PBAT/PLA humic acid biodegradable film applied on solar greenhouse tomato plants increased lycopene and decreased total acid contents

Lignin-polybutylene adipate-co-terephthalate(PBAT)-starch@urea bilayer nanohybrid biocomposite enable superior controlled slow-released fertilizer with good water-retention

Slow-release fertilizers (SRFs) have revolutionized agricultural practices by enhancing nutrient utilization efficiency and minimizing environmental contamination. However, conventional SRFs face significant limitations, including unpredictable release patterns, dependence on non-biodegradable synthetic coatings, and inadequate performance in arid soil conditions. To address these challenges, we have developed an innovative approach to transform agricultural waste biomass into a multifunctional lignin-based SRF with superior water retention properties. Our bilayer lignin-based slow-release urea fertilizer (PSLB-SRF) was engineered using cost-effective, biodegradable materials: starch, poly(butylene adipate-co-terephthalate) (PBAT), and lignin derived from corn stover, a major agricultural byproduct. The resulting nanohybrid biocomposite exhibits exceptional controlled-release properties, demonstrating only 55 % cumulative urea release over 28 days - well within the Chinese National Standard GB requirement of <60 %. Furthermore, the material shows remarkable water retention capabilities, as evidenced by its ability to maintain 100 % chickweed survival under simulated drought conditions in field experiments. This breakthrough highlights the composite's potential for arid region applications. This cost-effective, biodegradable, and multifunctional lignin-based nanohybrid biocomposite represents a significant advancement in sustainable agriculture, offering a dual solution for agricultural waste valorization and developing high-performance fertilizers for sustainable farming practices.

Polylactic acid degradable mulching film modified by N-TiO2/g-C3N4 photocatalyst for removal of carbendazim in water and soil under visible light

Non-degradable plastic mulching films and pesticide residues pose significant environmental pollution and ecological challenges. In this work, polylactic acid mulch film (PLA-MF) was successfully modified by nitrogen-doping titanium dioxide (N-TiO2) and g-C3N4 composites (N-TiO2/g-C3N4, defined as g-CNNT), which was used for the photocatalytic degradation of carbendazim (CBD) in water and soil under visible light irradiation. In water system, the PLA-MF/g-CNNT exhibited excellent photocatalytic performance for CBD removal with the 99 % of degradation efficiency after 7 h. Active oxidative species played primarily roles for CBD degradation with the contributions of •O2- > h+ > •OH by electron paramagnetic resonance (EPR). The proposed degradation pathway for CBD involved hydroxylation, demethylation, decarboxylation, and deamination, ultimately leading to its mineralization into CO2, H2O, NH3, and NH4+. In the soil system (with moisture contents of 70-80 % and a soil thickness of 0.5-1 mm), the degradation efficiency of CBD reached 50-60 % after 8 h. In addition, pot experiments confirmed that PLA-MF/g-CNNT system could promote Chinese white cabbage's growth compared with traditional plastic mulching film. Meanwhile, g-CNNT and PLA-MF/g-CNNT could facilitate the improvement on the contents of microbial carbon and microbial nitrogen, total carbon and total nitrogen in soil. This study proposes a promising approach for the removal of pesticide residues in surface water and soil using photocatalytic technology integrated with degradable mulch films.

Necroecological Trophic Transfer of Microplastics: Insights into the Ecotoxicity of Petroleum-Derived and Biodegradable Polymers

Although the toxicity of petroleum-derived microplastics (MPs) has been widely investigated, the impact of biomicroplastics (BioMPs) remains controversial, and the necroecological trophic transfer of both is still poorly understood. Our study reveals that biomicroplastics may pose ecotoxicological risks comparable to or greater than those of petroleum-derived plastics, a finding that should raise concern. We aimed to evaluate the possible translocation of polystyrene (PS) and polylactic acid (PLA) MPs from mice to the necrophagous fly Synthesiomyia nudiseta and their potential effects on the larval stage. Mice were inoculated intraperitoneally with different doses of MPs [9 (I) and 90 mg/kg (II)] and subjected to the decomposition process (for ten days), allowing colonization by larvae. Our results confirmed the translocation of MPs from mice to S. nudiseta larvae, resulting in a greater accumulation of PLA-MPs compared to PS-MPs. We observed that exposure to MPs significantly influenced biomass accumulation, with larvae from the PS-I and PLA-I groups showing increased biomass. In contrast, those from the PLA-II group exhibited lower biomass. AChE activity was modulated in a concentration-dependent manner, with an increase observed in larvae exposed to PLA-MPs, indicating a potential neurotoxic effect. In addition, there was an increased production of reactive oxygen species (ROS), especially in the groups exposed to higher concentrations of MPs, without a proportional response of antioxidant enzymes, suggesting a redox imbalance and oxidative stress. The elevated serotonin levels and reduced dopamine observed in larvae exposed to MPs indicate a possible redirection of energy resources and changes related to a metabolic adaptation to the stress imposed by MPs. Principal component analysis (PCA) showed that PC1 was strongly influenced by biomarkers such as trypsin, chymotrypsin, AChE, ROS, and dopamine activity, highlighting that PLA-MPs (at the highest concentration) induced more pronounced toxic effects than PS-MPs. This finding was corroborated by discriminant analysis, which revealed a clear separation between the experimental groups, and by multiple regression analysis, which confirmed a strong relationship between MP concentration and larval biomarker responses, indicating that the type and concentration of MPs explained approximately 65% ​​of the variation in the biomarkers evaluated. In conclusion, our study demonstrates for the first time the necroecological trophic translocation of MPs between vertebrates and invertebrates, highlighting the potential risks of biomicroplastics.

Efficient biodegradation of poly(butylene adipate-co-terephthalate) in mild temperature by cutinases derived from a marine fungus

Poly(butylene adipate-co-terephthalate) (PBAT) waste gradually accumulates in the environment, posing ecological risks. Enzymatic hydrolysis holds great potential in the end-of-life management of PBAT, but reported enzymes require high reaction temperatures, limiting their practical industrial applications. In this study, we discovered that the marine fungus Alternaria alternata FB1 can efficiently degrade PBAT at 28 °C. Two cutinases designated as AaCut4 and AaCut10, were identified and verified as key enzymes responsible for this degradation process. Notably, the recombinant AaCut10 was able to depolymerize 82.14 % PBAT within 24 h and fully decompose it within 48 h at 37 °C. Through protein engineering, the yield of terephthalic acid monomer was increased to 96.01 %, highlighting its potential for facilitating PBAT upcycling. Furthermore, based on the investigation of the distribution patterns of PBAT hydrolases, novel degradative agents have been identified within unique ecological niches, leading to the establishment of a comprehensive screening repository of PBAT hydrolases. Overall, our study provides new candidates for enzymatic PBAT recycling with low energy consumption and offers insights into the PBAT degradation manner in ecosystems.

Comparing environmental fate and ecotoxicity of conventional and biodegradable plastics: A critical review

Plastic pollution is a consequential problem worldwide, prompting the widespread use of biodegradable plastics (BPs). However, not all BPs are completely degradable under natural conditions, but instead produce biodegradable microplastics (BMPs), release chemical additives, and absorb micropollutants, thus causing toxicity to living organisms in similar manners to conventional plastics (CPs). The new problems caused by biodegradable plastics cannot be ignored and requires a thorough comparison of the differences between conventional and biodegradable plastics and microplastics. This review comprehensively compares their environmental fates, such as biodegradation and micropollutant sorption, and ecotoxicity in soil and water environments. The results showed that it is difficult to determine the natural conditions required for the complete biodegradation of BPs. Some chemical additives in BPs differ from those in CPs and may pose new threats to ecosystems. Because of functional group differences, most BMPs had higher micropollutant sorption capacities than conventional microplastics (CMPs). The ecotoxicity comparison showed that BMPs had similar or even greater adverse effects than CMPs. This review highlights several knowledge gaps in this new field and suggests directions for future studies.

Biodegradable microplastics reduce the effectiveness of biofertilizers by altering rhizospheric microecological functions

The effectiveness of biofertilizers as a cost-effective crop yield enhancer can be compromised by residual soil pollutants. However, the impact of accumulated polyadipate/butylene terephthalate microplastics (PBAT-MPs) from biodegradable mulch films on biofertilizer application and the consequent growth of crop plants remains unclear. Here, the effects of different levels of PBAT-MPs in soil treated with Bacillus amyloliquefaciens biofertilizer were assessed in a four-week potted experiment. PBAT-MPs significantly decreased the growth-promoting effect of the biofertilizer on Brassica chinensis L., resulting in a notable reduction in both above- and belowground biomass (up to 52.91% and 57.53%, respectively), as well as nitrate and crude fiber contents (up to 12.18% and 13.64%, respectively). In the rhizosphere microenvironment, PBAT-MPs increased soil organic carbon by 2.63-fold and organic matter by 2.68-fold, while enhancing sucrase (from 67.55% to 108.89%) and cellulase (from 31.26% to 49.10%) activities. PBAT-MPs also altered the rhizospheric bacterial community composition/diversity, resulting in more complex microbial networks. With regard to microbial function, PBAT-MPs impacted carbon metabolic function by inhibiting the 3-hydroxypropionate/4-hydroxybutyrate fixation pathway and influencing chitin and lignin degradation processes. Overall, the rhizospheric microbial profiles (composition, function, and network interactions) were the main contributors to plant growth inhibition. This study provides a practical case and theoretical basis for rational use of biodegradable mulch films and indicates that the residue of biodegradable films needs pay attention.

Mechanical, chemical, and bio-recycling of biodegradable plastics: A review

The extensive use of petroleum-based non-biodegradable plastics for various applications has led to global concerns regarding the severe environmental issues associated with them. However, biodegradable plastics are emerging as green alternatives to petroleum-based non-biodegradable plastics. Biodegradable plastics, which include bio-based and petroleum-based biodegradable polymers, exhibit advantageous properties such as renewability, biocompatibility, and non-toxicity. Furthermore, certain biodegradable plastics are compatible with existing recycling streams intended for conventional plastics and are biodegradable in controlled and/or predicted environments. Recycling biodegradable plastics before their end-of-life (EOL) degradation further enhances their sustainability and reduces their carbon footprint. Since the production of biodegradable plastic is increasing and these materials will coexist with conventional plastics for many years to come, it is essential to identify the optimal recycling options for each of the most prevalent biodegradable plastics. The substitution of virgin biodegradable plastics by their recyclates leads to higher savings in the primary energy demand and reduces global warming impact. This review covers the current state of the mechanical, chemical, and bio-recycling of post-industrial and post-consumer waste of biodegradable plastics and their related composites. The effects of recycling on the chemical structure and thermomechanical properties of biodegradable plastics are also reported. Additionally, the improvement of biodegradable plastics by blending them with other polymers and nanoparticles is comprehensively discussed. Finally, the status of bioplastic usage, life cycle assessment, EOL management, bioplastic market, and the challenges associated with the recyclability of biodegradable plastics are addressed. This review gives comprehensive insights into the recycling processes that may be employed for the recycling of biodegradable plastics.