ABSTRACTMany bacteria form biofilms to protect themselves from predators or stressful environment... more ABSTRACTMany bacteria form biofilms to protect themselves from predators or stressful environmental conditions. In the biofilm, bacteria are embedded in a protective extracellular matrix composed of polysaccharides, proteins and extracellular DNA (eDNA). eDNA most often arises from lysed cells, and it is the only matrix component most biofilms appear to have in common. However, little is known about the form DNA takes in the extracellular space, and how different non-canonical DNA structures such as Z-DNA or G-quadruplex formation might contribute to its function in the biofilm.The aim of this study was to determine if non-canonical DNA structures form in eDNA-rich staphylococcal biofilms, and if these structures protect the biofilm from degradation by nucleases. We grewStaphylococcus epidermidisbiofilms in laboratory media amended with hemin and NaCl to stabilize secondary DNA structures and visualized their location by immunolabelling and fluorescence microscopy. We furthermore vi...
Staphylococcus epidermidis causes some of the most hard-to-treat clinical infections by forming b... more Staphylococcus epidermidis causes some of the most hard-to-treat clinical infections by forming biofilms: Multicellular communities of bacteria encased in a protective matrix, supporting immune evasion and tolerance against antibiotics. Biofilms occur most commonly on medical implants, and a key event in implant colonization is the robust adherence to the surface, facilitated by interactions between bacterial surface proteins and host matrix components. S. epidermidis is equipped with a giant adhesive protein, Embp, which facilitates bacterial interactions with surface-deposited, but not soluble fibronectin. The structural basis behind this selective binding process has remained obscure. Using a suite of single-cell and single-molecule analysis techniques, we show that S. epidermidis is capable of such distinction because Embp binds specifically to fibrillated fibronectin on surfaces, while ignoring globular fibronectin in solution. S. epidermidis adherence is critically dependent o...
Anaerobic sewer biofilm is a composite of many different microbial populations, including sulfate... more Anaerobic sewer biofilm is a composite of many different microbial populations, including sulfate reducing bacteria (SRB), methanogens and heterotrophic bacteria. Nitrate addition to sewers in an attempt to control hydrogen sulfide concentrations affects the behaviour of these populations, which in turn impacts on wastewater characteristics. Experiments were carried out on a laboratory reactor system simulating a rising main to determine
Representatives of the genus Bacillus are common milk contaminants that cause spoilage and flavor... more Representatives of the genus Bacillus are common milk contaminants that cause spoilage and flavor alterations of dairy products. Bacillus sp. FMQ74 was isolated from raw milk on a Danish dairy farm. To elucidate the genomic basis of this strain's survival in the dairy industry, a high-quality draft genome was produced.
During sweating, bacteria from the skin enter the worn textile along with the sweat. Once inside ... more During sweating, bacteria from the skin enter the worn textile along with the sweat. Once inside the clothes, the bacteria produce sweat malodor and form colonies that are extremely hard to remove by washing.
Graphical Listeria monocytogenes activates the two-component system LisRK under stress, and becom... more Graphical Listeria monocytogenes activates the two-component system LisRK under stress, and becomes more adhesive and highly tolerant to ampicillin.
<p>Colonization of textiles and subsequent metabolic degradation of sweat and sebum... more <p>Colonization of textiles and subsequent metabolic degradation of sweat and sebum components by axillary skin bacteria cause the characteristic sweat malodor and discoloring of dirty clothes. Once inside the textile, the bacteria can form biofilms that are hard to remove by conventional washing. When the biofilm persists after washing, the textiles retain the sweat odor. In addition to posing a huge industrial problem, textile biofilms constitute an interesting case study of bacterial behavior in periodically wetted and dried substrates with varying surface hydrophobicity. Here we aim to study the bacterial behavior in each of the four stages of the bacterial lifecycle in textiles: adhesion, growth, drying and washing. To accomplish this, we designed a novel in vitro model to mimic physiological sweating while wearing cotton and polyester textiles. The hydrophobic polyester adhered bacteria more strongly and absorbed more sebum, the bacteria’s primary nutrient source. Bacteria were therefore initially more active in polyester textiles than in cotton. However, polyester did not bind water as well as cotton. The increased water content of cotton allowed the bacteria to retain a higher activity after the textile had dried. However, neither of the textiles retained enough water upon drying to prevent the bacteria from irreversibly adhering to the textile fibers by capillary action. This demonstrates that bacterial colonization depends on the hydrophobic and hygroscopic properties of the colonized material while highlighting the possibility of controlling bacterial behavior by either changing the surface properties or the surrounding environment.</p>
Amyloids are typically associated with neurodegenerative diseases, but recent research demonstrat... more Amyloids are typically associated with neurodegenerative diseases, but recent research demonstrates that several bacteria utilize functional amyloid fibrils to fortify the biofilm extracellular matrix and thereby resist antibiotic treatments. In Pseudomonas aeruginosa, these fibrils are composed predominantly of FapC, a protein with high-sequence conservation among the genera. Previous studies established FapC as the major amyloid subunit, but its mechanism of fibril formation in P. aeruginosa remained largely unexplored. Here, we examine the FapC sequence in greater detail through a combination of bioinformatics and protein engineering, and we identify specific motifs that are implicated in amyloid formation. Sequence regions of high evolutionary conservation tend to coincide with regions of high amyloid propensity, and mutation of amyloidogenic motifs to a designed, non-amyloidogenic motif suppresses fibril formation in a pH-dependent manner. We establish the particular significan...
Nanozymes, nanoparticles that mimic the natural activity of enzymes, are intriguing academically ... more Nanozymes, nanoparticles that mimic the natural activity of enzymes, are intriguing academically and are important in the context of Origin of Life. However, current nanozymes offer mimicry to a narrow range of mammalian enzymes, near-exclusively performing redox reactions. In this work, we present an unexpected discovery of non-proteinaceous enzymes based on metals, metal oxides, 1D/2D-materials, and non-metallic nanomaterials. Specific novelty of our findings lies in the identification of nanozymes with apparent mimicry of diverse mammalian enzymes, including unique pan-glycosidases. Further novelty lies in the identification of the substrate scope for the lead candidates, specifically in the context of bioconversion of glucuronides, that is, human metabolites and privileged prodrugs in the field of enzyme-prodrug therapies. Lastly, nanozymes are employed for conversion of glucuronide prodrugs into marketed anti-inflammatory and antibacterial agents, as well as "nanozyme prodrug therapy" to mediate antibacterial measures.
Journal of labelled compounds & radiopharmaceuticals, Jan 23, 2018
The development of bacteria-specific infection radiotracers is of considerable interest to improv... more The development of bacteria-specific infection radiotracers is of considerable interest to improve diagnostic accuracy and enabling therapy monitoring. The aim of this study was to determine if the previously reported radiolabelled 1,4,7,10-tetraazacyclododecane-N,N',N″,N‴-tetraacetic acid (DOTA) conjugated peptide [ Ga]Ga-DOTA-K-A9 could detect a staphylococcal infection in vivo and distinguish it from aseptic inflammation. An optimized [ Ga]Ga-DOTA-K-A9 synthesis omitting the use of acetone was developed, yielding 93 ± 0.9% radiochemical purity. The in vivo infection binding specificity of [ Ga]Ga-DOTA-K-A9 was evaluated by micro positron emission tomography/magnetic resonance imaging of 15 mice with either subcutaneous Staphylococcus aureus infection or turpentine-induced inflammation and compared with 2-deoxy-2-[ F]fluoro-D-glucose ([ F]FDG). The scans showed that [ Ga]Ga-DOTA-K-A9 accumulated in all the infected mice at injected doses ≥3.6 MBq. However, the tracer was not f...
Implant-associated infections caused by bacterial biofilms are difficult to treat. Surgical inter... more Implant-associated infections caused by bacterial biofilms are difficult to treat. Surgical intervention is often necessary to cure the patient, as the antibiotic recalcitrance of biofilms renders them untreatable with conventional antibiotics. Intermittent hyperbaric oxygen treatment (HBOT) has been proposed as an adjuvant to conventional antibiotic treatment and it has been speculated that combining HBOT with antibiotics could improve treatment outcomes for biofilm infections. In this study we addressed whether HBOT could improve treatment outcomes of daptomycin and rifampicin combination therapy. The effect of HBOT on the treatment outcomes of daptomycin and rifampicin against implant-associated osteomyelitis was quantified in a murine model. In total, 80 mice were randomized into two groups receiving antibiotics, either alone or in combination with daily intermittent HBOT (304 kPa for 60 min) following injection of antibiotics. Treatment was initiated 11 days after animals were ...
Epigallocatechin-3-gallate (EGCG) is the major polyphenol in green tea. It has antimicrobial prop... more Epigallocatechin-3-gallate (EGCG) is the major polyphenol in green tea. It has antimicrobial properties and disrupts the ordered structure of amyloid fibrils involved in human disease. The antimicrobial effect of EGCG against the opportunistic pathogen Pseudomonas aeruginosa has been shown to involve disruption of quorum sensing (QS). Functional amyloid fibrils in P. aeruginosa (Fap) are able to bind and retain quorum-sensing molecules, suggesting that EGCG interferes with QS through structural remodeling of amyloid fibrils. Here we show that EGCG inhibits the ability of Fap to form fibrils; instead, EGCG stabilizes protein oligomers. Existing fibrils are remodeled by EGCG into non-amyloid aggregates. This fibril remodeling increases the binding of pyocyanin, demonstrating a mechanism by which EGCG can affect the QS function of functional amyloid. EGCG reduced the amyloid-specific fluorescent thioflavin T signal in P. aeruginosa biofilms at concentrations known to exert an antimicro...
ABSTRACTMany bacteria form biofilms to protect themselves from predators or stressful environment... more ABSTRACTMany bacteria form biofilms to protect themselves from predators or stressful environmental conditions. In the biofilm, bacteria are embedded in a protective extracellular matrix composed of polysaccharides, proteins and extracellular DNA (eDNA). eDNA most often arises from lysed cells, and it is the only matrix component most biofilms appear to have in common. However, little is known about the form DNA takes in the extracellular space, and how different non-canonical DNA structures such as Z-DNA or G-quadruplex formation might contribute to its function in the biofilm.The aim of this study was to determine if non-canonical DNA structures form in eDNA-rich staphylococcal biofilms, and if these structures protect the biofilm from degradation by nucleases. We grewStaphylococcus epidermidisbiofilms in laboratory media amended with hemin and NaCl to stabilize secondary DNA structures and visualized their location by immunolabelling and fluorescence microscopy. We furthermore vi...
Staphylococcus epidermidis causes some of the most hard-to-treat clinical infections by forming b... more Staphylococcus epidermidis causes some of the most hard-to-treat clinical infections by forming biofilms: Multicellular communities of bacteria encased in a protective matrix, supporting immune evasion and tolerance against antibiotics. Biofilms occur most commonly on medical implants, and a key event in implant colonization is the robust adherence to the surface, facilitated by interactions between bacterial surface proteins and host matrix components. S. epidermidis is equipped with a giant adhesive protein, Embp, which facilitates bacterial interactions with surface-deposited, but not soluble fibronectin. The structural basis behind this selective binding process has remained obscure. Using a suite of single-cell and single-molecule analysis techniques, we show that S. epidermidis is capable of such distinction because Embp binds specifically to fibrillated fibronectin on surfaces, while ignoring globular fibronectin in solution. S. epidermidis adherence is critically dependent o...
Anaerobic sewer biofilm is a composite of many different microbial populations, including sulfate... more Anaerobic sewer biofilm is a composite of many different microbial populations, including sulfate reducing bacteria (SRB), methanogens and heterotrophic bacteria. Nitrate addition to sewers in an attempt to control hydrogen sulfide concentrations affects the behaviour of these populations, which in turn impacts on wastewater characteristics. Experiments were carried out on a laboratory reactor system simulating a rising main to determine
Representatives of the genus Bacillus are common milk contaminants that cause spoilage and flavor... more Representatives of the genus Bacillus are common milk contaminants that cause spoilage and flavor alterations of dairy products. Bacillus sp. FMQ74 was isolated from raw milk on a Danish dairy farm. To elucidate the genomic basis of this strain's survival in the dairy industry, a high-quality draft genome was produced.
During sweating, bacteria from the skin enter the worn textile along with the sweat. Once inside ... more During sweating, bacteria from the skin enter the worn textile along with the sweat. Once inside the clothes, the bacteria produce sweat malodor and form colonies that are extremely hard to remove by washing.
Graphical Listeria monocytogenes activates the two-component system LisRK under stress, and becom... more Graphical Listeria monocytogenes activates the two-component system LisRK under stress, and becomes more adhesive and highly tolerant to ampicillin.
<p>Colonization of textiles and subsequent metabolic degradation of sweat and sebum... more <p>Colonization of textiles and subsequent metabolic degradation of sweat and sebum components by axillary skin bacteria cause the characteristic sweat malodor and discoloring of dirty clothes. Once inside the textile, the bacteria can form biofilms that are hard to remove by conventional washing. When the biofilm persists after washing, the textiles retain the sweat odor. In addition to posing a huge industrial problem, textile biofilms constitute an interesting case study of bacterial behavior in periodically wetted and dried substrates with varying surface hydrophobicity. Here we aim to study the bacterial behavior in each of the four stages of the bacterial lifecycle in textiles: adhesion, growth, drying and washing. To accomplish this, we designed a novel in vitro model to mimic physiological sweating while wearing cotton and polyester textiles. The hydrophobic polyester adhered bacteria more strongly and absorbed more sebum, the bacteria’s primary nutrient source. Bacteria were therefore initially more active in polyester textiles than in cotton. However, polyester did not bind water as well as cotton. The increased water content of cotton allowed the bacteria to retain a higher activity after the textile had dried. However, neither of the textiles retained enough water upon drying to prevent the bacteria from irreversibly adhering to the textile fibers by capillary action. This demonstrates that bacterial colonization depends on the hydrophobic and hygroscopic properties of the colonized material while highlighting the possibility of controlling bacterial behavior by either changing the surface properties or the surrounding environment.</p>
Amyloids are typically associated with neurodegenerative diseases, but recent research demonstrat... more Amyloids are typically associated with neurodegenerative diseases, but recent research demonstrates that several bacteria utilize functional amyloid fibrils to fortify the biofilm extracellular matrix and thereby resist antibiotic treatments. In Pseudomonas aeruginosa, these fibrils are composed predominantly of FapC, a protein with high-sequence conservation among the genera. Previous studies established FapC as the major amyloid subunit, but its mechanism of fibril formation in P. aeruginosa remained largely unexplored. Here, we examine the FapC sequence in greater detail through a combination of bioinformatics and protein engineering, and we identify specific motifs that are implicated in amyloid formation. Sequence regions of high evolutionary conservation tend to coincide with regions of high amyloid propensity, and mutation of amyloidogenic motifs to a designed, non-amyloidogenic motif suppresses fibril formation in a pH-dependent manner. We establish the particular significan...
Nanozymes, nanoparticles that mimic the natural activity of enzymes, are intriguing academically ... more Nanozymes, nanoparticles that mimic the natural activity of enzymes, are intriguing academically and are important in the context of Origin of Life. However, current nanozymes offer mimicry to a narrow range of mammalian enzymes, near-exclusively performing redox reactions. In this work, we present an unexpected discovery of non-proteinaceous enzymes based on metals, metal oxides, 1D/2D-materials, and non-metallic nanomaterials. Specific novelty of our findings lies in the identification of nanozymes with apparent mimicry of diverse mammalian enzymes, including unique pan-glycosidases. Further novelty lies in the identification of the substrate scope for the lead candidates, specifically in the context of bioconversion of glucuronides, that is, human metabolites and privileged prodrugs in the field of enzyme-prodrug therapies. Lastly, nanozymes are employed for conversion of glucuronide prodrugs into marketed anti-inflammatory and antibacterial agents, as well as "nanozyme prodrug therapy" to mediate antibacterial measures.
Journal of labelled compounds & radiopharmaceuticals, Jan 23, 2018
The development of bacteria-specific infection radiotracers is of considerable interest to improv... more The development of bacteria-specific infection radiotracers is of considerable interest to improve diagnostic accuracy and enabling therapy monitoring. The aim of this study was to determine if the previously reported radiolabelled 1,4,7,10-tetraazacyclododecane-N,N',N″,N‴-tetraacetic acid (DOTA) conjugated peptide [ Ga]Ga-DOTA-K-A9 could detect a staphylococcal infection in vivo and distinguish it from aseptic inflammation. An optimized [ Ga]Ga-DOTA-K-A9 synthesis omitting the use of acetone was developed, yielding 93 ± 0.9% radiochemical purity. The in vivo infection binding specificity of [ Ga]Ga-DOTA-K-A9 was evaluated by micro positron emission tomography/magnetic resonance imaging of 15 mice with either subcutaneous Staphylococcus aureus infection or turpentine-induced inflammation and compared with 2-deoxy-2-[ F]fluoro-D-glucose ([ F]FDG). The scans showed that [ Ga]Ga-DOTA-K-A9 accumulated in all the infected mice at injected doses ≥3.6 MBq. However, the tracer was not f...
Implant-associated infections caused by bacterial biofilms are difficult to treat. Surgical inter... more Implant-associated infections caused by bacterial biofilms are difficult to treat. Surgical intervention is often necessary to cure the patient, as the antibiotic recalcitrance of biofilms renders them untreatable with conventional antibiotics. Intermittent hyperbaric oxygen treatment (HBOT) has been proposed as an adjuvant to conventional antibiotic treatment and it has been speculated that combining HBOT with antibiotics could improve treatment outcomes for biofilm infections. In this study we addressed whether HBOT could improve treatment outcomes of daptomycin and rifampicin combination therapy. The effect of HBOT on the treatment outcomes of daptomycin and rifampicin against implant-associated osteomyelitis was quantified in a murine model. In total, 80 mice were randomized into two groups receiving antibiotics, either alone or in combination with daily intermittent HBOT (304 kPa for 60 min) following injection of antibiotics. Treatment was initiated 11 days after animals were ...
Epigallocatechin-3-gallate (EGCG) is the major polyphenol in green tea. It has antimicrobial prop... more Epigallocatechin-3-gallate (EGCG) is the major polyphenol in green tea. It has antimicrobial properties and disrupts the ordered structure of amyloid fibrils involved in human disease. The antimicrobial effect of EGCG against the opportunistic pathogen Pseudomonas aeruginosa has been shown to involve disruption of quorum sensing (QS). Functional amyloid fibrils in P. aeruginosa (Fap) are able to bind and retain quorum-sensing molecules, suggesting that EGCG interferes with QS through structural remodeling of amyloid fibrils. Here we show that EGCG inhibits the ability of Fap to form fibrils; instead, EGCG stabilizes protein oligomers. Existing fibrils are remodeled by EGCG into non-amyloid aggregates. This fibril remodeling increases the binding of pyocyanin, demonstrating a mechanism by which EGCG can affect the QS function of functional amyloid. EGCG reduced the amyloid-specific fluorescent thioflavin T signal in P. aeruginosa biofilms at concentrations known to exert an antimicro...
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Papers by Rikke Meyer