorescence images of the optically captured spore at 2- to 10-s intervals; and (iv) analyzing the acquired data for the loss of spore refractility, changes in spore-specific molecules (in particular, dipicolinic acid) and uptake of the nucleic acid stain. This information leads to precise correlations between various germination events, and takes 1-2 h to complete. The method can also be adapted to use multi-trap Raman spectroscopy or phase-contrast microscopy of spores adhered on a cover slip to simultaneously obtain germination parameters for multiple individual spores.
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47
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Kinetics of germination of wet-heat-treated individual spores of Bacillus species, monitored by Raman spectroscopy and differential interference contrast microscopy. Appl Environ Microbiol 2011; 77:3368-79. [PMID: 21441336 DOI: 10.1128/aem.00046-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Raman spectroscopy and differential interference contrast (DIC) microscopy were used to monitor the kinetics of nutrient and nonnutrient germination of multiple individual untreated and wet-heat-treated spores of Bacillus cereus and Bacillus megaterium, as well as of several isogenic Bacillus subtilis strains. Major conclusions from this work were as follows. (i) More than 90% of these spores were nonculturable but retained their 1:1 chelate of Ca²+ and dipicolinic acid (CaDPA) when incubated in water at 80 to 95°C for 5 to 30 min. (ii) Wet-heat treatment significantly increased the time, T(lag), at which spores began release of the great majority of their CaDPA during the germination of B. subtilis spores with different nutrient germinants and also increased the variability of T(lag) values. (iii) The time period, ΔT(release), between T(lag) and the time, T(release), at which a spore germinating with nutrients completed the release of the great majority of its CaDPA, was also increased in wet-heat-treated spores. (iv) Wet-heat-treated spores germinating with nutrients had higher values of I(release), the intensity of a spore's DIC image at T(release), than did untreated spores and had much longer time periods, ΔT(lys), for the reduction in I(release) intensities to the basal value due to hydrolysis of the spore's peptidoglycan cortex, probably due at least in part to damage to the cortex-lytic enzyme CwlJ. (v) Increases in T(lag) and ΔT(release) were also observed when wet-heat-treated B. subtilis spores were germinated with the nonnutrient dodecylamine, while the change in I(release) was less significant. (vi) The effects of wet-heat treatment on nutrient germination of B. cereus and B. megaterium spores were generally similar to those on B. subtilis spores. These results indicate that (i) some proteins important in spore germination are damaged by wet-heat treatment, (ii) the cortex-lytic enzyme CwlJ is one germination protein damaged by wet heat, and (iii) the CaDPA release process itself seems likely to be the target of wet-heat damage which has the greatest effect on spore germination.
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48
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Germination of spores of Bacillales and Clostridiales species: mechanisms and proteins involved. Trends Microbiol 2010; 19:85-94. [PMID: 21112786 DOI: 10.1016/j.tim.2010.10.004] [Citation(s) in RCA: 262] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 10/13/2010] [Accepted: 10/28/2010] [Indexed: 12/29/2022]
Abstract
Under conditions that are not conducive to growth, such as nutrient depletion, many members of the orders Bacillales and Clostridiales can sporulate, generating dormant and resistant spores that can survive in the absence of nutrients for years under harsh conditions. However, when nutrients are again present, these spores can return to active growth through the process of germination. Many of the components of the spore germination machinery are conserved between spore forming members of the Bacillales and Clostridiales orders. However, recent studies have revealed significant differences between the germination of spores of Clostridium perfringens and that of spores of a number of Bacillus species, both in the proteins and in the signal transduction pathways involved. In this review, the roles of components of the spore germination machinery of C. perfringens and several Bacillus species and the bioinformatic analysis of germination proteins in the Bacillales and Clostridiales orders are discussed and models for the germination of spores of these two orders are proposed.
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49
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Li Y, Wang G, Yao HL, Liu J, Li YQ. Dual-trap Raman tweezers for probing dynamics and heterogeneity of interacting microbial cells. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:067008. [PMID: 21198212 DOI: 10.1117/1.3526357] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report on development of dual-trap Raman tweezers for monitoring cellular dynamics and heterogeneity of interacting living cells suspended in a liquid medium. Dual-beam optical tweezers were combined with Raman spectroscopy, which allows capturing two cells that are in direct contact or closely separated by a few micrometers and simultaneously acquiring their Raman spectra with an imaging CCD spectrograph. As a demonstration, we recorded time-lapse Raman spectra of budding yeast cells held in dual traps for over 40 min to monitor the dynamic growth in a nutrient medium. We also monitored two germinating Bacillus spores after the initiation with L-alanine and observed their heterogeneity in the release of CaDPA under identical microenvironment.
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Affiliation(s)
- Yan Li
- Guangxi Academy of Sciences Biophysics Laboratory Nanning, Guangxi 530003, China.
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50
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Zhang P, Kong L, Setlow P, Li YQ. Multiple-trap laser tweezers Raman spectroscopy for simultaneous monitoring of the biological dynamics of multiple individual cells. OPTICS LETTERS 2010; 35:3321-3323. [PMID: 20967053 DOI: 10.1364/ol.35.003321] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report the development of a multiple-trap laser tweezers Raman spectroscopy (LTRS) array for simultaneously acquiring Raman spectra of individual cells in physiological environments. This LTRS-array technique was also combined with phase contrast and fluorescence microscopy, allowing measurement of Raman spectra, refractility, and fluorescence images of individual cells with a temporal resolution of ~5 s. As a demonstration, we used this technique to monitor multiple Bacillus cereus spores germinating in a nutrient medium for up to 90min and observed the kinetics of dipicolinic acid release and uptake of nucleic acid-binding stain molecules during spore germination.
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Affiliation(s)
- Pengfei Zhang
- 1Department of Physics, East Carolina University, Greenville, North Carolina 27858-4353, USA
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