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Two-year investigation of spore-formers through the production chain at two cheese plants in Norway.Food Research International (Ottawa,... Aug 2024Spore-forming bacteria are the most complex group of microbes to eliminate from the dairy production line due to their ability to withstand heat treatment usually used...
Spore-forming bacteria are the most complex group of microbes to eliminate from the dairy production line due to their ability to withstand heat treatment usually used in dairy processing. These ubiquitous microorganisms have ample opportunity for multiple points of entry into the milk chain, creating issues for food quality and safety. Certain spore-formers, namely bacilli and clostridia, are more problematic to the dairy industry due to their possible pathogenicity, growth, and production of metabolites and spoilage enzymes. This research investigated the spore-forming population from raw milk reception at two Norwegian dairy plants through the cheesemaking stages until ripening. Samples were collected over two years and examined by amplicon sequencing in a culture independent manner and after an anaerobic spore-former enrichment step. In addition, a total of 608 isolates from the enriched samples were identified at the genus or species level using MALDI-TOF analysis. Most spore-forming isolates belong to the genera Bacillus or Clostridium, with the latter dominating the enriched MPN tubes of raw milk and bactofugate. Results showed a great variation among the clostridia and bacilli detected in the enriched MPN tubes. However, B. licheniformis and C. tyrobutyricum were identified in all sample types from both plants throughout the 2-year study. In conclusion, our results shed light on the fate of different spore-formers at different processing stages in the cheese production chain, which could facilitate targeted actions to reduce quality problems.
Topics: Norway; Cheese; Food Microbiology; Spores, Bacterial; Milk; Clostridium; Animals; Bacillus; Food Handling; Dairying
PubMed: 38945575
DOI: 10.1016/j.foodres.2024.114610 -
Bioresource Technology Jun 2024This study addressed the treatment of high ammonia, low biodegradable chemical oxygen demand (bCOD) anaerobically digested molasses wastewater, utilizing an aerobic...
This study addressed the treatment of high ammonia, low biodegradable chemical oxygen demand (bCOD) anaerobically digested molasses wastewater, utilizing an aerobic granular sludge (AGS) reactor. The AGS achieved 99 % ammonia removal regardless of the bCOD supplementation. By adding low ammonia (<60 mg/L), high bCOD raw molasses wastewater (before anaerobic digestion) as a carbon source, enhanced nitrogen removal, increasing from 10 % to 97 %, and improved sludge settleability via bio-induced calcite precipitation were observed. Functional genes prediction suggested two potential denitrification pathways, including heterotrophic denitrification by Paracoccus and Thauera, and autotrophic denitrification, specifically sulfide-oxidizing autotrophic denitrification by Thiobacillus. An increase in the relative abundance of microorganisms involved in heterotrophic denitrification was observed with the addition of high bCOD raw molasses wastewater. Consequently, incorporating raw molasses wastewater into the AGS presents a sustainable approach to achieve mixotrophic denitrification, maintain stable granular sludge and ensure stable treatment performance when treating anaerobically digested molasses wastewater.
PubMed: 38945503
DOI: 10.1016/j.biortech.2024.131056 -
The Journal of Infection Jun 2024Cervicitis is associated with important reproductive sequelae. Primary causes include chlamydia and gonorrhoea, but a known sexually transmitted infection (STI) is not...
OBJECTIVES
Cervicitis is associated with important reproductive sequelae. Primary causes include chlamydia and gonorrhoea, but a known sexually transmitted infection (STI) is not identified in >50% of cases (i.e. STI-negative cervicitis). Bacterial vaginosis (BV) and specific BV-associated bacteria have also been associated with cervicitis, but data are limited. We investigated the association between STI-negative cervicitis and vaginal microbiota composition.
METHODS
This was a case-control sub-study of the OhMG study conducted at the Melbourne Sexual Health Centre. Cases were women with cervicitis who tested negative for STIs (STI-negative cervicitis, n=64). Controls were STI-negative asymptomatic women attending for STI-screening (n=128). The vaginal microbiota was characterised using 16S rRNA gene sequencing. Vaginal community state types were compared between cases and controls using logistic regression. Differential abundance analysis was performed to identify taxa associated with STI-negative cervicitis.
RESULTS
STI-negative cervicitis cases were more likely than controls to have a Lactobacillus-deficient non-optimal microbiota (adjusted-odds-ratio 2·55, 95%CI 1·18-5·50). Compared to controls, cases had increased abundance of four BV-associated bacteria (Gardnerella, Fannyhessea vaginae, Prevotella bivia, Dialister micraerophilus) and decreased abundance of optimal lactobacilli.
CONCLUSIONS
We report a positive association between non-optimal vaginal microbiota composition and STI-negative cervicitis. Specific anaerobic BV-associated bacteria may represent infectious causes of cervicitis.
PubMed: 38944285
DOI: 10.1016/j.jinf.2024.106210 -
The Journal of Biological Chemistry Jun 2024One of seven natural CO fixation pathways, the anaerobic Wood-Ljungdahl Pathway (WLP) is unique in generating CO as a metabolic intermediate, operating through...
One of seven natural CO fixation pathways, the anaerobic Wood-Ljungdahl Pathway (WLP) is unique in generating CO as a metabolic intermediate, operating through organometallic intermediates, and in conserving (versus utilizing) net ATP. The key enzyme in the WLP is acetyl-CoA synthase (ACS), which uses an active site [2Ni-4Fe-4S] cluster (A-cluster), a CO tunnel, and an organometallic (Ni-CO, Ni-methyl, and Ni-acetyl) reaction sequence to generate acetyl-CoA. Here we reveal that an alcove, which interfaces the tunnel and the A-cluster, is essential for CO fixation and autotrophic growth by the WLP. In vitro spectroscopy, kinetics, binding, and in vivo growth experiments reveal that a Phe229A substitution at one wall of the alcove decreases CO affinity thirty-fold and abolishes autotrophic growth; however, a F229W substitution enhances CO binding 80-fold. Our results indicate the structure of the alcove is exquisitely tuned to concentrate CO near the A-cluster; protect ACS from CO loss during catalysis, provide a haven for inhibitory CO, and stabilize the tetrahedral coordination at the Ni site where CO binds. The directing, concentrating, and protective effects of the alcove explain the inability of F209A to grow autotrophically. The alcove also could help explain current controversies over whether ACS binds CO and methyl through a random or ordered mechanism. Our work redefines what we historically refer to as the metallocenter "active site". The alcove is so crucial for enzymatic function that we propose it is part of the active site. The community should now look for such alcoves in all "gas handling" metalloenzymes.
PubMed: 38944127
DOI: 10.1016/j.jbc.2024.107503 -
Journal of Hazardous Materials Jun 2024Deep geological repositories (DGRs) stand out as one of the optimal options for managing high-level radioactive waste (HLW) such as uranium (U) in the near future. Here,...
Deep geological repositories (DGRs) stand out as one of the optimal options for managing high-level radioactive waste (HLW) such as uranium (U) in the near future. Here, we provide novel insights into microbial behavior in the DGR bentonite barrier, addressing potential worst-case scenarios such as waste leakage (e.g., U) and groundwater infiltration of electron rich donors in the bentonite. After a three-year anaerobic incubation, Illumina sequencing results revealed a bacterial diversity dominated by anaerobic and spore-forming microorganisms mainly from the phylum Firmicutes. Highly U tolerant and viable bacterial isolates from the genera Peribacillus, Bacillus, and some SRB such as Desulfovibrio and Desulfosporosinus, were enriched from U-amended bentonite. The results obtained by XPS and XRD showed that U was present as U(VI) and as U(IV) species. Regarding U(VI), we have identified biogenic U(VI) phosphates, U(UO)·(PO) located in the inner part of the bacterial cell membranes in addition to U(VI)-adsorbed to clays such as montmorillonite. Biogenic U(IV) species as uraninite may be produced as result of bacterial enzymatic U(VI) reduction. These findings suggest that under electron donor-rich water-saturation conditions, bentonite microbial community can control U speciation, immobilizing it, and thus enhancing future DGR safety if container rupture and waste leakage occurs.
PubMed: 38943881
DOI: 10.1016/j.jhazmat.2024.135044 -
Microbial Ecology Jun 2024Plastic pollution poses a worldwide environmental challenge, affecting wildlife and human health. Assessing the biodegradation capabilities of natural microbiomes in...
Plastic pollution poses a worldwide environmental challenge, affecting wildlife and human health. Assessing the biodegradation capabilities of natural microbiomes in environments contaminated with microplastics is crucial for mitigating the effects of plastic pollution. In this work, we evaluated the potential of landfill leachate (LL) and estuarine sediments (ES) to biodegrade polyethylene (PE), polyethylene terephthalate (PET), and polycaprolactone (PCL), under aerobic, anaerobic, thermophilic, and mesophilic conditions. PCL underwent extensive aerobic biodegradation with LL (99 ± 7%) and ES (78 ± 3%) within 50-60 days. Under anaerobic conditions, LL degraded 87 ± 19% of PCL in 60 days, whereas ES showed minimal biodegradation (3 ± 0.3%). PE and PET showed no notable degradation. Metataxonomics results (16S rRNA sequencing) revealed the presence of highly abundant thermophilic microorganisms assigned to Coprothermobacter sp. (6.8% and 28% relative abundance in anaerobic and aerobic incubations, respectively). Coprothermobacter spp. contain genes encoding two enzymes, an esterase and a thermostable monoacylglycerol lipase, that can potentially catalyze PCL hydrolysis. These results suggest that Coprothermobacter sp. may be pivotal in landfill leachate microbiomes for thermophilic PCL biodegradation across varying conditions. The anaerobic microbial community was dominated by hydrogenotrophic methanogens assigned to Methanothermobacter sp. (21%), pointing at possible syntrophic interactions with Coprothermobacter sp. (a H-producer) during PCL biodegradation. In the aerobic experiments, fungi dominated the eukaryotic microbial community (e.g., Exophiala (41%), Penicillium (17%), and Mucor (18%)), suggesting that aerobic PCL biodegradation by LL involves collaboration between fungi and bacteria. Our findings bring insights on the microbial communities and microbial interactions mediating plastic biodegradation, offering valuable perspectives for plastic pollution mitigation.
Topics: Biodegradation, Environmental; Microbiota; Microplastics; Waste Disposal Facilities; Bacteria; Water Pollutants, Chemical; Polyesters; Geologic Sediments; RNA, Ribosomal, 16S; Estuaries; Polyethylene; Polyethylene Terephthalates
PubMed: 38943017
DOI: 10.1007/s00248-024-02399-8 -
European Journal of Dentistry Jun 2024This study aims to investigate DSM 17938's antibiofilm effects on and , common causes of alveolar osteitis. It seeks topical alternatives to prevent this condition...
OBJECTIVES
This study aims to investigate DSM 17938's antibiofilm effects on and , common causes of alveolar osteitis. It seeks topical alternatives to prevent this condition posttooth extraction. The secondary objective is to assess these effects under different pH conditions (pH 4.5 and pH 7), mimicking oral cavity saliva pH dynamics.
MATERIALS AND METHODS
Ethical approval was secured for the saliva collection process involving five healthy adult participants who had undergone wisdom tooth extraction. Saliva samples were diligently collected on the 7th day post-surgery. The unstimulated saliva underwent a series of treatments, including the addition of phenylmethylsulfonyl fluoride (PMSF), pH adjustments, centrifugation, and filtration. The pH levels were re-measured, and subsequent adjustments were made to achieve pH values of 4.5 or 7. DSM 17938, with a concentration of 1×10 colony-forming units (CFU) per 5 drops, was utilized in the study. Biofilm testing involved incubating saliva samples with varying pH (4.5 or 7) alongside bacterial suspensions (, or a mixed species). The Interlac suspension was introduced, and plates were anaerobically incubated for 24 hours. Biofilm results were obtained using a spectrometer. The test is conducted in triplicate.
STATISTICAL ANALYSIS
To scrutinize the impact of pH on biofilm development, the acquired data underwent a two-way ANOVA test in SPSS as part of the statistical analysis. A significance level of <0.05 was used to determine statistical significance.
RESULTS
DSM 17938 significantly reduced biofilm formation across bacterial strains ( = 0.000). Statistical analysis indicated a significant impact of pH on biofilm development ( = 0.000) compared to no saliva samples, with higher formation observed under acidic conditions (pH 4.5). However, the pH levels of 4.5 and 7 did not result in significantly different bacterial biofilm formation ( = 0.529).
CONCLUSION
This research highlights DSM 17938's potency in inhibiting biofilm formation of and . Salivary pH variations significantly influence biofilm development, emphasizing the need to consider pH when assessing probiotic effectiveness. Despite limitations in saliva sample sterilization, this study provides valuable insights into alternative approaches for preventing alveolar osteitis. Further research should explore clinical applications and refine sterilization methods for more accurate results.
PubMed: 38942052
DOI: 10.1055/s-0044-1786846 -
PloS One 2024The measurement of chemical oxygen demand (COD) is very important in the process of sewage treatment. The value of COD reflects the effectiveness and trend of sewage...
The measurement of chemical oxygen demand (COD) is very important in the process of sewage treatment. The value of COD reflects the effectiveness and trend of sewage treatment to a certain extent, but obtaining accurate data requires high cost and labor intensity. To1 solve this problem, this paper proposes an online soft measurement method for COD based on Convolutional Neural Network-Bidirectional Long Short-Term Memory Network-Attention Mechanism (CNN-BiLSTM-Attention) algorithm. Firstly, by analyzing the mechanism of the aerobic tank stage in the Anaerobic-Anoxic-Oxic (A2O) wastewater treatment process, the selection range of input variables was preliminarily determined, and the collected sample dataset was subjected to correlation analysis. Finally, pH, dissolved oxygen (DO), electrical conductivity (EC), and water temperature (T) were determined as input variables for soft measurement prediction of COD.Then, based on the feature extraction ability of CNN and the advantage that BiLSTM is able to capture the backward and forward dependencies in time series data, combined with the attention mechanism that can assign higher weights to the key data, a CNN-BiLSTM-Attention algorithm model was established to soft measure COD in the effluent from the aerobic zone of the A2O wastewater treatment process. At the same time, root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE) and coefficient of determination (R2) were utilized Three indicators were used to evaluate the model, and the results showed that the model can accurately predict the value of COD and has a high accuracy. At the same time, compared with models such as CNN-LSTM-Attention, CNN-BiLSTM, CNN-LSTM, LSTM, RNN, BP, SVM, XGBoost, and RF etc., the results showed that the CNN-BiLSTM Attention model performed the best, proving the superiority of the algorithm model.The Wilcoxon signed-rank test indicates significant differences between the CNN-BiLSTM-Attention model and other models.
Topics: Algorithms; Biological Oxygen Demand Analysis; Neural Networks, Computer; Oxygen; Wastewater; Waste Disposal, Fluid; Sewage
PubMed: 38941339
DOI: 10.1371/journal.pone.0305216 -
MSystems Jun 2024We use metagenome-assembled genomes (MAGs) to understand single-carbon (C1) compound-cycling-particularly methane-cycling-microorganisms in montane riparian floodplain...
Diverse and unconventional methanogens, methanotrophs, and methylotrophs in metagenome-assembled genomes from subsurface sediments of the Slate River floodplain, Crested Butte, CO, USA.
We use metagenome-assembled genomes (MAGs) to understand single-carbon (C1) compound-cycling-particularly methane-cycling-microorganisms in montane riparian floodplain sediments. We generated 1,233 MAGs (>50% completeness and <10% contamination) from 50- to 150-cm depth below the sediment surface capturing the transition between oxic, unsaturated sediments and anoxic, saturated sediments in the Slate River (SR) floodplain (Crested Butte, CO, USA). We recovered genomes of putative methanogens, methanotrophs, and methylotrophs ( = 57). Methanogens, found only in deep, anoxic depths at SR, originate from three different clades (, , and ), each with a different methanogenesis pathway; putative methanotrophic MAGs originate from within the Archaea ( Methanoperedens) in anoxic depths and uncultured bacteria (. Binatia) in oxic depths. Genomes for canonical aerobic methanotrophs were not recovered. Methanoperedens were exceptionally abundant (~1,400× coverage, >50% abundance in the MAG library) in one sample that also contained aceticlastic methanogens, indicating a potential C1/methane-cycling hotspot. . Methylomirabilis MAGs from SR encode pathways for methylotrophy but do not harbor methane monooxygenase or nitrogen reduction genes. Comparative genomic analysis supports that one clade within the . Methylomirabilis genus is not methanotrophic. The genetic potential for methylotrophy was widespread, with over 10% and 19% of SR MAGs encoding a methanol dehydrogenase or substrate-specific methyltransferase, respectively. MAGs from uncultured archaea in the . Gimiplasmatales (UBA10834) contain pathways that may allow for anaerobic methylotrophic acetogenesis. Overall, MAGs from SR floodplain sediments reveal a potential for methane production and consumption in the system and a robust potential for methylotrophy.IMPORTANCEThe cycling of carbon by microorganisms in subsurface environments is of particular relevance in the face of global climate change. Riparian floodplain sediments contain high organic carbon that can be degraded into C1 compounds such as methane, methanol, and methylamines, the fate of which depends on the microbial metabolisms present as well as the hydrological conditions and availability of oxygen. In the present study, we generated over 1,000 MAGs from subsurface sediments from a montane river floodplain and recovered genomes for microorganisms that are capable of producing and consuming methane and other C1 compounds, highlighting a robust potential for C1 cycling in subsurface sediments both with and without oxygen. Archaea from the . Methanoperedens genus were exceptionally abundant in one sample, indicating a potential C1/methane-cycling hotspot in the Slate River floodplain system.
PubMed: 38940520
DOI: 10.1128/msystems.00314-24 -
The rapidly progressing and fatal outcome of rhombencephalitis by listeriosis in a 61-year-old male.Annals of Agricultural and... Jun 2024Listeria monocytogenes is a Gram-positive facultative anaerobic bacterium that is ubiquitous in the environment and can cause severe infections in immunocompromised...
Listeria monocytogenes is a Gram-positive facultative anaerobic bacterium that is ubiquitous in the environment and can cause severe infections in immunocompromised individuals, pregnant women, and newborns. Listeriosis can manifest as meningitis, encephalitis, or sepsis, and its diagnosis requires a high index of suspicion. The case is reported of a rare presentation of rhombencephalitis by listeriosis in a 61-year-old male who initially suffered from subacute gastric disturbances and fever. Neurological consultation showed abnormal functions of cranial nerves and meningeal signs were observed. MRI revealed a poorly demarcated focus of approximately 45 × 16 × 15mm, indicating possible inflammatory processes, necessitating a lumbar puncture. Assessment of the CSF indicated infection with the bacterium- Listeria Monocytogenes, with the final diagnosis of Listeriosis encephalitis. Despite antibiotic therapy of Ceftazidine and Ampicillin, the patient's condition deteriorated, followed by death.
Topics: Humans; Male; Listeriosis; Middle Aged; Fatal Outcome; Listeria monocytogenes; Encephalitis; Anti-Bacterial Agents; Rhombencephalon
PubMed: 38940119
DOI: 10.26444/aaem/178178