The recombinant φ11 endolysin hydrolyzed heat-killed staphylococci as well as staphylococcal biofilms. Cell wall targeting appeared to be a prerequisite for lysis of whole cells, and the combined ...action of the endopeptidase and amidase domains was necessary for maximum activity. In contrast, the φ12 endolysin was inactive and caused aggregation of the cells.
Abstract
Slaughterhouse wastewater is considered a reservoir for antibiotic-resistant bacteria and antibiotic residues, which are not sufficiently removed by conventional treatment processes. This ...study focuses on the occurrence of ESKAPE bacteria (
Enterococcus
spp.,
S. aureus
,
K. pneumoniae
,
A. baumannii
,
P. aeruginosa
,
Enterobacter
spp.), ESBL (extended-spectrum β-lactamase)-producing
E. coli
, antibiotic resistance genes (ARGs) and antibiotic residues in wastewater from a poultry slaughterhouse. The efficacy of conventional and advanced treatments (i.e., ozonation) of the in-house wastewater treatment plant regarding their removal was also evaluated. Target culturable bacteria were detected only in the influent and effluent after conventional treatment. High abundances of genes (e.g.,
bla
TEM
,
bla
CTX-M-15
,
bla
CTX-M-32
,
bla
OXA-48
,
bla
CMY
and
mcr-1
) of up to 1.48 × 10
6
copies/100 mL were detected in raw influent. All of them were already significantly reduced by 1–4.2 log units after conventional treatment. Following ozonation,
mcr-1
and
bla
CTX-M-32
were further reduced below the limit of detection. Antibiotic residues were detected in 55.6% (n = 10/18) of the wastewater samples. Despite the significant reduction through conventional and advanced treatments, effluents still exhibited high concentrations of some ARGs (e.g.,
sul1
,
ermB
and
bla
OXA-48
), ranging from 1.75 × 10
2
to 3.44 × 10
3
copies/100 mL. Thus, a combination of oxidative, adsorptive and membrane-based technologies should be considered.
Literature lacks sufficient data regarding addition of natural antibacterial agents to glass ionomer cement (GICs). Hence, the aim of the study was to increase the antimicrobial properties of GICs ...through its modification with mixture of plant extracts to be evaluated along with an 0.5% chlorohexidine-modified GIC (CHX-GIC) with regard to biological and compressive strength properties. Conventional GIC (freeze-dried version) and CHX were used. Alcoholic extract of
Salvadora persica, Olea europaea
, and
Ficus carcia
leaves were prepared using a Soxhlet extractor for 12 h. The plant extract mixture (PE) was added in three different proportions to the water used for preparation of the dental cement (Group 1:1 PE, 2:1 PE, and 1:2 PE). Specimens were then prepared and tested against the unmodified GIC (control) and the 0.5% CHX-GIC. Chemical analysis of the extract mixture was performed using Gas chromatography–mass spectrometry. Antimicrobial activity was evaluated using agar diffusion assay against
Micrococcus luteus
and
Streptoccocus mutans
. Compressive strength was evaluated according to ISO 9917-1:2007 using a Zwick testing machine at a crosshead speed of 0.5 mm/min. Antimicrobial activity against
Streptoccocus mutans
was significantly increased for all the extract-modified materials compared to the unmodified cement, and the highest concentration was comparable to the CHX-GIC mixture. The activity against
Micrococcus luteus
was also significantly increased, but only for the material with the highest extract concentration, and here the CHX-GIC group showed statistically the highest antimicrobial activity. Compressive strength results revealed that there was no statistically significant difference between the different mixtures and the control except for the highest tested concentration that showed the highest mean values. The plant extracts (PEs) enhanced the antimicrobial activity against
S. mutans
and also against
M. luteus
in the higher concentration while compressive strength was improved by addition of the PE at higher concentrations.
Abstract The immense potential of bacteria for production of antimicrobials represents an inexhaustible source of new antibiotics. An emerging class of natural products is constituted by ribosomally ...synthesized and posttranslationally modified peptides (RiPPs). “Lantibiotics” ( lan thionine and/or methyl-lanthionine containing an tibiotics ) belong to the earliest members of this class. The characteristic thioether amino acids are introduced into the precursor peptides by enzyme-mediated posttranslational modifications. The encouraging antimicrobial activity of lantibiotics against multiresistant clinical pathogens, their stability against proteases, heat and oxidation make lantibiotics interesting candidates for novel antimicrobial applications in many areas of the healthcare sector and associated industries. In addition to applications as alternatives to classical antibiotics, lantibiotics can be used as probiotics, prophylactics or additives. Furthermore, the in vitro activity of the lantibiotic modification machinery opens the possibility to generate either improved synthetic lantibiotic peptides or to introduce thioether cross-links into existing therapeutics.
Various medicinal plant parts and extracts have been proven to be sources of biologically active compounds, many of which have been incorporated in the production of new pharmaceutical compounds. ...Thus, the aim of this study was to increase the antimicrobial properties of a glass ionomer cement (GIC) through its modification with a mixture of plant extracts, which were evaluated along with a 0.5% chlorohexidine-modified GIC (CHX-GIC) with regard to the water sorption, solubility, and flexural strength. Methods: Salvadora persica, Olea europaea, and Ficus carcia leaves were prepared for extraction with ethyll alcohol using a Soxhlet extractor for 12 h. The plant extract mixture (PE) was added in three different concentrations to the water used for preparation of a conventional freeze-dried GIC (groups 1:1, 2:1, and 1:2). Specimens were then mixed according to the manufacturer’s instructions and tested against the unmodified GIC (control) and a GIC modified with 0.5% chlorhexidine. Water sorption and solubility were evaluated after 7 days of immersion in distilled water. Flexural strength was evaluated in a three-point bending test after 24 h using a universal material testing machine at a crosshead speed of 1 mm/min. One-way analysis of variance (ANOVA) was used for comparison between the groups. Tukey’s post hoc test was used for pairwise comparison when the ANOVA test was significant. Results: There were no statistically significant differences between the control (M = 20.5%), CHX-GIC (M = 19.6%), 1:1 (M = 20.0%), 1:2 (M = 19.5%), and 2:1 (19.7%) groups with regard to the percentage of water sorption, while for water solubility the 2:1 (M = −0.39%) plant-modified group was significantly different from all of the other groups. Flexural strength test results showed that the 2:1 group (M = 26.1 MPa) recorded significantly higher mean values compared to all other tested groups. Conclusion and clinical relevance: The plant extracts did not negatively affect the water sorption and solubility of the GIC, while the flexural strength was improved by the addition of the plant extract at higher concentrations.
The genetic plasticity of Staphylococcus aureus has facilitated the evolution of many virulent and drug-resistant strains. Here we present the sequence of the 2.74 Mbp genome of S. aureus ...SG511-Berlin, which is frequently used for antibiotic screening. Although S. aureus SG511 and the related methicillin-resistant S. aureus MRSA252 share a high similarity in their core genomes, indicated by an average nucleotide identity (ANI) of 99.83%, the accessory genomes of these strains differed, as nearly no mobile elements and resistance determinants were identified in the genome of S. aureus SG511. Susceptibility testing showed that S. aureus SG511 was susceptible to most of the tested antibiotics of different classes. Intriguingly, and in contrast to the standard laboratory strain S. aureus HG001, S. aureus SG511 was even hyper-susceptible towards cell wall and membrane targeting agents, with the exception of the MurA-inhibitor fosfomycin. In depth comparative genome analysis revealed that, in addition to the loss of function mutation in the antibiotic sensor histidine kinase gene graS, further mutations had occurred in the lysyltransferase gene mprF, the structural giant protein gene ebh, and the regulator genes codY and saeR, which might contribute to antibiotic susceptibility. In addition, an insertion element in agrC abolishes Agr-activity in S. aureus SG511, and the spa and sarS genes, which encode the surface protein SpA and its transcriptional regulator, were deleted. Thus, the lack of mobile resistance genes together with multiple mutations affecting cell envelope morphology may render S. aureus SG511 hyper-susceptible towards most cell wall targeting agents.
•Genome of S. aureus SG511-Berlin, a screening strain for antibiotic lead structures.•Strain is hyper-susceptible towards cell wall and membrane targeting agents.•Genome displays a lack of mobile elements when compared to S. aureus MRSA252.•Amino acid substitutions identified in CodY, SarZ, TcaR, SaeR, GdpP, and Rny.•Truncation of ebh, inactivation of graS, and agrC, as well as loss of spa and sarS.
Experiments are reported to reconstruct the taphonomic pathways of fish toward fossilisation. Acrylic glass autoclaves were designed that allow experiments to be carried out at elevated pressure up ...to 11 bar, corresponding to water depths of 110 m. Parameters controlled or monitored during decay reactions are pressure, salinity, proton activities (pH), electrochemical potentials (Eh), and bacterial populations. The most effective environmental parameters to delay or prevent putrefaction before a fish carcass is embedded in sediment are (1) a hydrostatic pressure in the water column high enough that a fish carcass may sink to the bottom sediment, (2) hypersaline conditions well above seawater salinity, and (3) a high pH to suppress the reproduction rate of bacteria. Anoxia, commonly assumed to be the key parameter for excellent preservation, is important in keeping the bottom sediment clear of scavengers but it does not seem to slow down or prevent putrefaction. We apply our results to the world-famous Konservat-Lagerstätten Eichstätt-Solnhofen, Green River, and Messel where fish are prominent fossils, and reconstruct from the sedimentary records the environmental conditions that may have promoted preservation. For Eichstätt-Solnhofen an essential factor may have been hypersaline conditions. Waters of the Green River lakes were at times highly alkaline and hypersaline because the lake stratigraphy includes horizons rich in sodium carbonate and halite. In the Messel lake sediments some fossiliferous horizons are rich in FeCO
siderite, a mineral indicating highly reduced conditions and a high pH.
Biofilms are important in the natural process of plant tissue degradation. However, fundamental knowledge of biofilm community structure and succession on decaying leaves under different oxygen ...conditions is limited. Here, we used 16S rRNA and ITS gene amplicon sequencing to investigate the composition, temporal dynamics, and community assembly processes of bacterial and fungal biofilms on decaying leaves in vitro. Leaves harvested from three plant species were immersed in lake water under aerobic and anaerobic conditions in vitro for three weeks. Biofilm-covered leaf samples were collected weekly and investigated by scanning electron microscopy. The results showed that community composition differed significantly between biofilm samples under aerobic and anaerobic conditions, though not among plant species. Over three weeks, a clear compositional shift of the bacterial and fungal biofilm communities was observed. The alpha diversity of prokaryotes increased over time in aerobic assays and decreased under anaerobic conditions. Oxygen availability and incubation time were found to be primary factors influencing the microbial diversity of biofilms on different decaying plant species in vitro. Null models suggest that stochastic processes governed the assembly of biofilm communities of decaying leaves in vitro in the early stages of biofilm formation and were further shaped by niche-associated factors.
This review presents recommended nomenclature for the biosynthesis of ribosomally synthesized and post-translationally modified peptides (RiPPs), a rapidly growing class of natural products. The ...current knowledge regarding the biosynthesis of the >20 distinct compound classes is also reviewed, and commonalities are discussed.
Phosphatized fish fossils occur in various locations worldwide. Although these fossils have been intensively studied over the past decades they remain a matter of ongoing research. The mechanism of ...the permineralization reaction itself remains still debated in the community. The mineralization in apatite of a whole fish requires a substantial amount of phosphate which is scarce in seawater, so the origin of the excess is unknown. Previous research has shown that alkaline phosphatase, a ubiquitous enzyme, can increase the phosphate content in vitro in a medium to the degree of saturation concerning apatite. We applied this principle to an experimental setup where fish scales were exposed to commercial bovine alkaline phosphatase. We analyzed the samples with SEM and TEM and found that apatite crystals had formed on the remaining soft tissue. A comparison of these newly formed apatite crystals with fish fossils from the Solnhofen and Santana fossil deposits showed striking similarities. Both are made up of almost identically sized and shaped nano-apatites. This suggests a common formation process: the spontaneous precipitation from an oversaturated solution. The excess activity of alkaline phosphatase could explain that effect. Therefore, our findings could provide insight into the formation of well-preserved fossils.
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