New insights on the degradation of polystyrene and polypropylene by larvae of the superworm Zophobas atratus and gut bacterial consortium enrichments obtained under different culture conditions.

This study aims to deepen knowledge of the biodegradation of plastics, focusing on polypropylene (PP) fabric from surgical masks and polystyrene (PS) by larvae of Zophobas atratus as well as of specialized bacterial consortia from their gut, which were obtained in different enrichment conditions (aerobic, anaerobic, presence or absence of combined nitrogen). Plastics ingested by larvae obtained in Spain did not show any signs of oxidation but only limited depolymerization, preferably from the lowest molecular weight chains. Gut microbiota composition changed as an effect of plastic feeding. Such differences were more evident in bacterial enrichment cultures, where the polymer type influenced the composition more than by culture conditions, with an increase in the presence of nitrogen-fixers in anaerobic conditions. PS and PP degradation by different enrichment cultures was confirmed under aerobic and anaerobic conditions by respirometry tests, with anaerobic conditions favouring a more active plastic degradation. In addition, exposure to selected bacterial consortia in aerobiosis induced limited surface oxidation of PS. This possibly indicates that different biochemical routes are being utilized in the anaerobic gut and in aerobic conditions to degrade the polymer.

Two-way role of iron-carbon in biochemical reactions: Microelectrolysis and enhanced activity of aerobic granular sludge for efficient refractory wastewater treatment.

Industrial wastewater contained a large amount of refractory organics, and single treatment processes had limitations. This study investigated the mechanism of refractory organics removal using iron-carbon built-in coupled activated sludge (ICAS) and explored the role and function of iron-carbon (IC) within the ICAS system. The aerobic granular sludge (AGS) cultivated with IC exhibited a loose surface and a tight interior structure. Iron in the AGS concentrated near the outer layer to form a crust, which protected the inner microorganisms. IC promoted EPS secretion and regulated the abundance of positive and negative signaling molecules to maintain AGS stability. Experiments using quinoline as a model refractory organic showed that both physical adsorption by IC and biological adsorption by sludge rapidly fixed a large amount of pollutants, providing a buffer capacity for the system. The iron mineral crust on the AGS surface enhanced quinoline adsorption. Hydroxylation was the first step in quinoline degradation, with IC upregulating the genes iorA/B, qorB, and wrbA involved in this process, and the relative abundances of quinoline-degrading bacteria. Both pyridine ring opening and benzene ring cleavage occurred in the single IC system, and the microelectrolysis process produced •OH and [H], which made degradation pathway for quinoline through IC more complex than microbial degradation. Although the IC-mediated pathway accounted for only a small part of overall quinoline removal in the ICAS system, the ICAS system not only preserved the microelectrolysis process but also enhanced microbial metabolic activity. This work provided insights into the synergistic removal of pollutants and maintenance of AGS stability by the ICAS process, ensuring efficient treatment of refractory organic wastewater.

Enhanced aerobic granular sludge by thermally-treated dredged sediment in wastewater treatment under low superficial gas velocity.

The positive contributions of carriers to aerobic granulation have been wildly appreciated. In this study, as a way resource utilization, the dredged sediment was thermally-treated to prepared as carriers to promote aerobic granular sludge (AGS) formation and stability. The system was started under low superficial gas velocity (SGV, 0.6 cm/s)for a lower energy consumption. Two sequencing batch reactors (SBR) labeled R1 (no added carriers) and R2 (carriers added), were used in the experiment. R2 had excellent performance of granulation time (shortened nearly 43%). The maximum mean particle size at the maturity stage of AGS in R2 (0.545 mm) was larger compared to R1 (0.296 mm). The sludge settling performance in R2 was better. The reactors exhibited high chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) removal rates. The total phosphorus (TP) removal rate in R2 was higher than R1 (almost 15% higher) on stage II (93-175d). R2 had a higher microbial abundance and dominant bacteria content. The relative abundance of dominant species was mainly affected by the carrier. However, the enrichment of dominant microorganisms and the evolution of subdominant species were more influenced by the increase of SGV. The results indicated that the addition of carriers induced the secretion of extracellular polymeric substances (EPS) by microorganisms and accelerated the rapid formation of initial microbial aggregates. This work provided a low-cost method and condition to enhance aerobic granulation, which may be helpful in optimizing wastewater treatment processes.

Simultaneous aerobic nitrogen and phosphorus removal by novel halotolerant fungus Mucor circinelloides SNDM1: Function and metabolism pathway.

Fungi capable of simultaneous nitrogen and phosphorus removal from wastewater is rarely found. Here, a novel fungal strain (SNDM1) performing heterotrophic nitrification, aerobic denitrification, and phosphate removal was isolated and identified as Mucor circinelloides. The favorable nutrient removal conditions by the strain using glucose were C/N ratios of 25-30, salinities of 0 %-3 %, and pH of 7.5. Strain SNDM1 achieved ammonium, nitrite, nitrate, and phosphate removal rates of 5.23, 10.08, 4.88, and 0.97 mg/L/h. Nitrogen balance indicated that gaseous (18.60 %-24.55 %) and intracellular nitrogen (43.76 %-70.63 %) were primary fate of initial nitrogen. Enzyme activity revealed that ammonium removal occurred through heterotrophic nitrification and aerobic denitrification. Removed phosphorus was mainly transformed into cell membranes (56 %-64 %) and extracellular polymeric substances (20 %-26 %). Orthophosphate was the major intracellular phosphorus species, while polyphosphate and pyrophosphate existed extracellularly. These findings highlight the potential of this fungal strain for bioremediating polluted wastewater.

Deciphering the role of micro/nano-hydroxyapatite in aerobic granular sludge system: Effects on treatment performance and enhancement mechanism.

Hydroxyapatite (HAP), a mineral nucleus identified within aerobic granular sludge (AGS), plays a vital role in enhancing the AGS systems. However, the microscopic mechanism underlying their roles remains largely unexplored. Herein, a systematic investigation was carried out to elucidate the impact and enhanced mechanisms associated with HAP of different sizes, i.e. micro-HAP (mHAP) and nano-HAP (nHAP), on the aerobic granulation, nutrient removal and microbial diversity of AGS. Results showed that the presence of nHAP and mHAP significantly shortened the granulation process to 15 and 20 days, respectively. This might be ascribed to the fact that the large specific surface area of nHAP aggregates was conducive to microbial adhesion, biomass accumulation and sludge granulation. Compared with mHAP, the granules with nHAP showed better settlement performance, mechanical strength and larger diameter. The X-ray diffraction (XRD) and Raman spectrometer analysis confirmed the presence of HAP within the granules, which was found to stimulate the secretion of extracellular polymeric substance, improve the compactness of granule structure and suppress the growth of filamentous bacteria, thereby contributing to a stable AGS system. The presence of HAP, especially nHAP, effectively enriched the functional microorganisms, such as nitrifying and denitrifying bacteria (e.g. Candidatus_Competibacter) and phosphorus accumulating organisms (e.g. Flavobacterium), leading to the improved nutrient removal efficiencies (COD > 96%, TN > 76%, and TP > 74%). Further analysis revealed the up-regulation of functional enzymes (e.g. nitrite oxidoreductase and polyphosphate kinase) involved in nutrient metabolism, underlying the inherent mechanisms for the excellent nutrient removal. This study deepens the understanding of granulation mechanisms from the perspective of mineral cores, and proposes an economically feasible strategy for rapid initiation and stabilization of AGS reactors.

Microbial response to the chronic toxicity effect of graphene and graphene oxide nanomaterials within aerobic granular sludge systems.

Nanomaterials present in wastewater can pose a significant threat to aerobic granular sludge (AGS) systems. Herein, we found that compared to graphene nanomaterials (G-NMs), the long-term presence (95 days) of graphene oxide nanomaterials (GO-NMs) resulted in an increased proliferation of filamentous bacteria, poorer sedimentation performance (SVI30 of 74.1 mL/g) and smaller average particle size (1224.4 µm) of the AGS. In particular, the GO-NMs posed a more significant inhibitory effect to the total nitrogen removal efficiency of AGS (decreased by 14.3 %), especially for the denitrification process. The substantial accumulation of GO-NMs within the sludge matrix resulted in a higher level of reactive oxygen species in AGS compared to G-NMs, thereby inducing lactate dehydrogenase release, and enhancing superoxide oxidase and catalase activities. Such excessive oxidative stress could potentially result in a significant reduction in the activity of nitrogen metabolism enzymes (e.g., nitrate reductase and nitrite reductase) and the expression of key functional genes (e.g., nirS and nirK). Altogether, compared to G-NMs, prolonged exposure to GO-NMs had a more significant chronic toxicity effect on AGS systems. These findings implied that the presence of G-NMs and GO-NMs is a hidden danger to biological nitrogen removal and should receive more attention.

Sponge iron enriches autotrophic/aerobic denitrifying bacteria to enhance denitrification in sequencing batch reactor.

Sponge iron (SFe) coupled with a sludge system has great potential for improving biological denitrification; however, the underlying mechanism is not yet fully understood. In this study, the denitrification performance and microbial characteristics of ordinary sludge and SFe-sludge systems were investigated. Overall, the SFe-sludge reactor had faster ammonium degradation rate (94.0 %) and less nitrate accumulation (1.5-53.3 times lower) than ordinary reactor during the complete operation cycle of sequencing batch reactors. The addition of SFe increased the activities of nitrate and nitrite reductases. The total relative abundance of autotrophic denitrifying bacteria (Acidovorax, Arenimonas, etc.) in the SFe-sludge system after 38 days of operation was found to be 10.6 % higher than that in the ordinary sludge reactor. The aerobic denitrifying bacteria (Dokdonella, Phaeodactylibacter, etc.) was 5.3 % higher than ordinary sludge. The SFe-sludge system improved denitrification by enriching autotrophic/aerobic denitrifying bacteria in low carbon-to-nitrogen ratio wastewater treatment.

Phosphorous speciation in EPS extracted from Aerobic Granular Sludge.

Wastewater treatment technologies opened the door for recovery of extracellular polymeric substances (EPS), presenting novel opportunities for use across diverse industrial sectors. Earlier studies showed that a significant amount of phosphorus (P) is recovered within extracted EPS. P recovered within the extracted EPS is an intrinsic part of the recovered material that potentially influences its properties. Understanding the P speciation in extracted EPS lays the foundation for leveraging the incorporated P in EPS to manipulate its properties and industrial applications. This study evaluated P speciation in EPS extracted from aerobic granular sludge (AGS). A fractionation lab protocol was established to consistently distinguish P species in extracted EPS liquid phase and polymer chains. 31P nuclear magnetic resonance (NMR) spectroscopy was used as a complementary technique to provide additional information on P speciation and track changes in P species during the EPS extraction process. Findings showed the dominance of organic phosphorus and orthophosphates within EPS, besides other minor fractions. On average, 25% orthophosphates in the polymer liquid phase, 52% organic phosphorus (equal ratio of mono and diesters) covalently bound to the polymer chains, 16% non-apatite inorganic phosphorus (NAIP) precipitates mainly FeP and AlP, and 7% pyrophosphates (6% in the liquid phase and 1% attached to the polymer chains) were identified. Polyphosphates were detected in initial AGS but hydrolyzed to orthophosphates, pyrophosphates, and possibly organic P (forming new esters) during the EPS extraction process. The knowledge created in this study is a step towards the goal of EPS engineering, manipulating P chemistry along the extraction process and enriching certain P species in EPS based on target properties and industrial applications.

LncRNA PCIF1 promotes aerobic glycolysis in A549/DDP cells by competitively binding miR-326 to regulate PKM expression.

OBJECTIVE: Utilizing transcriptome analysis to investigate the mechanisms and therapeutic approaches for cisplatin resistance in non-small cell lung cancer (NSCLC). METHODS: Firstly, the biological characters of A549 cells and A549/DDP cells were detected by RNA sequencing, CCK-8 and hippocampal energy analyzer. Then, the differential Genes were functionally enriched by GO and KEGG and the competitive endogenous RNA network map was constructed. Finally, the effects of the predicted biogenesis pathway on the biological functions of A549/DDP cells were verified by in vitro and in vivo experiments. RESULT: The differentially transcribed genes of A549 and A549/DDP cells were analyzed by enrichment analysis and cell biological characteristics detection. The results showed that A549/DDP cells showed significantly increased resistance to cisplatin, glucose metabolism signaling pathway and glycolysis levels compared with A549 cells. Among glycolysis-related transcription genes, PKM had the most significant difference Fold Change is 8. LncRNA PCIF1 is a new marker of A549/DDP cells and can be used as a molecular sponge to regulate the expression of PKM. LncRNA PCIF1 targets miR-326 to induce PKM expression, promote glycolysis level, and enhance the resistance of A549/DDP cells to cisplatin. CONCLUSION: LncRNA PCIF1 as biomarkers of A549/DDP cells, higher expression can induce the PKM, promote cell glycolysis, lead to the occurrence of cisplatin resistance. LncRNA PCIF1 can be considered as a potential target for treating cisplatin-resistant NSCLC.

Stable-isotope probing combined with amplicon sequencing and metagenomics identifies key bacterial benzene degraders under microaerobic conditions.

The primary aim of the present study was to reveal the major differences between benzene-degrading bacterial communities evolve under aerobic versus microaerobic conditions and to reveal the diversity of those bacteria, which can relatively quickly degrade benzene even under microaerobic conditions. For this, parallel aerobic and microaerobic microcosms were set up by using groundwater sediment of a BTEX-contaminated site and 13C labelled benzene. The evolved total bacterial communities were first investigated by 16S rRNA gene Illumina amplicon sequencing, followed by a density gradient fractionation of DNA and a separate investigation of "heavy" and "light" DNA fractions. Results shed light on the fact that the availability of oxygen strongly determined the structure of the degrading bacterial communities. While members of the genus Pseudomonas were overwhelmingly dominant under clear aerobic conditions, they were almost completely replaced by members of genera Malikia and Azovibrio in the microaerobic microcosms. Investigation of the density resolved DNA fractions further confirmed the key role of these two latter genera in the microaerobic degradation of benzene. Moreover, analysis of a previously acquired metagenome-assembled Azovibrio genome suggested that benzene was degraded through the meta-cleavage pathway by this bacterium, with the help of a subfamily I.2.I-type catechol 2,3-dioxygenase. Overall, results of the present study implicate that under limited oxygen availability, some potentially microaerophilic bacteria play crucial role in the aerobic degradation of aromatic hydrocarbons.

Unraveling the effects and mechanisms of antibiotics on aerobic simultaneous nitrogen and phosphorus removal by Acinetobacter indicus CZH-5.

The effects of antibiotics, such as tetracycline, sulfamethoxazole, and ciprofloxacin, on functional microorganisms are of significant concern in wastewater treatment. This study observed that Acinetobacter indicus CZH-5 has a limited capacity to remove nitrogen and phosphorus using antibiotics (5 mg/L) as the sole carbon source. When sodium acetate was supplied (carbon/nitrogen ratio = 7), the average removal efficiencies of ammonia-N, total nitrogen, and orthophosphate-P increased to 52.46 %, 51.95 %, and 92.43 %, respectively. The average removal efficiencies of antibiotics were 84.85 % for tetracycline, 39.32 % for sulfamethoxazole, 18.85 % for ciprofloxacin, and 23.24 % for their mixtures. Increasing the carbon/nitrogen ratio to 20 further improved the average removal efficiencies to 72.61 % for total nitrogen and 97.62 % for orthophosphate-P (5 mg/L antibiotics). Additionally, the growth rate and pollutant removal by CZH-5 were unaffected by the presence of 0.1-1 mg/L antibiotics. Transcriptomic analysis revealed that the promoted translation of aceE, aarA, and gltA genes provided ATP and proton -motive forces. The nitrogen metabolism and polyphosphate genes were also affected. The expression of acetate kinase, dehydrogenase, flavin mononucleotide enzymes, and cytochrome P450 contributed to antibiotic degradation. Intermediate metabolites were investigated to determine the reaction pathways.

Ultra-rapid development of 'solid' aerobic granular sludge by stable transition/filling of inoculated 'hollow' mycelial pellets in hypersaline wastewater.

To overcome the long start-up period in cultivating aerobic granular sludge (AGS) under hypersaline environment, mycelial pellets (MPs) of halotolerant fungus Cladosporium tenuissimum NCSL-XY8 were inoculated to try to realize the ultra-rapid development of salt-tolerant AGS by stable transition of 'hollow' MPs into 'solid' AGS without apparent fragmentation. The granules directly met the standard of AGS after inoculating MPs (Day 0), and it basically satisfied relatively strict standards of AGS (SVI30 < 50 mL/g, D50 > 300 µm, D10 > 200 µm and SVI30/SVI5 > 0.9) under anaerobic/aerobic mode during whole cultivation processes. Microstructure of the granular cross section clarified that MPs with hollow/loose inner layer transitioned into solid/dense AGS under anaerobic/aerobic mode within 7 days, while formed skin-like floating pieces and unstable double-layer hollow granules under aerobic mode. Organics removal reached relatively stable within 13 days under anaerobic/aerobic mode, 6 days faster than aerobic mode. This study provided a strategy for ultra-rapid and stable development of AGS, which showed the shortest granulation period in various AGS-cultivation strategies.

Nickel augmented biochar for sustaining produced water treatment to decarbonize oil and gas industrial waste using anaerobic-aerobic granular cylindrical periodic discontinuous batch reactors.

This study assessed the efficacy of granular cylindrical periodic discontinuous batch reactors (GC-PDBRs) for produced water (PW) treatment by employing eggshell and waste activated sludge (WAS) derived Nickel (Ni) augmented biochar. The synthesized biochar was magnetized to further enhance its contribution towards achieving carbon neutrality due to carbon negative nature, Carbon dioxide (CO2) sorption, and negative priming effects. The GC-PDBR1 and GC-PDBR2 process variables were optimized by the application of central composite design (CCD). This is to maximize the decarbonization rate. Results showed that the systems could reduce total phosphorus (TP) and chemical oxygen demand (COD) by 76-80% and 92-99%, respectively. Optimal organic matter and nutrient removals were achieved at 80% volumetric exchange ratio (VER), 5 min settling time and 3000 mg/L mixed liquor suspended solids (MLSS) concentration with desirability values of 0.811 and 0.954 for GC-PDBR1 and GC-PDBR2, respectively. Employing four distinct models, the biokinetic coefficients of the GC-PDBRs treating PW were calculated. The findings indicated that First order (0.0758-0.5365) and Monod models (0.8652-0.9925) have relatively low R2 values. However, the Grau Second-order model and Modified Stover-Kincannon model have high R2 values. This shows that, the Grau Second Order and Modified Stover-Kincannon models under various VER, settling time, and MLSS circumstances, are more suited to explain the removal of pollutants in the GC-PDBRs. Microbiological evaluation demonstrated that a high VER caused notable rises in the quantity of several microorganisms. Under high biological selective pressure, GC-PDBR2 demonstrated a greater percentage of nitrogen removal via autotrophic denitrification and a greater number of nitrifying bacteria. The overgrowth of bacteria such as Actinobacteriota spp. Bacteroidota spp, Gammaproteobacteria, Desulfuromonas Mesotoga in the phylum, class, and genus, has positively impacted on granule formation and stability. Taken together, our study through the introduction of intermittent aeration GC-PDBR systems with added magnetized waste derived biochar, is an innovative approach for simultaneous aerobic sludge granulation and PW treatment, thereby providing valuable contributions in the journey toward achieving decarbonization, carbon neutrality and sustainable development goals (SDGs).

A comprehensive comparison of microbial communities between aerobic granular sludge and flocculent sludge for nutrient removal in full-scale wastewater treatment plants.

Understanding the microbial community structure of sludge is crucial for improving the design, operation and optimisation of full-scale wastewater treatment plants (WWTPs). This study aimed to have a comprehensive comparison of microbial communities between aerobic granular sludge and flocculent sludge from two full-scale sequential batch reactors-based WWTPs with nutrient removal for the first time. To better understand key functional bacteria such as polyphosphate accumulating bacteria (PAOs), competitive bacteria such as glycogen accumulating bacteria (GAOs) and nitrifying bacteria for both nitrogen and phosphorus removal, another two full-scale WWTPs with only carbon (C) removal and C and nitrogen (N) removal were compared too. It was found that the richness and diversity of the microbial population in sludge increased with pollutant removal from only C, C and N, to C,N, P removal. For C, N P removal, granule structure led to a more diverse and rich microbial community structure than flocculent structure. Although more abundant nitrifying bacteria were enriched in granular sludge than flocculent sludge, the abundance of total putative PAOs was equivalent. However, the most typical putative PAOs such as Tetrasphaera and Candidatus Accumulibacter seemed to be more correlated with biological phosphorus removal performance, which might be more proper to be used as an indication for P removal potential. The higher abundance of GAOs in flocculent sludge with better phosphorus removal performance might suggest that further investigation is needed to understand the functions of GAOs. In addition, the equivalent abundances of PAOs in the WWTPs with only C removal and with C, N, and P removal, respectively, indicate that many newly reported putative PAOs might not contribute to P removal. This study provides insight into the microbial communities and functional bacteria in aerobic granular sludge and flocculent sludge in full-scale SBRs, which can provide microbes-informed optimisation of reactor operation for better nutrient removal.

Mixotrophic aerobic denitrification facilitated by denitrifying bacterial-fungal communities assisted with iron in micro-polluted water: Performance, metabolic activity, functional genes abundance, and community co-occurrence.

Low-dosage nitrate pollutants can contribute to eutrophication in surface water bodies, such as lakes and reservoirs. This study employed assembled denitrifying bacterial-fungal communities as bio-denitrifiers, in combination with zero-valent iron (ZVI), to treat micro-polluted water. Immobilized bacterial-fungal mixed communities (IBFMC) reactors demonstrated their ability to reduce nitrate and organic carbon by over 43.2 % and 53.7 %, respectively. Compared to IBFMC reactors, IBFMC combined with ZVI (IBFMC@ZVI) reactors exhibited enhanced removal efficiencies for nitrate and organic carbon, reaching the highest of 31.55 % and 17.66 %, respectively. The presence of ZVI in the IBFMC@ZVI reactors stimulated various aspects of microbial activity, including the metabolic processes, electron transfer system activities, abundance of functional genes and enzymes, and diversity and richness of microbial communities. The contents of adenosine triphosphate and electron transfer system activities enhanced more than 5.6 and 1.43 folds in the IBFMC@ZVI reactors compared with IBFMC reactors. Furthermore, significant improvement of crucial genes and enzyme denitrification chains was observed in the IBFMC@ZVI reactors. Iron played a central role in enhancing microbial diversity and activity, and promoting the supply, and transfer of inorganic electron donors. This study presents an innovative approach for applying denitrifying bacterial-fungal communities combined with iron enhancing efficient denitrification in micro-polluted water.

Phosphorus removal from fermented dairy manure concurrent with polyhydroxybutyrate-co-valerate synthesis under aerobic conditions.

Wastewater phosphorus removal achieved biologically is associated with the process known as enhanced biological phosphorus removal (EBPR). In contrast with canonical EBPR operations that employ alternating anaerobic-aerobic conditions and achieve asynchronous carbon and phosphorus storage, research herein focused on phosphorus removal achieved under aerobic conditions synchronously with volatile fatty acid (VFA) storage as polyhydroxybutyrate-co-valerate (PHBV). 90.3 ± 3.4 % soluble phosphorus removal was achieved from dairy manure fermenter liquor; influent and effluent concentrations were 38.6 ± 9.5 and 3.7 ± 0.8 mgP/L, respectively. Concurrently, PHBV yield ranged from 0.17 to 0.64 mgCOD/mgCOD, yielding 147-535 mgCODPHBV/L. No evidence of EBPR mechanisms was observed, nor were canonical phosphorus accumulating organisms present; additionally, the polyphosphate kinase gene was not present in the microbial biomass. Phosphorus removal was primarily associated with biomass growth and secondarily with biomass complexation. Results demonstrate that concurrent PHBV synthesis and phosphorus recovery can be achieved microbially under aerobic dynamic feeding conditions when fed nutrient rich wastewater.

Large enrichments in fatty acid 2H/1H ratios distinguish respiration from aerobic fermentation in yeast Saccharomyces cerevisiae.

Shifts in the hydrogen stable isotopic composition (2H/1H ratio) of lipids relative to water (lipid/water 2H-fractionation) at natural abundances reflect different sources of the central cellular reductant, NADPH, in bacteria. Here, we demonstrate that lipid/water 2H-fractionation (2εfattyacid/water) can also constrain the relative importance of key NADPH pathways in eukaryotes. We used the metabolically flexible yeast Saccharomyces cerevisiae, a microbial model for respiratory and fermentative metabolism in industry and medicine, to investigate 2εfattyacid/water. In chemostats, fatty acids from glycerol-respiring cells were >550‰ 2H-enriched compared to those from cells aerobically fermenting sugars via overflow metabolism, a hallmark feature in cancer. Faster growth decreased 2H/1H ratios, particularly in glycerol-respiring cells by 200‰. Variations in the activities and kinetic isotope effects among NADP+-reducing enzymes indicate cytosolic NADPH supply as the primary control on 2εfattyacid/water. Contributions of cytosolic isocitrate dehydrogenase (cIDH) to NAPDH production drive large 2H-enrichments with substrate metabolism (cIDH is absent during fermentation but contributes up to 20 percent NAPDH during respiration) and slower growth on glycerol (11 percent more NADPH from cIDH). Shifts in NADPH demand associated with cellular lipid abundance explain smaller 2εfattyacid/water variations (<30‰) with growth rate during fermentation. Consistent with these results, tests of murine liver cells had 2H-enriched lipids from slower-growing, healthy respiring cells relative to fast-growing, fermenting hepatocellular carcinoma. Our findings point to the broad potential of lipid 2H/1H ratios as a passive natural tracker of eukaryotic metabolism with applications to distinguish health and disease, complementing studies that rely on complex isotope-tracer addition methods.

Microbiome structure and function in parallel full-scale aerobic granular sludge and activated sludge processes.

Aerobic granular sludge (AGS) and conventional activated sludge (CAS) are two different biological wastewater treatment processes. AGS consists of self-immobilised microorganisms that are transformed into spherical biofilms, whereas CAS has floccular sludge of lower density. In this study, we investigated the treatment performance and microbiome dynamics of two full-scale AGS reactors and a parallel CAS system at a municipal WWTP in Sweden. Both systems produced low effluent concentrations, with some fluctuations in phosphate and nitrate mainly due to variations in organic substrate availability. The microbial diversity was slightly higher in the AGS, with different dynamics in the microbiome over time. Seasonal periodicity was observed in both sludge types, with a larger shift in the CAS microbiome compared to the AGS. Groups important for reactor function, such as ammonia-oxidising bacteria (AOB), nitrite-oxidising bacteria (NOB), polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs), followed similar trends in both systems, with higher relative abundances of PAOs and GAOs in the AGS. However, microbial composition and dynamics differed between the two systems at the genus level. For instance, among PAOs, Tetrasphaera was more prevalent in the AGS, while Dechloromonas was more common in the CAS. Among NOB, Ca. Nitrotoga had a higher relative abundance in the AGS, while Nitrospira was the main nitrifier in the CAS. Furthermore, network analysis revealed the clustering of the various genera within the guilds to modules with different temporal patterns, suggesting functional redundancy in both AGS and CAS. KEY POINTS: • Microbial community succession in parallel full-scale aerobic granular sludge (AGS) and conventional activated sludge (CAS) processes. • Higher periodicity in microbial community structure in CAS compared to in AGS. • Similar functional groups between AGS and CAS but different composition and dynamics at genus level.

Distinguished denitrifying phosphorus removal in the high-rate anoxic/microaerobic system for sewage treatment.

This study re-evaluated the role of anoxic and anaerobic zones during the enhanced biological phosphorus (P) removal process by investigating the potential effect of introducing an anoxic zone into a high-rate microaerobic activated sludge (MAS) system (1.60-1.70 kg chemical oxygen demand (COD) m-3 d-1), i.e., a high-rate anoxic/microaerobic (A/M) system for sewage treatment. In the absence of a pre-anaerobic zone, introducing an anoxic zone considerably reduced effluent NOx--N concentrations (7.2 vs. 1.5 mg L-1) and remarkably enhanced total nitrogen (75% vs. 89%) and total P (18% vs. 60%) removal and sludge P content (1.48% vs. 1.77% (dry weight)) due to further anoxic denitrifying P removal in the anoxic zone (besides simultaneous nitrification and denitrification in the microaerobic zone). High-throughput pyrosequencing demonstrated the niche differentiation of different polyphosphate accumulating organism (PAO) clades (including denitrifying PAO [DPAO] and non-DPAO) in both systems. Introducing an anoxic zone considerably reduced the total PAO abundance in sludge samples by 42% and modified the PAO community structure, including 17-19 detected genera. The change was solely confined to non-DPAOs, as no obvious change in total abundance or community structure of DPAOs including 7 detected genera was observed. Additionally, introducing an anoxic zone increased the abundance of ammonia-oxidizing bacteria by 39%. The high-rate A/M process provided less aeration, higher treatment capacity, a lower COD requirement, and a 75% decrease in the production of waste sludge than the conventional biological nutrient removal process.

Nitrosative stress under microaerobic conditions triggers inositol metabolism in Pseudomonas extremaustralis.

Bacteria are exposed to reactive oxygen and nitrogen species that provoke oxidative and nitrosative stress which can lead to macromolecule damage. Coping with stress conditions involves the adjustment of cellular responses, which helps to address metabolic challenges. In this study, we performed a global transcriptomic analysis of the response of Pseudomonas extremaustralis to nitrosative stress, induced by S-nitrosoglutathione (GSNO), a nitric oxide donor, under microaerobic conditions. The analysis revealed the upregulation of genes associated with inositol catabolism; a compound widely distributed in nature whose metabolism in bacteria has aroused interest. The RNAseq data also showed heightened expression of genes involved in essential cellular processes like transcription, translation, amino acid transport and biosynthesis, as well as in stress resistance including iron-dependent superoxide dismutase, alkyl hydroperoxide reductase, thioredoxin, and glutathione S-transferase in response to GSNO. Furthermore, GSNO exposure differentially affected the expression of genes encoding nitrosylation target proteins, encompassing metalloproteins and proteins with free cysteine and /or tyrosine residues. Notably, genes associated with iron metabolism, such as pyoverdine synthesis and iron transporter genes, showed activation in the presence of GSNO, likely as response to enhanced protein turnover. Physiological assays demonstrated that P. extremaustralis can utilize inositol proficiently under both aerobic and microaerobic conditions, achieving growth comparable to glucose-supplemented cultures. Moreover, supplementing the culture medium with inositol enhances the stress tolerance of P. extremaustralis against combined oxidative-nitrosative stress. Concordant with the heightened expression of pyoverdine genes under nitrosative stress, elevated pyoverdine production was observed when myo-inositol was added to the culture medium. These findings highlight the influence of nitrosative stress on proteins susceptible to nitrosylation and iron metabolism. Furthermore, the activation of myo-inositol catabolism emerges as a protective mechanism against nitrosative stress, shedding light on this pathway in bacterial systems, and holding significance in the adaptation to unfavorable conditions.