1
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Ye X, Li J, Gao D, Ma P, Wu Q, Song D. A Dual-Mode Fluorescent Nanoprobe for the Detection and Visual Screening of Pathogenic Bacterial Spores. Anal Chem 2024; 96:6012-6020. [PMID: 38564412 DOI: 10.1021/acs.analchem.4c00443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Bacterial vegetative cells turn into metabolically dormant spores in certain environmental situations. Once suitable conditions trigger the germination of spores belonging to the pathogenic bacterial category, public safety and environmental hygiene will be threatened, and lives will even be endangered when encountering fatal ones. Instant identification of pathogenic bacterial spores remains a challenging task, since most current approaches belonging to complicated biological methods unsuitable for onsite sensing or emerging alternative chemical techniques are still inseparable from professional instruments. Here we developed a polychromatic fluorescent nanoprobe for ratiometric detection and visual inspection of the pathogenic bacterial spore biomarker, dipicolinic acid (DPA), realizing rapidly accurate screening of pathogenic bacterial spores such as Bacillus anthracis spores. The nanoprobe is made of aminoclay-coated silicon nanoparticles and functionalized with europium ions, exhibiting selective and sensitive response toward DPA and Bacillus subtilis spores (simulants for Bacillus anthracis spores) with excellent linearity. The proposed sensing strategy allowing spore determination of as few as 0.3 × 105 CFU/mL within 10 s was further applied to real environmental sample detection with good accuracy and reliability. Visual quantitative determination can be achieved by analyzing the RGB values of the corresponding test solution color via a color recognition APP on a smartphone. Different test samples can be photographed at the same time, hence the efficient accomplishment of examining bulk samples within minutes. Potentially employed in various on-site sensing occasions, this strategy may develop into a powerful means for distinguishing hazardous pathogens to facilitate timely and proper actions of dealing with multifarious security issues.
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Affiliation(s)
- Xiwen Ye
- Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun 130012, China
| | - Jingkang Li
- Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun 130012, China
| | - Dejiang Gao
- Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun 130012, China
| | - Pinyi Ma
- Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun 130012, China
| | - Qiong Wu
- Key Laboratory of Pathobiology, Ministry of Education, Nanomedicine and Translational Research Center, China-Japan Union Hospital of Jilin University, Changchun 130030, China
| | - Daqian Song
- Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, College of Chemistry, Jilin University, Qianjin Street 2699, Changchun 130012, China
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2
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Yu B, Kanaan J, Shames H, Wicander J, Aryal M, Li Y, Korza G, Brul S, Kramer G, Li YQ, Nichols FC, Hao B, Setlow P. Identification and characterization of new proteins crucial for bacterial spore resistance and germination. Front Microbiol 2023; 14:1161604. [PMID: 37113233 PMCID: PMC10126465 DOI: 10.3389/fmicb.2023.1161604] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 03/17/2023] [Indexed: 04/29/2023] Open
Abstract
2Duf, named after the presence of a transmembrane (TM) Duf421 domain and a small Duf1657 domain in its sequence, is likely located in the inner membrane (IM) of spores in some Bacillus species carrying a transposon with an operon termed spoVA 2mob. These spores are known for their extreme resistance to wet heat, and 2Duf is believed to be the primary contributor to this trait. In this study, we found that the absence of YetF or YdfS, both Duf421 domain-containing proteins and found only in wild-type (wt) B. subtilis spores with YetF more abundant, leads to decreased resistance to wet heat and agents that can damage spore core components. The IM phospholipid compositions and core water and calcium-dipicolinic acid levels of YetF-deficient spores are similar to those of wt spores, but the deficiency could be restored by ectopic insertion of yetF, and overexpression of YetF increased wt spore resistance to wet heat. In addition, yetF and ydfS spores have decreased germination rates as individuals and populations with germinant receptor-dependent germinants and increased sensitivity to wet heat during germination, potentially due to damage to IM proteins. These data are consistent with a model in which YetF, YdfS and their homologs modify IM structure to reduce IM permeability and stabilize IM proteins against wet heat damage. Multiple yetF homologs are also present in other spore forming Bacilli and Clostridia, and even some asporogenous Firmicutes, but fewer in asporogenous species. The crystal structure of a YetF tetramer lacking the TM helices has been reported and features two distinct globular subdomains in each monomer. Sequence alignment and structure prediction suggest this fold is likely shared by other Duf421-containing proteins, including 2Duf. We have also identified naturally occurring 2duf homologs in some Bacilli and Clostridia species and in wt Bacillus cereus spores, but not in wt B. subtilis. Notably, the genomic organization around the 2duf gene in most of these species is similar to that in spoVA 2mob, suggesting that one of these species was the source of the genes on this operon in the extremely wet heat resistant spore formers.
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Affiliation(s)
- Benjamin Yu
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States
| | - Julia Kanaan
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States
| | - Hannah Shames
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States
| | - James Wicander
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States
| | - Makunda Aryal
- Department of Physics, East Carolina University, Greenville, NC, United States
| | - Yunfeng Li
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States
| | - George Korza
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States
| | - Stanley Brul
- Molecular Biology and Microbial Food Safety, University of Amsterdam, Amsterdam, Netherlands
| | - Gertjan Kramer
- Laboratory for Mass Spectrometry of Biomolecules, Swammerdam Institute for Life Science, University of Amsterdam, Amsterdam, Netherlands
| | - Yong-qing Li
- Department of Physics, East Carolina University, Greenville, NC, United States
| | - Frank C. Nichols
- Division of Periodontology, UConn Health, Farmington, CT, United States
| | - Bing Hao
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States
- Bing Hao,
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States
- *Correspondence: Peter Setlow,
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3
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Gonzalez LE, Szalwinski LJ, Sams TC, Dziekonski ET, Cooks RG. Metabolomic and Lipidomic Profiling of Bacillus Using Two-Dimensional Tandem Mass Spectrometry. Anal Chem 2022; 94:16838-16846. [DOI: 10.1021/acs.analchem.2c03961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- L. Edwin Gonzalez
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Lucas J. Szalwinski
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Thomas C. Sams
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Eric T. Dziekonski
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - R. Graham Cooks
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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4
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Gao Y, Barajas-Ornelas RDC, Amon JD, Ramírez-Guadiana FH, Alon A, Brock KP, Marks DS, Kruse AC, Rudner DZ. The SpoVA membrane complex is required for dipicolinic acid import during sporulation and export during germination. Genes Dev 2022; 36:634-646. [PMID: 35654455 PMCID: PMC9186386 DOI: 10.1101/gad.349488.122] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/16/2022] [Indexed: 11/24/2022]
Abstract
In response to starvation, endospore-forming bacteria differentiate into stress-resistant spores that can remain dormant for years yet rapidly germinate and resume growth in response to nutrients. The small molecule dipicolinic acid (DPA) plays a central role in both the stress resistance of the dormant spore and its exit from dormancy during germination. The spoVA locus is required for DPA import during sporulation and has been implicated in its export during germination, but the molecular bases are unclear. Here, we define the minimal set of proteins encoded in the Bacillus subtilis spoVA operon required for DPA import and demonstrate that these proteins form a membrane complex. Structural modeling of these components combined with mutagenesis and in vivo analysis reveal that the C and Eb subunits form a membrane channel, while the D subunit functions as a cytoplasmic plug. We show that point mutations that impair the interactions between D and the C-Eb membrane complex reduce the efficiency of DPA import during sporulation and reciprocally accelerate DPA release during germination. Our data support a model in which DPA transport into spores involves cycles of unplugging and then replugging the C-Eb membrane channel, while nutrient detection during germination triggers DPA release by unplugging it.
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Affiliation(s)
- Yongqiang Gao
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | - Jeremy D Amon
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | - Assaf Alon
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Kelly P Brock
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Debora S Marks
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Andrew C Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - David Z Rudner
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, USA
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5
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Yin M, Xiao D, Wang C, Zhang L, Dun B, Yue Q. The regulation of BbLaeA on the production of beauvericin and bassiatin in Beauveria bassiana. World J Microbiol Biotechnol 2021; 38:1. [PMID: 34817662 DOI: 10.1007/s11274-021-03162-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 10/04/2021] [Indexed: 10/19/2022]
Abstract
Beauvericin and bassiatin are two valuable compounds with various bioactivities biosynthesized by the supposedly same nonribosomal peptide synthetase BbBEAS in entomopathogenic fungus Beauveria bassiana. To evaluate the regulatory effect of global regulator LaeA on their production, we constructed BbLaeA gene deletion and overexpression mutants, respectively. Deletion of BbLaeA resulted in a decrease of the beauvericin titer, while overexpression of BbLaeA increased its production by 1-2.26 times. No bassiatin could be detected in ΔBbLaeA and wild type strain of B. bassiana, but 4.26-5.10 µg/mL bassiatin was produced in OE::BbLaeA. Furthermore, additional metabolites with increased production in OE::BbLaeA were isolated and identified as primary metabolites. Among them, 4-hydroxyphenylacetic acid showed antibacterial bioactivity against Ralstonia solanacearum. These results indicated that BbLaeA positively regulates the production of beauvericin, bassiatin and various bioactive primary metabolites.
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Affiliation(s)
- Miaomiao Yin
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Dongliang Xiao
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Chen Wang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Liwen Zhang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Baoqing Dun
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Qun Yue
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
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6
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Singh AP, Singh MP, Baruah JB. Changes in the proportions of an active pharmaceutical through cocrystals. Drug Dev Res 2021; 82:1144-1153. [PMID: 33792939 DOI: 10.1002/ddr.21818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/18/2021] [Accepted: 03/12/2021] [Indexed: 11/06/2022]
Abstract
In this study, the modulation of amounts sulfathiazolium cations in different 2,6-pyridinedicarboxylates is demonstrated. An uncommon monoionic sulfathiazolium zinc 2,6-pyridinedicarboxylate (1:1 electrolyte) complex was characterized. Conventional sulfathiazolium zinc-bis-2,6-pyridinedicarboxylate dianionic complexes (2:1 electrolyte) were formed when hydroxyaromatic compounds such as 1,3-dihydroxybenzene or 3-nitrophenol were used as guest components. Thus, with the aid of the hydroxyaromatic molecules the zinc-bis-2,6-pyridinedicarboxylate complexes were stabilized with the relatively large sized sulfathiazolium cations. It was a consequence of domain expansion by the phenolic compounds. Sandwiched aromatic guests between the 2,6-pyridinedicarboxylates provided appropriate packing to accommodate the two large cations in the self-assemblies, which helped to modulate the amounts of sulfathiazole in different formulations. Antibacterial activities with E. coli DH5α have shown that the salt and the complexes have lower g/ml antibacterial activity than the parent drug.
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Affiliation(s)
- Abhay Pratap Singh
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Munendra Pal Singh
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam, India.,Research and Development Center, Sun Pharmaceutical Industries Ltd, Gurgaon, Haryana, India
| | - Jubaraj B Baruah
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam, India
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7
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Beskrovnaya P, Sexton DL, Golmohammadzadeh M, Hashimi A, Tocheva EI. Structural, Metabolic and Evolutionary Comparison of Bacterial Endospore and Exospore Formation. Front Microbiol 2021; 12:630573. [PMID: 33767680 PMCID: PMC7985256 DOI: 10.3389/fmicb.2021.630573] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/15/2021] [Indexed: 12/20/2022] Open
Abstract
Sporulation is a specialized developmental program employed by a diverse set of bacteria which culminates in the formation of dormant cells displaying increased resilience to stressors. This represents a major survival strategy for bacteria facing harsh environmental conditions, including nutrient limitation, heat, desiccation, and exposure to antimicrobial compounds. Through dispersal to new environments via biotic or abiotic factors, sporulation provides a means for disseminating genetic material and promotes encounters with preferable environments thus promoting environmental selection. Several types of bacterial sporulation have been characterized, each involving numerous morphological changes regulated and performed by non-homologous pathways. Despite their likely independent evolutionary origins, all known modes of sporulation are typically triggered by limited nutrients and require extensive membrane and peptidoglycan remodeling. While distinct modes of sporulation have been observed in diverse species, two major types are at the forefront of understanding the role of sporulation in human health, and microbial population dynamics and survival. Here, we outline endospore and exospore formation by members of the phyla Firmicutes and Actinobacteria, respectively. Using recent advances in molecular and structural biology, we point to the regulatory, genetic, and morphological differences unique to endo- and exospore formation, discuss shared characteristics that contribute to the enhanced environmental survival of spores and, finally, cover the evolutionary aspects of sporulation that contribute to bacterial species diversification.
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Affiliation(s)
| | | | | | | | - Elitza I. Tocheva
- Department of Microbiology and Immunology, Life Sciences Institute, Health Sciences Mall, The University of British Columbia, Vancouver, BC, Canada
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8
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Rattray JE, Chakraborty A, Li C, Elizondo G, John N, Wong M, Radović JR, Oldenburg TBP, Hubert CRJ. Sensitive quantification of dipicolinic acid from bacterial endospores in soils and sediments. Environ Microbiol 2020; 23:1397-1406. [PMID: 33264453 PMCID: PMC8048543 DOI: 10.1111/1462-2920.15343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 11/30/2020] [Indexed: 11/27/2022]
Abstract
Endospore-forming bacteria make up an important and numerically significant component of microbial communities in a range of settings including soils, industry, hospitals and marine sediments extending into the deep subsurface. Bacterial endospores are non-reproductive structures that protect DNA and improve cell survival during periods unfavourable for bacterial growth. An important determinant of endospores withstanding extreme environmental conditions is 2,6-pyridine dicarboxylic acid (i.e. dipicolinic acid, or DPA), which contributes heat resistance. This study presents an improved HPLC-fluorescence method for DPA quantification using a single 10-min run with pre-column Tb3+ chelation. Relative to existing DPA quantification methods, specific improvements pertain to sensitivity, detection limit and range, as well as the development of new free DPA and spore-specific DPA proxies. The method distinguishes DPA from intact and recently germinated spores, enabling responses to germinants in natural samples or experiments to be assessed in a new way. DPA-based endospore quantification depends on accurate spore-specific DPA contents, in particular, thermophilic spores are shown to have a higher DPA content, meaning that marine sediments with plentiful thermophilic spores may require spore number estimates to be revisited. This method has a wide range of potential applications for more accurately quantifying bacterial endospores in diverse environmental samples.
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Affiliation(s)
- Jayne E Rattray
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Anirban Chakraborty
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Carmen Li
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Gretta Elizondo
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Nisha John
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Michelle Wong
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Jagoš R Radović
- Department of Geoscience, University of Calgary, Calgary, T2N 1N4, Canada
| | | | - Casey R J Hubert
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
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9
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McClintock MK, Fahnhorst GW, Hoye TR, Zhang K. Engineering the production of dipicolinic acid in E. coli. Metab Eng 2018; 48:208-217. [DOI: 10.1016/j.ymben.2018.05.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/09/2018] [Accepted: 05/16/2018] [Indexed: 10/16/2022]
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10
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Ramírez-Guadiana FH, Meeske AJ, Rodrigues CDA, Barajas-Ornelas RDC, Kruse AC, Rudner DZ. A two-step transport pathway allows the mother cell to nurture the developing spore in Bacillus subtilis. PLoS Genet 2017; 13:e1007015. [PMID: 28945739 PMCID: PMC5629000 DOI: 10.1371/journal.pgen.1007015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/05/2017] [Accepted: 09/09/2017] [Indexed: 11/18/2022] Open
Abstract
One of the hallmarks of bacterial endospore formation is the accumulation of high concentrations of pyridine-2,6-dicarboxylic acid (dipicolinic acid or DPA) in the developing spore. This small molecule comprises 5–15% of the dry weight of dormant spores and plays a central role in resistance to both wet heat and desiccation. DPA is synthesized in the mother cell at a late stage in sporulation and must be translocated across two membranes (the inner and outer forespore membranes) that separate the mother cell and forespore. The enzymes that synthesize DPA and the proteins required to translocate it across the inner forespore membrane were identified over two decades ago but the factors that transport DPA across the outer forespore membrane have remained mysterious. Here, we report that SpoVV (formerly YlbJ) is the missing DPA transporter. SpoVV is produced in the mother cell during the morphological process of engulfment and specifically localizes in the outer forespore membrane. Sporulating cells lacking SpoVV produce spores with low levels of DPA and cells engineered to express SpoVV and the DPA synthase during vegetative growth accumulate high levels of DPA in the culture medium. SpoVV resembles concentrative nucleoside transporters and mutagenesis of residues predicted to form the substrate-binding pocket supports the idea that SpoVV has a similar structure and could therefore function similarly. These findings provide a simple two-step transport mechanism by which the mother cell nurtures the developing spore. DPA produced in the mother cell is first translocated into the intermembrane space by SpoVV and is then imported into the forespore by the SpoVA complex. This pathway is likely to be broadly conserved as DPA synthase, SpoVV, and SpoVA proteins can be found in virtually all endospore forming bacteria. All pathogenic and non-pathogenic bacteria that differentiate into dormant endospores including Clostridium difficile, Bacillus anthracis, and Bacillus subtilis, contain very high concentrations of the small molecule dipicolinic acid (DPA). This molecule displaces water in the spore core where it plays an integral role in spore resistance and dormancy. DPA and its contribution to spore dehydration were discovered in 1953 but the molecular basis for its accumulation in the spore has remained unclear. The developing endospore resides within a mother cell that assembles protective layers around the spore and nurtures it by providing mother-cell-produced molecules. DPA is produced in the mother cell at a late stage in development and then must be translocated across two membranes into the spore core. Here, we report the discovery of the missing DPA transporter, homologs of which are present in virtually all endospore-forming bacteria. Our data provide evidence for a simple two-step transport pathway in which the mother cell nurtures the developing spore by sequentially moving DPA across the two membranes that surround it.
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Affiliation(s)
| | - Alexander J. Meeske
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | | | | | - Andrew C. Kruse
- Department of Biochemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States of America
| | - David Z. Rudner
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
- * E-mail:
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11
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Noell AC, Ely T, Bolser DK, Darrach H, Hodyss R, Johnson PV, Hein JD, Ponce A. Spectroscopy and viability of Bacillus subtilis spores after ultraviolet irradiation: implications for the detection of potential bacterial life on Europa. ASTROBIOLOGY 2015; 15:20-31. [PMID: 25590531 DOI: 10.1089/ast.2014.1169] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
One of the most habitable environments in the Solar System outside of Earth may exist underneath the ice on Europa. In the near future, our best chance to look for chemical signatures of a habitable environment (or life itself) will likely be at the inhospitable icy surface. Therefore, it is important to understand the ability of organic signatures of life and life itself to persist under simulated europan surface conditions. Toward that end, this work examined the UV photolysis of Bacillus subtilis spores and their chemical marker dipicolinic acid (DPA) at temperatures and pressures relevant to Europa. In addition, inactivation curves for the spores at 100 K, 100 K covered in one micron of ice, and 298 K were measured to determine the probability for spore survival at the surface. Fourier transform infrared spectra of irradiated DPA showed a loss of carboxyl groups to CO2 as expected but unexpectedly showed significant opening of the heterocyclic ring, even for wavelengths>200 nm. Both DPA and B. subtilis spores showed identical unknown spectral bands of photoproducts after irradiation, further highlighting the importance of DPA in the photochemistry of spores. Spore survival was enhanced at 100 K by ∼5× relative to 298 K, but 99.9% of spores were still inactivated after the equivalent of ∼25 h of exposure on the europan surface.
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Affiliation(s)
- Aaron C Noell
- NASA Astrobiology Institute and Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
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12
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Jensen KR, Voorhees KJ. Analytical applications of electron monochromator-mass spectrometry. MASS SPECTROMETRY REVIEWS 2015; 34:24-42. [PMID: 24272909 DOI: 10.1002/mas.21395] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 06/17/2013] [Accepted: 06/17/2013] [Indexed: 06/02/2023]
Abstract
An electron monochromator (EM) produces an electron beam with a narrow energy distribution that can be utilized with mass spectrometry (MS). The history and development of the EM from an initial research design to a commercial model are reviewed along with MS research applications. An EM incorporated with a mass spectrometer showed significant improvement in sensitivity over traditional methods for negative-ion generation and selectivity for compounds with electrophilic character. Sensitivity of EM-MS has been shown to be 25 fg for hexachlorobenzene in positive-ion mode and 10 fg for nitrobenzene in negative-ion mode. Reports regarding the analysis of chlorinated compounds, explosives, pesticides, phthalates, polychlorodibenzo-p-dioxins, polycyclic aromatic hydrocarbons (PAHs), nitro-polycyclic aromatic hydrocarbons (NPAHs), antioxidants, and bacterial biomarkers are discussed. Additionally, theoretical methods to predict electron-capture properties are presented.
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Affiliation(s)
- Kirk R Jensen
- Colorado School of Mines, Department of Chemistry and Geochemistry, 1012 14th Street #204, Golden, Colorado, 80401
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13
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Hill SC, Pan YL, Williamson C, Santarpia JL, Hill HH. Fluorescence of bioaerosols: mathematical model including primary fluorescing and absorbing molecules in bacteria. OPTICS EXPRESS 2013; 21:22285-313. [PMID: 24104120 DOI: 10.1364/oe.21.022285] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
This paper describes a mathematical model of fluorescent biological particles composed of bacteria, viruses, or proteins. The fluorescent and/or light absorbing molecules included in the model are amino acids (tryptophan, etc.); nucleic acids (DNA, RNA, etc.); coenzymes (nicotinamide adenine dinucleotides, flavins, and vitamins B₆ and K and variants of these); and dipicolinates. The concentrations, absorptivities, and fluorescence quantum yields are estimated from the literature, often with large uncertainties. The bioparticles in the model are spherical and homogeneous. Calculated fluorescence cross sections for particles excited at 266, 280, and 355 nm are compared with measured values from the literature for several bacteria, bacterial spores and albumins. The calculated 266- and 280-nm excited fluorescence is within a factor of 3.2 of the measurements for the vegetative cells and proteins, but overestimates the fluorescence of spores by a factor of 10 or more. This is the first reported modeling of the fluorescence of bioaerosols in which the primary fluorophores and absorbing molecules are included.
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14
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Kazemi SH, Eshtiagh-Hosseini H, Mirzaei M. Computational study of the intramolecular proton transfer reactions of dipicolinic acid (pyridine-2,6-dicarboxylic acid) and its dimers. COMPUT THEOR CHEM 2013. [DOI: 10.1016/j.comptc.2012.10.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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15
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Nackos AN, Truong TV, Pulsipher TC, Kimball JA, Tolley HD, Robison RA, Bartholomew CH, Lee ML. One-step conversion of to its using salts for GC-MSdetection of bacterial endospores. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2011; 3:245-258. [PMID: 32938021 DOI: 10.1039/c0ay00270d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Methyl sulfate (MeSO4-) salts were explored as thermochemolysis-methylation (TCM) reagents for gas chromatographic (GC) analysis of dipicolinic acid (DPA) as its dimethyl ester (Me2DPA) from bacterial endospores. The reaction was carried out under non-pyrolytic conditions by inserting a small coiled wire filament coated with the sample and reagents directly inside a GC injection port at 290 °C. Above 10 : 1 methyl donor/DPA ratios, alkali metal salts of MeSO4- effected 80-90% conversion of DPA to Me2DPA, which was 10-20 times more active than the same amount of tetramethylammonium hydroxide (TMA-OH) at this temperature. A quaternary salt mixture consisting of 1 : 3 : 1 : 3 TMA+/Na+/OH-/MeSO4- methylated spore DPA with an average conversion of 86% (mean conversion by TMA-OH under the same conditions was 4%). Therefore, the sensitivity for detection of bacterial endospores was increased over 20-fold compared to that observed with the more commonly employed TMA-OH methylating reagent. The limit of detection by this method was 9 × 104 total spores. Mechanisms describing the observed behavior are proposed and discussed. This is the first use of MeSO4- as a TCM reagent for GC.
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Affiliation(s)
- Aaron N Nackos
- Department of Chemical Engineering, Brigham Young University, Provo, UT 84602, USA.
| | - Tai V Truong
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
| | | | - Jon A Kimball
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
| | - H Dennis Tolley
- Department of Statistics, Brigham Young University, Provo, UT 84602, USA
| | - Richard A Robison
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT 84602, USA
| | - Calvin H Bartholomew
- Department of Chemical Engineering, Brigham Young University, Provo, UT 84602, USA.
| | - Milton L Lee
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
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Hashimoto T, Gerhardt P. Monochromatic Ultraviolet Microscopy of Microorganisms: Preliminary Observations on Bacterial Spores. J Biophys Biochem Cytol 2010; 7:195-6. [PMID: 19866565 PMCID: PMC2224874 DOI: 10.1083/jcb.7.1.195] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- T Hashimoto
- Department of Bacteriology, The University of Michigan Medical School, Ann Arbor
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Seale RB, Bremer PJ, Flint SH, McQuillan AJ. Characterization of spore surfaces from a Geobacillus sp. isolate by pH dependence of surface charge and infrared spectra. J Appl Microbiol 2010; 109:1339-48. [PMID: 20522147 DOI: 10.1111/j.1365-2672.2010.04760.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS The surfaces of spores from a Geobacillus sp. isolated from a milk powder production line were examined to obtain fundamental information relevant to bacterial spore adhesion to materials. MATERIALS AND RESULTS The surfaces of spores were characterized using transmission electron microscopy and infrared spectroscopy. Thin sections of spores stained with ruthenium red revealed an exosporium with a hair-like nap around the spores. Attenuated total reflection infrared spectra of the spores exposed to different pH solutions on a ZnSe prism revealed that pH-sensitive carboxyl and phosphodiester groups associated with proteins and polysaccharides contributed to the spore's negative charge which was revealed by our previous zeta potential measurements on the spores. Lowering the pH to the isoelectric point of spores resulted in an increase in intensity of all spectral bands, indicating that the spores moved closer to the zinc selenide (ZnSe) surface as the charged surface groups were neutralized and the spore surface polymers compressed. The attachment of spores to stainless steel was threefold higher at pH 3 compared with pH 7. CONCLUSIONS This research showed that spore attachment to surfaces is influenced by electrostatic interactions, surface polymer conformation and associated steric interactions. SIGNIFICANCE AND IMPACT OF THE STUDY The adhesion of thermophilic spores is largely controlled by functional groups of surface polymers and polymer conformation.
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Affiliation(s)
- R B Seale
- Department of Food Science, University of Otago, Dunedin, New Zealand
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Truong TV, Nackos AN, Murray JA, Kimball JA, Hawkes JE, Harvey DJ, Tolley HD, Robison RA, Bartholomew CH, Lee ML. Sample introduction in gas chromatography using a coiled wire filament. J Chromatogr A 2009; 1216:6852-7. [DOI: 10.1016/j.chroma.2009.08.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Revised: 08/01/2009] [Accepted: 08/10/2009] [Indexed: 10/20/2022]
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Abstract
The increased demand for sterile products has created the need for rapid technologies capable of validating the hygiene of industrial production processes. Bacillus endospores are in standard use as biological indicators for evaluating the effectiveness of sterilization processes. Currently, culture-based methods, requiring more than 2 days before results become available, are employed to verify endospore inactivation. We describe a rapid, microscopy-based endospore viability assay (microEVA) capable of enumerating germinable endospores in less than 15 min. MicroEVA employs time-gated luminescence microscopy to enumerate single germinable endospores via terbium-dipicolinate (Tb-DPA) luminescence, which is triggered under UV excitation as 10(8) DPA molecules are released during germination on agarose containing Tb(3+) and a germinant (e.g., L-alanine). Inactivation of endospore populations to sterility was monitored with microEVA as a function of thermal and UV dosage. A comparison of culturing results yielded nearly identical decimal reduction values, thus validating microEVA as a rapid biodosimetry method for monitoring sterilization processes. The simple Tb-DPA chemical test for germinability is envisioned to enable fully automated instrumentation for in-line monitoring of hygiene in industrial production processes.
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Fichtel J, Sass H, Rullkötter J. Assessment of spore contamination in pepper by determination of dipicolinic acid with a highly sensitive HPLC approach. Food Control 2008. [DOI: 10.1016/j.foodcont.2007.09.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Palacios P, Burgos J, Hoz L, Sanz B, Ordóñez J. Study of substances released by ultrasonic treatment from Bacillus stearothermophilus spores. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1991.tb03815.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Curien G, Biou V, Mas-Droux C, Robert-Genthon M, Ferrer JL, Dumas R. Amino acid biosynthesis: new architectures in allosteric enzymes. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2008; 46:325-339. [PMID: 18272376 DOI: 10.1016/j.plaphy.2007.12.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Indexed: 05/25/2023]
Abstract
This review focuses on the allosteric controls in the Aspartate-derived and the branched-chain amino acid biosynthetic pathways examined both from kinetic and structural points of view. The objective is to show the differences that exist among the plant and microbial worlds concerning the allosteric regulation of these pathways and to unveil the structural bases of this diversity. Indeed, crystallographic structures of enzymes from these pathways have been determined in bacteria, fungi and plants, providing a wonderful opportunity to obtain insight into the acquisition and modulation of allosteric controls in the course of evolution. This will be examined using two enzymes, threonine synthase and the ACT domain containing enzyme aspartate kinase. In a last part, as many enzymes in these pathways display regulatory domains containing the conserved ACT module, the organization of ACT domains in this kind of allosteric enzymes will be reviewed, providing explanations for the variety of allosteric effectors and type of controls observed.
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Affiliation(s)
- Gilles Curien
- Laboratoire de Physiologie Cellulaire Végétale, Université Joseph Fourier, Commissariat à l'Energie Atomique, Institut de Recherche et de Technologie des Sciences du Vivant, 38054 Grenoble, France
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Fichtel J, Köster J, Rullkötter J, Sass H. Spore dipicolinic acid contents used for estimating the number of endospores in sediments. FEMS Microbiol Ecol 2007; 61:522-32. [PMID: 17623026 DOI: 10.1111/j.1574-6941.2007.00354.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Endospores are heat-resistant bacterial resting stages that can remain viable for long periods of time and may thus accumulate in sediments as a function of sediment age. The number of spores in sediments has only rarely been quantified, because of methodological problems, and consequently little is known about the quantitative contribution of endospores to the total number of prokaryotic cells. We here report on a protocol to determine the number of endospores in sediments and cultures. The method is based on the fluorimetric determination of dipicolinic acid (DPA), a spore core-specific compound, after reaction with terbium chloride. The concentration of DPA in natural samples is converted into endospore numbers using endospore-forming pure cultures as standards. Quenching of the fluorescence by sediment constituents and background fluorescence due to humic substances hampered direct determination of DPA in sediments. To overcome those interferences, DPA was extracted using ethyl acetate prior to fluorimetric measurements of DPA concentrations. The first results indicated that endospore numbers obtained with this method are orders of magnitude higher than numbers obtained by cultivation after pasteurization. In one of the explored sediment cores, endospores accounted for 3% of all stainable prokaryotic cells.
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Affiliation(s)
- Jörg Fichtel
- Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky-Strasse 9-11, Oldenburg, Germany
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Baweja RB, Zaman MS, Mattoo AR, Sharma K, Tripathi V, Aggarwal A, Dubey GP, Kurupati RK, Ganguli M, Chaudhury NK, Sen S, Das TK, Gade WN, Singh Y. Properties of Bacillus anthracis spores prepared under various environmental conditions. Arch Microbiol 2007; 189:71-9. [PMID: 17713759 DOI: 10.1007/s00203-007-0295-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2006] [Revised: 07/28/2007] [Accepted: 08/04/2007] [Indexed: 01/23/2023]
Abstract
Bacillus anthracis makes highly stable, heat-resistant spores which remain viable for decades. Effect of various stress conditions on sporulation in B. anthracis was studied in nutrient-deprived and sporulation medium adjusted to various pH and temperatures. The results revealed that sporulation efficiency was dependent on conditions prevailing during sporulation. Sporulation occurred earlier in culture sporulating at alkaline pH or in PBS than control. Spores formed in PBS were highly sensitive towards spore denaturants whereas, those formed at 45 degrees C were highly resistant. The decimal reduction time (D-10 time) of the spores formed at 45 degrees C by wet heat, 2 M HCl, 2 M NaOH and 2 M H(2)O(2) was higher than the respective D-10 time for the spores formed in PBS. The dipicolinic acid (DPA) content and germination efficiency was highest in spores formed at 45 degrees C. Since DPA is related to spore sensitivity towards heat and chemicals, the increased DPA content of spores prepared at 45 degrees C may be responsible for increased resistance to wet heat and other denaturants. The size of spores formed at 45 degrees C was smallest amongst all. The study reveals that temperature, pH and nutrient availability during sporulation affect properties of B. anthracis spores.
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Affiliation(s)
- Renu B Baweja
- Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
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Fichtel J, Köster J, Scholz-Böttcher B, Sass H, Rullkötter J. A highly sensitive HPLC method for determination of nanomolar concentrations of dipicolinic acid, a characteristic constituent of bacterial endospores. J Microbiol Methods 2007; 70:319-27. [PMID: 17573136 DOI: 10.1016/j.mimet.2007.05.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 05/11/2007] [Accepted: 05/11/2007] [Indexed: 11/24/2022]
Abstract
A high-performance liquid chromatographic method with indirect fluorescence detection has been developed for quantification of dipicolinic acid, a major constituent of bacterial endospores. After separation on a reversed-phase column, a post-column reagent of sodium acetate at 1 mol l(-1) with 50 micromol l(-1) terbium chloride was added for complexation of dipicolinic acid. Terbium monodipicolinate complexes formed were quantified by measuring the fluorescence emission maximum at 548 nm after excitation with UV light at 270 nm wavelength. Parameters of post-column complexation were optimized to achieve a detection limit of 0.5 nmol DPA l(-1), corresponding to about 10(3) Desulfosporosinus orientis endospores per ml. The method was applied to the analysis of spore contamination in tuna and for estimating the endospore numbers in marine sediments.
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Affiliation(s)
- Jörg Fichtel
- Institut für Chemie und Biologie des Meeres, Carl von Ossietzky Universität Oldenburg, D-26129 Oldenburg, Germany.
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Liu YS, Walter TM, Chang WJ, Lim KS, Yang L, Lee SW, Aronson A, Bashir R. Electrical detection of germination of viable model Bacillus anthracis spores in microfluidic biochips. LAB ON A CHIP 2007; 7:603-10. [PMID: 17476379 DOI: 10.1039/b702408h] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
In this paper, we present a new impedance-based method to detect viable spores by electrically detecting their germination in real time within microfluidic biochips. We used Bacillus anthracis Sterne spores as the model organism. During germination, the spores release polar and ionic chemicals, such as dipicolinic acid (DPA), calcium ions, phosphate ions, and amino acids, which correspondingly increase the electrical conductivity of the medium in which the spores are suspended. We first present macro-scale measurements demonstrating that the germination of spores can be electrically detected at a concentration of 10(9) spores ml(-1) in sample volumes of 5 ml, by monitoring changes in the solution conductivity. Germination was induced by introducing an optimized germinant solution consisting of 10 mM L-alanine and 2 mM inosine. We then translated these results to a micro-fluidic biochip, which was a three-layer device: one layer of polydimethylsiloxane (PDMS) with valves, a second layer of PDMS with micro-fluidic channels and chambers, and the third layer with metal electrodes deposited on a pyrex substrate. Dielectrophoresis (DEP) was used to trap and concentrate the spores at the electrodes with greater than 90% efficiency, at a solution flow rate of 0.2 microl min(-1) with concentration factors between 107-109 spores ml(-1), from sample volumes of 1-5 microl. The spores were captured by DEP in deionized water within 1 min (total volume used ranged from 0.02 microl to 0.2 microl), and then germinant solution was introduced to the flow stream. The detection sensitivity was demonstrated to be as low as about a hundred spores in 0.1 nl, which is equivalent to a macroscale detection limit of approximately 10(9) spores ml(-1). We believe that this is the first demonstration of this application in microfluidic and BioMEMS devices.
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Affiliation(s)
- Yi-Shao Liu
- Birck Nanotechnology Center, Brindley Bioscience Center, School of Electrical and Computer Engineering, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, USA
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Nyiri L. Effect of CO2 on the germination of Penicillium chrysogenum spores. J Basic Microbiol 2007. [DOI: 10.1002/jobm.19670070205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Shafaat HS, Ponce A. Applications of a rapid endospore viability assay for monitoring UV inactivation and characterizing arctic ice cores. Appl Environ Microbiol 2006; 72:6808-14. [PMID: 17021233 PMCID: PMC1610317 DOI: 10.1128/aem.00255-06] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Accepted: 06/22/2006] [Indexed: 11/20/2022] Open
Abstract
We have developed a rapid endospore viability assay (EVA) in which endospore germination serves as an indicator for viability and applied it to (i) monitor UV inactivation of endospores as a function of dose and (ii) determine the proportion of viable endospores in arctic ice cores (Greenland Ice Sheet Project 2 [GISP2] cores; 94 m). EVA is based on the detection of dipicolinic acid (DPA), which is released from endospores during germination. DPA concentrations were determined using the terbium ion (Tb3+)-DPA luminescence assay, and germination was induced by L-alanine addition. The concentrations of germinable endospores were determined by comparison to a standard curve. Parallel EVA and phase-contrast microscopy experiments to determine the percentage of germinable spores yielded comparable results (54.3% +/- 3.8% and 48.9% +/- 4.5%, respectively), while only 27.8% +/- 7.6% of spores produced CFU. EVA was applied to monitor the inactivation of spore suspensions as a function of UV dose, yielding reproducible correlations between EVA and CFU inactivation data. The 90% inactivation doses were 2,773 J/m2, 3,947 J/m2, and 1,322 J/m2 for EVA, phase-contrast microscopy, and CFU reduction, respectively. Finally, EVA was applied to quantify germinable and total endospore concentrations in two GISP2 ice cores. The first ice core contained 295 +/- 19 germinable spores/ml and 369 +/- 36 total spores/ml (i.e., the percentage of germinable endospores was 79.9% +/- 9.3%), and the second core contained 131 +/- 4 germinable spores/ml and 162 +/- 17 total spores/ml (i.e., the percentage of germinable endospores was 80.9% +/- 8.8%), whereas only 2 CFU/ml were detected by culturing.
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Affiliation(s)
- Hannah S Shafaat
- Jet Propulsion Laboratory, MS 302-205, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
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Préstamo G, Pedrazuela A, Guignon B, Sanz PD. Synergy between high-pressure, temperature and ascorbic acid on the inactivation of Bacillus cereus. Eur Food Res Technol 2006. [DOI: 10.1007/s00217-006-0469-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Lee WH, Ordal ZJ. REVERSIBLE ACTIVATION FOR GERMINATION AND SUBSEQUENT CHANGES IN BACTERIAL SPORES. J Bacteriol 2006; 85:207-17. [PMID: 16561987 PMCID: PMC278109 DOI: 10.1128/jb.85.1.207-217.1963] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lee, W. H. (University of Illinois, Urbana) and Z. John Ordal. Reversible activation for germination and subsequent changes in bacterial spores. J. Bacteriol. 85:207-217. 1963.-It was possible to isolate refractile spores of Bacillus megaterium, from a calcium dipicolinate germination solution, that were activated and would germinate spontaneously in distilled water. Some of the characteristics of the initial phases of bacterial spore germination were determined by studying these unstable activated spores. Activated spores of B. megaterium were resistant to stains and possessed a heat resistance intermediate between that of dormant and of germinated spores. The spontaneous germination of activated spores was inhibited by copper, iron, silver, or mercury salts, saturated o-phenanthroline, or solutions having a low pH value, but not by many common inhibitors. These inhibitions could be partially or completely reversed by the addition of sodium dipicolinate. The activated spores could be deactivated and made similar to dormant spores by treatment with acid. Analyses of the exudates from the variously treated spore suspensions revealed that whatever inhibited the germination of activated spores also inhibited the release of spore material. The composition of the germination exudates was different than that of extracts of dormant spores. Although heavy suspensions of activated spores gradually became swollen and dark when suspended in solutions of o-phenanthroline or at pH 4, the materials released resembled those found in extracts of dormant spores rather than those of normal germination exudates.
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Affiliation(s)
- W H Lee
- Department of Food Technology, University of Illinois, Urbana, Illinois
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Carroll TM, Setlow P. Site-directed mutagenesis and structural studies suggest that the germination protease, GPR, in spores of Bacillus species is an atypical aspartic acid protease. J Bacteriol 2005; 187:7119-25. [PMID: 16199582 PMCID: PMC1251623 DOI: 10.1128/jb.187.20.7119-7125.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Germination protease (GPR) initiates the degradation of small, acid-soluble spore proteins (SASP) during germination of spores of Bacillus and Clostridium species. The GPR amino acid sequence is not homologous to members of the major protease families, and previous work has not identified residues involved in GPR catalysis. The current work has focused on identifying catalytically essential amino acids by mutagenesis of Bacillus megaterium gpr. A residue was selected for alteration if it (i) was conserved among spore-forming bacteria, (ii) was a potential nucleophile, and (iii) had not been ruled out as inessential for catalysis. GPR variants were overexpressed in Escherichia coli, and the active form (P41) was assayed for activity against SASP and the zymogen form (P46) was assayed for the ability to autoprocess to P41. Variants inactive against SASP and unable to autoprocess were analyzed by circular dichroism spectroscopy and multi-angle laser light scattering to determine whether the variant's inactivity was due to loss of secondary or quaternary structure, respectively. Variation of D127 and D193, but no other residues, resulted in inactive P46 and P41, while variants of each form were well structured and tetrameric, suggesting that D127 and D193 are essential for activity and autoprocessing. Mapping these two aspartate residues and a highly conserved lysine onto the B. megaterium P46 crystal structure revealed a striking similarity to the catalytic residues and propeptide lysine of aspartic acid proteases. These data indicate that GPR is an atypical aspartic acid protease.
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Affiliation(s)
- Thomas M Carroll
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, CT 06032, USA
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Kort R, O'Brien AC, van Stokkum IHM, Oomes SJCM, Crielaard W, Hellingwerf KJ, Brul S. Assessment of heat resistance of bacterial spores from food product isolates by fluorescence monitoring of dipicolinic acid release. Appl Environ Microbiol 2005; 71:3556-64. [PMID: 16000762 PMCID: PMC1169001 DOI: 10.1128/aem.71.7.3556-3564.2005] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study is aimed at the development and application of a convenient and rapid optical assay to monitor the wet-heat resistance of bacterial endospores occurring in food samples. We tested the feasibility of measuring the release of the abundant spore component dipicolinic acid (DPA) as a probe for heat inactivation. Spores were isolated from the laboratory type strain Bacillus subtilis 168 and from two food product isolates, Bacillus subtilis A163 and Bacillus sporothermodurans IC4. Spores from the lab strain appeared much less heat resistant than those from the two food product isolates. The decimal reduction times (D values) for spores from strains 168, A163, and IC4 recovered on Trypticase soy agar were 1.4, 0.7, and 0.3 min at 105 degrees C, 120 degrees C, and 131 degrees C, respectively. The estimated Z values were 6.3 degrees C, 6.1 degrees C, and 9.7 degrees C, respectively. The extent of DPA release from the three spore crops was monitored as a function of incubation time and temperature. DPA concentrations were determined by measuring the emission at 545 nm of the fluorescent terbium-DPA complex in a microtiter plate fluorometer. We defined spore heat resistance as the critical DPA release temperature (Tc), the temperature at which half the DPA content has been released within a fixed incubation time. We found Tc values for spores from Bacillus strains 168, A163, and IC4 of 108 degrees C, 121 degrees C, and 131 degrees C, respectively. On the basis of these observations, we developed a quantitative model that describes the time and temperature dependence of the experimentally determined extent of DPA release and spore inactivation. The model predicts a DPA release rate profile for each inactivated spore. In addition, it uncovers remarkable differences in the values for the temperature dependence parameters for the rate of spore inactivation, DPA release duration, and DPA release delay.
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Affiliation(s)
- Remco Kort
- Laboratory for Microbiology, Room C-809, Swammerdam Institute for Life Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018WV Amsterdam, The Netherlands.
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Sarasanandarajah S, Kunnil J, Bronk BV, Reinisch L. Two-dimensional multiwavelength fluorescence spectra of dipicolinic acid and calcium dipicolinate. APPLIED OPTICS 2005; 44:1182-1187. [PMID: 15765697 DOI: 10.1364/ao.44.001182] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Dipicolinic acid (DPA) and the Ca2+ complex of DPA (CaDPA) are major chemical components of bacterial spores. With fluorescence being considered for the detection and identification of spores, it is important to understand the optical properties of the major components of the spores. We report in some detail on the room-temperature fluorescence excitation and emission spectra of DPA and its calcium ion complex and provide a comparison of the excitation-emission spectrum in a dry, wet paste and aqueous form. DPA solutions have weak, if any, fluorescence, with increased fluorescence when the DPA is dry. After exposure to a broad source UV light of the DPA, wet or dry, we observe a large increase in fluorescence with a maximum intensity emission peak at around 440 nm for excitation light with a wavelength of around 360 nm. There is a slight blueshift in the absorption spectra of UV-exposed DPA from the unexposed DPA solution. CaDPA in solution shows a slight fluorescence with increased fluorescence in the dry form, and a substantial increase of fluorescence was observed after UV exposure with an emission peak of around 410 nm for excitation around 305 nm. The detailed excitation-emission spectra are necessary for better interpretation of the fluorescence spectra of bacterial spores where DPA is a major chemical component.
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Nelson WH, Dasari R, Feld M, Sperry JF. Intensities of calcium dipicolinate and Bacillus subtilis spore Raman spectra excited with 244 nm light. APPLIED SPECTROSCOPY 2004; 58:1408-1412. [PMID: 15606952 DOI: 10.1366/0003702042641290] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Ultraviolet (UV) resonance Raman spectra of Bacillus subtilis endospores have been excited at 244 nm. Spectra can be interpreted in terms of contributions from calcium dipicolinate and nucleic acid components. Differences between spectra of spores and vegetative cells are very large and are due to the dominance of the dipicolinate features in the spore spectra. Because the DNA and RNA composition of B. subtilis spores is known and because the cross-sections of Raman bands belonging to DNA and RNA bases are known, it is possible to calculate resonance Raman spectral cross-sections for the spore Raman peaks associated with the nucleic acids. The cross-sections of peaks associated with calcium dipicolinate have been measured from aqueous solutions. Cross-section values of the dominant 1017 cm(-1) calcium dipicolinate peak measured from the Bacillus spores have been shown to be consistent with a calcium dipicolinate composition of ten percent or less by weight in the spores. It is suggested that spectral cross-sections of endospores excited at 244 nm can be estimated to be the sum of the cross-sections of the calcium dipicolinate, DNA, and RNA components of the spore. It appears that the peaks due to DNA and RNA can be used as an internal standard in the calculation of spore Raman peak cross-sections, and potentially the amount of calcium dipicolinate in spores. It is estimated on the basis of known nucleic acid base cross-sections that the most intense Raman band of the Bacillus subtilis spore spectra has a cross-section of no more than 4 x 10(-18) cm(2)/mol-sr.
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Affiliation(s)
- W H Nelson
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, USA
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Foster NS, Thompson SE, Valentine NB, Amonette JE, Johnson TJ. Identification of sporulated and vegetative bacteria using statistical analysis of fourier transform mid-infrared transmission data. APPLIED SPECTROSCOPY 2004; 58:203-211. [PMID: 15000715 DOI: 10.1366/000370204322842940] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A combined mid-infrared spectroscopic/statistical modeling approach for the discrimination and identification, at the strain level, of both sporulated and vegetative bacterial samples is presented. Transmission mode spectra of bacteria dried on ZnSe windows were collected using a Fourier transform mid-infrared (FT-IR) spectrometer. Five Bacillus bacterial strains (B. atrophaeus 49337, B. globigii Dugway, B. thuringiensis spp. kurstaki 35866, B. subtilis 49760, and B. subtilis 6051) were used to construct a reference spectral library and to parameterize a four-step statistical model for the systematic identification of bacteria. The statistical methods used in this initial feasibility study included principal component analysis (PCA), classification and regression trees (CART), and Mahalanobis distance calculations. Internal cross-validation studies successfully classified 100% of the samples into their correct physiological state (sporulated or vegetative) and identified 67% of the samples correctly as to their bacterial strain. Analysis of thirteen blind samples, which included reference and other bacteria, nonbiological materials, and mixtures of both nonbiological and bacterial samples, yielded comparable accuracy. The primary advantage of this approach is the accurate identification of unknown bacteria, including spores, in a matter of minutes.
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Affiliation(s)
- Nancy S Foster
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA.
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PERRY JJ, FOSTER JW. Studies on the biosynthesis of dipicolinic acid in spores of Bacillus cereus var. mycoides. J Bacteriol 2003; 69:337-46. [PMID: 14367284 PMCID: PMC357538 DOI: 10.1128/jb.69.3.337-346.1955] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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MICHENER HD, THOMPSON PA, LEWIS JC. Search for substances which reduce the heat resistance of bacterial spores. Appl Microbiol 2000; 7:166-73. [PMID: 13650521 PMCID: PMC1057496 DOI: 10.1128/am.7.3.166-173.1959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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POWELL JF. The changes in the total vitamin B6 and the pyridoxal phosphate content of cells of Bacillus sphaericus during growth and sporulation: their possible relationships with alphaepsilon-diaminopimelic acid metabolism. Biochem J 2000; 70:91-6. [PMID: 13584306 PMCID: PMC1196630 DOI: 10.1042/bj0700091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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YOUNG IE. A relationship between the free amino acid pool, dipicolinic acid, calcium from resting spores of Bacillus megaterium. Can J Microbiol 2000; 5:197-202. [PMID: 13638897 DOI: 10.1139/m59-024] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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WOESE CR. Effect of withholding glutamic acid and asparagine on the germination of spores of Bacillus subtilis. J Bacteriol 2000; 77:690-4. [PMID: 13664647 PMCID: PMC290450 DOI: 10.1128/jb.77.6.690-694.1959] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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WOESE C, MOROWITZ HJ. Kinetics of the release of dipicolinic acid from spores of Bacillus subtilis. J Bacteriol 2000; 76:81-3. [PMID: 13563394 PMCID: PMC290157 DOI: 10.1128/jb.76.1.81-83.1958] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Beverly MB, Voorhees KJ, Hadfield TL. Direct mass spectrometric analysis of Bacillus spores. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 1999; 13:2320-2326. [PMID: 10567929 DOI: 10.1002/(sici)1097-0231(19991215)13:23<2320::aid-rcm791>3.0.co;2-q] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Spores from the Bacillus species, B. cereus, B. anthracis, B. thuringensis, B. lichenformis, B. globigi, and B. subtilis, were examined by direct probe mass spectrometry using electron ionization (EI) and positive and negative chemical ionization (CI). Molecular ions from free fatty acids and nucleic acids were observed in the 70eV spectra as were fragments from glycerides. Spectra obtained with isobutane positive chemical ionization (CI(+)) were dominated by ions associated with pyranose compounds such as N-acetylglucosamine (NAG). Unlike the positive ion spectra, the negative ion spectra of the spores were very simple and contained few peaks. The M(-.) ion from dipicolinic acid (DPA) was the base peak in the negative ion spectra of all spore species except those from B. lichenformis. The negative ion of DPA produced such a strong signal that 10(8) colony forming units (CFUs) of B. cereus spores could be detected directly in 0.5 g of ground rice. Principal component analysis (PCA) of the spectra revealed that only CI(+) spectra contained differences that could be used to identify the spectra by species. Differentiation of the CI(+) spectra by PCA was attributed to variances in the peaks associated with the bacterial polymer poly(3-hydroxybutyrate) (PHB) and NAG. Similar differences in PHB and NAG peaks were detected in the CI(+) spectra of a suite of vegetative Bacillus stains grown with various media.
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Affiliation(s)
- M B Beverly
- Chemistry and Geochemistry Department, Colorado School of Mines, Golden, CO 80401, USA
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CHALOUPKA J, KRECKOVA P, RIHOVA L. Changes in the character of the cell wall in growth of Bacillus megaterium cultures. Folia Microbiol (Praha) 1998; 7:269-74. [PMID: 14019927 DOI: 10.1007/bf02928656] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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WALKER HW, MATCHES JR, AYRES JC. Chemical composition and heat resistance of some aerobic bacterial spores. J Bacteriol 1998; 82:960-6. [PMID: 14004586 PMCID: PMC279283 DOI: 10.1128/jb.82.6.960-966.1961] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Walker, Homer W. (Iowa State University of Science and Technology, Ames), Jack R. Matches, and John C. Ayres. Chemical composition and heat resistance of some aerobic bacterial spores. J. Bacteriol. 82:960-966. 1961.-Analyses of spores of Bacillus species for nitrogen, carbohydrate, dipicolinic acid, and phosphorus showed little correlation with heat resistance. However, as the molar concentration of magnesium increased in relation to dipicolinic acid and calcium concentrations, heat resistance generally decreased. Analyses of several batches of spores indicated that this relationship between calcium, magnesium, and dipicolinic acid did not always hold true. Therefore, while these materials apparently play an important role, other factors need to be included before a full explanation of thermal stability of spores can be made.
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GOLLAKOTA KG, HALVORSON HO. Biochemical changes occurring during sporulation of Bacillus cereus. Inhibition of sporulation by alpha-picolinic acid. J Bacteriol 1998; 79:1-8. [PMID: 13850820 PMCID: PMC278626 DOI: 10.1128/jb.79.1.1-8.1960] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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