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A pilot-scale field experiment demonstrated that a one-time amendment of emulsified vegetable oil (EVO) reduced groundwater U(VI) concentrations for 1 year in a fast-flowing aquifer. However, little is known about how EVO amendment stimulates the functional gene composition, structure, and dynamics of groundwater microbial communities toward prolonged U(VI) reduction. In this study, we hypothesized that EVO amendment would shift the functional gene composition and structure of groundwater microbial communities and stimulate key functional genes/groups involved in EVO biodegradation and reduction of electron acceptors in the aquifer. To test these hypotheses, groundwater microbial communities after EVO amendment were analyzed using a comprehensive functional gene microarray. Our results showed that EVO amendment stimulated sequential shifts in the functional composition and structure of groundwater microbial communities. Particularly, the relative abundance of key functional genes/groups involved in EVO biodegradation and the reduction of NO3 (-), Mn(IV), Fe(III), U(VI), and SO4 (2-) significantly increased, especially during the active U(VI) reduction period. The relative abundance for some of these key functional genes/groups remained elevated over 9 months. Montel tests suggested that the dynamics in the abundance, composition, and structure of these key functional genes/groups were significantly correlated with groundwater concentrations of acetate, NO3 (-), Mn(II), Fe(II), U(VI), and SO4 (2-). Our results suggest that EVO amendment stimulated dynamic succession of key functional microbial communities. This study improves our understanding of the composition, structure, and function changes needed for groundwater microbial communities to sustain a long-term U(VI) reduction.

Due to the environmental persistence and ecotoxological impacts of plastic waste and debris, pollution as the result of micro- and nano-plastics is a global concern. Here we provide a comprehensive review of both the history of research into the biodegradation of plastics as well as future trends in this area. A systematic literature search and review was carried out via Google Scholar by using predefined criteria to define a compilation of sources from January 1960 to May 2023, which indicated that research on plastics degradation has increased explosively since 1991. After a primary search, bibiometric analysis was employed using the Web of Science Core Collection's (WoSCC) of online databases to provide an additional core of 1500 significant original articles on biodegradation of petroleum-based synthetic plastics from January 1991 to May 2023. Studies on biodeterioration and biodegradation of petroleum-derived plastics were first conducted in the mid-1960s, with a focus on polyvinyl chloride. Soon, all major plastics were found to be extremely persistent to biodegradation. Research altered to develop biodegradable plastics. In the 1990s, microbial degradation of polyethylene plastics and enzymatic degradation of polyethylene terethphalate were confirmed and research accelerated rapidly. The discovery of plastics-degrading enzymes from bacteria and fungi and rapid biodegradation of all major plastics in some insect gut on an hourly basis opened the door to solve plastics pollution. Using the bibliometric tool Cite Space, we analyzed collaborative mapping domains, top researchers, hot research areas, and trends on plastic biodegradation with the aim of gaining a thorough understanding of current research trends. A current focus in research is enzyme-mediated biodegradation of plastics by microorganisms (fungi, bacteria, etc.) and insects. Plastics biodegradation associated with microbiome, metabolome, proteome and transcriptome of environmental microbes, gut microbes, and host insects will lead future research perspectives. [Display omitted] • Research on plastic biodegradation started in 1960s and become global mainstream. • Persistence to plastic degradation has brought new challenges and opportunities. • Microbial and enzymatic degradation has been expansively studied since 1990s. • Degradation by enzymes, microbes, and insects and fungi is research frontier. • Biodegradation of plastics will sustain on multi-omics and solution application. [ABSTRACT FROM AUTHOR]

Abstract Academics researchers and "citizen scientists" from 22 countries confirmed that yellow mealworms, the larvae of Tenebrio molitor Linnaeus, can survive by eating polystyrene (PS) foam. More detailed assessments of this capability for mealworms were carried out by12 sources: five from the USA, six from China, and one from Northern Ireland. All of these mealworms digested PS foam. PS mass decreased and depolymerization was observed, with appearance of lower molecular weight residuals and functional groups indicative of oxidative transformations in extracts from the frass (insect excrement). An addition of gentamycin (30 mg g−1), a bactericidal antibiotic, inhibited depolymerization, implicating the gut microbiome in the biodegradation process. Microbial community analyses demonstrated significant taxonomic shifts for mealworms fed diets of PS plus bran and PS alone. The results indicate that mealworms from diverse locations eat and metabolize PS and support the hypothesis that this capacity is independent of the geographic origin of the mealworms, and is likely ubiquitous to members of this species. Graphical abstract Image 1 Highlights • Consumption of polystyrene (PS) by mealworms observed in 22 countries. • PS degrades in mealworms obtained from 12 locations in the USA, UK and China. • Addition of nutrition enhances survival rate and PS consumption rate. • Antibiotics depresses gut microbes and severely inhibits PS degradation. • PS feeding shifts mealworm gut microbiome. [ABSTRACT FROM AUTHOR]

Vermiculite is one of matrix material used for constructed wetland (CW) for the treatment of municipal wastewater. Arthrobacter sp. strain C21 (CGMCC No. 7671), isolated from a constructed wetland receiving municipal wastewater, forms biofilm on the surface of vermiculite. Di-(2-ethylhexyl) phthalate (DEHP), a typical phthalate pollutant in environment, can be degraded by the biofilm of strain C21 formed on vermiculite. Results of laboratory studies indicated that DEHP was removed from aqueous phase via biodegradation, adsorption by vermiculite, and adsorption by biofilm biomass. Synergistic effect of these three reactions enhanced the overall DEHP removal efficiency. During a batch incubation test with vermiculite and the cell suspension, bacterial adhesion to the media surface occurred within 5 h and the phthalate esters (PEs) removal was due to both biodegradation and vermiculite adsorption. As the biofilm developed on surface of vermiculite (5–36 h), biodegradation became the predominance for PEs removal. As mature biofilm was formed (36–54 h), the adsorption of PEs by biofilm biomass became a main driving force for the removal of PEs from aqueous phase. The content of extracellular polymers (EPS) of the biofilm and DEHP removal performance showed a significant positive correlation ( r p > 0.86). [ABSTRACT FROM AUTHOR]

Heavy oil-produced water (HOPW) is a by-product during heavy oil exploitation and can cause serious environmental pollution if discharged without adequate treatment. Commercial biochemical treatment units are important parts of HOPW treatment processes, but many are not in stable operation because of the toxic and refractory substances, salt, present. Therefore, pilot-scale experiments were conducted to evaluate the performance of hydrolytic acidification-biological filter with airlift aeration (HA-BFAA), a novel HOPW treatment system. Four strains isolated from oily sludge were used for bioaugmentation to enhance the biodegradation of organic pollutants. The isolated bacteria were evaluated using 3-day biochemical oxygen demand, oil, dodecyl benzene sulfonic acid, and chemical oxygen demand (COD) removals as evaluation indices. Bioaugmentation enhanced the COD removal by 43.5 mg/L under a volume load of 0.249 kg COD/m day and hydraulic retention time of 33.6 h. The effluent COD was 70.9 mg/L and the corresponding COD removal was 75.0 %. The optimum volumetric air-to-water ratio was below 10. The removal ratios of the total extractable organic pollutants, alkanes, and poly-aromatic hydrocarbons were 71.1, 94.4, and 94.0 %, respectively. Results demonstrated that HA-BFAA was an excellent HOPW treatment system. [ABSTRACT FROM AUTHOR]

Abstract: Microcosm tests with uranium contaminated sediments were performed to explore the feasibility of using oleate as a slow-release electron donor for U(VI) reduction in comparison to ethanol. Oleate degradation proceeded more slowly than ethanol with acetate produced as an intermediate for both electron donors under a range of initial sulfate concentrations. A kinetic microbial reduction model was developed and implemented to describe and compare the reduction of sulfate and U(VI) with oleate or ethanol. The reaction path model considers detailed oleate/ethanol degradation and the production and consumption of intermediates, acetate and hydrogen. Although significant assumptions are made, the model tracked the major trend of sulfate and U(VI) reduction and describes the successive production and consumption of acetate, concurrent with microbial reduction of aqueous sulfate and U(VI) species. The model results imply that the overall rate of U(VI) bioreduction is influenced by both the degradation rate of organic substrates and consumption rate of intermediate products. [Copyright &y& Elsevier]

Larvae of Zophobas atratus (synonym as Z. morio , or Z. rugipes Kirsch, Coleoptera: Tenebrionidae) are capable of eating foams of expanded polystyrene (EPS) and low-density polyethylene (LDPE), similar to larvae of Tenebrio molitor. We evaluated biodegradation of EPS and LDPE in the larvae from Guangzhou, China (strain G) and Marion, Illinois, U.S. (strain M) at 25 °C. Within 33 days, strain G larvae ingested respective LDPE and PS foams as their sole diet with respective consumption rates of 58.7 ± 1.8 mg and 61.5 ± 1.6 mg 100 larvae−1d−1. Meanwhile, strain M required co-diet (bran or cabbage) with respective consumption rates of 57.1 ± 2.5 mg and 30.3 ± 7.7 mg 100 larvae−1 d−1. Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and thermal gravimetric analyses indicated oxidation and biodegradation of LDPE and EPS in the two strains. Gel permeation chromatography analysis revealed that strain G performed broad depolymerization of EPS, i.e., both weight-average molecular weight (M w) and number-average molecular weight (M n) of residual polymers decreased, while strain M performed limited extent depolymerization, i.e., M w and M n increased. However, both strains performed limited extent depolymerization of LDPE. After feeding antibiotic gentamicin, gut microbes were suppressed, and M w and M n of residual LDPE and EPS in frass were basically unchanged, implying a dependence on gut microbes for depolymerization/biodegradation. Our discoveries indicate that gut microbe-dependent LDPE and EPS biodegradation is present within Z. atratus in Tenebrionidae, but that the limited extent depolymerization pattern resulted in undigested polymers with high molecular weights in egested frass. Image 1 • Zophobas atratus eat low-density polyethylene (LDPE) and expanded polystyrene (EPS) foams. • Larvae from two sources biodegraded LDPE via limited extent depolymerization. • Larvae from different sources biodegraded EPS via broad or limited extent depolymerization. • Antibiotics inhibited depolymerization of LDPE and EPS, indicating gut-microbial dependence. Major findings are that first demonstrated depolymerization/biodegradation of LDPE and confirmed biodegradation of EPS in Zophobas atratus larvae from two different sources; verified gut-microbe dependent LDPE and EPS degradation; and discovered two different depolymerization patterns during plastic biodegradation. [ABSTRACT FROM AUTHOR]

The biodegradation of polychlorinated biphenyls (PCBs) occurs slowly when the degrading bacteria enter a low activity state, such as a viable but nonculturable (VBNC) state, under unfavorable environmental conditions. The introduction of resuscitation-promoting factor (Rpf) can re-activate VBNC bacteria. This study tested the feasibility of enhancing PCB biodegradation via supplementing Rpf in liquid culture and soil microcosms inoculated with Rhodococcus biphenylivorans strain TG9T. Exogenous Rpf resuscitated TG9T cells that had previously entered the VBNC state after 90 d of nutrient starvation, resulting in the significantly enhanced degradation of PCB by 24.3% over 60 h in liquid medium that originally contained 50 mg L−1 Aroclor 1242. In soil microcosms containing 50 mg kg−1 Aroclor 1242 and inoculated with VBNC TG9T cells, after 49 d of supplementation with Rpf, degradation efficiency of PCB reached 34.2%, which was significantly higher than the control. Our results confirmed that exogenous Rpf resuscitated VBNC TG9T cells by stimulating endogenous expression of rpf gene orthologs. The enhanced PCB-degrading capability was likely due to the increased cell numbers and the strong expression of PCB catabolic genes. This study demonstrated the role of Rpf in enhancing PCB degradation via resuscitating PCB-degrading bacteria, indicating a promising approach for the remediation of PCB contamination. Image 1 • VBNC state was studied for Rhodococcus biphenylivorans strain TG9T. • Rpf resuscitated VBNC TG9T cells and enhanced PCB biodegradation. • Exogenous Rpf stimulated endogenous expression of rpf and PCB catabolic genes. • Results highlight the feasibility of enhancing aerobic PCB degradation using Rpf. Results highlight the role of Rpf in enhancing PCB degradation via resuscitating PCB-degrading bacteria, indicating a promising approach for the remediation of PCB contamination. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET or polyester) is a commonly used plastic and also contributes to the majority of plastic wastes. Mealworms (Tenebrio molitor larvae) are capable of biodegrading major plastic polymers but their degrading ability for PET has not been characterized based on polymer chain size molecular size, gut microbiome, metabolome and transcriptome. We verified biodegradation of commercial PET by T. molitor larvae in a previous report. Here, we reported that biodegradation of commercial PET (M w 29.43 kDa) was further confirmed by using the δ13C signature as an indication of bioreaction, which was increased from − 27.50‰ to − 26.05‰. Under antibiotic suppression of gut microbes, the PET was still depolymerized, indicating that the host digestive enzymes could degrade PET independently. Biodegradation of high purity PET with low, medium, and high molecular weights (MW), i.e. , M w values of 1.10, 27.10, and 63.50 kDa with crystallinity 53.66%, 33.43%, and 4.25%, respectively, showed a mass reduction of > 95%, 86%, and 74% via broad depolymerization. Microbiome analyses indicated that PET diets shifted gut microbiota to three distinct structures, depending on the low, medium, and high MW. Metagenome sequencing, transcriptomic, and metabolic analyses indicated symbiotic biodegradation of PET by the host and gut microbiota. After PET was fed, the host's genes encoding degradation enzymes were upregulated, including genes encoding oxidizing, hydrolyzing, and non-specific CYP450 enzymes. Gut bacterial genes for biodegrading intermediates and nitrogen fixation also upregulated. The multiple-functional metabolic pathways for PET biodegradation ensured rapid biodegradation resulting in a half-life of PET less than 4 h with less negative impact by PET MW and crystallinity. [Display omitted] • High-crystallinity PET biodegradation was confirmed by testing change of δ13C. • Depolymerization is independent of gut microbes. • Polymer molecular size influences degradation rates. • Gut microbiomes synergistically biodegrade intermediates and provide nitrogen sources. • Upregulation of host genes for PET depolymerization and metabolism. [ABSTRACT FROM AUTHOR]

It is widely understood that microplastics (MPs) can induce various biological stresses in macroinvertebrates that are incapable of biodegrading plastics. However, the biodegradation and physiological responses of plastic-degrading macroinvertebrates toward MPs of different degradability levels remain unexplored. In this study, Tenebrio molitor larvae (mealworms) were selected as a model of plastics-degrading macroinvertebrate, and were tested against three common plastics of different degradability rankings: polyvinyl chloride (PVC), polystyrene (PS), and polylactic acid (PLA) MPs (size <300 μm). These three MPs were biodegraded with the rate sequence of PLA > PS > PVC, resulting in a reversed order of negative physiological responses (body weight loss, decreased survival, and biomass depletion) of mealworms. Simultaneously, the levels of reactive oxygen species (ROS), antioxidant enzyme activities, and lipid peroxidation were uniformly increased as polymer degradability decreased and intermediate toxicity increased. PVC MPs exhibited higher toxicity than the other two polymers. The oxidative stresses were effectively alleviated by supplementing co-diet bran. The T. molitor larvae fed with PLA plus bran showed sustainable growth without an increase in oxidative stress. The results provide new insights into the biotoxicity of MPs on macroinvertebrates and offer comprehensive information on the physiological stress responses of plastic-degrading macroinvertebrates during the biodegradation of plastics with different degradability levels. [Display omitted] • Microplastics (MPs) degradation rate by mealworms with sequence of PLA > PS > PVC. • Physiological responses were dependent on polymer degradability and intermediate toxicity. • Supplementing nutrient-rich co-diets alleviated oxidative stress by MPs. • Nanoplastics were not detected in frass after microplastics biodegradation. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) is a mass-produced fossil-based plastic polymer that contributes to catastrophic levels of plastic pollution. Here we demonstrated that Tenebrio molitor (mealworms) was capable of rapidly biodegrading two commercial PET resins (microplastics) with respective weight-average molecular weight (M w) of 39.33 and 29.43 kDa and crystallinity of 22.8 ± 3.06% and 18 ± 2.25%, resulting in an average mass reduction of 71.03% and 73.28% after passage of their digestive tract, and respective decrease by 9.22% and 11.36% in M w of residual PET polymer in egested frass. Sequencing of 16 S rRNA gene amplicons of gut microbial communities showed that dominant bacterial genera were enriched and associated with PET degradation. Also, PICRUSt prediction exhibited that oxidases (monooxygenases and dioxygenases), hydrolases (cutinase, carboxylesterase and chitinase), and PET metabolic enzymes, and chemotaxis related functions were up-regulated in the PET-fed larvae. Additionally, metabolite analyses revealed that PET uptake caused alterations of stress response and plastic degradation related pathways, and lipid metabolism pathways in the T. molitor larvae could be reprogrammed when the larvae fed on PET. This study provides new insights into gut microbial community adaptation to PET diet under nutritional stress (especially nitrogen deficiency) and its contribution to PET degradation. [Display omitted] • Confirmation of commercial PET biodegradation by Tenebrio molitor. • Minor difference in degradation performance of two PET polymers. • Spiroplasma , Dysgonomonas and Hafnia-Obesumbacterium associated with PET degradation. • Both host and gut microbiota contributed enzyme repertoire to PET degradation. • A plausible mechanism was proposed based on 16 S rRNA and metabolome analyses. [ABSTRACT FROM AUTHOR]

Commercial production of polystyrene (PS) -a persistent plastic that is not biodegradable at appreciable rates in most environments-has led to its accumulation as a major contaminant of land, rivers, lakes, and oceans. Recently, however, an environment was identified in which PS is susceptible to rapid biodegradation: the larval gut of Tenebrio molitor Linnaeus (yellow mealworms). In this study, we evaluate PS degradation capabilities of a previously untested strain of T. molitor and assess its survival and PS biodegradation rates for a range of conditions (two simulated food wastes, three temperatures, seven PS waste types). For larvae fed PS alone, the %PS removed in the short (12–15 h) residence time of the mealworm gut gradually increased for 2–3 weeks then stabilized at values up to 65%. Thirty two-day survival rates were >85% versus 54% for unfed larvae. For mealworms fed ∼10% w/w PS and ∼90% bran, an agricultural byproduct, rates of PS degradation at 25 °C nearly doubled compared to mealworms fed PS alone. Polymer residues in the frass showed evidence of partial depolymerization and oxidation. All of the tested PS wastes degraded, with the less dense foams degrading most rapidly. Mealworms fed bran and PS completed all life cycle stages (larvae, pupae, beetles, egg), and the second generation had favorable PS degradation, opening the door for selective breeding. [ABSTRACT FROM AUTHOR]

Bacillus sp. strain YP1, isolated from the gut of waxworm (the larvae of Plodia interpunctella ) which ate polyethylene (PE) plastic, is capable of degrading PE and utilizing PE as sole carbon source. Here we report the complete genome sequence of strain YP1, which is relevant to polyethylene depolymerization and biodegradation. [ABSTRACT FROM AUTHOR]

In this study, biodegradation of polystyrene (PS) and low-density polyethylene (LDPE) by Zophobas atratus larvae was characterized to investigate fragmentation of ingested polymers, larval physiology, gut microbiota, and microbial functional enzymes over a 28-day test. The larvae maintained high survival rates and low cannibal rates, but their body fat content decreased when fed with PS or LDPE with respective consumption rates of 43.3 ± 1.5 and 52.9 ± 3.1 mg plastics/100 larvae per day. The larvae biodegraded PS via broad depolymerization and LDPE via limited-extent depolymerization. The ingested PS and LDPE were fragmented into microplastics with a mean size of 174 and 185 μm on a volume basis, and the particles with a size of 6.3 and 5.9 μm reached a maximum number, respectively, with no nanoplastics generated. Chemical modifications of the polymers were confirmed. Significant shifts and clustering in the gut microbiota were detected with the relative abundance of Citrobacter sp. increasing when PS and LDPE were fed, as reported for other species of Tenebrionidae. Microbial functional enzymes, possibly associated with plastic degradation, including arylesterase and serine-hydrolase, were upregulated in both PS-fed and PE-fed larvae. This work provides new insights into insect-mediated biodegradation of persistent plastics for future investigations. [Display omitted] • Zophobas atratus biodegraded PS and LDPE in different depolymerization patterns. • Digestive fragmentation into microplastics occurred with no nanoplastics generated. • Significant clustering in the gut microbiota was attributed to PS and LDPE digestion. • Expression levels of functional enzymes were upregulated during plastic degradation. [ABSTRACT FROM AUTHOR]

The challenge of energy generation from biodegradation of recalcitrant organics in microbial fuel cells (MFCs) is mainly attributed to their persistence to degradation under anaerobic condition in anode chamber of MFCs. In this work, we demonstrated that electricity generation from aniline, a typical recalcitrant organic matter under anaerobic condition was remarkably facilitated by employing oxygen into bioanode of MFCs. By exposing bioanode to air, electrons of 47.2 ± 6.9 C were recovered with aniline removal efficiency of 91.2 ± 2.2% in 144 h. Limited oxygen supply (the anodic headspace was initially filled with air and then closed) resulted in the decrease of electrons recovery and aniline removal efficiency by 52.5 ± 9.4% and 74.2 ± 2.1%, respectively, and further decline by respective 64.3 ± 4.5% and 82.7 ± 1.0% occurred under anaerobic condition. Community analysis showed that anode biofilm was predominated by several aerobic aniline degrading bacteria (AADB) and anode-respiration bacteria (ARB), which likely cooperated with each other and finally featured the energy recovery from aniline. Cyclic voltammetry indicated that anodic bacteria transferred electrons to anode mainly through electron shuttle. This study provided a new sight to acquaint us with the positive role of oxygen in biodegradation of recalcitrant organics on anode as well as electricity generation. [ABSTRACT FROM AUTHOR]

Abstract: Anaerobic digestion of Taihu blue algae was tested in laboratory scale, continuous feed digesters (hydraulic retention time 10days) at 35°C and various organic loading rates (OLR). The methane production and biomass digestion performed well at OLR below 4.00gVSL−1 d−1 but deteriorated as OLR increased due to the increased ammonia concentration, causing inhibition mainly to acetate and propionate degradation. Supplementing corn straw as co-feedstock significantly improved the digestion performance. The optimal C/N ratio for the co-digestion was 20:1 at OLR of 6.00gVSL−1 d−1. Methane yield of 234mL CH4 gVS−1 and methane productivity of 1404mL CH4 L−1 d−1 were achieved with solid removal of 63%. Compared with the algae alone, the methane productivity was increased by 46% with less accumulation of ammonia and fatty acids. The reactor rate-limiting step was acetate and propionate degradation. [Copyright &y& Elsevier]

Abstract: We analyze reactive transport during in-situ bioremediation in a nonuniform flow field, involving multiple extraction and injection wells, by the method of transfer functions. Gamma distributions are used as parametric models of the transfer functions. Apparent parameters of classical transport models may be estimated from those of the gamma distributions by matching temporal moments. We demonstrate the method by application to measured data taken at a field experiment on bioremediation conducted in a multiple-well system in Oak Ridge, TN. Breakthrough curves (BTCs) of a conservative tracer (bromide) and a reactive compound (ethanol) are measured at multi-level sampling (MLS) wells and in extraction wells. The BTCs of both compounds are jointly analyzed to estimate the first-order degradation rate of ethanol. To quantify the tracer loss, we compare the approaches of using a scaling factor and a first-order decay term. Results show that by including a scaling factor both gamma distributions and inverse-Gaussian distributions (transfer functions according to the advection–dispersion equation) are suitable to approximate the transfer functions and estimate the reactive rate coefficients for both MLS and extraction wells. However, using a first-order decay term for tracer loss fails to describe the BTCs at the extraction well, which is affected by the nonuniform distribution of travel paths. [Copyright &y& Elsevier]

Plastic biodegradation by mealworm is regarded as an emerging strategy for plastic disposal. In this study, the polystyrene (PS) and low density polyethylene (LDPE) degradation efficiency by yellow mealworms (Tenebrio molitor larvae) supplemented with bran and the effects of plastics on the gut core microbiome were explored to construct a circular and continuous reactor for plastic biodegradation in the future. The gut microbiome was also investigated with dietary shift to explore the relationship between specific diets and gut microbes. The bran plus plastic (7:1 ratio, w/w) co-diet contributed to the mealworm survival and growth. The formation of −C˭O−/−C−O− groups in the plastic-fed mealworms frass represented the oxidation process of plastic biodegradation in the mealworm gut. The changes in molecular weights (M w , M n and M z) of residual PS and LDPE in mealworms frass compared with that of PS and PE feedstock confirmed the plastic depolymerization and biodegradation. Lactobacillus and Mucispirillum were significantly associated with PE + bran diet compared to bran diet and PE diet, representing the response of mealworm gut microbiome to the bran and plastic mixture was distinguished from either bran or plastics alone. The gut microbiome changed substantially with the diet shift, indicating that microbial community assembly was a stochastic process and diverse plastic-degrading bacteria might occur in the mealworm gut. [Display omitted] • A 7:1 mass ratio for bran to plastic facilitated growth of plastic-fed larvae. • The larvae gut microbiome was shaped by the synergistic effect of bran and plastic. • A diet shift caused reassembly of the gut microbial community. • The same nutrients at different feeding stages caused a shift in the gut microbiome. • Microbial community assembly in the gut might be dominated by stochastic processes. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is biodegraded rapidly under composting or thermophilic temperature but slowly under natural conditions with substantial microplastics generated. In this study, we examined the feasibility of PLA biodegradation and developed a novel approach for PLA waste management using yellow mealworms (Tenebrio molitor larvae) to achieve biodegradation and resource recovery simultaneously. Results confirmed PLA biodegradation in mealworms as sole PLA and PLA-bran mixtures (10%, 20%, 30% and 50% PLA, wt/wt). Feeding PLA-bran mixtures supported the larval development with higher survival rates and lower cannibal rates than feeding PLA only at ambient temperature. The PLA conversion efficiency was 90.9% with 100% PLA diet and was around 81.5–86.9% with PLA-bran mixtures. A peak insect biomass yield was achieved at a PLA ratio of 20%. PLA biodegradation was verified via detection of chemical and thermal modifications. Gut microbial community analysis indicated that intestinal communities shifted with PLA biodegradation, resulting in clusters with OTUs unique to the PLA diet. Based on these findings, we propose a circular approach for PLA waste management via resource recovery of used PLA as the feedstock for insect biomass production, management of mealworm excrement waste as fertilizer, and utilization of agricultural products for PLA production. [Display omitted] • Mealworms digested polylactic acid (PLA) to support their life activities. • Biodegradation of PLA in mealworms was confirmed via FTIR and TGA. • A peak biomass yield was achieved at 20% PLA with a co-diet bran (wt/wt). • The removal efficiency of PLA ingested was more than 81.5% in mealworms. • The gut microbiome significantly shifted due to PLA biodegradation. [ABSTRACT FROM AUTHOR]

Polypropylene (PP), a fossil-based polyolefin plastics widely used worldwide, is non-hydrolyzable and resistant to biodegradation as a major source of plastic pollutants in environment. This study focused on feasibility of PP biodegradation in the larvae of two species of darkling beetles (Coleoptera: Tenebrionidae) i.e., yellow mealworms (Tenebrio molitor) and superworms (Zophobas atratus) using PP foam with number-, weight-, and size-average molecular weights (M n , M w , and M z) of 109.8, 356.2, and 765.0 kDa, respectively. The tests were conducted in duplicates with respective larvae (300 T. molitor and 200 Z. atratus each incubator) at 25 °C and 65% humidity for over a 35-day period. The larvae of T. molitor and Z. atratus fed with PP foam as sole diet consumed PP at 1.0 ± 0.4 and 3.1 ± 0.4 mg 100 larvae−1 days−1, respectively; when fed the PP foam plus wheat bran, the consumption rates were enhanced by 68.11% and 39.70%, respectively. Gel permeation chromatography analyses of the frass of T. molitor and Z. atratus larvae fed PP only indicated that M w was decreased by 20.4 ± 0.8% and 9.0 ± 0.4%; M n was increased by 12.1 ± 0.4% and 61.5 ± 2.5%; M z was decreased by 33.8 ± 1.5% and 32.0 ± 1.1%, indicating limited extent depolymerization. Oxidation and biodegradation of PP was confirmed through analysis of the residual PP in frass. Depression of gut microbes with the antibiotic gentamicin inhibited PP depolymerization in both T. molitor and Z. atratus larvae. High throughput 16S rRNA sequencing revealed that Citrobacter sp. and Enterobacter sp. were associated with PP diets in the gut microbiome of Z. atratus larvae while Kluyvera was predominant in the T. molitor larvae. The results indicated that PP can be biodegraded in both T. molitor and Z. atratus larvae via gut microbe-dependent depolymerization with diversified microbiomes. Unlabelled Image • Tenebrio molitor and Zophobas atratus consumed PP foam. • PP was biodegraded via limited extent depolymerization with M z reduction >32%. • Antibiotic tests indicated gut-microbe dependent biodegradation in both larvae. • Microbiome shifted with distinct dominant species during PP degradation. [ABSTRACT FROM AUTHOR]

Yellow mealworms (Tenebrio molitor larvae) are capable of biodegrading polystyrene (PS) and low-density polyethylene (LDPE). This study tested biodegradation of one expanded PS (EPS) with a weight-average molecular weight (M w) 256.4 kDa and two LDPE foams with respective M w of 130.6 kDa (PE-1) and 288.7 kDa (PE-2) in T. monitor larvae obtained in Beijing, China. The larvae consumed EPS and both LDPEs over a 60 day. Fourier transform infrared spectroscopy and thermogravimetric analyses of frass confirmed the formation of new oxygen-containing functional groups, as well as a change in physical property and chemical modification, indicating that biodegradation of EPS and LDPE occurred. Gel permeation chromatography analysis confirmed broad depolymerization of EPS and PE-1 (i.e., a decrease in both M w and a number-average molecular weight (M n)) but revealed limited extent depolymerization of PE-2 (i.e. , increase in M n and decrease in M w). For all materials, the size-average molecular weight (M z) was decreased. Biodegradation and oxidation of EPS and LDPE were confirmed using FTIR and TGA analysis. Depression of gut microbes by the antibiotic gentamicin resulted in significant inhibition of EPS depolymerization but did not stop LDPE depolymerization, resulting in the increase in M n and revealing that PS biodegradation was gut microbe-dependent but LDPE biodegradation was less dependent or independent of gut microbes. Gut microbial community analysis indicated that, as expected, under different dietary conditions, the intestinal flora significantly shifted to communities associated with biodegradation of EPS and LDPE. The results indicated the complexity and limitation of biodegradation of plastics in plastics-eating T. molitor larvae. Image 1 • Biodegradation of PS and two LDPE with decreased M z by Tenebrio molitor larvae. • Broad depolymerization of PS and one LDPE with decreased both M w and M n. • Limited extent depolymerization of LDPE with decreased M w but increased M n. • The antibiotic gentamicin inhibited depolymerization of PS but not LDPE. • Distinct microbiomes observed with three different diets bran, PS, and LDPE. [ABSTRACT FROM AUTHOR]

• PVC ingested in Tenebrio molitor larvae was broadly depolymerized within 12–15 h. • Biodegradation of PVC was confirmed by polymer modification. • PVC was partially mineralized with about 3% to chloride. • Depolymerization was inhibited by gentamicin thus gut microbe dependent. • Gut microbiome shifted significantly after feeding PVC. Tenebrio molitor larvae (Coleoptera: Tenebrionidae) are capable of depolymerizing and biodegrading polystyrene and polyethylene. We tested for biodegradation of Polyvinyl Chloride (PVC) in T. molitor larvae using rigid PVC microplastic powders (MPs) (70–150 μm) with weight-, number-, and size-average molecular weights (M w , M n and M z) of 143,800, 82,200 and 244,900 Da, respectively, as sole diet at 25 °C. The ingestion rate was 36.62 ± 6.79 mg MPs 100 larvae-1 d-1 during a 16-day period. The egested frass contained about 34.6% of residual PVC polymer, and chlorinated organic carbons. Gel permeation chromatography (GPC) analysis indicated a decrease in the M w , M n and M z by 33.4%, 32.8%, and 36.4%, respectively, demonstrating broad depolymerization. Biodegradation and oxidation of the PVC MPs was supported by the formation of O C and O C functional groups using frontier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H NMR), and by significant changes in the thermal characteristics using thermo-gravimetric analysis (TGA). Chloride released was counted as about 2.9% of the PVC ingested, indicating limited mineralization of the PVC MPs. T. molitor larvae survived with PVC as sole diet at up to 80% over 5 weeks but did not complete their life cycle with a low survival rate of 39% in three months. With PVC plus co-diet wheat bran (1:5, w/w), they completed growth and pupation as same as bran only in 91 days. Suppression of gut microbes with the antibiotic gentamicin severely inhibited PVC depolymerization, indicating that the PVC depolymerization/biodegradation was gut microbe-dependent. Significant population shifts and clustering in the gut microbiome and unique OTUs were observed after PVC MPs consumption. The results indicated that T. molitor larvae are capable of performing broad depolymerization/biodegradation but limited mineralization of PVC MPs. [ABSTRACT FROM AUTHOR]

Despite increasing evidence of widespread plastic pollution in soil, it remains largely unknown about the fate of plastic influenced by soil animals. In this study, ingestion and biodegradation capability of expanded polystyrene (PS) foam was investigated in a globally distributed soil invertebrate, Achatina fulica. After 4-week exposure, 18.5 ± 2.9 mg polystyrene was ingested per snail, and egested microplastics (1.343 ± 0.625 mm) in feces with significant mass loss of mean 30.7%. Gel permeation chromatography analysis indicated a significant increase in weight-average molecular weight (M w) and number-average molecular weight (M n) of feces-residual PS, indicating limited extent depolymerization. Fourier transform infrared spectroscopy and proton nuclear magnetic resonance confirmed the formation of functional groups of oxidized intermediates. Suppression of gut microbes with oxytetracycline did not affect the depolymerization, indicating the independence of gut microbes. High-throughput sequencing analysis revealed significant shifts in the gut microbiome after ingestion of PS, with an increase of family Enterobacteriaceae , Sphingobacteriaceae , and Aeromonadaceae , suggesting that gut microorganisms were associated with PS biodegradation. These findings suggest that plastic litter can be disintegrated into microplastics and partially biodegraded by A. fulica , which highlights the significance of soil animals for the fate of plastic and its biodegradation in soil environments. Unlabelled Image • Every land snail A. fulica ingested mean 18.5 mg expanded polystyrene for 4 weeks. • Snails egested microplastics in feces with significant mass loss of mean 30.7%. • GPC showed an increase in PS molecular weights in feces, confirming depolymerization. • FTIR, 1HNMR showed oxidation of PS polymers and chemical modification in feces. • Significant shifts in gut microbial community appeared after the snails ingested PS. [ABSTRACT FROM AUTHOR]