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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.

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 3 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.

Fossilization processes and especially the role of bacterial activity during the preservation of organic material has not yet been well understood. Here, we report the results of controlled taphonomic experiments with crayfish in freshwater and sediment. 16S rRNA amplicon analyzes showed that the development of the bacterial community composition over time was correlated with different stages of decay and preservation. Three dominating genera, Aeromonas , Clostridium and Acetobacteroides were identified as the main drivers in the decomposition of crayfish in freshwater. Using micro-computed tomography (µ-CT), scanning electron microscopy (SEM) and confocal Raman spectroscopy (CRS), calcite clusters were detected after 3–4 days inside crayfish carcasses during their decomposition in freshwater at 24 °C. The precipitation of calcite clusters during the decomposition process was increased in the presence of the bacterial genus Proteocatella . Consequently, Proteocatella might be one of the bacterial genera responsible for fossilization.

Understanding the intricate dynamics of sediment-mediated microbial interactions and their impact on plant tissue preservation is crucial for unraveling the complexities of leaf decay and preservation processes. To elucidate the earliest stages of leaf preservation, a series of decay experiments was carried out for three months on Nymphaea water lily leaves in aquariums with pond water and one of three distinctly different, sterilized, fine-grained substrates—commercially purchased kaolinite clay or fine sand, or natural pond mud. One aquarium contained only pond water as a control. We use 16S and ITS rRNA gene amplicon sequencing to identify and characterize the complex composition of the bacterial and fungal communities on leaves. Our results reveal that the pond mud substrate produces a unique community composition in the biofilms compared to other substrates. The mud substrate significantly influences microbial communities, as shown by the correlation between high concentrations of minerals in the water and bacterial abundance. Furthermore, more biofilm formers are observed on the leaves exposed to mud after two months, contrasting with declines on other substrates. The mud substrate also enhanced leaf tissue preservation compared to the other sediment types, providing insight into the role of sediment and biofilms in fossilization processes. Notably, leaves on kaolinite clay have the fewest biofilm formers by the end of the experiment. We also identify key biofilm-forming microbes associated with each substrate. The organic-rich mud substrate emerges as a hotspot for biofilm formers, showing that it promotes biofilm formation on leaves and may increase the preservation potential of leaves better than other substrates. The mud’s chemical composition, rich in minerals such as silica, iron, aluminum, and phosphate, may slow or suspend decay and facilitate biomineralization, thus paving the way toward leaf preservation. Our study bridges the information gap between biofilms observed on modern leaves and the mineral encrustation on fossil leaves by analyzing the microbial response in biofilms to substrate types in which fossil leaves are commonly found.

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.

Background This study aimed to evaluate the efficacy of polydopamine (PDA) functionalization on orthodontic brackets in inhibiting biofilm formation and promoting surface bioactivity to buffer the acidity of caries-causing bacteria around orthodontic brackets and prevent demineralization. The stability of the coating in artificial saliva (AS) and distilled water was evaluated, along with its effect on pH changes in simulated body fluid (SBF) and distilled water. Methods Maxillary incisor orthodontic brackets underwent PDA functionalization using a dopamine hydrochloride solution following a specific protocol. Biofilm formation on both control (Br-0) and coated (Br-PDA) brackets was assessed immediately after coating and after two months of aging (Aged Br-PDA) in artificial saliva. The adherent biofilm bacteria on brackets were quantified with colony count assessment and optical density. Surface morphology, Bioactivity, and coating stability were analyzed using Scanning Electron Microscopy (SEM). Coated and uncoated samples were immersed in SBF and deionized water, and pH changes were monitored over 7 days using a pH meter. Results PDA-functionalized brackets, both freshly coated (1.08 OD) and aged for two months (1.6 OD), showed significantly reduced biofilm formation compared to non-functionalized control brackets (2.07 OD), with p-value < 0.05. This reduction was confirmed through optical density measurements and colony-forming unit (CFU) counts (1.63E + 06, 4.53E + 07, and 7.56E + 07 respectively, p-value < 0.05). SEM analysis revealed alterations in surface morphology and composition, suggesting enhanced biointeraction in the coated brackets. Stability assessments in artificial saliva and deionized water demonstrated the durability of the coating. pH measurements indicated minimal changes in SBF and water, with PDA-functionalized brackets showing slight alterations. Conclusions Our research findings suggest that PDA-functionalized brackets possess promising antimicrobial properties and stability, offering potential applications in orthodontic treatment to mitigate biofilm formation and prevent white spot lesions around orthodontic brackets. Further investigation is required to optimize the coating formulation and explore its long-term efficacy in clinical settings.

Livestock-associated bacteria with resistance to two or more antibiotic drug classes have heightened our awareness for the consequences of antibiotic consumption and spread of resistant bacterial strains in the veterinary field. In this study we assessed the prevalence of concomitant colonization with livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) and enterobacteriaceae expressing extended-spectrum betalactamases (ESBL-E) in farms at the German-Dutch border region. Nasal colonization of pigs with MRSA (113/547 (20.7%)) was less frequent than rectal colonization with ESBL-E (163/540 (30.2%)). On the individual farm level MRSA correlated with ESBL-E recovery. The data further provide information on prevalence at different stages of pig production, including abattoirs, as well as in air samples and humans living and working on the farms. Notably, MRSA was detected in stable air samples of 34 out of 35 pig farms, highlighting air as an important MRSA transmission reservoir. The majority of MRSA isolates, including those from humans, displayed tetracycline resistance and spa types t011 and t034 characteristic for LA-MRSA, demonstrating transmission from pigs to humans. ESBL-E positive air samples were detected on 6 out of 35 farms but no pig-to-human transmission was found. Detection of ESBL-E, e.g. mostly Escherichia coli with CTX-M-type ESBL, was limited to these six farms. Molecular typing revealed transmission of ESBL-E within the pig compartments; however, related strains were also found on unrelated farms. Although our data suggest that acquisition of MRSA and ESBL-E might occur among pigs in the abattoirs, MRSA and ESBL-E were not detected on the carcasses. Altogether, our data define stable air (MRSA), pig compartments (ESBL-E) and abattoir waiting areas (MRSA and ESBL-E) as major hot spots for transmission of MRSA and/or ESBL-E along the pig production chain.

The YycFG two-component regulatory system (TCS) of Staphylococcus aureus represents the only essential TCS that is almost ubiquitously distributed in gram-positive bacteria with a low G+C-content. YycG (WalK/VicK) is a sensor histidine-kinase and YycF (WalR/VicR) is the cognate response regulator. Both proteins play an important role in the biosynthesis of the cell envelope and mutations in these proteins have been involved in development of vancomycin and daptomycin resistance. Here we present high yield expression and purification of the full-length YycG and YycF proteins as well as of the auxiliary proteins YycH and YycI of Staphylococcus aureus. Activity tests of the YycG kinase and a mutated version, that harbours an Y306N exchange in its cytoplasmic PAS domain, in a detergent-micelle-model and a phosholipid-liposome-model showed kinase activity (autophosphorylation and phosphoryl group transfer to YycF) only in the presence of elevated concentrations of alkali salts. A direct comparison of the activity of the kinases in the liposome-model indicated a higher activity of the mutated YycG kinase. Further experiments indicated that YycG responds to fluidity changes in its microenvironment. The combination of high yield expression, purification and activity testing of membrane and membrane-associated proteins provides an excellent experimental basis for further protein-protein interaction studies and for identification of all signals received by the YycFGHI system.

Staphylococcus capitis is a member of the human and mammal skin microbiomes and is considered less harmful than Staphylococcus aureus . S. capitis subsp. urealyticus BN2 was isolated from a cat and expressed strong antibacterial activity against a range of Gram‐positive species, most notably including S. aureus strains with resistance to methicillin (MRSA) and strains with intermediate resistance to vancomycin (VISA). These latter strains are normally relatively resistant to bacteriocins, due to cell wall and cell membrane modifications. Genomic sequencing showed that the strain harboured at least two complete gene clusters for biosynthesis of antagonistic substances. The complete biosynthetic gene cluster of the well‐known lantibiotic gallidermin was encoded on a large plasmid and the mature peptide was present in isopropanol cell extracts. In addition, a chromosomal island contained a novel non‐ribosomal peptide synthetase (NRPS) gene cluster. Accidental deletion of two NRPS modules and partial purification of the anti‐VISA activity showed that this novel bacteriocin represents a complex of differently decorated, non‐ribosomal peptides. Additionally, a number of phenol‐soluble modulins (PSMs) was detected by mass spectrometry of whole cells. Producing these compounds, the strain was able to outcompete several S. aureus strains, including MRSA and VISA, in tube cultures.