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Article: Thyrotoxic periodic paralysis in a Caucasian man without identifiable genetic predisposition: a case report.

Heydorn, Arne / Bertelsen, Birgitte / Nolsöe, Rúna Louise Mortansdóttir / Eiken, Pia / Kristensen, Peter Lommer

2023 Volume 16, Issue 1, Page(s) 10

Abstract: Background: Thyrotoxic periodic paralysis (TPP) is a rare condition characterized by muscle paralysis, thyrotoxicosis, and hypokalemia. It presents with paralysis of both proximal and distal musculature in upper and lower limbs and may affect ... ...

Abstract	Background: Thyrotoxic periodic paralysis (TPP) is a rare condition characterized by muscle paralysis, thyrotoxicosis, and hypokalemia. It presents with paralysis of both proximal and distal musculature in upper and lower limbs and may affect respiratory musculature and the cardiac conduction system. Early diagnosis is essential, as the condition is potentially reversible by oral or intravenous potassium treatment, leading to rapid resolution without lasting weakness. Overlooking the diagnosis may result in respiratory failure and cardiac arrhythmias including QT prolongation, Torsades de points, and ventricular arrhythmias. Case presentation: A 19-year-old Caucasian man was admitted acutely with paralysis in upper and lower limbs and tachycardia. Over several months, he had experienced anxiousness, sweating more than usual, had daily palpitations, shortness of breath on exertion, and loose stools, and had lost 21 kg over the last year. Initial blood gas showed very low potassium of 1.4 mM, and blood tests showed decreased Thyroid-stimulating hormone (TSH) < 0.01 × 10 Conclusion: TPP is very rare in Caucasians but more often affects young men in East Asian populations. The case presents a Caucasian man with TPP where genetic testing of CACNA1S, KCNJ18, SCN4A, KCNJ2, KCNE3, and ABCC8 shows no pathogenic variants in genes previously associated with TPP.
Language	English
Publishing date	2023-05-01
Publishing country	England
Document type	Journal Article
ZDB-ID	2454440-1
ISSN	1756-6614
ISSN	1756-6614
DOI	10.1186/s13044-023-00152-w
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Article ; Online: Animal models of chronic and recurrent Pseudomonas aeruginosa lung infection: significance of macrolide treatment.

Thomsen, Kim / Kobayashi, Osamu / Kishi, Kenji / Shirai, Ryo / Østrup Jensen, Peter / Heydorn, Arne / Hentzer, Morten / Calum, Henrik / Christophersen, Lars / Høiby, Niels / Moser, Claus

APMIS : acta pathologica, microbiologica, et immunologica Scandinavica

2021 Volume 130, Issue 7, Page(s) 458–476

Abstract: Animal models of human diseases are invaluable and inevitable elements in identifying and testing novel treatments for serious diseases, including severe infections. Planning and conducting investigator-initiated human trials are generally accepted as ... ...

Abstract	Animal models of human diseases are invaluable and inevitable elements in identifying and testing novel treatments for serious diseases, including severe infections. Planning and conducting investigator-initiated human trials are generally accepted as being enormously challenging. In contrast, it is often underestimated how much planning, including background and modifying experiments, is needed to establish a relevant infectious disease animal model. However, representative animal infectious models, well designed to test generated hypotheses, are useful to improve our understanding of pathogenesis, virulence factors and host response and to identify novel treatment candidates and therapeutic strategies. Such results can subsequently proceed to clinical testing if suitable. The present review aims at presenting all the pulmonary Pseudomonas aeruginosa infectious models we have knowledge of and the detailed descriptions of established animal models in our laboratory focusing on macrolide therapy are presented.
MeSH term(s)	Animals ; Anti-Bacterial Agents/therapeutic use ; Cystic Fibrosis/drug therapy ; Disease Models, Animal ; Humans ; Lung ; Macrolides/pharmacology ; Macrolides/therapeutic use ; Pseudomonas Infections/drug therapy ; Pseudomonas aeruginosa/physiology
Chemical Substances	Anti-Bacterial Agents ; Macrolides
Language	English
Publishing date	2021-07-21
Publishing country	Denmark
Document type	Journal Article ; Review
ZDB-ID	93340-5
ISSN	1600-0463 ; 0903-4641
ISSN (online)	1600-0463
ISSN	0903-4641
DOI	10.1111/apm.13161
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Article ; Online: An analytical tool-box for comprehensive biochemical, structural and transcriptome evaluation of oral biofilms mediated by mutans streptococci.

Klein, Marlise I / Xiao, Jin / Heydorn, Arne / Koo, Hyun

Journal of visualized experiments : JoVE

2011 , Issue 47

Abstract: Biofilms are highly dynamic, organized and structured communities of microbial cells enmeshed in an extracellular matrix of variable density and composition (1, 2). In general, biofilms develop from initial microbial attachment on a surface followed by ... ...

Abstract	Biofilms are highly dynamic, organized and structured communities of microbial cells enmeshed in an extracellular matrix of variable density and composition (1, 2). In general, biofilms develop from initial microbial attachment on a surface followed by formation of cell clusters (or microcolonies) and further development and stabilization of the microcolonies, which occur in a complex extracellular matrix. The majority of biofilm matrices harbor exopolysaccharides (EPS), and dental biofilms are no exception; especially those associated with caries disease, which are mostly mediated by mutans streptococci (3). The EPS are synthesized by microorganisms (S. mutans, a key contributor) by means of extracellular enzymes, such as glucosyltransferases using sucrose primarily as substrate (3). Studies of biofilms formed on tooth surfaces are particularly challenging owing to their constant exposure to environmental challenges associated with complex diet-host-microbial interactions occurring in the oral cavity. Better understanding of the dynamic changes of the structural organization and composition of the matrix, physiology and transcriptome/proteome profile of biofilm-cells in response to these complex interactions would further advance the current knowledge of how oral biofilms modulate pathogenicity. Therefore, we have developed an analytical tool-box to facilitate biofilm analysis at structural, biochemical and molecular levels by combining commonly available and novel techniques with custom-made software for data analysis. Standard analytical (colorimetric assays, RT-qPCR and microarrays) and novel fluorescence techniques (for simultaneous labeling of bacteria and EPS) were integrated with specific software for data analysis to address the complex nature of oral biofilm research. The tool-box is comprised of 4 distinct but interconnected steps (Figure 1): 1) Bioassays, 2) Raw Data Input, 3) Data Processing, and 4) Data Analysis. We used our in vitro biofilm model and specific experimental conditions to demonstrate the usefulness and flexibility of the tool-box. The biofilm model is simple, reproducible and multiple replicates of a single experiment can be done simultaneously (4, 5). Moreover, it allows temporal evaluation, inclusion of various microbial species (5) and assessment of the effects of distinct experimental conditions (e.g. treatments (6); comparison of knockout mutants vs. parental strain (5); carbohydrates availability (7)). Here, we describe two specific components of the tool-box, including (i) new software for microarray data mining/organization (MDV) and fluorescence imaging analysis (DUOSTAT), and (ii) in situ EPS-labeling. We also provide an experimental case showing how the tool-box can assist with biofilms analysis, data organization, integration and interpretation.
MeSH term(s)	Biofilms ; Gene Expression Profiling/methods ; Molecular Imaging/methods ; Mouth/microbiology ; Oligonucleotide Array Sequence Analysis ; Polysaccharides, Bacterial/analysis ; Polysaccharides, Bacterial/metabolism ; Streptococcus mutans/genetics ; Streptococcus mutans/metabolism ; Streptococcus mutans/physiology
Chemical Substances	Polysaccharides, Bacterial ; exopolysaccharide, Streptococcus
Language	English
Publishing date	2011-01-25
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Video-Audio Media
ZDB-ID	2259946-0
ISSN	1940-087X ; 1940-087X
ISSN (online)	1940-087X
ISSN	1940-087X
DOI	10.3791/2512
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Article: An analytical tool-box for comprehensive biochemical, structural and transcriptome evaluation of oral biofilms mediated by mutans streptococci

Klein, Marlise I / Xiao, Jin / Heydorn, Arne / Koo, Hyun

Journal of visualized experiments. 2011 Jan. 25, , no. 47

2011

Abstract: Biofilms are highly dynamic, organized and structured communities of microbial cells enmeshed in an extracellular matrix of variable density and composition 1, 2. In general, biofilms develop from initial microbial attachment on a surface followed by ... ...

Abstract	Biofilms are highly dynamic, organized and structured communities of microbial cells enmeshed in an extracellular matrix of variable density and composition 1, 2. In general, biofilms develop from initial microbial attachment on a surface followed by formation of cell clusters (or microcolonies) and further development and stabilization of the microcolonies, which occur in a complex extracellular matrix. The majority of biofilm matrices harbor exopolysaccharides (EPS), and dental biofilms are no exception; especially those associated with caries disease, which are mostly mediated by mutans streptococci 3. The EPS are synthesized by microorganisms (S. mutans, a key contributor) by means of extracellular enzymes, such as glucosyltransferases using sucrose primarily as substrate 3. Studies of biofilms formed on tooth surfaces are particularly challenging owing to their constant exposure to environmental challenges associated with complex diet-host-microbial interactions occurring in the oral cavity. Better understanding of the dynamic changes of the structural organization and composition of the matrix, physiology and transcriptome/proteome profile of biofilm-cells in response to these complex interactions would further advance the current knowledge of how oral biofilms modulate pathogenicity. Therefore, we have developed an analytical tool-box to facilitate biofilm analysis at structural, biochemical and molecular levels by combining commonly available and novel techniques with custom-made software for data analysis. Standard analytical (colorimetric assays, RT-qPCR and microarrays) and novel fluorescence techniques (for simultaneous labeling of bacteria and EPS) were integrated with specific software for data analysis to address the complex nature of oral biofilm research. The tool-box is comprised of 4 distinct but interconnected steps (Figure 1): 1) Bioassays, 2) Raw Data Input, 3) Data Processing, and 4) Data Analysis. We used our in vitro biofilm model and specific experimental conditions to demonstrate the usefulness and flexibility of the tool-box. The biofilm model is simple, reproducible and multiple replicates of a single experiment can be done simultaneously 4, 5. Moreover, it allows temporal evaluation, inclusion of various microbial species 5 and assessment of the effects of distinct experimental conditions (e.g. treatments 6; comparison of knockout mutants vs. parental strain 5; carbohydrates availability 7). Here, we describe two specific components of the tool-box, including (i) new software for microarray data mining/organization (MDV) and fluorescence imaging analysis (DUOSTAT), and (ii) in situ EPS-labeling. We also provide an experimental case showing how the tool-box can assist with biofilms analysis, data organization, integration and interpretation.
Keywords	bacteria ; bioassays ; biofilm ; colorimetry ; computer software ; exopolysaccharides ; extracellular enzymes ; extracellular matrix ; fluorescence ; glucosyltransferases ; information processing ; knockout mutants ; microarray technology ; models ; mouth ; pathogenicity ; physiology ; proteome ; quantitative polymerase chain reaction ; reverse transcriptase polymerase chain reaction ; sucrose ; transcriptome
Language	English
Dates of publication	2011-0125
Size	p. e2512.
Publishing place	Journal of Visualized Experiments
Document type	Article
ZDB-ID	2259946-0
ISSN	1940-087X
ISSN	1940-087X
DOI	10.3791/2512
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Article: Protein translocation assays: key tools for accessing new biological information with high-throughput microscopy.

Heydorn, Arne / Lundholt, Betina K / Praestegaard, Morten / Pagliaro, Len

Methods in enzymology

2006 Volume 414, Page(s) 513–530

Abstract: Redistribution technology is a cell-based assay technology that uses protein translocation as the primary readout for the activity of cellular signaling pathways and other intracellular events. Protein targets are labeled with the green fluorescent ... ...

Abstract	Redistribution technology is a cell-based assay technology that uses protein translocation as the primary readout for the activity of cellular signaling pathways and other intracellular events. Protein targets are labeled with the green fluorescent protein, and stably transfected cell lines are generated. The assays are read using a high-throughput, optical microscope-based instrument, several of which have become available commercially. Protein translocation assays can be formatted as agonist assays, in which compounds are tested for their ability to promote protein translocation, or as antagonist assays, in which compounds are tested for their ability to inhibit protein translocation caused by a known agonist. Protein translocation assays are high-content, high-throughput assays primarily used for profiling of lead series, primary screening of compound libraries, and as readouts for gene-silencing studies using siRNAs. This chapter describes two novel high-content Redistribution assay technologies: (1) The p53:hdm2 GRIP interaction assay, in which one high-content image feature is used for detection of primary hits, whereas a different feature is used to deselect compounds with unwanted mode of action, and (2) application of siRNAs to Redistribution assays, exemplified by knockdown of Akt isoforms in a FKHR translocation assay reporting on the PI3 kinase signaling pathway.
MeSH term(s)	Animals ; Biochemistry/instrumentation ; Biochemistry/methods ; CHO Cells ; Cell Line, Tumor ; Cricetinae ; Green Fluorescent Proteins/metabolism ; Humans ; Image Processing, Computer-Assisted ; Microscopy, Fluorescence/instrumentation ; Microscopy, Fluorescence/methods ; Phosphatidylinositol 3-Kinases/metabolism ; Phosphorylation ; Protein Transport ; Proto-Oncogene Proteins c-akt/metabolism ; RNA, Small Interfering/metabolism ; Signal Transduction
Chemical Substances	RNA, Small Interfering ; Green Fluorescent Proteins (147336-22-9) ; Phosphatidylinositol 3-Kinases (EC 2.7.1.-) ; Proto-Oncogene Proteins c-akt (EC 2.7.11.1)
Language	English
Publishing date	2006
Publishing country	United States
Document type	Journal Article
ISSN	0076-6879
ISSN	0076-6879
DOI	10.1016/S0076-6879(06)14027-6
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Article: A simple cell-based HTS assay system to screen for inhibitors of p53-Hdm2 protein-protein interactions.

Lundholt, Betina Kerstin / Heydorn, Arne / Bjørn, Sara Petersen / Praestegaard, Morten

Assay and drug development technologies

2006 Volume 4, Issue 6, Page(s) 679–688

Abstract: Green fluorescent protein-assisted readout for interacting proteins (GRIP) is a universal protein interaction discovery system that can be used to generate truly high throughput screening-compatible cellular assays to be used to screen for inhibitors of ... ...

Abstract	Green fluorescent protein-assisted readout for interacting proteins (GRIP) is a universal protein interaction discovery system that can be used to generate truly high throughput screening-compatible cellular assays to be used to screen for inhibitors of protein-protein interactions. The technology uses a "bait and prey" principle based on the distinct translocation behavior of the human cyclic AMP phosphodiesterase 4A4. Here we use the p53-Hdm2 Redistribution assay (Fisher BioImage ApS, Søborg, Denmark) as an example to describe the GRIP technology. The p53-Hdm2 Redistribution assay is a high content imaging assay based on the GRIP technology that is designed to measure the interaction between Hdm2 and the tumor suppressor p53. Hdm2 regulates p53 and inhibits its function by modulating its transcriptional activity and stability. Activation of p53 in tumor cells through inhibition of its physical interaction with Hdm2 is therefore a focus of cancer drug discovery. We have performed a pilot screen by screening 3,165 compounds from a diverse small-molecule library for inhibitors of the p53-Hdm2 interaction by using the p53-Hdm2 Redistribution assay. Here we show that by taking advantage of the translocation behavior of nonbound p53, it is possible to identify true inhibitors of the p53-Hdm2 interaction by extracting high content information from the acquired images.
MeSH term(s)	Animals ; CHO Cells ; Cell Line, Tumor ; Cricetinae ; Cricetulus ; Dose-Response Relationship, Drug ; Drug Evaluation, Preclinical/methods ; Green Fluorescent Proteins/metabolism ; Humans ; Protein Transport ; Proto-Oncogene Proteins c-mdm2/antagonists & inhibitors ; Tumor Suppressor Protein p53/antagonists & inhibitors
Chemical Substances	Tumor Suppressor Protein p53 ; Green Fluorescent Proteins (147336-22-9) ; MDM2 protein, human (EC 2.3.2.27) ; Proto-Oncogene Proteins c-mdm2 (EC 2.3.2.27)
Language	English
Publishing date	2006-12
Publishing country	United States
Document type	Journal Article
ISSN	1540-658X
ISSN	1540-658X
DOI	10.1089/adt.2006.4.679
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Article ; Online: The exopolysaccharide matrix modulates the interaction between 3D architecture and virulence of a mixed-species oral biofilm.

Xiao, Jin / Klein, Marlise I / Falsetta, Megan L / Lu, Bingwen / Delahunty, Claire M / Yates, John R / Heydorn, Arne / Koo, Hyun

PLoS pathogens

2012 Volume 8, Issue 4, Page(s) e1002623

Abstract: Virulent biofilms are responsible for a range of infections, including oral diseases. All biofilms harbor a microbial-derived extracellular-matrix. The exopolysaccharides (EPS) formed on tooth-pellicle and bacterial surfaces provide binding sites for ... ...

Abstract	Virulent biofilms are responsible for a range of infections, including oral diseases. All biofilms harbor a microbial-derived extracellular-matrix. The exopolysaccharides (EPS) formed on tooth-pellicle and bacterial surfaces provide binding sites for microorganisms; eventually the accumulated EPS enmeshes microbial cells. The metabolic activity of the bacteria within this matrix leads to acidification of the milieu. We explored the mechanisms through which the Streptococcus mutans-produced EPS-matrix modulates the three-dimensional (3D) architecture and the population shifts during morphogenesis of biofilms on a saliva-coated-apatitic surface using a mixed-bacterial species system. Concomitantly, we examined whether the matrix influences the development of pH-microenvironments within intact-biofilms using a novel 3D in situ pH-mapping technique. Data reveal that the production of the EPS-matrix helps to create spatial heterogeneities by forming an intricate network of exopolysaccharide-enmeshed bacterial-islets (microcolonies) through localized cell-to-matrix interactions. This complex 3D architecture creates compartmentalized acidic and EPS-rich microenvironments throughout the biofilm, which triggers the dominance of pathogenic S. mutans within a mixed-species system. The establishment of a 3D-matrix and EPS-enmeshed microcolonies were largely mediated by the S. mutans gtfB/gtfC genes, expression of which was enhanced in the presence of Actinomyces naeslundii and Streptococcus oralis. Acidic pockets were found only in the interiors of bacterial-islets that are protected by EPS, which impedes rapid neutralization by buffer (pH 7.0). As a result, regions of low pH (<5.5) were detected at specific locations along the surface of attachment. Resistance to chlorhexidine was enhanced in cells within EPS-microcolony complexes compared to those outside such structures within the biofilm. Our results illustrate the critical interaction between matrix architecture and pH heterogeneity in the 3D environment. The formation of structured acidic-microenvironments in close proximity to the apatite-surface is an essential factor associated with virulence in cariogenic-biofilms. These observations may have relevance beyond the mouth, as matrix is inherent to all biofilms.
MeSH term(s)	Animals ; Biofilms/growth & development ; Humans ; Hydrogen-Ion Concentration ; Mouth/microbiology ; Polysaccharides/metabolism ; Streptococcus mutans/growth & development ; Streptococcus mutans/metabolism ; Streptococcus mutans/pathogenicity ; Streptococcus oralis/growth & development ; Streptococcus oralis/metabolism ; Streptococcus oralis/pathogenicity ; Virulence Factors/metabolism
Chemical Substances	Polysaccharides ; Virulence Factors
Language	English
Publishing date	2012-04-05
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	2205412-1
ISSN	1553-7374 ; 1553-7374
ISSN (online)	1553-7374
ISSN	1553-7374
DOI	10.1371/journal.ppat.1002623
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Article: Molecular analysis of rugosity in a Vibrio cholerae O1 El Tor phase variant.

Yildiz, Fitnat H / Liu, Xiaole S / Heydorn, Arne / Schoolnik, Gary K

Molecular microbiology

2004 Volume 53, Issue 2, Page(s) 497–515

Abstract: Reversible phase variation between the rugose and smooth colony variants is predicted to be important for the survival of Vibrio cholerae in natural aquatic habitats. Microarray expression profiling studies of the rugose and smooth variants of the same ... ...

Abstract	Reversible phase variation between the rugose and smooth colony variants is predicted to be important for the survival of Vibrio cholerae in natural aquatic habitats. Microarray expression profiling studies of the rugose and smooth variants of the same strain led to the identification of 124 differentially regulated genes. Further expression profiling experiments showed how these genes are regulated by the VpsR and HapR transcription factors, which, respectively, positively and negatively regulate production of VPS(El Tor), a rugose-associated extracellular polysaccharide. The study of mutants of rpoN and rpoS demonstrated the effects of these alternative sigma factors on phase variation-specific gene expression. Bioinformatics analysis of these expression data shows that 'rugosity' and 'smoothness' are determined by a complex hierarchy of positive and negative regulators, which also affect the biofilm, surface hydrophobicity and motility phenotypes of the organism.
MeSH term(s)	Adaptation, Physiological ; Bacterial Proteins/genetics ; Bacterial Proteins/physiology ; Biofilms/growth & development ; DNA-Binding Proteins/genetics ; DNA-Binding Proteins/physiology ; DNA-Directed RNA Polymerases/genetics ; DNA-Directed RNA Polymerases/physiology ; Gene Expression Profiling ; Gene Expression Regulation, Bacterial ; Genes, Bacterial ; Hydrophobic and Hydrophilic Interactions ; Movement ; Mutation ; Oligonucleotide Array Sequence Analysis ; Polysaccharides, Bacterial/biosynthesis ; Polysaccharides, Bacterial/metabolism ; RNA Polymerase Sigma 54 ; Regulon ; Repressor Proteins/physiology ; Sigma Factor/genetics ; Sigma Factor/physiology ; Signal Transduction ; Trans-Activators/physiology ; Vibrio cholerae O1/genetics ; Vibrio cholerae O1/physiology
Chemical Substances	Bacterial Proteins ; DNA-Binding Proteins ; Polysaccharides, Bacterial ; Repressor Proteins ; Sigma Factor ; Trans-Activators ; VpsR protein, Vibrio cholerae ; sigma factor KatF protein, Bacteria ; LuxR autoinducer binding proteins (115038-68-1) ; DNA-Directed RNA Polymerases (EC 2.7.7.6) ; RNA Polymerase Sigma 54 (EC 2.7.7.6)
Language	English
Publishing date	2004-07
Publishing country	England
Document type	Comparative Study ; Journal Article ; Research Support, U.S. Gov't, P.H.S.
ZDB-ID	619315-8
ISSN	1365-2958 ; 0950-382X
ISSN (online)	1365-2958
ISSN	0950-382X
DOI	10.1111/j.1365-2958.2004.04154.x
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Article: Metabolic commensalism and competition in a two-species microbial consortium.

Christensen, Bjarke B / Haagensen, Janus A J / Heydorn, Arne / Molin, Søren

Applied and environmental microbiology

2001 Volume 68, Issue 5, Page(s) 2495–2502

Abstract: We analyzed metabolic interactions and the importance of specific structural relationships in a benzyl alcohol-degrading microbial consortium comprising two species, Pseudomonas putida strain R1 and Acinetobacter strain C6, both of which are able to ... ...

Abstract	We analyzed metabolic interactions and the importance of specific structural relationships in a benzyl alcohol-degrading microbial consortium comprising two species, Pseudomonas putida strain R1 and Acinetobacter strain C6, both of which are able to utilize benzyl alcohol as their sole carbon and energy source. The organisms were grown either as surface-attached organisms (biofilms) in flow chambers or as suspended cultures in chemostats. The numbers of CFU of P. putida R1 and Acinetobacter strain C6 were determined in chemostats and from the effluents of the flow chambers. When the two species were grown together in chemostats with limiting concentrations of benzyl alcohol, Acinetobacter strain C6 outnumbered P. putida R1 (500:1), whereas under similar growth conditions in biofilms, P. putida R1 was present in higher numbers than Acinetobacter strain C6 (5:1). In order to explain this difference, investigations of microbial activities and structural relationships were carried out in the biofilms. Insertion into P. putida R1 of a fusion between the growth rate-regulated rRNA promoter rrnBP1 and a gfp gene encoding an unstable variant of the green fluorescent protein made it possible to monitor the physiological activity of P. putida R1 cells at different positions in the biofilms. Combining this with fluorescent in situ hybridization and scanning confocal laser microscopy showed that the two organisms compete or display commensal interactions depending on their relative physical positioning in the biofilm. In the initial phase of biofilm development, the growth activity of P. putida R1 was shown to be higher near microcolonies of Acinetobacter strain C6. High-pressure liquid chromatography analysis showed that in the effluent of the Acinetobacter strain C6 monoculture biofilm the metabolic intermediate benzoate accumulated, whereas in the biculture biofilms this was not the case, suggesting that in these biofilms the excess benzoate produced by Acinetobacter strain C6 leaks into the surrounding environment, from where it is metabolized by P. putida R1. After a few days, Acinetobacter strain C6 colonies were overgrown by P. putida R1 cells and new structures developed, in which microcolonies of Acinetobacter strain C6 cells were established in the upper layer of the biofilm. In this way the two organisms developed structural relationships allowing Acinetobacter strain C6 to be close to the bulk liquid with high concentrations of benzyl alcohol and allowing P. putida R1 to benefit from the benzoate leaking from Acinetobacter strain C6. We conclude that in chemostats, where the organisms cannot establish in fixed positions, the two strains will compete for the primary carbon source, benzyl alcohol, which apparently gives Acinetobacter strain C6 a growth advantage, probably because it converts benzyl alcohol to benzoate with a higher yield per time unit than P. putida R1. In biofilms, however, the organisms establish structured, surface-attached consortia, in which heterogeneous ecological niches develop, and under these conditions competition for the primary carbon source is not the only determinant of biomass and population structure.
MeSH term(s)	Acinetobacter/physiology ; Antibiosis ; Biofilms/growth & development ; Pseudomonas putida/physiology
Language	English
Publishing date	2001-10-13
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	223011-2
ISSN	1098-5336 ; 0099-2240
ISSN (online)	1098-5336
ISSN	0099-2240
DOI	10.1128/AEM.68.5.2495-2502.2002
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Article: A complex multilevel attack on Pseudomonas aeruginosa algT/U expression and AlgT/U activity results in the loss of alginate production

Sautter, Robert / Ramos, Damaris / Schneper, Lisa / Ciofu, Oana / Wassermann, Tina / Koh, Chong-Lek / Heydorn, Arne / Hentzer, Morton / Høiby, Niels / Kharazmi, Arsalan / Molin, Søren / DeVries, Caroline A / Ohman, Dennis E / Mathee, Kalai

Gene. 2012 May 1, v. 498, no. 2

2012

Abstract: Infection by the opportunistic pathogen Pseudomonas aeruginosa is a leading cause of morbidity and mortality seen in cystic fibrosis (CF) patients. This is mainly due to the genotypic and phenotypic changes of the bacteria that cause conversion from a ... ...

Abstract	Infection by the opportunistic pathogen Pseudomonas aeruginosa is a leading cause of morbidity and mortality seen in cystic fibrosis (CF) patients. This is mainly due to the genotypic and phenotypic changes of the bacteria that cause conversion from a typical nonmucoid to a mucoid form in the CF lung. Mucoid conversion is indicative of overproduction of a capsule-like polysaccharide called alginate. The alginate-overproducing (Alg⁺) mucoid phenotype seen in the CF isolates is extremely unstable. Low oxygen tension growth of mucoid variants readily selects for nonmucoid variants. The switching off mechanism has been mapped to the algT/U locus, and the molecular basis for this conversion was partially attributed to mutations in the algT/U gene itself. To further characterize molecular changes resulting in the unstable phenotype, an isogenic PAO1 derivative that is constitutively Alg⁺ due to the replacement of the mucA with mucA22 (PDO300) was used. The mucA22 allele is common in mucoid CF isolates. Thirty-four spontaneous nonmucoid variants, or sap (suppressor of alginate production) mutants, of PDO300 were isolated under low oxygen tension. About 40% of the sap mutants were rescued by a plasmid carrying algT/U (Group A). The remaining sap mutants were not (Group B). The members of Group B fall into two subsets: one similar to PAO1, and another comparable to PDO300. Sequence analysis of the algT/U and mucA genes in Group A shows that mucA22 is intact, whereas algT/U contains mutations. Genetic complementation and sequencing of one Group B sap mutant, sap22, revealed that the nonmucoid phenotype was due to the presence of a mutation in PA3257. PA3257 encodes a putative periplasmic protease. Mutation of PA3257 resulted in decreased algT/U expression. Thus, inhibition of algT/U is a primary mechanism for alginate synthesis suppression.
Keywords	Pseudomonas aeruginosa ; alleles ; bacteria ; cystic fibrosis ; genetic complementation ; loci ; morbidity ; mortality ; mutants ; mutation ; oxygen ; pathogens ; patients ; phenotype ; plasmids ; proteinases ; sequence analysis
Language	English
Dates of publication	2012-0501
Size	p. 242-253.
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	391792-7
ISSN	1879-0038 ; 0378-1119
ISSN (online)	1879-0038
ISSN	0378-1119
DOI	10.1016/j.gene.2011.11.005
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