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Frontiers in Microbiology 2020Skin offers protection against external insults, with the skin microbiota playing a crucial defensive role against pathogens that gain access when the skin barrier is...
Skin offers protection against external insults, with the skin microbiota playing a crucial defensive role against pathogens that gain access when the skin barrier is breached. Linkages between skin microbes, biofilms and disease have not been well established although single-species biofilm formation by skin microbiota has been extensively studied. Consequently, the purpose of this work was to optimize and validate a simple polymicrobial biofilm keratinocyte model for investigating commensal, pathogen and keratinocyte interactions and for evaluating therapeutic agents or health promoting interventions. The model incorporates the commensals ( and ) and pathogens ( and ) which form robust polymicrobial biofilms on immortalized keratinocytes (HaCat cells). We observed that the commensals reduce the damage caused to the keratinocyte monolayer by either pathogen. When the commensals were combined with and , much thinner biofilms were observed than those formed by the pathogens alone. When was inoculated with in the presence or absence of , the commensals formed a layer between the keratinocytes and pathogen. Although completely inhibited the growth of in dual-species biofilms, inclusion of in triple or quadruple species biofilms, enabled to retain viability. Using this polymicrobial biofilm keratinocyte model, we demonstrate that a quorum sensing (QS) deficient mutant, in contrast to the parent, failed to damage the keratinocyte monolayer unless supplied with the exogenous cognate autoinducing peptide. In addition, we show that treatment of the polymicrobial keratinocyte model with nanoparticles containing an inhibitor of the PQS QS system reduced biofilm thickness and localization in mono- and polymicrobial biofilms.
PubMed: 32161578
DOI: 10.3389/fmicb.2020.00291 -
Journal of Bacteriology Jul 1984Nucleotide sequences of 5S rRNAs from four bacteria, Staphylococcus aureus Smith (diffuse), Staphylococcus epidermidis ATCC 14990, Micrococcus luteus ATCC 9341 and... (Comparative Study)
Comparative Study
Nucleotide sequences of 5S rRNAs from four bacteria, Staphylococcus aureus Smith (diffuse), Staphylococcus epidermidis ATCC 14990, Micrococcus luteus ATCC 9341 and Micrococcus luteus ATCC 4698, were determined. The secondary structural models of S. aureus and S. epidermidis sequences showed characteristics of the gram-positive bacterial 5S rRNA (116-N type [H. Hori and S. Osawa, Proc. Natl. Acad. Sci. U.S.A. 76:381-385, 1979]). Those of M. luteus ATCC 9341 and M. luteus ATCC 4698 together with that of Streptomyces griseus (A. Simoncsits, Nucleic Acids Res. 8:4111-4124, 1980) showed intermediary characteristics between the gram-positive and gram-negative (120-N type [H. Hori and S. Osawa, 1979]) 5S rRNAs. This and previous studies revealed that there exist at least three major groups of eubacteria having distinct 5S rRNA and belonging to different stems in the 5S rRNA phylogenic tree.
Topics: Base Sequence; Micrococcus; Molecular Weight; Nucleic Acid Conformation; Phylogeny; RNA, Ribosomal; Species Specificity; Staphylococcus aureus; Staphylococcus epidermidis
PubMed: 6735981
DOI: 10.1128/jb.159.1.233-237.1984 -
Marine Drugs Mar 2019Sponges are a well-known bioresource for bioactive compounds. In this study, antibacterial activity-guided fractionation of the extract from an Indonesian marine sponge...
Sponges are a well-known bioresource for bioactive compounds. In this study, antibacterial activity-guided fractionation of the extract from an Indonesian marine sponge led to the discovery of four merosesquiterpenoids, namely, a new sesquiterpenoid aminoquinone nakijiquinone V (), along with illimaquinone (), smenospongine (), and dyctioceratine C (). The structure of compound was elucidated by 1D and 2D NMR as well as by LC-HRESIMS data analysis. Compounds ⁻ showed moderate to low antimicrobial activity against DSM32 with a minimum inhibitory concentration (MIC) of 32 μg/mL, 32 μg/mL, and 64 μg/mL, respectively. Furthermore, compounds and both inhibited ATCC 4698 with a MIC of 32 μg/mL. In conclusion, the isolated merosesquiterpenoids, which are known for their cytotoxic effects, showed antibacterial activity and prompt future structure activity relationship (SAR) studies concerning the various bioactivities observed for this group of natural products.
Topics: Animals; Anti-Bacterial Agents; Bacillus megaterium; Biological Products; Indonesia; Microbial Sensitivity Tests; Micrococcus luteus; Molecular Structure; Porifera; Quinones; Sesquiterpenes
PubMed: 30857135
DOI: 10.3390/md17030158 -
The Journal of Biological Chemistry Feb 1991The promoters of Micrococcus luteus, a bacterium whose chromosomal DNA has a high G + C content (74%), diverge from the consensus prokaryotic promoter in having GC-rich...
The promoters of Micrococcus luteus, a bacterium whose chromosomal DNA has a high G + C content (74%), diverge from the consensus prokaryotic promoter in having GC-rich DNA sequences at less important positions (Nakayama, M., Fujita, N., Ohama, T., Osawa, S., and Ishihama, A. (1989) Mol. Gen. Genet. 218, 384-389). In order to compare the promoter selectivity of RNA polymerase between M. luteus and Escherichia coli, we purified the enzyme from both organisms. The sets of promoters recognized by the two RNA polymerases were found to overlap partly. Some, but not all, E. coli promoters were found to be correctly transcribed in vitro by M. luteus RNA polymerase as well as the E. coli enzyme. One molecular species of M. luteus sigma factor, with the apparent molecular mass of 60 kDa, was isolated from purified RNA polymerase. By the addition of either M. luteus or E. coli core enzyme it was reconstituted into active holoenzyme. Likewise, M. luteus core enzyme was reconstituted into a hybrid holoenzyme by the addition of E. coli sigma subunit. Both hybrid holoenzymes were, however, able to initiate transcription only from promoters which were recognized by both of the native holoenzymes.
Topics: Binding, Competitive; DNA-Directed RNA Polymerases; Electrophoresis, Polyacrylamide Gel; Escherichia coli; Isoenzymes; Micrococcus; Promoter Regions, Genetic; Sigma Factor
PubMed: 1993665
DOI: No ID Found -
FEMS Immunology and Medical Microbiology Aug 2010Microorganisms tend to form biofilms on surfaces, thereby causing deterioration of the underlaying material. In addition, biofilm is a potential health risk to humans.... (Comparative Study)
Comparative Study
Microorganisms tend to form biofilms on surfaces, thereby causing deterioration of the underlaying material. In addition, biofilm is a potential health risk to humans. Therefore, microorganism growth is not only an issue on Earth but also in manned space habitats like the International Space Station (ISS). The aim of the study was to identify physiological processes relevant for Micrococcus luteus attachment under microgravity conditions. The results demonstrate that simulated microgravity influences physiological processes which trigger bacterial attachment and biofilm formation. The ISS strains produced larger amounts of exopolymeric substances (EPS) compared with a reference strain from Earth. In contrast, M. luteus strains were growing faster, and Earth as well as ISS isolates produced a higher yield of biomass under microgravity conditions than under normal gravity. Furthermore, microgravity caused a reduction of the colloidal EPS production of ISS isolates in comparison with normal gravity, which probably influences biofilm thickness and stability as well.
Topics: Bacterial Adhesion; Biomass; Biopolymers; Humans; Micrococcus luteus; Stress, Physiological; Weightlessness
PubMed: 20482631
DOI: 10.1111/j.1574-695X.2010.00683.x -
The Journal of Antibiotics Feb 1979Methylated and acetylated derivatives of iturin A and mycosubtilin and methylated derivatives of bacillomycin L were prepared and their antibacterial activity on...
Methylated and acetylated derivatives of iturin A and mycosubtilin and methylated derivatives of bacillomycin L were prepared and their antibacterial activity on Micrococcus luteus was compared with the activity of the original substance. the results obtained show the importance of polar groups for the antibiotic activity of the substances of iturin group.
Topics: Anti-Bacterial Agents; Bacillus subtilis; Chemical Phenomena; Chemistry; Micrococcus; Peptides, Cyclic; Spectrophotometry, Ultraviolet
PubMed: 108238
DOI: 10.7164/antibiotics.32.136 -
Antimicrobial Agents and Chemotherapy Apr 1986The ability of norfloxacin, amifloxacin, cinoxacin, ciprofloxacin, flumequine, nalidixic acid, ofloxacin (OFL), oxolinic acid, perfloxacin, pipemidic acid, and rosoxacin...
The ability of norfloxacin, amifloxacin, cinoxacin, ciprofloxacin, flumequine, nalidixic acid, ofloxacin (OFL), oxolinic acid, perfloxacin, pipemidic acid, and rosoxacin to inhibit the in vitro supercoiling activity of Micrococcus luteus DNA gyrase was compared with the ability of each drug to inhibit the growth of the M. luteus strain from which the gyrase was purified. The potency of the quinolones as DNA gyrase inhibitors did not always correlate with antimicrobial potency. For example, OFL was a less potent inhibitor of gyrase than rosoxacin, yet the MIC of OFL was 16-fold lower than that of rosoxacin. Similarly, the MICs of norfloxacin and ciprofloxacin (the most potent of the antibiotics tested in these assays) were several hundredfold lower than the MIC of nalidixic acid (the least potent of these antibiotics), but the inhibition of purified gyrase by these two quinolones was only 8- to 16-fold lower than that of nalidixic acid. These results suggest that factors in addition to inhibition of gyrase supercoiling activity are important in determining the potency of these drugs. Further studies indicated that the uptake of norfloxacin, OFL, and amifloxacin by M. luteus cells may not account for the large differences in MICs observed for these drugs (MICs of 0.8, 2.0, and 128 micrograms/ml, respectively).
Topics: Anti-Bacterial Agents; Dose-Response Relationship, Drug; Microbial Sensitivity Tests; Micrococcus; Norfloxacin; Quinolizines; Structure-Activity Relationship; Topoisomerase II Inhibitors
PubMed: 3010848
DOI: 10.1128/AAC.29.4.598 -
Iranian Journal of Microbiology Apr 2021Bacteriocins are considered alternative non-conventional antimicrobials produced by certain bacteria with activity against closely related species. The present study...
BACKGROUND AND OBJECTIVES
Bacteriocins are considered alternative non-conventional antimicrobials produced by certain bacteria with activity against closely related species. The present study focuses on screening, characterization, and partial purification of bacteriocins produced by sp. isolated from different clinical sources such as pus and blood.
MATERIALS AND METHODS
A total of 100 isolates were screened for bacteriocin production using spot on lawn assay and agar diffusion method against five indicator bacteria. Bacteriocins from five selected highly active isolates were subjected to proteinase-K enzyme, different pH, and heating at different temperatures, and investigated the stabilities of their antimicrobials. Two selected isolates, MK65 and MK88, were molecularly identified by gene sequencing, explored for the presence of 18 bacteriocin genes, and liquid chromatography-high resolution electrospray ionization mass spectrometry (LC-HRESIMS) was used to identify their different metabolites.
RESULTS
Twenty isolates exhibited inhibitory effect against at least one indicator bacteria. ATCC 4698 showed the highest sensitivity to such bacteriocins. Proteinase K, acidic pH, and heating at 100°C triggered marked activity inhibition. However, amylase enzyme, alkaline pH, and heating at 80°C caused trivial effects. Four out of eighteen bacteriocin genes were detected using PCR. Fermentation, partial purification, and LC-HRESIMS of total protein extracts of two selected isolates, MK65 and MK88, revealed the production of different antimicrobial peptides.
CONCLUSION
To the best of our knowledge, this is the first study to report the production of micrococcin and α-circulocin from MK65 and the production of amonabactin from MK88.
PubMed: 34540157
DOI: 10.18502/ijm.v13i2.5983 -
IDCases 2020Over the past years there has been a considerable increase in the use of aortic bioprostheses for treating aortic valve disease. With the increasing use of implanted...
Over the past years there has been a considerable increase in the use of aortic bioprostheses for treating aortic valve disease. With the increasing use of implanted medical devices, the incidence of prosthetic valve endocarditis has also increased. This is accompanied by a shift in the microbiology of infectious endocarditis. species are usually regarded as contaminants from skin and mucous membranes that rarely cause infectious diseases, however, they have the capacity to create biofilms from prosthetic materials and hence, to cause disease. We report the case of a 54-year-old woman who developed native valve infective endocarditis due to . To our knowledge, only 18 cases of prosthetic valve endocarditis have been described, none in the English literature.
PubMed: 32195120
DOI: 10.1016/j.idcr.2020.e00743 -
Applied and Environmental Microbiology Jul 2013The oral bacterium Streptococcus mutans, strain JH1140, produces the antibiotic mutacin 1140. Mutacin 1140 belongs to a group of antibiotics called lanthipeptides. More...
The oral bacterium Streptococcus mutans, strain JH1140, produces the antibiotic mutacin 1140. Mutacin 1140 belongs to a group of antibiotics called lanthipeptides. More specifically, mutacin 1140 is related to the epidermin type A(I) lanthipeptides. Mutagenesis experiments of this group of lanthipeptides have been primarily restricted to the posttranslationally modified meso-lanthionine and 3-methyllanthionine residues. Site-directed mutagenesis of the core peptide of mutacin 1140 was performed using the suicide vector pVA891. Substitutions of the N-terminal residue, the charged residue in the hinge region, and residues in ring A and intertwined rings C and D were investigated. A truncation and insertion of residues in ring A and intertwined rings C and D were also performed to determine whether or not they would alter the antimicrobial activity of the producing strain. Bioassays revealed that five of 14 mutants studied had improved antimicrobial activity against the indicator strain Micrococcus luteus ATCC 10240. MICs against Streptococcus mutans UA159, Streptococcus pneumoniae ATCC 27336, Staphylococcus aureus ATCC 25923, Clostridium difficile UK1, and Micrococcus luteus ATCC 10240 were determined for three mutacin 1140 variants that had the most significant increases in bioactivity in the M. luteus bioassay. This mutagenesis study of the epidermin group of lanthipeptides shows that antimicrobial activity can be significantly improved.
Topics: Bacteriocins; Biotechnology; Clostridioides difficile; Genes, Transgenic, Suicide; Genetic Vectors; Micrococcus luteus; Molecular Structure; Mutagenesis, Site-Directed; Peptides; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Staphylococcus aureus; Streptococcus; Streptococcus mutans
PubMed: 23603688
DOI: 10.1128/AEM.00704-13