Strategies for efficient management of microplastics to achieve life cycle assessment and circular economy

The anticipated increase in the influx of plastic waste into aquatic environments has propelled the identification and elimination of plastic waste into the global agenda. The plastics sector generates a significant volume of materials, which, due to their extended durability, accumulate rapidly in natural ecosystems. Consequently, this indiscriminate utilization, along with the deposition of plastic waste (PW) in landfills and inadequate recycling practices, leads to diverse economic, social, and environmental consequences. Microplastics (MPs) are a type of PW that has been fragmented into particles measuring less than 5 mm. These particles have been found in several environments, including the air, soil, freshwater, and ocean ecosystems, where they accumulate in large quantities. In order to gain insight into the ecological risks and resource implications associated with a plastic product, it is strongly advised to conduct life cycle and sustainability analyses. Therefore, this paper examines various strategies aimed at achieving effective management of MP waste in order to develop a conceptual framework for MPs in circular economy and life cycle assessment (LCA). The findings of this study provides a new avenue for future research and contribution to manage MP waste as well as reduce their environmentally hazardous impact.

Decolorization of reactive azo dye using novel halotolerant yeast consortium HYC and proposed degradation pathway

The presence of high salinity levels in textile wastewater poses a significant obstacle to the process of decolorizing azo dyes. The present study involved the construction of a yeast consortium HYC, which is halotolerant and was recently isolated from wood-feeding termites. The consortium HYC was mainly comprised of Sterigmatomyces halophilus SSA-1575 and Meyerozyma guilliermondii SSA-1547. The developed consortium demonstrated a decolourization efficiency of 96.1% when exposed to a concentration of 50 mg/l of Reactive Black 5 (RB5). The HYC consortium significantly decolorized RB5 up to concentrations of 400 mg/l and in the presence of NaCl up to 50 g/l. The effects of physicochemical factors and the degradation pathway were systematically investigated. The optimal pH, salinity, temperature, and initial dye concentration were 7.0, 3%, 35 °C and 50 mg/l, respectively. The co-carbon source was found to be essential, and the addition of glucose resulted in a 93% decolorization of 50 mg/l RB5. The enzymatic activity of various oxido-reductases was assessed, revealing that NADH-DCIP reductase and azo reductase exhibited greater activity in comparison to other enzymes. UV-Visible (UV-vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography-mass spectrometry (GC-MS) were utilized to identify the metabolites generated during the degradation of RB5. Subsequently, a metabolic pathway was proposed. The confirmation of degradation was established through alterations in the functional groups and modifications in molecular weight. The findings indicate that this halotolerant yeast consortium exhibits promising potential of degrading dye compounds. The results of this study offer significant theoretical basis and crucial perspectives for the implementation of halotolerant yeast consortia in the bioremediation of textile and hypersaline wastewater. This approach is particularly noteworthy as it does not produce aromatic amines.

Low-density lipoprotein cholesterol, statin therapy, and cerebral microbleeds: The CIRCLE study

BACKGROUND

Current evidence suggests a potential association between cerebral microbleeds (CMBs), low-density lipoprotein cholesterol (LDL-C) levels, and statin use, but the exact relationship remains unclear. This study aims to prospectively examine these relationships in a stroke-free population.

METHODS

From January 2010 to January 2020, we enrolled stroke-free individuals with at least one cerebral small vessel disease imaging marker from the CIRCLE study (ClinicalTrials.gov ID: NCT03542734). Participants underwent baseline and 1-year follow-up susceptibility-weighted imaging (SWI), and baseline LDL-C testing. New CMBs were categorized as strictly lobar and deep CMBs based on location.

RESULTS

A total of 209 individuals were included. Baseline serum LDL-C levels were divided into quartiles: Q1 (≤1.76 mmol/L), Q2 (1.77-2.36 mmol/L), Q3 (2.37-2.93 mmol/L), and Q4 (>2.93 mmol/L). The incidence of new deep CMBs was 30.0%, 11.1%, 10.9%, 8.2% in Q1, Q2, Q3, Q4, respectively. Multivariate logistic model revealed that only LDL-C in Q1 was associated with increased incidence of new deep CMBs (OR = 4.256; 95% CI: 1.156-15.666; p = 0.029). In a subset of 169 participants without prior statin use, the use of atorvastatin was associated with reduced occurrence of new deep CMBs (OR = 0.181; 95% CI: 0.035-0.928; p = 0.040), while it was not found with rosuvastatin (OR = 0.808; 95% CI: 0.174-3.741; p = 0.785).

CONCLUSIONS

While lower LDL-C levels were associated with higher CMB development, statin therapy did not increase the risk of new CMBs. Atorvastatin even demonstrated a protective effect.

Characterization and bioactivities of exopolysaccharide produced from Azotobacter salinestris EPS-AZ-6

This study involved the extraction of an exopolysaccharide (EPS) from Azotobacter salinestris AZ-6, which was isolated from soil cultivated with leguminous plants. In a medium devoid of nitrogen, the AZ-6 strain displayed a maximum EPS yield of 1.1 g/l and the highest relative viscosity value of 3.4. The homogeneity of the polymer was demonstrated by the average molecular weight of 1.61 × 106 Da and a retention time of 17.211 min for levan. The presence of characteristic functional groups and structural units of carbohydrate polymers has been confirmed through spectroscopic analyses utilizing Fourier-transform infrared (FT-IR) and nuclear magnetic resonance (NMR) techniques. Thermogravimetric analysis (TGA) revealed a noteworthy decrease in weight (74 %) in the temperature range spanning from 260 to 350 °C. X-ray diffraction (XRD) was utilized to verify the crystalline and amorphous characteristics of EPS-AZ-6. The EPS-AZ-6 exhibited significant cytotoxicity against the MCF-7 tumor cell line, as evidenced by an IC50 value of 6.39 ± 0.05 μg/ml. It also demonstrated a moderate degree of cytotoxicity towards HepG-2 cell line, as indicated by an IC50 value of 29.79 ± 0.41 μg/ml. EPS-AZ-6 exhibited potent antioxidant and in vitro antibacterial properties. These characteristics suggest the potential application value of EPS-AZ-6 in the food industry and pharmaceutical applications.

Construction of Data-Driven Performance Digital Twin for a Real-World Gas Turbine Anomaly Detection Considering Uncertainty

Anomaly detection and failure prediction of gas turbines is of great importance for ensuring reliable operation. This work presents a novel approach for anomaly detection based on a data-driven performance digital twin of gas turbine engines. The developed digital twin consists of two parts: uncertain performance digital twin (UPDT) and fault detection capability. UPDT is a probabilistic digital representation of the expected performance behavior of real-world gas turbine engines operating under various conditions. Fault detection capability is developed based on detecting UPDT outputs that have low probability under the training distribution. A novel anomaly measure based on the first Wasserstein distance is proposed to characterize the entire flight data, and a threshold can be applied to this measure to detect anomaly flights. The proposed UPDT with uncertainty quantification is trained with the sensor data from an individual physical reality and the outcome of the UPDT is intended to deliver the health assessment and fault detection results to support operation and maintenance decision-making. The proposed method is demonstrated on a real-world dataset from a typical type of commercial turbofan engine and the result shows that the F1 score reaches a maximum of 0.99 with a threshold of 0.45. The case study demonstrated that the proposed novel anomaly detection method can effectively identify the abnormal samples, and it is also possible to isolate anomalous behavior in a single performance signal, which is helpful for further fault diagnosis once an anomaly is detected.

Glymphatic function plays a protective role in ageing-related cognitive decline

OBJECTIVE

The glymphatic pathway, characterised as a cerebral drainage system, influences cognitive function in neurodegenerative diseases; however, evidence is limited in a normal ageing population. The aim of this study was to investigate the effect of glymphatic function on ageing-related cognitive decline.

METHODS

We retrospectively reviewed the Cognitive Impairment, Retinopathy, and Cerebrovascular Lesions in the Elderly (CIRCLE) study, and participants with multi-model magnetic resonance imaging (MRI) scans and Mini-Mental State Examinations (MMSE) were enrolled. Glymphatic function was evaluated via the diffusion tensor imaging along the perivascular space (DTI-ALPS) index. Regression models were used to estimate the impact of the DTI-ALPS index on cognitive decline cross-sectionally and longitudinally. We further analysed the mediation effect of the DTI-ALPS on age and cognitive function.

RESULTS

A total of 633 participants were included in this study (48.2% female; mean age, 62.8 ± 8.9 years). The DTI-ALPS index was positively associated with cognitive function cross-sectionally (β = 0.108, P = 0.003), and was an independent protective factor for cognitive decline longitudinally (odds ratio (OR) = 0.029, P = 0.007). The DTI-ALPS index declined progressively with ageing (r = -0.319, P <0.001), and the decrease was more pronounced after 65 years of age. Furthermore, the DTI-ALPS index mediated the relationship between age and MMSE score (β = -0.016, P <0.001). The mediation effect accounted for 21.3%, which was higher in subjects aged over 65 years (25.3%) compared with those aged under 65 years (5.3%).

CONCLUSION

Glymphatic function played a protective role in normal ageing-related cognitive decline, which may serve as a potential therapeutic target against cognitive decline in future.

Bioplastic production in terms of life cycle assessment: A state-of-the-art review

The current transition to sustainability and the circular economy can be viewed as a socio-technical response to environmental impacts and the need to enhance the overall performance of the linear production and consumption paradigm. The concept of biowaste refineries as a feasible alternative to petroleum refineries has gained popularity. Biowaste has become an important raw material source for developing bioproducts and biofuels. Therefore, effective environmental biowaste management systems for the production of bioproducts and biofuels are crucial and can be employed as pillars of a circular economy. Bioplastics, typically plastics manufactured from bio-based polymers, stand to contribute to more sustainable commercial plastic life cycles as part of a circular economy in which virgin polymers are made from renewable or recycled raw materials. Various frameworks and strategies are utilized to model and illustrate additional patterns in fossil fuel and bioplastic feedstock prices for various governments' long-term policies. This review paper highlights the harmful impacts of fossil-based plastic on the environment and human health, as well as the mass need for eco-friendly alternatives such as biodegradable bioplastics. Utilizing new types of bioplastics derived from renewable resources (e.g., biowastes, agricultural wastes, or microalgae) and choosing the appropriate end-of-life option (e.g., anaerobic digestion) may be the right direction to ensure the sustainability of bioplastic production. Clear regulation and financial incentives are still required to scale from niche polymers to large-scale bioplastic market applications with a truly sustainable impact.

The epidemic of acute lymphoid leukemia in China: current trends and future prediction

Background

China has experienced one of the fastest increases in the incidence of acute lymphoid leukemia (ALL). The aim of this study was to assess the long-term trends of the incidence and mortality of ALL in mainland China between 1990 and 2019 and to project these trends through 2028.

Methods

Data on ALL were extracted from the Global Burden of Disease Study 2019; population data were extracted from World Population Prospects 2019. An age-period-cohort framework was used in the analysis.

Results

The net drift for the incidence of ALL was 7.5% (95% confidence interval [CI]: 7.1%, 7.8%) per year in women and 7.1% (95% CI: 6.7%, 7.6%) in men, and local drift was found to be higher than 0 in every studied age group (p<0.05). The net drift for mortality was 1.2% (95% CI: 1.0%, 1.5%) in women and 2.0% (95% CI: 1.7%, 2.3%) in men. Local drift was lower than 0 in boys aged 0-4 years and girls aged 0-9 years and higher than 0 in men aged 10-84 years and women aged 15-84 years. The estimated period relative risks (RRs) for both incidence and mortality showed increasing trends in the recent period. The cohort RRs for incidence showed increasing trends in both sexes; however, the cohort RR for mortality was decreased in the recent birth cohort (women born after 1988-1992 and men born after 2003-2007). Compared with that in 2019, the incidence of ALL in 2028 is projected to increase by 64.1% in men and 75.0% in women, and the mortality is predicted to decrease by 11.1% in men and 14.3% in women. The proportion of older adult/adults individuals with incident ALL and ALL-related death was projected to increase.

Conclusions

Over the last three decades, the incidence and mortality rates of ALL have generally increased. It is projected that the incidence rate of ALL in mainland China will continue to increase in the future, but the associated mortality rate will decline. The proportion of older adult/adults individuals with incident ALL and ALL-related death was projected to increase gradually among both sexes. More efforts are needed, especially for older adult/adults individuals.

The integrating sphere system plus in-situ absorption monitoring: A new scheme to study absorption enhancement of black carbon in ambient aerosols

Black carbon (BC) is the strongest light-absorbing aerosol in the atmosphere. The coating process causes lensing effects to enhance the BC absorption. The reported BC absorption enhancement values (E_abs) significantly differ partly due to the measurement methods used. The biggest difficulty in measuring the E_abs values is how to denude the coated particles so that the true value of absorption without coatings can be distinguished from lensing effects. In this study, we proposed a new approach based on an integrating sphere (IS) system plus in-situ absorption monitoring instrument to study E_abs in ambient aerosols. This approach is capable of (i) "de-lensing through solvent dissolution and solvent de-refraction", by which the absorption coefficient of denuded BC is acquired, and (ii) monitoring in-situ absorption with photoacoustic spectroscopy. With the help of the EC concentration measured by a thermal/optical carbon analyser, the E_abs values were calculated as the quotient of in-situ mass absorption efficiency divided by denude mass absorption efficiency. We applied this new approach to measure the E_abs values of four seasons in Beijing and found an annual mean of 1.90 ± 0.41 in 2019. More importantly, a previous assumption that BC absorption efficiency may be progressively enhanced by increased air pollution was validated and quantified using a logarithmic relationship of E_abs = 0.6 ln (PM_2.5 ̶ 3.59) ̶ 0.43 (R² = 0.99). This signals a continued drop of E_abs for future ambient aerosols with the sustained improvement in local air quality in China, meriting serious attention to its influences in climate, air quality, and atmospheric chemistry.

Biodegradation of willow sawdust by novel cellulase-producing bacterial consortium from wood-feeding termites for enhancing methane production

This study was designed to develop a cellulase-producing bacterial consortium (CBC) from wood-feeding termites that could effectively degrade willow sawdust (WSD) and consequently enhance methane production. The bacterial strains Shewanella sp. SSA-1557, Bacillus cereus SSA-1558, and Pseudomonas mosselii SSA-1568 exhibited significant cellulolytic activity. Their CBC consortium showed positive effects on cellulose bioconversion, resulting in accelerated WSD degradation. After nine days of pretreatment, the WSD had lost 63%, 50%, and 28% of its cellulose, hemicellulose, and lignin, respectively. The hydrolysis rate of treated WSD (352 mg/g) was much higher than that of untreated WSD (15.2 mg/g). The highest biogas production (66.1 NL/kg VS) with 66% methane was observed in the anaerobic digester M-2, which contained a combination of pretreated WSD and cattle dung in a 50/50 ratio. The findings will enrich knowledge for the development of cellulolytic bacterial consortia from termite guts for biological wood pretreatment in lignocellulosic anaerobic digestion biorefineries.

Fabrication of bio-inspired anisotropic structures from biopolymers for biomedical applications: A review

The anisotropic features play indispensable roles in regulating various life activities in different organisms. Increasing efforts have been made to learn and mimic various tissues' intrinsic anisotropic structure or functionality for broad applications in different areas, especially in biomedicine and pharmacy. This paper discusses the strategies for fabricating biomaterials using biopolymers for biomedical applications with the case study analysis. Biopolymers, including different polysaccharides, proteins, and their derivates, that have been confirmed with sound biocompatibility for different biomedical applications are summarized, with a special focus on nanocellulose. Advanced analytical techniques for understanding and characterizing the biopolymer-based anisotropic structures for various biomedical applications are also summarized. Challenges still exist in precisely constructing biopolymers-based biomaterials with anisotropic structures from molecular to macroscopic levels and fitting the dynamic processes in native tissue. It is foreseeable that with the advancement of biopolymers' molecular functionalization, biopolymer building block orientation manipulation strategies, and structural characterization techniques, developing anisotropic biopolymer-based biomaterials for different biomedical applications would significantly contribute to a friendly disease-curing and healthcare experience.

Host-Specific Diversity of Culturable Bacteria in the Gut Systems of Fungus-Growing Termites and Their Potential Functions towards Lignocellulose Bioconversion

Fungus-growing termites are eusocial insects that represent one of the most efficient and unique systems for lignocellulose bioconversion, evolved from a sophisticated symbiosis with lignocellulolytic fungi and gut bacterial communities. Despite a plethora of information generated during the last century, some essential information on gut bacterial profiles and their unique contributions to wood digestion in some fungus-growing termites is still inadequate. Hence, using the culture-dependent approach, the present study aims to assess and compare the diversity of lignocellulose-degrading bacterial symbionts within the gut systems of three fungus-growing termites: Ancistrotermes pakistanicus, Odontotermes longignathus, and Macrotermes sp. A total of 32 bacterial species, belonging to 18 genera and 10 different families, were successfully isolated and identified from three fungus-growing termites using Avicel or xylan as the sole source of carbon. Enterobacteriaceae was the most dominant family represented by 68.1% of the total bacteria, followed by Yersiniaceae (10.6%) and Moraxellaceae (9%). Interestingly, five bacterial genera such as Enterobacter, Citrobacter, Acinetobacter, Trabulsiella, and Kluyvera were common among the tested termites, while the other bacteria demonstrated a termite-specific distribution. Further, the lignocellulolytic potential of selected bacterial strains was tested on agricultural waste to evaluate their capability for lignocellulose bioconversion. The highest substrate degradation was achieved with E. chengduensis MA11 which degraded 45.52% of rice straw. All of the potential strains showed endoglucanase, exoglucanase, and xylanase activities depicting a symbiotic role towards the lignocellulose digestion within the termite gut. The above results indicated that fungus-growing termites harbor a diverse array of bacterial symbionts that differ from species to species, which may play an inevitable role to enhance the degradation efficacy in lignocellulose decomposition. The present study further elaborates our knowledge about the termite-bacteria symbiosis for lignocellulose bioconversion which could be helpful to design a future biorefinery.

Biodegradation of low-density polyethylene plastic waste by a constructed tri-culture yeast consortium from wood-feeding termite: Degradation mechanism and pathway

Polyethylene (PE) is one of the most common synthetic polymers, and PE waste pollution has been an environmental and health concern for decades. Biodegradation is the most eco-friendly and effective approach for plastic waste management. Recently, an emphasis has been placed on novel symbiotic yeasts isolated from termite guts as promising microbiomes for multiple biotechnological applications. This study might be the first to explore the potential of a constructed tri-culture yeast consortium, designated as DYC, isolated from termites for the degradation of low-density polyethylene (LDPE). The yeast consortium DYC stands for the molecularly identified species Sterigmatomyces halophilus, Meyerozyma guilliermondii, and Meyerozyma caribbica. The LDPE-DYC consortium showed a high growth rate on UV-sterilized LDPE as a sole carbon source, resulting in a reduction in tensile strength (TS) of 63.4% and a net LDPE mass reduction of 33.2% compared to the individual yeasts. All yeasts, individually and in consortium, showed a high production rate for LDPE-degrading enzymes. The hypothetical LDPE biodegradation pathway that was proposed revealed the formation of several metabolites, including alkanes, aldehydes, ethanol, and fatty acids. This study emphasizes a novel concept for using LDPE-degrading yeasts from wood-feeding termites for plastic waste biodegradation.

Choroid Plexus Enlargement Exacerbates White Matter Hyperintensity Growth through Glymphatic Impairment

OBJECTIVE

Choroid plexus (CP) is a key regulator in cerebrospinal fluid production, but its contribution to glymphatic clearance function and association with white matter hyperintensity (WMH) remains unclear.

METHODS

This retrospective study included 2 prospective 3.0-T magnetic resonance imaging (MRI) cohorts. In cohort 1, patients with indications for lumbar puncture underwent 3-dimensional T1-weighted sequence (3D-T1) before and at 39 hours after intrathecal administration of contrast agent (glymphatic MRI). In cohort 2, patients with WMH were enrolled from the CIRCLE study and had a median follow-up time of 1.4 years. WMH and CP of the lateral ventricles were automatically segmented on T2 fluid-attenuated inversion recovery (FLAIR) and 3D-T1, respectively. CP volume was expressed as a ratio to intracranial volume. Glymphatic clearance was measured as signal percentage change from baseline to 39 hours at 8 brain locations based on glymphatic MRI in the first cohort, or as noninvasive diffusion tensor image analysis along the perivascular space (DTI-ALPS) index based on DTI in the second cohort.

RESULTS

In cohort 1, a total of 52 patients were included. Higher CP volume was correlated with slower glymphatic clearance rate in all brain locations. In cohort 2, a total of 197 patients were included. Baseline CP volume was positively associated with WMH volume and its growth. Furthermore, DTI-ALPS index partially mediated the association of CP with both WMH load and growth.

INTERPRETATIONS

Enlarged CP volume could be an indicator for larger growth of WMH, potentially involving impaired glymphatic clearance function. The exploration of CP may provide a novel perspective to clarify the mechanism of WMH pathogenesis, as well as other glymphatic-related disorders. ANN NEUROL 2023.

Characterization and 3D printing of a biodegradable polylactic acid/thermoplastic polyurethane blend with laccase-modified lignin as a nucleating agent

Polylactic acid (PLA) has been used in fused deposition method (FDM) based 3D printing for many years. Alkali lignin is an undervalued industrial by-product that could upgrade PLA's poor mechanical properties. This work presents a biotechnological approach consisting of a partial degradation of alkali lignin using Bacillus ligniniphilus laccase (Lacc) L1 for its use as a nucleating agent in a polylactic acid/thermoplastic polyurethane (PLA/TPU) blend. Results showed that adding enzymatically modified lignin (EL) increased the elasticity modulus to a maximum of 2.5-fold than the control and conferred a maximum biodegradability rate of 15 % after 6 months under the soil burial method. Furthermore, the printing quality rendered satisfactory smooth surfaces, geometries and a tunable addition of a woody color. These findings open a new door for using laccase as a tool to upgrade lignin's properties and its use as a scaffold in manufacturing more environmentally sustainable filaments with improved mechanical properties for 3D printing.

Inferior Frontal Sulcal Hyperintensity on FLAIR Is Associated with Small Vessel Disease but not Alzheimer's Disease Pathology

BACKGROUND

The inferior frontal sulci are essential sites on the route of cerebrospinal fluid outflow. A recent study suggests that inferior frontal sulcal hyperintensities (IFSH) on FLAIR images might be related to glymphatic dysfunction.

OBJECTIVE

To investigate whether IFSH is associated with Alzheimer's disease (AD) pathology and cerebral small vessel disease (SVD) burden.

METHODS

We retrospectively collected data from 272 non-demented subjects in the ADNI3 database. The IFSH was assessed on 3D fluid-attenuated inversion recovery images. The standardized uptake value ratios of amyloid and tau PET were used to reflect the AD pathology burden. To measure the SVD burden, we assessed white matter hyperintensities (WMH), dilation of perivascular spaces, microbleeds, and lacunes. Finally, we performed ordinal logistic regression analyses to investigate the associations between the IFSH score and AD pathology and SVD burden.

RESULTS

The IFSH score was associated with the deep WMH score (OR, 1.79; 95% CI, 1.24 - 2.59) controlling for age and sex. The association remained significant in the multivariable regression models. There was no association between the IFSH score and AD pathology burden.

CONCLUSION

This study suggests that the IFSH sign is associated with SVD but not AD pathology. Further studies are needed to confirm the findings.

Extraction of bioactive polysaccharide from Ulva prolifera biomass waste toward potential biomedical application

Ulva prolifera macroalgae blooming caused by water eutrophication seriously affects the marine ecological environment. Exploring an efficient approach to turning algae biomass waste into high-value-added products is significant. The present work aimed to demonstrate the feasibility of the bioactive polysaccharide extraction from Ulva prolifera and to evaluate its potential biomedical application. A short autoclave process was proposed and optimized using the response surface methodology to extract Ulva polysaccharides (UP) with high molar mass. Our results indicated that UP with high molar mass (9.17 × 10⁵ g/mol) and competitive radical scavenging activity (up to 53.4 %) could be effectively extracted with the assistance of Na₂CO₃ (1.3 %, wt.) at a solid-liquid ratio of 1/10 in 26 min. The obtained UP mainly composes of galactose (9.4 %), glucose (73.1 %), xylose (9.6 %), and mannose (4.7 %). The biocompatibility of the UP and its potential application as a bioactive ingredient in 3D cell culture has been evaluated and confirmed by confocal laser scanning microscopy and fluorescence microscope imaging inspection. This work demonstrated the feasibility of extracting bioactive sulfated polysaccharides with potential applications in biomedicine from biomass waste. Meanwhile, this work also provided an alternative solution to deal with the environmental challenges incurred by algae blooming worldwide.

Biodegradability of polyethylene by efficient bacteria from the guts of plastic-eating waxworms and investigation of its degradation mechanism

Polyethylene (PE) has been regarded as non-biodegradable for decades, and the evidence for its degradation by bacteria remains unclear in the literature. Waxworms have recently gained attention for their ability to degrade natural long-chain polymers and synthetic plastic. This study aims to explore the potential of low-density polyethylene (LDPE)-degrading bacteria from the gut symbionts of lesser waxworm (Achroia grisella) larvae for the effective biodegradation of LEDP. Two bacterial isolates (LDPE-DB1 and LDPE-DB2) exhibited the greatest reduction in tensile strength among all isolates (P < 0.0001), reaching 51.3% and 58.3%, respectively. The bacterial strains LDPE-DB1 and LDPE-DB2 stand for molecularly identified species, Citrobacter freundii and Bacillus sp., respectively. After 5 days of incubation, the cell density of LDPE-DB1 and LDPE-DB2 reached 2.20 × 10⁸ and 1.8 × 10⁸ CFU/mL, respectively. However, after 30 days of incubation, the cell density reached 7.3 × 10⁸ and 5.9 × 10⁸, respectively. The formed cavities indicate the high activity of the isolated bacteria from Achroia grisella larvae where the cavities reach a depth of up to 1.2 µm. The findings of this study demonstrated the presence of LDPE-degrading bacteria in Achroia grisella and provide promising evidence for the biodegradation of plastic waste management in the environment.

Can wood-feeding termites solve the environmental bottleneck caused by plastics? A critical state-of-the-art review

The abundance of synthetic polymers has become an ever-increasing environmental threat in the world. The excessive utilization of plastics leads to the accumulation of such recalcitrant pollutants in the environment. For example, during the COVID-19 pandemic, unprecedented demand for personal protective equipment (PPE) kits, face masks, and gloves made up of single-use items has resulted in the massive generation of plastic biomedical waste. As secondary pollutants, microplastic particles (<5 mm) are derived from pellet loss and degradation of macroplastics. Therefore, urgent intervention is required for the management of these hazardous materials. Physicochemical approaches have been employed to degrade synthetic polymers, but these approaches have limited efficiency and cause the release of hazardous metabolites or by-products into the environment. Therefore, bioremediation is a proper option as it is both cost-efficient and environmentally friendly. On the other hand, plants evolved lignocellulose to be resistant to destruction, whereas insects, such as wood-feeding termites, possess diverse microorganisms in their guts, which confer physiological and ecological benefits to their host. Plastic and lignocellulose polymers share a number of physical and chemical properties, despite their structural and recalcitrance differences. Among these similarities are a hydrophobic nature, a carbon skeleton, and amorphous/crystalline regions. Compared with herbivorous mammals, lignocellulose digestion in termites is accomplished at ordinary temperatures. This unique characteristic has been of great interest for the development of a plastic biodegradation approach by termites and their gut symbionts. Therefore, transferring knowledge from research on lignocellulosic degradation by termites and their gut symbionts to that on synthetic polymers has become a new research hotspot and technological development direction to solve the environmental bottleneck caused by synthetic plastic polymers.

Microalgae-based wastewater treatment: Mechanisms, challenges, recent advances, and future prospects

The rapid expansion of both the global economy and the human population has led to a shortage of water resources suitable for direct human consumption. As a result, water remediation will inexorably become the primary focus on a global scale. Microalgae can be grown in various types of wastewaters (WW). They have a high potential to remove contaminants from the effluents of industries and urban areas. This review focuses on recent advances on WW remediation through microalgae cultivation. Attention has already been paid to microalgae-based wastewater treatment (WWT) due to its low energy requirements, the strong ability of microalgae to thrive under diverse environmental conditions, and the potential to transform WW nutrients into high-value compounds. It turned out that microalgae-based WWT is an economical and sustainable solution. Moreover, different types of toxins are removed by microalgae through biosorption, bioaccumulation, and biodegradation processes. Examples are toxins from agricultural runoffs and textile and pharmaceutical industrial effluents. Microalgae have the potential to mitigate carbon dioxide and make use of the micronutrients that are present in the effluents. This review paper highlights the application of microalgae in WW remediation and the remediation of diverse types of pollutants commonly present in WW through different mechanisms, simultaneous resource recovery, and efficient microalgae-based co-culturing systems along with bottlenecks and prospects.

Cobalt oxide nanoparticles as a new strategy for enhancing methane production from anaerobic digestion of noxious aquatic weeds

This study investigated the effect of cobalt oxide nanoparticles (Co₃O₄-NPs) supplementation on anaerobic microbial population changes and anaerobic digestion (AD) performance and production. Co₃O₄-NPs (3 mg/L) showed the maximum enhancement of biogas yield over the cow dung (CD) as control and the co-digestion process of CD with water hyacinth (WH) by 58.9 and 27.2 %, respectively. Furthermore, methane (CH₄) yield was enhanced by 89.96 and 43.4 % over CD and co-digestion processes, respectively. Additionally, the microbiological assessment analysis using VIT® gene probe technology showed that Co₃O₄-NPs enhance the viability of total bacterial cells by 9 %. The techno-economic analysis reflects the revenue of this strategy on the highest net energy content of biogas, which was achieved with 3 mg/L Co₃O₄-NPs and was 428.05 kWh with a net profit of 67.66 USD/m³ of the substrate. Therefore, nanoparticle supplementation to the AD process can be considered a promising approach to enhance biogas and CH₄.

Environmental and Human Health Impact of Disposable Face Masks During the COVID-19 Pandemic: Wood-Feeding Termites as a Model for Plastic Biodegradation

The ongoing COVID-19 pandemic has resulted in an unprecedented form of plastic pollution: personal protective equipment (PPE). On the eve of the COVID-19 pandemic, there is a tremendous increase in the production of plastic-based PPE. To control the spread of the virus, face masks (FMs) are used as primary PPE. Thus, the production and usage of FM significantly increased as the COVID-19 pandemic was still escalating. The primary raw materials for the manufacturing of FMs are non-biodegradable synthetic polymers derived from petrochemicals. This calls for an urgent need to develop novel strategies for the efficient degradation of plastics. Furthermore, most of these masks contain plastic or other derivatives of plastic. The extensive usage of FM generates millions of tons of plastic waste for the environment in a short span of time. However, their degradation in the environment and consequences are poorly understood. Therefore, the potential impacts of disposable FM on the environment and human health during the COVID-19 pandemic are clarified in the present study. Despite structural and recalcitrance variations, lignocellulose and plastic polymers have physicochemical features, including carbon skeletons with comparable chemical bonds as well as hydrophobic properties in amorphous and crystalline regions. In this review, we argue that there is much to be learned from termites by transferring knowledge from research on lignocellulose degradation by termites to that on plastic waste.

Genomic insights into the metabolic potential of a novel lignin-degrading and polyhydroxyalkanoates producing bacterium Pseudomonas sp. Hu109A

Lignin is the most abundant heterogeneous aromatic polymer present on planet Earth and is recalcitrant to degradation due to its complex structure, therefore, imposing a challenge to biorefinery procedures. Identifying new microbial strains with the potential to valorize lignin into useful compounds is indispensable to achieving green sustainable consumption. In this study, a novel Pseudomonas strain designated as Hu109A was isolated from the termite gut and the genome was sequenced and analyzed further. The genome contains a circular chromosome with the size of 5,131,917 bp having a GC content of 62.6% and 4698 genes. Genome annotation reveals that the strain possesses lignin-oxidizing enzymes such as DyP-type peroxidases, laccase, dioxygenase, and aromatic degradation gene clusters. The genome also contains O-methyltransferases which function in accelerating the lignin degradation by methylating the free hydroxyl phenolic compounds which in high concentration can inhibit the lignin peroxidase. Furthermore, the genome exhibits two gene clusters encoding the enzymes related to polyhydroxyalkanoates (PHA) synthesis. Pseudomonas strains are generally assumed to produce medium chain length PHAs (mcl-PHAs) only, however, strain Hu109A contains both Class II PHA synthase genes involved in mcl-PHAs and Class III PHA synthase gene involved in short-chain length PHAs (scl-PHAs). Gas Chromatography-Mass Spectrometry (GC-MS) analysis showed that using 1 g/L lignin as the sole carbon source, the maximum production of PHA observed was 103.68 mg/L, which increased to 186 mg/L with an increase in lignin concentration to 3 g/L. However, PHA production while using glucose as the sole carbon source was significantly lower than the lignin source, and maximum production was 125.6 mg/L with 3 g/L glucose. The strain Hu109A can tolerate a broad range of solvents including methanol, isopropanol, dimethylformamide, and ethanol, revealing its potential for industrial applications.

Impaired peri-olfactory cerebrospinal fluid clearance is associated with ageing, cognitive decline and dyssomnia

BACKGROUND

Animal experiments have demonstrated the dependency of cerebrospinal fluid clearance function on age and sleep, which partially underlay the cognitive decline in the elderly. However, human evidence is lacking, which could be mainly attributed to the limited methods of cerebrospinal fluid clearance function assessment.

METHOD

Serial T1-weighted and T2-fluid attenuated inversion recovery imaging were performed in 92 patients before and at multiple time points including 4.5 h, 15 h and 39 h after intrathecal injection of contrast agent to visualize the putative meningeal lymphatic pathway, peri-olfactory nerve pathway, and peri-optic nerve pathway. We defined the clearance function as the percentage change in signal unit ratio of critical locations in these pathways from baseline to 39 h after intrathecal injection, and further analysed their relationships with age, sleep, and cognitive function.

FINDINGS

Cerebrospinal fluid clearance through the putative meningeal lymphatic and perineural pathways were clearly visualized. The clearance function of putative meningeal lymphatic and perineural pathways were impaired with ageing (all P < 0.05). The clearance function through peri-olfactory nerve pathway in inferior turbinate was positively correlated with sleep quality and cognitive function (both P < 0.05), and mediated the association of sleep quality with cognitive function (percent change in β [bootstrap 95% CI]: 33% [-0.220, -0.007]).

INTERPRETATION

The impaired clearance through putative peri-olfactory nerve pathway may explain the cognitive decline in patients with sleep disturbance. The study shows a promising method to assess cerebrospinal fluid clearance function of putative peri-neural pathways via dynamic magnetic resonance imaging with intrathecal injection of contrast agent.

FUNDING

This work was supported by the National Natural Science Foundation of China (81971101, 82171276 and 82101365).