Human
ingestion of microplastics (MPs) is inevitable due to the
ubiquity of MPs in various foods and drinking water. Whether the ingestion
of MPs poses a substantial risk to human health is far from understood.
Here, by analyzing the characteristics of MPs in the feces of patients
with inflammatory bowel disease (IBD) and healthy people, for the
first time, we found that the fecal MP concentration in IBD patients
(41.8 items/g dm) was significantly higher than that in healthy people
(28.0 items/g dm). In total, 15 types of MPs were detected in feces,
with poly(ethylene terephthalate) (22.3–34.0%) and polyamide
(8.9–12.4%) being dominant, and their primary shapes were sheets
and fibers, respectively. We present evidence indicating that a positive
correlation exists between the concentration of fecal MPs and the
severity of IBD. Combining a questionnaire survey and the characteristics
of fecal MPs, we conclude that the plastic packaging of drinking water
and food and dust exposure are important sources of human exposure
to MPs. Furthermore, the positive correlation between fecal MPs and
IBD status suggests that MP exposure may be related to the disease
process or that IBD exacerbates the retention of MPs. The relative
mechanisms deserve further studies. Our results also highlight that
fecal MPs are useful for assessing human MP exposure and potential
health risks.
Applications of animal manure and
treated wastewater could enrich
antibiotic-resistant bacteria (ARB) and antibiotic resistance genes
(ARGs) in the plant microbiome. However, the mechanistic studies of
the transmission of ARB and ARGs from the environment to plant endophytic
bacteria were few. Herein, a genetically engineered fluorescent Escherichia coli harboring a conjugative RP4 plasmid
that carries three ARGs was used to trace its spread into Arabidopsis thaliana interior in a tetracycline-amended
hydroponic system in the absence or presence of a simulated soil bacterial
community. Confocal microscope observation demonstrated that E. coli was internalized into plant tissues and the
carried RP4 plasmid was transferred into plant endophytic bacteria.
More importantly, we observed that soil bacteria inhibited the internalization
of E. coli but substantially promoted
RP4 plasmid spread into the plant microbiome. The altered RP4-carrying
bacterial community composition in the plant microbiome and the increased
core-shared RP4-carrying bacteria number between plant interior and
exterior in the presence of soil bacteria collectively confirmed that
soil bacteria, especially Proteobacteria, might capture RP4 from E. coli and then translocate into plant microbiome,
resulting in the increased RP4 plasmid spread in the plant endophytes.
Overall, our findings provided important insights into the dissemination
of ARB and ARGs from the environment to the plant microbiome.
Understanding
the degradation of dissolved organic matter (DOM)
is vital for optimizing DOM control. However, the microbe-mediated
DOM transformation during wastewater treatment remains poorly characterized.
Here, microbes and DOM along full-scale biotreatment processes were
simultaneously characterized using comparative genomics and high-resolution
mass spectrometry-based reactomics. Biotreatments significantly increased
DOM’s aromaticity and unsaturation due to the overproduced
lignin and polyphenol analogs. DOM was diversified by over five times
in richness, with thousands of nitrogenous and sulfur-containing compounds
generated through microbe-mediated oxidoreduction, functional group
transfer, and C–N and C–S bond formation. Network analysis
demonstrated microbial division of labor in DOM transformation. However,
their roles were determined by their functional traits rather than
taxa. Specifically, network and module hubs exhibited rapid growth
potentials and broad substrate affinities but were deficient in xenobiotics-metabolism-associated
genes. They were mainly correlated to liable DOM consumption and its
transformation to recalcitrant compounds. In contrast, connectors
and peripherals were potential degraders of recalcitrant DOM but slow
in growth. They showed specialized associations with fewer DOM molecules
and probably fed on metabolites of hub microbes. Thus, developing
technologies (e.g., carriers) to selectively enrich peripheral degraders
and consequently decouple the liable and recalcitrant DOM transformation
processes may advance DOM removal.
Acesulfame (ACE) is listed as an emerging contaminant due to its environmental persistence and wide occurrence in the environment. ACE can be degraded partially in the regular UV disinfection process but the eco-toxicity of its irradiation products remains unclear. This study focused on the possible oxidative status change in the liver of Carassius auratus exposed to ACE and its irradiation products. The UV degradation of ACE follows pseudo-first-order kinetics, and eight irradiation products were identified. Fish were exposed 7days to 0.1 and 10mg/L ACE (ACE group) and ACE after UV irradiance (ACE-UV group). The oxidative stress in fish liver exposed to ACE group had no distinct change. However, in the ACE-UV group, the quantity of OH was induced by 17.96-55% and the MDA content increased by 16.28-68.28% compared to control. Time-effect exposure in the ACE-UV group showed that in the first 3days the quantity of OH reached its peak, causing severe inhibition of SOD and continuous inducement of GPx. GSH helped scavenge OH and decreased below control after 3days. An increased toxicity of ACE after UV irradiance was observed and its transfer after into aquatic environment needs to be recognized as an environmental risk.
The
question of whether long-term chronic exposure to microplastics
(MPs) could induce dose- and size-dependent adverse effects in mammals
remains controversial and poorly understood. Our study explored potential
health risks from dietary exposure to environmentally relevant doses
of polystyrene (PS) MPs, through a mouse model and integrated analyses
of the interruptions of fecal microbial metagenomes and plasma lipidomes.
After 21 weeks of exposure to the MPs (40–100 μm), mice
mainly exhibited gut microbiota dysbiosis, tissue inflammation, and
plasma lipid metabolism disorder, although no notable accumulation
of MPs was observed in the gut or liver. The change of the relative
abundance of microbiota was strongly associated with the exposure
dose and size of MPs while less significant effects were observed
in gut damage and abnormal lipid metabolism. Moreover, multiomics
data suggested that the host abnormal lipid metabolism was closely
related to bowel function disruptions, including gut microbiota dysbiosis,
increased gut permeability, and inflammation induced by MPs. We revealed
for the first time that even without notable accumulation in mouse
tissues, long-term exposure to MPs at environmentally relevant doses
could still induce widespread health risks. This raises concern on
the health risks from the exposure of humans and other mammals to
environmentally relevant dose MPs.
Five full-scale wastewater treatment plants (WWTPs) in China using typical biodegradation processes (SBR, oxidation ditch, A2/O) were selected to assess the removal of four popular artificial sweeteners (ASs). All four ASs (acesulfame (ACE), sucralose (SUC), cyclamate (CYC) and saccharin (SAC)) were detected, ranging from 0.43 to 27.34μg/L in the influent. Higher concentrations of ASs were measured in winter. ACE could be partly removed by 7.11–50.76% through biodegradation and especially through the denitrifying process. The A2/O process was the most efficient at biodegrading ASs. Adsorption (by granular activated carbon (GAC) and magnetic resin) and ultraviolet radiation-based advanced oxidation processes (UV/AOPs) were evaluated to remove ASs in laboratory-scale tests. The amounts of resin adsorbed were 3.33–18.51 times more than those of GAC except for SUC. The adsorption ability of resin decreased in the order of SAC > ACE > CYC > SUC in accordance with the pKa. Degradation of ASs followed pseudo-first-order kinetics in UV/H2O2 and UV/PDS. When applied to the secondary effluent, ASs could be degraded from 30.87 to 99.93% using UV/PDS in 30 minutes and UV/PDS was more efficient and economic.
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