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Ecotoxicology and Environmental Safety Oct 2022Flue gas lead emission during sludge incineration damages to human health and ecological environment seriously. Therefore, a denitrifying bio-trickling filter (DNBTF)...
Flue gas lead emission during sludge incineration damages to human health and ecological environment seriously. Therefore, a denitrifying bio-trickling filter (DNBTF) for lead removal in flue gas from sludge incineration was investigated. Lead removal efficiency was up to 90.7% in 60 days' operation. Lead speciation in biofilms of DNBTF consists of 84.27% residue lead, 15.18% organic bound lead, and less than 1% exchangeable and reducible lead. Lead resistant bacteria and lead resistant-denitrifying bacteria accounted for 85.04% and 58.25%, respectively. Lead resistant microorganisms(Pseudomonas, Azoarcus, Stappia, Pararhodobacter, Paracoccus, Azospirillum, Hyphomonas, Rhodobacter, Polymorphum, Brevunimonas, Stenotrophomonas) could resist the toxicity of Pb in flue gas by transport protein and binding protein, and detoxify Pb in flue gas by extracellular polymeric substances (EPS) adsorption, protein binding and precipitation under the action of resistance genes, such as pbrAB, golT, troABCD, znuABC, czcABCD, pcoB, copA, as shown by integrated metagenomic and metaproteomic analyses. The biofilm was characterized by FTIR, XRD, 3D-EEM, and SEM-EDS. XRD and SEM-EDS spectra indicated the formation of pyromorphite from bioconversion of lead in flue gas. Lead-containing flue gas was bio-stabilized in the form of pyromorphite and HA-Pb via complexation of humic acids in extracellular polymeric substances (EPS), biosorption and biodeposition. This provides a new way of sludge incineration flue gas lead removal using a denitrifying biotricking filter.
Topics: Carrier Proteins; Denitrification; Humans; Humic Substances; Incineration; Lead; Metagenomics; Minerals; Phosphates; Sewage
PubMed: 36087469
DOI: 10.1016/j.ecoenv.2022.114059 -
Frontiers in Microbiology 2022Bacterial biofilms are ubiquitous in natural environments and play an essential role in bacteria's environmental adaptability. Quorum sensing (QS), as the main signaling...
Bacterial biofilms are ubiquitous in natural environments and play an essential role in bacteria's environmental adaptability. Quorum sensing (QS), as the main signaling mechanism bacteria used for cell-to-cell communication, plays a key role in bacterial biofilm formation. However, little is known about the role of QS circuit in the N-transformation type strain, , especially for the regulatory protein PdeR. In this study, we found the overexpression of promoted bacterial aggregation and biofilm formation. Through RNA-seq analysis, we demonstrated that PdeR is a global regulator which could regulate 656 genes expression, involved in multiple metabolic pathways. Combined with transcriptome as well as biochemical experiments, we found the overexpressed mainly promoted the intracellular degradation of amino acids and fatty acids, as well as siderophore biosynthesis and transportation, thus providing cells enough energy and iron for biofilm development. These results revealed the underlying mechanism for PdeR in biofilm formation of , adding to our understanding of QS regulation in biofilm development.
PubMed: 36033861
DOI: 10.3389/fmicb.2022.966976 -
International Journal of Molecular... Aug 2022Denitrification consists of the sequential reduction of nitrate to nitrite, nitric oxide, nitrous oxide, and dinitrogen. Nitrous oxide escapes to the atmosphere,...
Denitrification consists of the sequential reduction of nitrate to nitrite, nitric oxide, nitrous oxide, and dinitrogen. Nitrous oxide escapes to the atmosphere, depending on copper availability and other environmental factors. Iron is also a key element because many proteins involved in denitrification contain iron-sulfur or heme centers. The NtrYX two-component regulatory system mediates the responses in a variety of metabolic processes, including denitrification. A quantitative proteomic analysis of a NtrY mutant grown under denitrifying conditions revealed the induction of different TonB-dependent siderophore transporters and proteins related to iron homeostasis. This mutant showed lower intracellular iron content than the wild-type strain, and a reduced growth under denitrifying conditions in iron-limited media. Under iron-rich conditions, it releases higher concentrations of siderophores and displayes lower nitrous oxide reductase (NosZ) activity than the wild-type, thus leading to nitrous oxide emission. Bioinformatic and qRT-PCR analyses revealed that NtrYX is a global transcriptional regulatory system that responds to iron starvation and, in turn, controls expression of the iron-responsive regulators , , and , the denitrification regulators and , the nitric oxide-responsive regulator , and a wide set of genes, including the -nitrite reductase NirS, nitrate/nitrite transporters and energy electron transport proteins.
Topics: Denitrification; Homeostasis; Iron; Nitrates; Nitric Oxide; Nitrites; Nitrous Oxide; Paracoccus denitrificans; Proteomics
PubMed: 36012437
DOI: 10.3390/ijms23169172 -
Frontiers in Cellular and Infection... 2022Thyroid-associated ophthalmopathy (TAO) is a chronic autoimmune disease. In this study, high-throughput sequencing was used to investigate the diversity and composition...
PURPOSE
Thyroid-associated ophthalmopathy (TAO) is a chronic autoimmune disease. In this study, high-throughput sequencing was used to investigate the diversity and composition of the ocular microbiota in patients with TAO.
METHODS
Patients with TAO did not receive treatment for the disease and did not have exposed keratitis. Patients with TAO (TAO group) and healthy individuals (control group) were compared. All samples were swabbed at the conjunctival vault of the lower eyelid. The V3 to V4 region of the 16S rDNA was amplified using polymerase chain reaction and sequenced on the Illumina HiSeq 2500 Sequencing Platform. Statistical analysis was performed to analyze the differences between the groups and the correlation between ocular surface microbiota and the disease. The ocular surface microbiota of patients and healthy individuals were cultured.
RESULTS
The ocular surface microbiota structure of TAO patients changed significantly. The average relative abundance of and increased significantly in the TAO group. had a significantly decreased relative abundance (P<0.05). , , , and were positively correlated with the severity of clinical manifestations or disease activity (P<0.05). and other opportunistic pathogens were obtained by culture from TAO patients.
CONCLUSIONS
This study found that the composition of ocular microbiota in patients with TAO was significantly different from that in healthy individuals. The ocular surface opportunistic pathogens, such as , , , and in TAO patients, increase the potential risk of ocular surface infection. The findings of this study provide a new avenue of research into the mechanism of ocular surface in TAO patients.
Topics: Conjunctiva; Graves Ophthalmopathy; Healthy Volunteers; High-Throughput Nucleotide Sequencing; Humans; Microbiota
PubMed: 35959376
DOI: 10.3389/fcimb.2022.914749 -
BMC Cardiovascular Disorders Jul 2022Little is known about the association between bacterial DNA in human blood and the risk of cardiovascular disease (CVD) mortality.
BACKGROUND
Little is known about the association between bacterial DNA in human blood and the risk of cardiovascular disease (CVD) mortality.
METHODS
A case-cohort study was performed based on a 9 ½ year follow-up of the Oslo II study from 2000. Eligible for this analysis were men born in 1923 and from 1926 to 1932. The cases were men (n = 227) who had died from CVD, and the controls were randomly selected participants from the same cohort (n = 178). Analysis of the bacterial microbiome was performed on stored frozen blood samples for both cases and controls. Association analyses for CVD mortality were performed by Cox proportional hazard regression adapted to the case-cohort design. We used the Bonferroni correction due to the many bacterial genera that were identified.
RESULTS
Bacterial DNA was identified in 372 (82%) of the blood samples and included 78 bacterial genera from six phyla. Three genera were significantly associated with CVD mortality. The genera Kocuria (adjusted hazard ratio (HR) 8.50, 95% confidence interval (CI) (4.05, 17.84)) and Enhydrobacter (HR 3.30 (2.01, 5.57)) indicate an association with CVD mortality with increasing levels. The genera Paracoccus (HR 0.29 (0.15, 0.57)) was inversely related. Significant predictors of CVD mortality were: the feeling of bad health; and the consumption of more than three cups of coffee per day. The following registered factors were borderline significant, namely: a history of heart failure; increased systolic blood pressure; and currently taking antihypertensive drugs now, versus previously.
CONCLUSIONS
The increasing levels of two bacterial genera Kocuria (skin and oral) and Enhydrobacter (skin) and low levels of Paracoccus (soil) were associated with CVD mortality independent of known risk factors for CVD.
Topics: Aged, 80 and over; Cardiovascular Diseases; Cohort Studies; DNA, Bacterial; Female; Humans; Male; Microbiota; Proportional Hazards Models; Risk Factors
PubMed: 35909117
DOI: 10.1186/s12872-022-02791-7 -
Biofilm Dec 2022In patients with acute respiratory failure, mechanical ventilation through an endotracheal tube (ET) may be required to correct hypoxemia and hypercarbia. However,...
In patients with acute respiratory failure, mechanical ventilation through an endotracheal tube (ET) may be required to correct hypoxemia and hypercarbia. However, biofilm formation on these ETs is a risk factor for infections in intubated patients, as the ET can act as a reservoir of microorganisms that can cause infections in the lungs. As severely ill COVID-19 patients often need to be intubated, a better knowledge of the composition of ET biofilms in this population is important. In Spring 2020, during the first wave of the COVID-19 pandemic in Europe, 31 ETs were obtained from COVID-19 patients at Ghent University Hospital (Ghent, Belgium). Biofilms were collected from the ET and the biofilm composition was determined using culture-dependent (MALDI-TOF mass spectrometry and biochemical tests) and culture-independent (16S and ITS1 rRNA amplicon sequencing) approaches. In addition, antimicrobial resistance was assessed for isolates collected via the culture-dependent approach using disc diffusion for 11 antimicrobials commonly used to treat lower respiratory tract infections. The most common microorganisms identified by the culture-dependent approach were those typically found during lung infections and included both presumed commensal and potentially pathogenic microorganisms like , , and . More unusual organisms, such as , were also identified, but each only in a few patients. The culture-independent approach revealed a wide variety of microbes present in the ET biofilms and showed large variation in biofilm composition between patients. Some biofilms contained a diverse set of bacteria of which many are generally considered as non-pathogenic commensals, whereas others were dominated by a single or a few pathogens. Antimicrobial resistance was widespread in the isolates, e.g. 68% and 53% of all isolates tested were resistant against meropenem and gentamicin, respectively. Different isolates from the same species recovered from the same ET biofilm often showed differences in antibiotic susceptibility. Our data suggest that ET biofilms are a potential risk factor for secondary infections in intubated COVID-19 patients, as is the case in mechanically-ventilated non-COVID-19 patients.
PubMed: 35720435
DOI: 10.1016/j.bioflm.2022.100079 -
Frontiers in Microbiology 2022Electrified biotrickling filters represent sustainable microbial electrochemical technology for treating organic carbon-deficient ammonium-contaminated waters. However,...
Electrified biotrickling filters represent sustainable microbial electrochemical technology for treating organic carbon-deficient ammonium-contaminated waters. However, information on the microbiome of the conductive granule bed cathode remains inexistent. For uncovering this black box and for identifying key process parameters, minimally invasive sampling units were introduced, allowing for the extraction of granules from different reactor layers during reactor operation. Sampled granules were analyzed using cyclic voltammetry and molecular biological tools. Two main redox sites [-288 ± 18 mV and -206 ± 21 mV vs. standard hydrogen electrode (SHE)] related to bioelectrochemical denitrification were identified, exhibiting high activity in a broad pH range (pH 6-10). A genome-centric analysis revealed a complex nitrogen food web and the presence of typical denitrifiers like and with none of these species being identified as electroactive microorganism so far. These are the first results to provide insights into microbial structure-function relationships within electrified biotrickling filters and underline the robustness and application potential of bioelectrochemical denitrification for environmental remediation.
PubMed: 35711746
DOI: 10.3389/fmicb.2022.869474 -
Journal of Inorganic Biochemistry Sep 2022Amicyanin is a type 1 copper protein with a single tryptophan residue. Using genetic code expansion, the tryptophan was selectively replaced with the unnatural amino...
Amicyanin is a type 1 copper protein with a single tryptophan residue. Using genetic code expansion, the tryptophan was selectively replaced with the unnatural amino acid, 5-hydroxytryptophan (5-HTP). The 5-HTP substituted amicyanin exhibited absorbance at 300-320 nm, characteristic of 5-HTP and not seen in native amicyanin. The fluorescence emission maximum in 5-HTP substituted amicyanin is redshifted from 318 nm in native amicyanin to 331 nm and to 348 nm in the unfolded protein. The fluorescence quantum yield of 5-HTP substituted amicyanin mutant was much less than that of native amicyanin. Differences in intrinsic fluorescence are explained by differences in the excited states of tryptophan versus 5-HTP and the intraprotein environment. The substitution of tryptophan with 5-HTP did not affect the visible absorbance and redox potential of the copper, which is 10 Å away. In amicyanin and other cupredoxins, an unexplained quenching of the intrinsic fluorescence by the bound copper is observed. However, the fluorescence of 5-HTP substituted amicyanin is not quenched by the copper. It is shown that the mechanism of quenching in native amicyanin is Förster, or fluorescence, resonance energy transfer (FRET). This does not occur in 5-HTP substituted amicyanin because the fluorescence quantum yield is significantly lower and the red-shift of fluorescence emission maximum decreases overlap with the near UV absorbance of copper. Characterization of the distinct fluorescence properties of 5-HTP relative to tryptophan in amicyanin provides a basis for spectroscopic interrogation of the protein microenvironment using 5-HTP, and long-distance interactions with transition metals.
Topics: 5-Hydroxytryptophan; Azurin; Bacterial Proteins; Copper; Energy Transfer; Metalloproteins; Paracoccus denitrificans; Tryptophan
PubMed: 35696758
DOI: 10.1016/j.jinorgbio.2022.111895 -
International Journal of Food... Sep 2022In nature, bacterial pathogens like L. monocytogenes, live in nature associated with other microbial species in spatially-structured communities called biofilms. In the...
In nature, bacterial pathogens like L. monocytogenes, live in nature associated with other microbial species in spatially-structured communities called biofilms. In the food industry, biofilms contribute to the survival and persistence of L. monocytogenes within processing facilities, thereby enhancing its risk of cross-contaminating food products. The challenge of combating biofilms has triggered the search for new antibiofilm strategies including devising ways to interfere with cell communication mechanisms (quorum-sensing) that are known to be involved with biofilm development regulation. The aim of this study was to explore cell communication signals in a L. monocytogenes-carrying microbial community isolated from a meat processing plant (location No. 96) in order to elucidate the ecological interactions that could serve as a starting point for the development of new antibiofilm strategies. Quorum quenching (QQ) and quorum sensing (QS) activities were screened among 31 bacterial strains isolated from location No. 96. Whereas no QQ activity was detected against short-chain lactone N-hexanoyl-DL-homoserine lactone (C6-HSL), it was detected against N-dodecanoyl-DL-homoserine lactone (C12-HSL) in 7 isolates (23%), particularly in Pseudomonas monteilli, Rhodococcus sp. and Rhodococcus erythropolis. QS activity assays detected HC4, C4, C6, OC6, HC10 and C16 in all the extracts, being C4, C6 and OC6 with predominantly produced by Pseudomonas monteilli, Pseudomonas gesardii, Psychrobacter maritimus and Paracoccus sp. High production levels of C16-HSL by Paracoccus sp. and the role of this long-chain lactone as a self-inhibitor of cell aggregation led us to carry out further studies focused on the effects of a Paracoccus lactone extract (PLE) against the biofilm formation by L. monocytogenes. A quantitative microscopic analysis demonstrated a significant decrease (p < 0.05) in the area occupied by biofilms formed on stainless steel (SS) coupons by different strains of L. monocytogenes in the presence of PLEs. Conversely, no significant differences were observed in the total number of viable adhered cells on SS coupons with or without PLE. The observed effect was partially reproduced by the addition of pure C16-HSL to 24 h-biofilms of L. monocytogenes L1.96. These results demonstrate that the observed effects can be attributed, at least partially, to the HSLs contained in the PLE. Overall, the present results highlight how interspecies communication within a biofilm can open up new insights for the development of new ways to combat biofilm.
Topics: Biofilms; Lactones; Listeria monocytogenes; Microbiota; Quorum Sensing
PubMed: 35689970
DOI: 10.1016/j.ijfoodmicro.2022.109773 -
Frontiers in Microbiology 2022Gut microbial communities of animals play key roles in host evolution, while the relationship between gut microbiota and host evolution in Tibetan birds remains unknown....
Gut microbial communities of animals play key roles in host evolution, while the relationship between gut microbiota and host evolution in Tibetan birds remains unknown. Herein, we sequenced the gut microbiota of 67 wild birds of seven species dwelling in the Tibetan wetlands. We found an obvious species-specific structure of gut microbiota among these plateau birds whose habitats were overlapped. Different from plateau mammals, there was no strict synergy between the hierarchical tree of gut microbial community and species phylogeny. In brown-headed gulls () as an example, the structure of gut microbiota differed in different habitats, and the relative abundance of bacteria, such as , , and , significantly correlated with altitude. Finally, we found various pathogenic bacteria in the birds of these plateau wetlands, and the interspecific differences were related to their diet and living environments.
PubMed: 35663854
DOI: 10.3389/fmicb.2022.848906