Human Exposure to Ambient Atmospheric Microplastics in a Megacity: Spatiotemporal Variation and Associated Microorganism-Related Health Risk.

Microplastics are found in various human tissues and are considered harmful, raising concerns about human exposure to microplastics in the environment. Existing research has analyzed indoor and occupational scenarios, but long-term monitoring of ambient atmospheric microplastics (AMPs), especially in highly polluted urban regions, needs to be further investigated. This study estimated human environmental exposure to AMPs by considering inhalation, dust ingestion, and dermal exposure in three urban functional zones within a megacity. The annual exposure quantity was 7.37 × 104 items for children and 1.06 × 105 items for adults, comparable with the human microplastic consumption from food and water. Significant spatiotemporal differences were observed in the characteristics of AMPs that humans were exposed to, with wind speed and rainfall frequency mainly driving these changes. The annual human AMP exposure quantity in urban green land spaces, which were recognized as relatively low polluted zones, was comparable with that in public service zones and residential zones. Notably, significant positive correlations between the AMP characteristics and the pathogenicity of the airborne bacterial community were discovered. AMP size and immune-mediated disease risks brought by atmospheric microbes showed the most significant relationship, where Sphingomonas might act as the potential key mediator.

Functional transcriptome reveals hepatopancreatic lipid metabolism during the molting cycle of the Chinese mitten crab Eriocheir sinensis.

Crustacean molting is highly related to energy and lipid metabolism. This study was conducted to detect the changes of total lipids (TL), triacylglyceride (TAG), phospholipid (PL) and lipid droplets in hepatopancreas, and then to investigate the gene expression patterns related to hepatopancreatic lipid metabolism during the molting cycle of Chinese mitten crab Eriocheir sinensis. Hepatopancreatic TL and TAG increased significantly from post-molt stage to pre-molt stage, then decreased significantly from pre-molt stage to ecdysis stage, which is consistent to the changes of neutral lipid-rich adipocytes in hepatopancreas. By transcriptomic analysis, 65,325 transcripts were sequenced and assembled, and 28,033 transcripts were annotated. Most genes were related to energy metabolism, and the enriched genes were involved in carbohydrate and lipid metabolism and biosynthesis, especially in de novo synthesis of fatty acids and TAG, and ketone body production. Compared to the inter-molt stages, acetyl-CoA carboxylase, fatty acid synthase and other genes related to the synthesis of fatty acids were upregulated in the pre-molt stage. TAG synthesis related genes, including Glycerol-3-phosphate acyltransferase and 1-acylglycerol-3-phosphate acyltransferases, were upregulated in the post-molt stage compared to the inter-molt stage. The expression of ketone body-related genes had no significant changes during the molting cycle. Compared to the TAG synthetic pathway, ketone body biosynthesis may contribute less/secondarily to fatty acid metabolic processes, which could be involved in the other physiological processes or metabolism. In conclusion, these results showed that TAG is the major lipid deposition during inter- and pre-molt stages, and the most genes are related to the fatty acids and TAG metabolism in the hepatopancreas during the molting cycle of E. sinensis.

Double-Walled Zn36@Zn104 Multicomponent Senary Metal-Organic Polyhedral Framework and Its Isoreticular Evolution.

Metal-organic polyhedral frameworks are attractive in gas storage and separation due to large voids with windows that can serve as traps for guest molecules. Introducing multivariant/multicomponent functionalities in them are ways of improving performances for certain targets. The high compatibility of organic linkers can generate multivariant MOFs, but by far, the diversity of secondary building units (SBUs) in a single metal-organic framework is still limited (no more than two in most cases). Here we report a new double-walled Zn36@Zn104 metal-organic polyhedral framework (HHU-8) with five types of topologically distinct SBUs and its isoreticular evolution to the Zn36@Zn136 counterpart (HHU-8s). Both MOFs are the first to be constructed with such high numbers of topologically distinct SBUs as well as topologically distinct nodes, and their formation and evolution provide new insight into SBU's controllability.

[Construction of synthetic microbial community and its application in polyhydroxyalkanoate biosynthesis].

Synthetic microbial communities are artificial systems composed of multiple microorganisms with well-defined genetic backgrounds. They are characterized by low complexity, high controllability, and strong stability, thus suitable for industrial production, disease management, and environmental remediation. This review summarizes the design principles and construction methods of synthetic microbial communities, and highlights their application in polyhydroxyalkanoate (PHA) biosynthesis. Constructing a synthetic microbial community represents a core research direction of synthetic ecology and an emerging frontier of synthetic biology. It requires strategies to design and control microbial interactions, spatial organization, robustness maintenance, and biocontainment to obtain an efficient, stable, and controllable synthetic microbial community. In recent years, synthetic microbial communities have been widely used to synthesize high-value chemicals such as drugs, biofuels, and biomaterials. As an ideal substitute for oil-based plastics, PHA has received much attention. Enhancing the capacity and broadening the range of carbon source utilization for PHA producers have become the research priority in the application of synthetic microbial communities for PHA biosynthesis, with the aim to reduce PHA production cost.

Potential environmental risks of field bio/non-degradable microplastic from mulching residues in farmland: Evidence from metagenomic analysis of plastisphere.

The plastisphere may act as reservoir of antibiotic resistome, accelerating global antimicrobial resistance dissemination. However, the environmental risks in the plastisphere of field microplastics (MPs) in farmland remain largely unknown. Here, antibiotic resistance genes (ARGs) and virulence factors (VFs) on polyethylene microplastics (PE-MPs) and polybutylene adipate terephthalate and polylactic acid microplastics (PBAT/PLA-MPs) from residues were investigated using metagenomic analysis. The results suggested that the profiles of ARG and VF in the plastisphere of PBAT/PLA-MPs had greater number of detected genes with statistically higher values of diversity and abundance than soil and PE-MP. Procrustes analysis indicated a good fitting correlation between ARG/VF profiles and bacterial community composition. Actinobacteria was the major host for tetracycline and glycopeptide resistance genes in the soil and PE-MP plastisphere, whereas the primary host for multidrug resistance genes changed to Proteobacteria in PBAT/PLA-MP plastisphere. Besides, three human pathogens, Sphingomonas paucimobilis, Lactobacillus plantarum and Pseudomonas aeruginosa were identified in the plastisphere. The PE-MP plastisphere exhibited a higher transfer potential of ARGs than PBAT/PLA-MP plastisphere. This work enhances our knowledge of potential environmental risks posed by microplastic in farmland and provides valuable insights for risk assessment and management of agricultural mulching applications.

Improvement of a highly sensitive and specific whole-cell biosensor by adding a positive feedback amplifier.

In this study, we designed a Cd2+ whole-cell biosensor with both positive and negative feedback cascade amplifiers in Pseudomonas putida KT2440 (LTCM) based on our previous design with only a negative feedback amplifier (TCM). The results showed that the newly developed biosensor LTCM was greatly improved compared to TCM. Firstly, the linear response range of LTCM was expanded while the maximum linear response range was raised from 0.05 to 0.1 µM. Meanwhile, adding a positive feedback amplifier further increased the fluorescence output signal of LTCM 1.11-2.64 times under the same culture conditions. Moreover, the response time of LTCM for detection of practical samples was reduced from 6 to 4 h. At the same time, LTCM still retained very high sensitivity and specificity, while its lowest detection limit was 0.1 nM Cd2+ and the specificity was 23.29 (compared to 0.1 nM and 17.55 in TCM, respectively). In summary, the positive and negative feedback cascade amplifiers effectively improved the performance of the biosensor LTCM, resulting in a greater linear response range, higher output signal intensity, and shorter response time than TCM while retaining comparable sensitivity and specificity, indicating better potential for practical applications.

Occurrence and distribution characteristics of aged microplastics in the surface water, sediment, and crabs of the aquaculture pond in the Yangtze River Delta of China.

The artificial breeding of freshwater crabs in China has become the main source, accounting for 45.69 % of the total output in 2020. However, microplastics widely exist in ponds due to the addition of meals, and the aging and breakage of plastic tools, and people know little about the occurrence of microplastics in the environment and the tissues of crabs during the cultivation of crabs in ponds. In this study, the abundance and characteristics of microplastics in ponds and crabs were studied finely, and the types of microplastics produced by meals and tools and the aging degree of microplastics in different media were studied in a typical aquaculture experimental base in the Yangtze Estuary of China. After we digested all the samples, there were microplastics in the water, sediment, and inedible part of crabs and crab meals, mainly in fiber shape, with a particle size of 100~300µm, and they have a certain degree of aging. The abundance of microplastics in surface water ranges from 4.4 to 10.8 items/L, and that in sediment ranges from 28.6 to 54.3 items/100 g·dry weight sediments. The average abundance of microplastics in crabs was 23.9 ± 15.9 items/individual. The content of microplastics in crabs' intestinal tissue was the highest, followed by gills and hepatopancreas. At the same time, the microplastics found in crabs were positively correlated with crab body weight and negatively correlated with hepatopancreas index. The results show that in the process of artificial breeding pond feeding, microplastics will be released from the process of meals dissolving in water, and fall off due to wear and tear during the use of tools. Microplastics found in the water, sediments and the tissues of crabs were all aged. Humans have a risk of ingesting microplastics when they eat the tissues of nonedible parts of crabs.

Artificial Consortium of Three E. coli BL21 Strains with Synergistic Functional Modules for Complete Phenanthrene Degradation.

Polycyclic aromatic hydrocarbons (PAHs) are highly toxic and persistent organic pollutions that can accumulate in the environment. In this study, an aromatic ring cleavage module, a salicylic acid synthesis module, and a catechol metabolism module were respectively constructed in three Escherichia coli BL21 strains. Subsequently, the engineered strains were cocultured as an artificial consortium for the biodegradation of phenanthrene, a typical PHA. Single factor experiments and response surface methodology were used to identify the optimal degradation conditions, including an inoculation interval of 6 h, inoculation ratio of 1:1:1, and IPTG concentration of 2 mM. Under these conditions, the 7-day degradation ratio of 100 mg/L phenanthrene reached 72.67%. Moreover, the engineered Escherichia coli BL21 strains showed good phenanthrene degradation ability at substrate concentrations 10 mg/L up to 500 mg/L. Enzyme activity assays combined with gas chromatography-mass spectrometry measurements confirmed that the three engineered strains behaved as a synergistic consortium in the phenanthrene degradation process. Based on the analysis of the key metabolites, the engineered bacteria were supplemented at 7-day intervals in batches so that each engineered strain maintained its optimal degradation ability. The 21-day degradation ratio finally reached 90.66%, which was much higher than what was observed with simultaneous inoculation. These findings suggest that the three engineered strains with separate modules constructed in this study offer an attractive solution for removing PAHs from the environment.

Highly Sensitive Whole-Cell Biosensor for Cadmium Detection Based on a Negative Feedback Circuit.

Although many whole-cell biosensors (WCBs) for the detection of Cd2+ have been developed over the years, most lack sensitivity and specificity. In this paper, we developed a Cd2+ WCB with a negative feedback amplifier in P. putida KT2440. Based on the slope of the linear detection curve as a measure of sensitivity, WCB with negative feedback amplifier greatly increased the output signal of the reporter mCherry, resulting in 33% greater sensitivity than in an equivalent WCB without the negative feedback circuit. Moreover, WCB with negative feedback amplifier exhibited increased Cd2+ tolerance and a lower detection limit of 0.1 nM, a remarkable 400-fold improvement compared to the WCB without the negative feedback circuit, which is significantly below the World Health Organization standard of 27 nM (0.003 mg/L) for cadmium in drinking water. Due to the superior amplification of the output signal, WCB with negative feedback amplifier can provide a detectable signal in a much shorter time, and a fast response is highly preferable for real field applications. In addition, the WCB with negative feedback amplifier showed an unusually high specificity for Cd2+ compared to other metal ions, giving signals with other metals that were between 17.6 and 41.4 times weaker than with Cd2+. In summary, the negative feedback amplifier WCB designed in this work meets the requirements of Cd2+ detection with very high sensitivity and specificity, which also demonstrates that genetic negative feedback amplifiers are excellent tools for improving the performance of WCBs.