La microflore de boues aérobies acclimatées à des teneurs élevées en graisse

Le travail présenté dans cet article a pour but d'isoler les principaux micro-organismes impliqués dans la biodégradation des lipides concentrés dans des réacteurs spécifiques de stations d'épuration des eaux et d'étudier leur action sur ce type de substrat.La microflore d'une boue activée « classique » est comparée à celle de boues acclimatées à des teneurs élevées en lipides selon un nouveau procédé « BIOMASTER® G ». Cela montre un enrichissement en bactéries fortement lipolytiques dans le système à l'équilibre. En effet, la boue activée « classique » ne contient aucun microorganisme fortement lipolytique alors qu'à partir de la boue acclimatée du même site on a pu en isoler, Acinetobacter calcoaceticus et Pseudomonas putida étant les constituants les plus actifs. L'utilisation de bioadditifs du commerce pour l'ensemencement des pilotes au lancement du système ne semble pas apporter d'avantages décisifs puisqu'on ne retrouve pas à l'équilibre les micro-organismes contenus dans ces bioadditifs. Par contre, d'autres microorganismes à pouvoir lipolytique élevé sont détectés tels que Pseudomonas sp., Aeromonas hydrophila et Staphylococcus sp . Le genre Pseudomonas est par ailleurs presque toujours rencontré quelle que soit la boue acclimatée examinée. De même, on peut noter la quasi absence de bactéries Gram positif.Tous les isolats Gram négatif dégradent plus ou moins les acides gras de longueur de chaîne variée. Le seul isolat Gram positif est inhibé ou même tué par les acides gras à chaîne moyenne ou courte et cela peut contribuer à la pauvreté en bactéries Gram positif dans les boues acclimatées. Les genres principaux que nous avons rencontrés, Pseudomonas, Acinetobacter et Aeromonas, sont capables d'assurer à la fois la lipolyse (libération des acides gras) et l'oxydation subséquente des acides gras. L'enrichissement naturel de la microflore lipolytique des boues activées dans le procédé aboutit à une microflore acclimatée capable d'assurer la biodégradation complète des lipides.In this study, the main microorganisms involved in lipid biodegradation in activated sludge sewage treatment plants were isolated and their action on triglycerides and on fatty acids was investigated.Six different sludge samples were studied. An activated sludge of the usual type (A) was used as reference. At the same site, activated sludge was adapted to higher lipid levels, through separation of fats reaching the sewage treatment plant, followed by their addition in higher proportion to activated sludge. In experiment B, adaptation took place in a « BIOMASTER® G » reactor, which is a new process for the elimination of fats by an aerobic treatment. Experiments C and D used the same original sludge plus lipid mixture, but with the addition of commercial bioadditives containing lipolytic bacteria. Finally, microorganisms isolated from two other systems, located at two other sites, were also studied (experiments E and F).The control activated sludge, A, did not contain any strongly lipolytic microorganisms. On the other hand, in the new system at equilibrium, after adaptation, bacteria with a strong lipolytic potential such as Acinetobacter calcoaceticus and, Pseudomonas putida were isolated. The use of bioadditives at the start of the incubation did not afford any notable advantage, since at equilibrium microorganisms contained in these additives were not reisolated. However, other microorganisms with high lipolytic power (activity higher than 0.1 µmole acid liberated per minute and per ml of culture broth) were isolated, such as Pseudomorns sp., Aeromonas hydrophila and Staphylococcus sp. The genus Pseudomozas was almost always detected, regardless of the acclimated sludge studied. Conversely, Gram positive bacteria were virtually absent.All Gram negative isolates were more or less capable of degrading fatty acids with various chain lengths. The only Gram positive isolate was inhibited, even killed, by short and medium chain fatty acids. In the present study, this might contribute to the paucity of Gram positive bacteria in the adapted sludges. The main genera encountered, Pseudomonas, Acinetobacter and Aeromonas, were able to perform both lipolysis (liberation of fatty acids) and the subsequent oxidation of the liberated fatty acids. The natural enrichment of the lipolltic microflora of activated sludges in the process leads to an acclimated microflora, able to completely biodegrade lipids

Elimination de la matière organique biodégradable par ultrafiltration

Les installations de production de la Compagnie des Eaux de banlieue (CEB) au Mont Valérien traitent l'eau de Seine en aval de Paris sur 2 filières de potabilisation comprenant pour la première (50 000 m3/J) une préozonation, une coagulation au sels d'Aluminium (Aqualenc), une décantation (super pulsator Degrémont), une filtration sur sable, une ozonation, une filtration sur charbon actif en grains (CAG) et une désinfection finale au bioxyde de chlore, et pour la deuxième, une filtration lente sur sable (80 000 m3/j) dite filtration "Chabale".Dans le cadre du remplacement de la filière "Chabale", une unité de démonstration (8 m3/h) eomprenaut une addition de charbon actif en poudre (CAP) avant ultrafiltration sur membrane a été mise en route.Dans cette étude, une comparaison du traitement conventionnel physico-chimique de l'usine et du nouveau procédé d'ultrafiltration a été effectuée. Pour cela, un suivi du carbone organique total et une évaluation du potentiel de reviviscence ont été réalisés en différents points des chaînes de traitement. La matière organique biodégradable (MOB) a été mesurée par la méthode Werner (1980).Les premiers résultats montrent :- l'élimination des MOB est comparable pour les différents procédés;- toutefois, la nature des MOB est sensiblement affectée à chaque type de traitement (ozonation, addition de CAP, filtration sur sable ou sur CAG)."Compagnie des Eaux de Banlieue" water facilities located at the Mont-Valérien treat the Seine river water downstream Paris. A first facility (5000 m3/day) includes the following processes : preozonation, coagulation, settling, sand filtration, postozonalion, GAC filtration and a final desinfection (CIO2). A second one consists in a biological sand filtration (80000 m3/day). An ultrafiltration demonstration plant including a CAP addition into the recirculation loop is currently tested on a small scale (8 m3/h) to compare the conventional treatments with new ultrafiltration process.In this study, the TOC removal as well as the biodegradable organic matter (BOM) removal are evaluated on the different processes. The BOM has been assessed by the Werner methodology (1980).During the cool season (october-january) all the biodegradable organic matter were removed by the clarification process (preozonation + coagulation decantation + sand filtration). More than 90 % of the BOM were also removed by the ultrafiltration demonstration plant (including granular activated carbon) although the addition of preozonation slightly increases the effluent BOM concentrations and modifies its composition. 80 % of the dissolved organic compounds were removed by the preozonation + ultrafiltration + powder treatment line. This performance should be compared with the 70 % removal obtained with conventional treatments.This study demonstrate that the combination 03 + UF + CAP can advantageously replace traditional treatment such as preozonation + coagulation clarification + ozonation + granular activated carbon + desinfection

Influence of dissolved oxygen on the nitrification kinetics in a circulating bed biofilm reactor

The influence of dissolved oxygen concentration on the nitrification kinetics was studied in the circulating bed reactor (CBR). The study was partly performed at laboratory scale with synthetic water, and partly at pilot scale with secondary effluent as feed water. The nitrifi- cation kinetics of the laboratory CBR as a function of the oxygen concentration can be described according to the half order and zero order rate equations of the diffusion-reaction model applied to porous catalysts. When oxygen was the rate limiting substrate, the nitrification rate was close to a half order function of the oxygen concentration. The average oxygen diffusion coefficient estimated by fitting the diffusion-reaction model to the experimental results was around 66% of the respective value in water. The experimental results showed that either the ammonia or the oxygen concentration could be limiting for the nitri fication kinetics. The latter occurred for an oxygen to ammonia concentration ratio below 1.5-2 gO2/gN-NH4+ for both laboratory and pilot scale reactors. The volumetric oxygen mass transfer coefficient (kLa) determined in the laboratory scale reactor was 0.017 sˉ¹ for a superficial air velocity of 0.02 m sˉ¹, and the one determined in the pilot scale reactor was 0.040 sˉ¹ for a superficial air velocity of 0.031 m sˉ¹. The kLa for the pilot scale reactor did not change significantly after biofilm development, compared to the value measured without biofilm.Fundação para a Ciência e a Tecnologia (FCT) - PRAXIS XXI, project 2/2.1/Bio/37/94.INTERREG

Generalization optimizing machine learning to improve CT scan radiomics and assess immune checkpoint inhibitors’ response in non-small cell lung cancer: a multicenter cohort study

BackgroundRecent developments in artificial intelligence suggest that radiomics may represent a promising non-invasive biomarker to predict response to immune checkpoint inhibitors (ICIs). Nevertheless, validation of radiomics algorithms in independent cohorts remains a challenge due to variations in image acquisition and reconstruction. Using radiomics, we investigated the importance of scan normalization as part of a broader machine learning framework to enable model external generalizability to predict ICI response in non-small cell lung cancer (NSCLC) patients across different centers.MethodsRadiomics features were extracted and compared from 642 advanced NSCLC patients on pre-ICI scans using established open-source PyRadiomics and a proprietary DeepRadiomics deep learning technology. The population was separated into two groups: a discovery cohort of 512 NSCLC patients from three academic centers and a validation cohort that included 130 NSCLC patients from a fourth center. We harmonized images to account for variations in reconstruction kernel, slice thicknesses, and device manufacturers. Multivariable models, evaluated using cross-validation, were used to estimate the predictive value of clinical variables, PD-L1 expression, and PyRadiomics or DeepRadiomics for progression-free survival at 6 months (PFS-6).ResultsThe best prognostic factor for PFS-6, excluding radiomics features, was obtained with the combination of Clinical + PD-L1 expression (AUC = 0.66 in the discovery and 0.62 in the validation cohort). Without image harmonization, combining Clinical + PyRadiomics or DeepRadiomics delivered an AUC = 0.69 and 0.69, respectively, in the discovery cohort, but dropped to 0.57 and 0.52, in the validation cohort. This lack of generalizability was consistent with observations in principal component analysis clustered by CT scan parameters. Subsequently, image harmonization eliminated these clusters. The combination of Clinical + DeepRadiomics reached an AUC = 0.67 and 0.63 in the discovery and validation cohort, respectively. Conversely, the combination of Clinical + PyRadiomics failed generalizability validations, with AUC = 0.66 and 0.59.ConclusionWe demonstrated that a risk prediction model combining Clinical + DeepRadiomics was generalizable following CT scan harmonization and machine learning generalization methods. These results had similar performances to routine oncology practice using Clinical + PD-L1. This study supports the strong potential of radiomics as a future non-invasive strategy to predict ICI response in advanced NSCLC

Purine metabolism regulates DNA repair and therapy resistance in glioblastoma

Intratumoral genomic heterogeneity in glioblastoma (GBM) is a barrier to overcoming therapy resistance. Treatments that are effective independent of genotype are urgently needed. By correlating intracellular metabolite levels with radiation resistance across dozens of genomically-distinct models of GBM, we find that purine metabolites, especially guanylates, strongly correlate with radiation resistance. Inhibiting GTP synthesis radiosensitizes GBM cells and patient-derived neurospheres by impairing DNA repair. Likewise, administration of exogenous purine nucleosides protects sensitive GBM models from radiation by promoting DNA repair. Neither modulating pyrimidine metabolism nor purine salvage has similar effects. An FDA-approved inhibitor of GTP synthesis potentiates the effects of radiation in flank and orthotopic patient-derived xenograft models of GBM. High expression of the rate-limiting enzyme of de novo GTP synthesis is associated with shorter survival in GBM patients. These findings indicate that inhibiting purine synthesis may be a promising strategy to overcome therapy resistance in this genomically heterogeneous disease

Transcriptome-wide association study reveals candidate causal genes for lung cancer.

We have recently completed the largest GWAS on lung cancer including 29,266 cases and 56,450 controls of European descent. The goal of our study has been to integrate the complete GWAS results with a large-scale expression quantitative trait loci (eQTL) mapping study in human lung tissues (n = 1,038) to identify candidate causal genes for lung cancer. We performed transcriptome-wide association study (TWAS) for lung cancer overall, by histology (adenocarcinoma, squamous cell carcinoma and small cell lung cancer) and smoking subgroups (never- and ever-smokers). We performed replication analysis using lung data from the Genotype-Tissue Expression (GTEx) project. DNA damage assays were performed in human lung fibroblasts for selected TWAS genes. As expected, the main TWAS signal for all histological subtypes and ever-smokers was on chromosome 15q25. The gene most strongly associated with lung cancer at this locus using the TWAS approach was IREB2 (pTWAS = 1.09E-99), where lower predicted expression increased lung cancer risk. A new lung adenocarcinoma susceptibility locus was revealed on 9p13.3 and associated with higher predicted expression of AQP3 (pTWAS = 3.72E-6). Among the 45 previously described lung cancer GWAS loci, we mapped candidate target gene for 17 of them. The association AQP3-adenocarcinoma on 9p13.3 was replicated using GTEx (pTWAS = 6.55E-5). Consistent with the effect of risk alleles on gene expression levels, IREB2 knockdown and AQP3 overproduction promote endogenous DNA damage. These findings indicate genes whose expression in lung tissue directly influences lung cancer risk

Immune-mediated genetic pathways resulting in pulmonary function impairment increase lung cancer susceptibility

Impaired lung function is often caused by cigarette smoking, making it challenging to disentangle its role in lung cancer susceptibility. Investigation of the shared genetic basis of these phenotypes in the UK Biobank and International Lung Cancer Consortium (29,266 cases, 56,450 controls) shows that lung cancer is genetically correlated with reduced forced expiratory volume in one second (FEV1: r(g) = 0.098, p = 2.3 x 10(-8)) and the ratio of FEV1 to forced vital capacity (FEV1/FVC: r(g) = 0.137, p = 2.0 x 10(-12)). Mendelian randomization analyses demonstrate that reduced FEV1 increases squamous cell carcinoma risk (odds ratio (OR) = 1.51, 95% confidence intervals: 1.21-1.88), while reduced FEV1/FVC increases the risk of adenocarcinoma (OR = 1.17, 1.01-1.35) and lung cancer in never smokers (OR = 1.56, 1.05-2.30). These findings support a causal role of pulmonary impairment in lung cancer etiology. Integrative analyses reveal that pulmonary function instruments, including 73 novel variants, influence lung tissue gene expression and implicate immune-related pathways in mediating the observed effects on lung carcinogenesis

Application of a risk-management framework for integration of stromal tumor-infiltrating lymphocytes in clinical trials

Stromal tumor-infiltrating lymphocytes (sTILs) are a potential predictive biomarker for immunotherapy response in metastatic triple-negative breast cancer (TNBC). To incorporate sTILs into clinical trials and diagnostics, reliable assessment is essential. In this review, we propose a new concept, namely the implementation of a risk-management framework that enables the use of sTILs as a stratification factor in clinical trials. We present the design of a biomarker risk-mitigation workflow that can be applied to any biomarker incorporation in clinical trials. We demonstrate the implementation of this concept using sTILs as an integral biomarker in a single-center phase II immunotherapy trial for metastatic TNBC (TONIC trial, NCT02499367), using this workflow to mitigate risks of suboptimal inclusion of sTILs in this specific trial. In this review, we demonstrate that a web-based scoring platform can mitigate potential risk factors when including sTILs in clinical trials, and we argue that this framework can be applied for any future biomarker-driven clinical trial setting