Carbon Source Research Articles

Valorization of whey for green synthesis of carbon dots and their potential applications

Purpose This paper aims to develop carbon dots using whey as a valuable resource and to create a sustainable and biocompatible nanomaterial with potential applications in a variety of fields owing to its unique optical properties and antimicrobial capabilities, which are frequently used as sensing agents for detecting specific molecules in food, environmental and biomedical applications. Versatility of carbon dots (CDs) allows the utilization of these dots for a wide range of applications in areas such as food safety, antibacterial properties, production of composite polymers for food packaging, treatment of different diseases and detection of food-borne pathogens. Owing to their high brightness, low toxicity and excellent biocompatibility, CDs have attracted significant interest in food safety. This is also a cutting-edge technology that bids new ideas for treating various diseases. Design/methodology/approach Literature review related to using whey as the carbon source for synthesis of CDs was collected and studied from different sources like Google Scholar, Research Gate, online journals available at library of Banaras Hindu University, Web of Science and Scopus. A database of more than 100 scientific sources from different sources was made as per the headings and sub headings of the paper. Findings Whey generated as a by-product from the cheese industry contained a good amount of carbon and nitrogen that can be used for the fabrication of CDs. CDs produced using whey exhibited great photostability, high sensitivity and outstanding biocompatibility and also showed that Fe3+ ions could be quickly, sensitively and extremely selectively detected in an aqueous solution of CDs, with a revealing limit of 0.409 µM in the linear range of 0–180 µM. CDs are a promising area of study to a key component of next-generation multifunctional nanomaterials, promoting creativity, sustainability and useful solutions across a variety of industries, including health care and energy. The susceptibility of S. typhimurium (Gram-negative) was found to be higher than that of L. monocytogenes (Gram-positive) bacteria with MIC and MBC of 500 and 1000 µL/mL, respectively. Originality/value Whey-derived CDs are an environmentally beneficial substitute for conventional additives and their biocompatibility guarantees that they adhere to food safety regulations. In light of the future, the green volarization of dairy waste for the synthesis of CDs is consistent with the increasing worldwide focus on environmental responsibility and sustainability.

Machine Learning-Guided Selection of Cyclodextrins for Enhanced Biosynthesis and Capture of Volatile Terpenes.

Nootkatone and limonene are valuable volatile organic compounds (VOCs), but their biosynthetic production is hindered by volatility. This study employed machine learning to guide cyclodextrin (CD) selection for encapsulating these VOCs, with a focus on nootkatone capture during fermentation to prevent losses and potentially replace dodecane as an organic solvent extractant. A LightGBM model accurately predicted complexation free energies (ΔG) between CDs and guest molecules (R2 = 0.80 on a 10% test set, with a mean absolute error of 1.31 kJ/mol and a root-mean-squared error of 1.90 kJ/mol). Experimental ranking of 7 CD types validated the model's ΔG predictions and encapsulation performance rankings. Nootkatone showed high encapsulation efficiencies ranging from 21.29% (α-CD) to 88.41% (Me-β-CD), capturing 22.61-116.71 mg/g CD. Notably, Hp-γ-CD, which is the least studied or used CD in research, performed well with nootkatone (63.64%, 84.01 mg/g CD) despite model discrepancies. For limonene, encapsulation efficiencies spanned from 0.62% (Hp-γ-CD) to 55.45% (β-CD), with 0.61-84.28 mg/g CD encapsulated. Constructed engineered Saccharomyces cerevisiae strains produced nootkatone (up to 97.30 mg/L captured by 10 mM Me-β-CD) from de novo fermentation using glucose as a carbon source. This approach demonstrated the potential of CDs to replace dodecane as an organic solvent for terpene extraction during fermentation. The study highlights machine learning's potential for guiding CD selection to enhance volatile terpene biosynthesis, capture, and utilization during fermentation, offering a more environmentally friendly alternative to traditional organic solvent-based extraction methods.

Identification and management of a novel Danshen leaf anthracnose caused by Colletotrichum karstii in Salvia miltiorrhiza Bunge in China

Danshen (Salvia miltiorrhiza Bunge), a member of the genus Salvia within the Lamiaceae family, holds significant economic and medicinal value. Regrettably, the emergence of a novel leaf anthracnose in 2020 has significantly impacted its cultivation, leading to decreased yield and compromised quality. This newly identified pathogen was meticulously isolated from affected leaves, employing meticulous single conidia isolation techniques. Subsequent confirmation of pathogenicity was achieved through strict adherence of Koch’s postulates. To ensure precise identification, morphological characteristics were supplemented with tandem sequence analysis targeting the rDNA internal transcribed spacer (ITS), β-tubulin (TUB), and histone (His3) regions. Combining molecular biology techniques with morphological observation and Koch’s postulates, the pathogen was conclusively identified as Colletotrichum karstii. Further investigations focused on understanding the environmental factors influencing the mycelial growth and sporulation of the pathogen. The optimum temperature for the growth of C.karstii is 25°C, the suitable light conditions are 12h light/12h dark or 24h dark, and the suitable pH is 5 to 9. Utilizing BIOLOG phenotypic analysis technique, the metabolic utilization of carbon and nitrogen sources by the pathogen was assessed across different temperatures (20°C, 25°C, and 30°C). Results indicated the highest utilization rates at 25°C, particularly for arbutin and L-tryptophan. Lastly, the efficacy of 15 chemical fungicides and six botanical fungiticide against C. karstii was evaluated in vitro, revealing fluazinam as the most potent inhibitor against mycelial growth with EC50 of 0.0725 mg/mL for mycelium and 0.0378 mg/mL for spore germination, respectively. The 1 % osthole emulsion in water was found to have the strongest inhibitory effect on the growth of mycelium, with an EC50 value of 4.8984 µg/mL. Spore germination was most strongly inhibited by the 80 % ethylicin EC, which had an EC50 value of 0.5541 µg/mL. This study represents the first documentation of C. karstii as a causative agent of anthrax in Danshen, underscoring the significance of these findings for agricultural management and disease control strategies.

Stabilization effect and mechanism of heavy metals by microbial consortium of phosphate-solubilizing bacteria and urease-producing bacteria

IntroductionStabilization of heavy metals through phosphate-solubilizing bacteria (PSB) induced phosphate precipitation and urease-producing bacteria (UPB) induced carbonate precipitation are promising bioremediation methods. However, little attention has been conducted on the combined action of the above two bioremediations to stabilize heavy metals.MethodsPSB and UPB were isolated from the environment and their growth characteristics and antagonistic properties were studied. A simulated solution of acidic leachate was prepared based on heavy metal contaminated soil. Microbial consortium of PSB and UPB were constructed for the stabilization of heavy metals by optimizing carbon and nitrogen sources. The microstructural and compositional changes during the biostabilization process were more deeply analyzed using XRD, FT-IR and SEM-EDS.Results and discussionThe precipitation of heavy metals could be promoted effectively when soluble starch (10.2 g/L) was used as carbon source and urea (7.8 g/L) as nitrogen source. The stabilization rates for Cu, Zn, Cd, and Pb were 98.35, 99.78, 99.09, and 92.26%, respectively. The stabilization rates of the combined action of PSB and UPB were significantly higher than that of the two microorganisms alone. An in-depth analysis showed that the composite metals were precipitated as dense precipitate encased in carbonate and phosphate, and additionally could be stabilized in the form of biosorption. Finally, the stabilization mechanism of heavy metals based on biomineralization and biosorption is proposed. These findings provide new theoretical support for sustainable remediation and management strategies for composite heavy metal polluted areas.

Enrichment of electrotrophic microorganisms from contrasting shallow-sea hydrothermal environments in bioelectrochemical reactors

IntroductionHydrothermal vents are inhabited by electrotrophic microorganisms, which are capable of oxidizing extracellular compounds, such as metals, to power their metabolisms. However, their diversity is poorly known, especially in shallow-sea hydrothermal vents where it has not been extensively studied. Bioelectrochemical reactors can be used to investigate such electrotrophic diversity by providing an electrode as an electron donor.MethodsHere, a total of 60 different reactors were set up and inoculated with either a microbial community coming from the shallow, acidic (ca. pH 5.5) and hot (ca. 120°C) hydrothermal system of Panarea, Aeolian islands, Italy, or the shallow, alkaline (pH 11) and mild (40°C) hydrothermal system of Prony Bay, New Caledonia.ResultsWith the alkaline sample, no electrical current increase was seen in any of the 15 reactors operated for 6 days under Prony hydrothermal conditions (pH 10, 30–75°C). By contrast, a 6-fold increase on average was observed in reactors operated under the Panarea hydrothermal fluid conditions (pH 4.5–7, 75°C). A Multi-Factor Analysis revealed that the overall bioelectrochemical performances of these reactors set them apart from all the other Panarea and Prony conditions, not only due to their higher current production but also archaeal abundances (measured through qPCR). Most reactors produced organic acids (up to 2.9 mM in 6 days). Still, coulombic efficiencies indicated that this might have been due to the (electro) fermentation of traces of yeast extract in the medium rather than CO2 fixation. Finally, microbial communities were described by 16S metabarcoding and ordination methods, and potential electrotrophic taxa were identified. In Panarea reactors, higher growth was correlated with a few bacterial genera, mainly Bacillus and Pseudoalteromonas, including, for the former, at higher temperatures (55°C and 75°C). In reactors reproducing the Prony Bay hydrothermal conditions, known facultative methylotrophs, such as Sphingomonas and Methylobacterium, were dominant and appeared to consume formate (provided as carbon source) but no electrons from the cathode.ConclusionThese results provide new insights into the distribution and diversity of electrotrophs in shallow-sea hydrothermal vents and allow the identification of potential novel biocatalysts for Microbial Electrosynthesis whereby electricity and carbon dioxide are converted into value-added products.

Synthesis and Characterization of Lignocellulose-Based Carbon Quantum Dots (CQDs) and Their Antimicrobial and Antioxidant Functionalities

Carbon quantum dots (CQDs) have recently drawn enormous attention due to not only their unique chemical, biological, and optical properties but also because a variety of renewable biomasses are readily utilized as carbon sources in their synthesis. This study investigated the synthesis, characterization, and functional evaluation of CQDs from unbleached mechanical pulp as a natural lignocellulosic resource. The CQDs were synthesized using a one-step hydrothermal synthesis with varying temperature, time, and pulp consistency. The resulting CQDs exhibit a spherical shape with a size distribution of 9.73 ± 0.82 nm and lattice parameters of 0.21 and 0.34 nm, indicating a graphite core. The photoluminescence spectra showed evident fluorescence characteristics, with an emission peak at 435 nm at an excitation wavelength of 370 nm. The as-prepared CQDs were also chemically composed of C=C and C=O bonds linked to the hydroxyl and carboxyl functional groups, which are typically found in lignocellulose-based CQDs. The CQDs demonstrated antibacterial activity exceeding 99.9% against E. coli at the lowest concentration of 0.75 mg/mL. Demonstrating its antioxidation property, the DPPH radical scavenging activity surpassed 90% with more than 40 µg/mL of the CQD solution.

Banana peel fermentation broth as a viable alternative carbon source for biological sulfate reduction in acid mine drainage

AbstractBACKGROUNDAcid mine drainage (AMD) is a major environmental threat in mining areas due to its strong acidity, high concentrations of sulfate, and heavy metals. Utilizing sulfate‐reducing bacteria (SRB) to reduce SO42− and remove heavy metals is a promising and economical AMD treatment. However, AMD lacks sufficient electron donors for sulfate reduction. Banana peel fermentation broth, containing various small‐molecule organic acids, is an effective alternative carbon source for SRB, promoting the use of agricultural waste in environmental remediation. This study aims to investigate the impact of adding banana peel fermentation broth to the bioreactor on pollutant removal performance and analyze its effect on the microbial community structure.RESULTSThe bioreactor utilising banana peel fermentation broth as an electron donor, demonstrated the effective removal of various pollutants, including sulfate (55.7%), Cu2+ (90.74%), Mn2+ (70.77%), Fe2+ (81.28%) and Cd2+ (100.00%), with an average reduction of 74.20% in chemical oxygen demand (COD). Sulfate reduction resulted in an increase in pH from 5.5 to 7.9. Microbial community structure analysis revealed that the primary genera involved in sulfate reduction were Desulfurispora and Desulfovibrio, while Delftia contributes to the immobilization of heavy metals. Additionally, the key genera responsible for fermentation to produce small molecule acids were Leptolinea and Sedimentibacter. In symbiosis with SRB, they play a crucial role in the removal efficiency of metals and sulfate.CONCLUSIONThe overall sulfate and heavy metals removal efficiency was found to be satisfactory after 30 days of continuous reactor operation. There was a notable increase in microbial abundance and community diversity within the reactor. Therefore, banana peel fermentation broth is a promising alternative organic carbon source in acid mine drainage(AMD) treatment. © 2025 Society of Chemical Industry (SCI).

Ultrasensitive and Selective Nitrogen-Doped Fluorescent Carbon Dots Probe for Quantification Analysis of Trace Cu2+ in the Aqueous Environment.

As a typical non-ferrous metal, copper is heavily used in the manufacturing and chemical industries. Copper pollution has been demonstrated to have a significant detrimental impact on the natural environment, as well as causing irreparable damage to the human body, such as elevated Cu2+ levels have been identified as a factor in the pathogenesis of AD (Alzheimer's disease). In this study, novel nanoscale carbon dots Blue-CDs (B-CDs) were obtained by the solvothermal approach in formamide solution utilizing citric acid as the carbon source and ethylenediamine as the nitrogen dopant. The particle size of B-CD was assessed to be 2.17nm, with a quantum yield (QY) of 10.28%. The B-CDs were found to be extinguished upon exposure to Cu2+, which exhibited a good fluorescence detection linear relationship within the concentration range of 0.25-10.0 µM Cu2+, showing a limit of detection (LOD) is 0.18 µM. B-CDs have been effectively used for the measurement of Cu2+ in actual aqueous systems. It is due to the chemical reactions that take place among the B-CDs and the Cu²⁺ that make the sensor highly sensitivities and highly selectivities. The results of the experiment demonstrate that the fluorescence quenching process is a consequence of Cu2+ binding to the amino groups of carbon dots, forming complexes via a non-radiative photoinduced electron transfer process. In conclusion, the described simple sensing techniques could be effectively utilized as monitoring tools for Cu2+ in environmental waters.

Restoring Soil Fertility through Organic Amendments: Impacts on Agriculture and Human Health

The application of organic amendments in agriculture has become a vital approach to addressing key challenges in Indian agriculture, such as fragmented landholdings, inadequate irrigation, and declining soil fertility. These amendments, which are added to soil to enhance its physical, chemical, and biological properties, play a significant role in promoting sustainable farming. Organic amendments like compost, manure, and green manure serve as excellent sources of organic carbon and essential nutrients. They improve soil structure, enhance drainage, and facilitate nutrient cycling while mitigating soil alkalinity and fostering microbial activity, thereby supporting overall soil health. Research highlights the effectiveness of organic amendments in improving soil quality. Organic amendments also offer notable benefits for human health by reducing dependence on synthetic fertilizers and minimizing toxic residues. They decrease the risks of heavy metal contamination and pesticide exposure. Adopting organic amendments supports the broader goals of sustainable agriculture by enhancing biodiversity, improving soil fertility, and reducing environmental and health risks. Nevertheless, further research is needed to refine these practices, optimize their application, and thoroughly evaluate their effects on human well-being and agricultural productivity. Organic amendments offer a promising solution to meet the growing food demands of an expanding population while maintaining ecological balance and ensuring food security.

Role of metabolism, resistance, and/or antagonism as drivers of endomicrobiomes assemblage in Origanum heracleoticum L

The understanding of selective forces driving the compartmentalization of microbiota in plants remains limited. In this study, we performed a phenotypic characterization of bacterial endophytes isolated from the medicinal plant Origanum heracleoticum, together with the determination of the antibiotic resistance profiles and the antagonistic interactions of communities within and across different plant organs. Results revealed organ-related differences in the metabolic capabilities of bacteria, with those associated with stems displaying the highest metabolic activity for carbon sources. Contrarily, the patterns of antibiotic resistance appeared closely aligned with the taxonomical classification of the endophytes. The presence of antagonistic interactions, likely spurred by resource limitations, favor bacteria exhibiting greater metabolic plasticity. In conclusion, this research advances our comprehension of the intricate dynamics between plants and their associated microbiota, indicating that its composition is mainly influenced by forces contributing to the selection of distinct functions and phenotypic traits.

Comparative anti-methanogenic ability of green algae (C. reinhardtii) with/without nanoparticles: in vitro gas and methane production

IntroductionThe purpose of this study was to investigate how in vitro gas production (GP) and ruminal fermentation characteristics were affected by increasing concentrations of green algae plant (C. reinhardtii) extracts in combination with nanoparticles MgO and MgS.MethodsA solution containing 0.1 M MgCl2 was prepared in 300 mL for the green production of MgCl nanoparticles. The mixture was refluxed for two hours at 85°C using a reflux condenser after 10 mL of pomegranate plant extract was added. The green algal plant (C. reinhardtii), which has many non-toxic antioxidants, was used as a carbon source to produce carbon quantum dots (CQD). Chemical analysis was conducted in accordance with AOAC (2005) recommendations. Rumen fluid from recently slaughtered calves is used to produce in vitro gas immediately following slaughter. Analysis of variance (ANOVA) was performed on the obtained data from the in vitro study in a completely randomized design using the mixed model of SAS (version 9.4; Inc., Cary NC, USA).Results and DiscussionThe variance analysis results and the average values of the chemical compositions were significantly influenced by the extracts (all p < 0.0001). In this line, the values of net gas, pH, OMD, ME, NEl, and ME were found to be the highest for Algae + 50 MgO and the lowest for Algae + 50 MgS, respectively (all p < 0.0001). These promising results imply that extracts from C. Reinhardtii may be able to mitigate the adverse consequences of rumen fermentation. To precisely ascertain the impact particular Rhodophyta on greenhouse gas emissions, additional investigation is needed.

Dynamic land-plant carbon sources in marine sediments inferred from ancient DNA

Terrigenous organic matter in marine sediments is considered a significant long-term carbon sink, yet our knowledge regarding its source taxa is severely limited. Here, we leverage land-plant ancient DNA from six globally distributed marine sediment cores covering the Last Glacial–Holocene transition as a proxy for the share, burial rate, preservation, and composition of terrigenous organic matter. We show that the spatial and temporal plant composition as revealed by sedimentary ancient DNA records reflects mainly the vegetation dynamics of nearby continents as revealed by comparison with pollen from land archives. However, we also find indications of a global north-to-south translocation of sedimentary ancient DNA. We also find that plant sedimentary ancient DNA has a higher burial rate in samples from the Late Glacial, which is characterized by high runoff and mineral load. This study provides an approach to understanding the global linkages between the terrestrial and marine carbon cycle, highlighting the need for further research to quantify the processes of DNA preservation and dispersal in marine sediments.

Application of Bacillus cereus for synthesis of polyhydroxyalkanoates from industrial corn starch residue.

Starch hydrolysate from corn is typically employed as a carbon source for citric acid production by Aspergillus niger. Enzymatic or acid hydrolysis of corn starch generates a corn starch residue (CSR), which represents a potential bio-fermentation carbon source. In addition, polyhydroxyalkanoates (PHAs) can be used as an alternative to traditional petrochemical plastics. In this study, the potential applications of CSR in microbial PHA production were investigated. Two Bacillus cereus strains, MG1 and MQ1, were isolated based on their ability to grow with CSR as the sole carbon source and their capacity for PHA accumulation. After introducing key genes involved in the PHA synthesis pathway and optimizing fermentation conditions, the PHA content of MG2 reached 61.61 % of the cell dry weight (CDW), representing the highest PHA content (CDW%) in B. cereus. To the best of our knowledge, this is the first report of PHA synthesis from CSR in B. cereus and provides a novel approach for the rational utilization of CSR.

Mechanism of chlorobenzene removal in biotrickling filter enhanced by non-thermal plasma: Insights from biodiversity and functional gene perspectives

Biotrickling filter (BTF) technology is inefficient in the treatment of Cl-containing volatile organic compounds (VOCs) such as chlorobenzene (CB). This study adopted non-thermal plasma (NTP) as a pretreatment and conducted in-depth analyses, especially in microorganisms, to investigate strengthening mechanism of a NTP to a BTF in the process. The introduction of NTP enhance efficiency of CB removal from 65 % to 90 %, and CO2 generation from 60 % to 85 %. It is found that the protein content of the extracellular polymeric substances increases from 212 × 10-3 mg·g−1 filler to 299 × 10-3 mg·g−1 filler, thus CB capturing and utilization enhanced. Metagenomic analysis showed that bacteria with CB-degrading properties were enriched in BTF, and CB was involved in cellular metabolism as a carbon source. The presence of active substances from NTP is found to stimulate the ability of BTF treatment. The findings of this study will provide theoretical support for the application of NTP–BTF technology.

Assessment of CO2 fluxes in the hinterland of the Gurbantunggut Desert and its response to climate change.

Desert ecosystems, as an important part of terrestrial ecosystems, are considered potential hidden carbon sinks in the global carbon cycle. The Gurbantunggut Desert, as China's largest fixed/semi-fixed desert, has received little research on its role in the global carbon cycle and future trends. This study utilizes continuous observational data from the Gurbantunggut Desert from 2018 to 2022 and integrates CMIP6 global climate model scenario data to study the evolution of carbon balance in the desert ecosystem, carbon source/sink functions, and future trends. The result showed that: 1) The CO2 flux in the Gurbantunggut Desert shows Carbon sink during the day and carbon source at night, with an annual cumulative carbon sink duration of over 240 days.2)From 2018 to 2020, the desert ecosystem of the Gurbantunggut Desert functioned as a net CO2 sink.3) Desert ecosystems were subjected to concurrent influences from multiple environmental factors across varying time scales, with photosynthetically active radiation, air temperature, and soil temperature identified as the most influential factors affecting CO2 flux in the Gurbantunggut Desert. 4) The climate of the Gurbantunggut Desert is projected to exhibit a trend of warming and increased humidity in the future. Against the backdrop of future warming and humidification, the Gurbantunggut desert ecosystem is anticipated to exhibit a pronounced carbon sink characteristic.

Elemental sulfur regeneration with different carbon sources in the simultaneous removal process of sulfide and nitrate under microaerobic conditions

Elemental sulfur regeneration with different carbon sources in the simultaneous removal process of sulfide and nitrate under microaerobic conditions

Production of polyhydroxyalkanoate from new isolated bacteria of Acidovorax diaphorobacter ZCH-15 using orange peel and its underlying metabolic mechanisms

Polyhydroxyalkanoate (PHA) is considered a sustainable alternative to traditional petroleum-based plastics due to its biodegradability and biocompatibility. In this study, Acidovorax diaphorobacter ZCH-15, an efficient PHA-producing strain, was isolated from activated sludge. Using food waste-derived orange peel as a substrate, the strain initially achieved a PHA concentration of 0.39 g/L. Under optimal fermentation conditions (30℃, pH 8, 2 % inoculum concentration, and 30 g/L carbon source), the PHA concentration increased by 138 % to reach a maximum of 0.93 g/L. Proton nuclear magnetic resonance spectroscopy and gas chromatography analyses identified the PHA composition as poly(3-hydroxybutyrate-co-3-hydroxyvalerate), which exhibited high crystallinity and structural stability. Metabolomic analysis indicated that the tricarboxylic acid cycle and pentose phosphate pathway were involved in producing succinyl-CoA, a precursor required for PHA synthesis. This study demonstrates the potential for cost-effective industrial PHA production while enabling the high-value utilization of food waste.

Engineering xylose utilization in Cupriavidus necator for enhanced poly(3-hydroxybutyrate) production from mixed sugars.

Lignocellulosic biomass is a promising renewable feedstock for biodegradable plastics like polyhydroxyalkanoates (PHAs). Cupriavidus necator, a versatile microbial host that synthesizes poly(3-hydroxybutyrate) (PHB), the most abundant type of PHA, has been studied to expand its carbon source utilization. Since C. necator NCIMB11599 cannot metabolize xylose, we developed xylose-utilizing strains by introducing synthetic xylose metabolic pathways, including the xylose isomerase, Weimberg, and Dahms pathways. Through rational and evolutionary engineering, the RXI22 and RXW62 strains were able to efficiently utilize xylose as the sole carbon source, producing 64.2 wt% (wt%) and 61.4 wt% PHB, respectively. Among the engineered strains, the xylose isomerase-based RXI22 strain demonstrated the most efficient co-fermentation performance, with a PHB content of 75.7 wt% and a yield of 0.32 (g PHB/g glucose and xylose) from mixed sugars. The strains developed in this study represent an enhanced PHA producer, offering a sustainable route for converting lignocellulosic biomass into bioplastics.

Insights into the impact of 6PPD-Q and 6PPD on nitrogen metabolism and microbial community in the anammox system.

N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) is an antioxidant commonly used in tire manufacturing, and its release into the environment has significantly increased due to rapid urbanization. When subjected to ozonation, 6PPD converts into the harmful pollutant 6PPD quinone (6PPDQ). These substances enter wastewater treatment plants (WWTPs) via stormwater runoff and pipelines, posing significant risks to the functional microorganisms. Anammox, a strictly controlled and sensitive microbial nitrogen removal process, is especially susceptible to the effects of the pollutants. This study investigates the comprehensive impact of 6PPD-Q and 6PPD on anammox communities based on characterization analysis and metagenomics. At environmental concentrations, 6PPD-Q at 200 ng/L-1000ng/L led to the disintegration of anammox granules. Extended exposure to both 6PPD-Q and 6PPD significantly reduces the population of anammox bacteria (AnAOB). By utilizing organic matter from dead cells and incoming carbonate as a carbon source, the system evolved into a nitrogen metabolism network primarily focused on denitrification and dissimilatory nitrate reduction to ammonium (DNRA). This transformation was accompanied by a reshuffling of the microbial community and associated genes, resulting in an accumulation of NH4+-N. These findings underscore the toxicity of 6PPD-Q and 6PPD to anammox and stress the importance of incorporating 6PPD into regulatory and preventive strategies.

Long-chain fatty acids as sole carbon source in polyhydroxyalkanoates production by Cupriavidus necator H16.

Polyhydroxyalkanoates (PHA) are promising eco-friendly alternatives to petrochemical plastics. This study investigated the impact of the main fatty acids present in waste and fresh oils -palmitic, stearic, oleic, and linoleic acid-on PHA production using Cupriavidus necator H16, focusing on production yield, polymer composition, thermal properties, and microbial viability. Experiments were conducted with low (5g/L) and high (15g/L) carbon content for 168h. Oleic acid was the most effective carbon source, yielding higher PHA production rates, especially noticeable at higher concentrations. The monomer composition and thermal properties of PHAs varied with the type and concentration of fatty acid used. Stearic acid produced PHAs with more 3-hydroxyvalerate and medium-chain length monomers. Microbial viability was consistent across all conditions, except for linoleic acid, which had a detrimental effect. These findings provide key insights into optimizing fatty acid selection to enhance PHA production and tailor polymer properties for industrial applications.