Biodegradation Efficiency Research Articles

Efficient biodegradation of flurochloridone herbicide by Streptomyces parvus strain F-G-2 and its degradation mechanism

Efficient biodegradation of flurochloridone herbicide by Streptomyces parvus strain F-G-2 and its degradation mechanism

Interaction of sulfate-reducing bacteria and methanogenic archaea in urban sewers, leads to increased risk of proliferation of antibiotic resistance genes.

Sewers are considered a potential reservoir of antibiotic resistance. However, the generation of antibiotic resistance genes (ARGs) in microbial communities in pipeline biofilms under antibiotic stress remains unexplored. In this study, the biodegradation efficiency of tetracycline (TCY) and sulfamethoxazole (SMX) was evaluated in a pilot reactor of the sewers. The results showed that under TCY and SMX stress, the degradation efficiency of sewage water was inhibited. The most abundant ARGs detected in the biofilm samples were TCY-related genes (e.g., tetW/N/W, tetC, and tetM), accounting for 34.1%. The microbial community composition varied, and the correlation analysis showed that antibiotic stress had a certain impact on the biological metabolic activity and function of the urban sewers. The community structure and diversity of biofilms enabled the evaluation of the bioconversion of antibiotics. Notably, Anaerocella and Paludibacter directly influenced the methanogenesis and sulfate reduction processes, playing a key role in the interaction between sulfate-reducing bacteria and methanogenic archaea. These microorganisms facilitated the proliferation of ARGs (tet and sul) in the biofilms through horizontal gene transfer. This study provides insight into the front-end control of ARGs, further improving sewage treatment plant processes and reducing the environmental and health risks caused by antibiotic abuse.

In situ generation of Copper sulfide within Poly(lactic-co-glycolic acid): A strategy for Safer photothermal therapy in Triple-Negative breast cancer.

Copper sulfide nanoparticles (CuS NPs) have garnered significant attention in photothermal therapy (PTT) owing to their facile synthesis, biodegradability, stability, and excellent photothermal conversion efficiency. Nonetheless, their potential toxic effects have restricted their application. This research focuses on the encapsulation of CuS NPs with the biocompatible polymer poly(lactic-co-glycolic acid) (PLGA) to enhance their biocompatibility, thereby improving the efficacy and safety of PTT in the treatment of triple-negative breast cancer (TNBC). Three distinct methods, namely aqueous phase loading method, oil phase loading method, and "in situ reduction" method were employed to synthesize PLGA-coated CuS (CuS@PLGA) NPs to optimize the encapsulation rate of CuS. Among these, the CuS@PLGA NPs fabricated via the "in situ reduction" method demonstrated the highest encapsulation efficiency for CuS, achieving a rate of (90.4 ± 3.3)%. The resulting CuS@PLGA NPs exhibited high stability, excellent photothermal effect, and good tumor-targeting ability. Moreover, CuS@PLGA NPs demonstrated enhanced anti-tumor efficacy and biocompatibility compared to CuS NPs in both in vitro and in vivo experiments. Consequently, this study offers an effective and safety strategy for PTT treatment of TNBC.

Biodegradation of Benzophenone-3 in Non-Sterile Culture Process Using Klebsiella huaxiensis W2

Benzophenone-3 (BP3) is an organic pollutant widely detected in soil and aquatic environments. The aims of this study were to isolate a bacterium which is capable of degrading BP3 and converting it into non-toxic products, and to design a non-sterile culture process which may be applied to the real biological treatment systems for the bioremediation of BP3. Klebsiella huaxiensis W2 (GenBank accession number: PQ143284) isolated from a wastewater treatment system was found to have high potency to degrade BP3. This bacterium degraded BP3 into two byproducts: phenol, 2,4-bis-(1,1-dimethylethyl) and benzyl benzoate. Oxygenases (P450 monooxygenases, dioxygenases etc.) were predicted to be effective in BP3 degradation. BP3-degradation products did not cause a toxicity on fibroblast cell line. Optimizing inoculum size, that is, inoculating the high size (1–2%) of the bacterial preculture into the wastewater-based medium, make the bacterium more dominant in this medium, thus enabling the bacterial cells to degrade BP3 under non-sterile culture conditions. In this process, biodegradation efficiency was not affected notably from temperature variations, and the bacterium was able to hydrolyze about 99.33% of 1 g/L BP3 within 120 h. Overall, K. huaxiensis W2 was deduced to possess the potency for being used as a bioremediation agent in non-sterile biological treatment systems, in which sterilization process, temperature control, and nutrient supplementation were not needed. The designed process may find applications in the bioremediation of wastewater and sewage effluents. This is the first study using K. huaxiensis in a non-sterile environment for BP3 degradation.

In silico analysis and gene expression patterns of lignin peroxidase isozymes in Phanerochaete chrysosporium.

Phanerochaete chrysosporium (Pc), is a prominent lignin-degrading fungus which serves as an important source for lignin-degrading enzymes (LDEs). The present study was focused on a detailed in silico analysis and gene expression patterns of lignin peroxidases (PcLiPs), which is a significant class of LDEs. In spite of extensive research on P. chrysosporium enzymes, the number of PcLiP isozymes remains unexplored. In the present study, ten PcLiP sequences were identified by the RedoXiBase and BLAST survey, displaying putative glycosylated extracellular protein which was approximately 38 to 39 kDa. Different domains of the protein included putative binding sites for stress, nutrient components, metal ions, peroxidase motifs, ligninase motifs, and also secretory signal peptides. Molecular docking analysis of all the PcLiPs, showed that the PcLiP4 had strong binding affinity towards hydrogen peroxide (H2O2), manganese(II) sulfate (MnSO4),and veratryl alcohol (VA) as compared to other PcLiPs. In order to analyze the PcLiPs gene expression, the fungus was incubated in potato dextrose broth medium (PDB). Notably, high expression levels of PcLiPs were observed during the 48-h growth stage of the fungus and there was variable gene expression under conditions of incubation with different stress factors and co-factors, such as H2O2, MnSO4, VA, and heat stress. Among the ten PcLiPs characterized, isozymes, such as, PcLiP4, PcLiP9, PcLiP10, and PcLiP8 exhibited varying concentrations of nutritional elements and stress levels together with high expression. Present study employing in silico analysis, molecular docking studies, and gene expression analysis demonstrated that the PcLiP4 could be an ideal candidate for lignin biodegradation. Results showed the operation of specific regulatory mechanisms which govern PcLiPs expression. As an outcome, regulatory factors towards obtaining high yield of PcLiPs and the best isozyme for heterologous gene expression were identified. These findings would contribute to enhancing the efficiency of biodegradation of lignocelluloses and related recalcitrant waste products.

Sustainable approach for the degradation of Contrast dye Evans blue by Enterobacter cloacae strain SD4-1

BackgroundDischarge of dye complexes through industrial effluents continues to be a never-ending problem for the environment. Several degradation techniques have been experimented with, of which utilizing biological entities for the effective degradation of these dye molecules is extensively studied and still being explored. The present study focuses on (i) isolation of bacterial strains from the contaminated agricultural lands (ii) screening the isolates for their decolourization efficiency of Evans blue dye (iii) optimization of culture parameters such as temperature, pH, concentration of dye and nitrogen source for effective decolourization (iv) analysing the effect of degradation of diazo dye Evan's blue by the selected strain using GCMS analysis. MethodsThe bacterial strains were isolated from contaminated agricultural lands in Chennai, Tamil Nadu, India. The collected samples were aseptically transferred to the laboratory and stored for further studies. The collected samples were serially diluted, and the colonies with distinct morphology were pure-cultured. The isolated strains were studied for their efficiency to decolourize the dye Evans blue dye. The strain with higher decolourization efficiency was selected and optimized for parameters such as temperature, pH, nitrogen source and concentration of dye. The degradation of dye by the isolate was analysed by GCMS. Significant FindingsThe investigation unveiled that the strain SD4-1 of Enterobacter cloacae effectively decolorizes Evans blue dye at 37°C and pH 6.0, utilizing Sodium nitrate as the nitrogen source. SD4-1 exhibited an impressive dye decolourization efficiency of approximately 75%. The comprehensive GCMS analysis verified the bacterium's capability to fully degrade the azo dye Evans blue. Consequently, this study concludes that the SD4-1 Enterobacter cloacae strain holds promising potential for the efficient biodegradation of Evan's blue dye. Its application as a highly effective biological agent in the practical removal of dyes from textile industries is envisaged. Notably, this organism demonstrates superior performance in comparison to other studies where a mixture of dyes or consortia of microorganisms were employed for dye decolourization.

Effect of hydraulic retention time and dissolved oxygen concentration on the biodegradation efficiency of phenol in an activated sludge reactor at different organic loading rates

Phenol is an important contaminant in wastewater from processing and refining plants, its presence in ecosystems is related to the production and degradation of numerous pesticides. Their toxic action is related to their hydrophobicity, generation of organic radicals and reactive oxygen species, causing mutagenesis and carcinogenesis in humans and other living organisms. In this research, an activated sludge system was studied for the treatment of wastewater with high concentration of phenol for reuse, varying the hydraulic retention time and dissolved oxygen concentration. The results showed the best COD removal rate (55%) and phenol biodegradation (49%) during experiment IV, at a wastewater dilution rate of 25% (v/v), dissolved oxygen (DO) feed of 1.5 ppm, hydraulic retention time (HRT) of 2.81 days and organic load (Bv=7.5kgCOD/m3.d).

Construction of Nanohydroxyapatite/Poly(sodium lipoate)-Based Bioactive Hydrogels for Cranial Bone Regeneration.

Persistent oxidative stress following bone defects significantly impedes the repair of bone tissue. Designing an antioxidative hydrogel with a suitable mechanical strength can help alter the local microenvironment and promote bone defect healing. In this work, α-lipoic acid (LA), a natural antioxidant small molecule, was chemically cross-linked with lipoic acid-functionalized poly(ethylene glycol) (PEGx, x = 6k or 10k) in sodium bicarbonate solution, to prepare LA-PEGx hydrogels (LPx, x = 6k or 10k). Furthermore, nanohydroxyapatite (nHA)-LA-PEGx (HLPx, x = 6k) hydrogels were constructed through incorporating nHA. The hydrogels exhibited moderate mechanical strength, facile injectability, self-healability, adhesion, biodegradability, biocompatibility, and promising antioxidation efficiency. We verify the advantage of the HLP6k-3 hydrogel in a rat cranial defect model. Through the regulation of reactive oxygen species (ROS), osteoconduction, and biomineralization capabilities, our system can promote new bone formation. Overall, bioactive hydrogels with multiple functions hold significant promise for repairing bone defects.

Biodegradation of Organophosphorus Insecticides by Bacillus Species Isolated From Soil.

This study investigates the biodegradation of methyl parathion, an organophosphate pesticide used in paddy fields. Microbial degradation transforms toxic pesticides into less harmful compounds, influenced by the microbial community in the soil. To isolate different microbial colonies, soil samples from an organophosphorus-treated groundnut field were plated on nutrient agar and MSM with 1% glucose and 0.25 mM methyl parathion. Biodegradation efficiency was determined by estimating the OP hydrolase enzyme activity spectrophotometrically. HPLC was used to quantify residual methyl parathion concentrations in the culture medium. The identified isolate effectively degraded methyl parathion in MSM with 0.25 mM methyl parathion which showed peak hydrolase activity (2.02 µmol/min/mg) after 96 h of incubation and the residual methyl parathion level was determined as 6.2 µmol by HPLC quantification. The efficient isolate was identified as Bacillus cereus by using a 16S rRNA molecular marker and the sequence was subjected to MEGA11 phylogenetic tree construction. The results show that the SM6 clade shared with B. cereus 16S rRNA sequence. B. cereus (SM6) showed substantial enzyme activity and the specific reported opdA gene-coded protein is involved in ATP hydrolysis. This OP hydrolase makes it a strong candidate for bioremediation of methyl parathion. Molecular analysis suggested that the opdA gene, likely chromosomally located, plays a key role in degradation, with potential involvement of the "Cell division protein FtsK" gene responsible for hydrolase activity. Organophosphorus compounds, widely used in agriculture, pose environmental concerns due to their persistence. This study focuses on isolating pesticide-degrading bacteria to expedite bioremediation, aiming for efficient degradation. This study highlights the cross-adaptation phenomenon, where B. cereus strains degrade similar compounds, improving bioremediation strategies.

Solar Energy-Promoted Bisphenol A Degradation with Immobilized Laccase in an Fe3O4-Embedded Metal-Organic Framework.

Bisphenol A (BPA) is a well-recognized endocrine-disrupting chemical that poses risks to both human health and the environment. Laccase can effectively biodegrade bisphenol A, but the low environmental temperature (∼25 °C) restricts the biodegradation efficiency. In this study, the enzyme laccase and Fe3O4 with solar-thermal conversion capability were coimmobilized into zeolitic imidazolate framework-8 (Lac@ZIF-8-Fe3O4) to facilitate efficient biodegradation of bisphenol A under simulated solar irradiation. Compared to free laccase, Lac@ZIF-8-Fe3O4 exhibited high activity recovery (115.5%), an ∼39% increased catalytic constant, more effective bisphenol A biodegradation (up to 24-fold) at extensive bisphenol A concentrations (5-100 mg/L), excellent thermal stability (50 °C, 12 h), acid-tolerance (pH 3), and storage ability in 10 days. Simulated solar irradiation (1 kW/m2) increased the temperature of Lac@ZIF-8-Fe3O4 solution (10 μg laccase/mL) from 25 to 42.5 °C within 15 min, resulting in 96.4% biodegradation of bisphenol A within 60 min, nearly double the biodegradation efficiency under dark condition (55.9%). Furthermore, Lac@ZIF-8-Fe3O4 maintained 99.0% biodegradation efficiency even after 12 recycles of use under simulated solar irradiation (5 mg/L bisphenol A, 80 min/cycle). This work has thus offered efficient biocatalysis for integrating solar-energy promotion and enzymatic catalysis in treating environmental BPA pollutants. Further, the experimental findings benefited from the development of more sustainable and high-performance immobilized enzyme preparations for pollutant treatment via solar-thermal promotions.

Dual-purpose elemental sulfur for capturing and accelerating biodegradation of petroleum hydrocarbons in anaerobic environment

Hydrophobic organic pollutants in aqueous environments are challenging to biodegrade due to limited contact between microorganisms, the pollutants and the electron acceptor, particularly under anaerobic or anoxic conditions. Here, we propose a novel strategy that uses inexpensive, dual-function elemental sulfur (S0) to enhance biodegradation. Using petroleum hydrocarbons as the target pollutants, we demonstrated that hydrophobic and nonpolar S° can concentrate hydrocarbons while simultaneously serving as an electron acceptor to enrich hydrocarbon-degrading bacteria. The permeable reactive barrier filled with S0 effectively removed petroleum hydrocarbons. In addition to rapid adsorption, we discovered, for the first time, that petroleum hydrocarbons underwent efficient biodegradation through the reduction of S0. Specifically, n-alkanes were degraded by 80 % to 90 % and polycyclic aromatic hydrocarbons by 40 % to 95 %. These degradation rates were 17 % to 30 % and 26 % to 43 % higher, respectively, compared to those observed without S0. Consecutive subcultures combined with untargeted metabolomics analysis revealed that bacteria capable of dissimilatory sulfur reduction enhanced the fermentation process. These bacteria provided electrons to the metabolic network, which facilitated the mineralization of petroleum hydrocarbons. Our findings highlight the significant potential of S° for removing hydrophobic organic pollutants in oxygen-free environments, demonstrate the feasibility of integrating adsorption, biodegradation, and electron supply to enhance pollutant removal.

Diclofenac Degradation by Immobilized Chlamydomonas reinhardtii and Scenedesmus obliquus.

Diclofenac (DCF), a commonly used anti-inflammatory medication, presents environmental concerns due to its presence in water bodies, resistance to conventional wastewater treatment methods, and detection at increasing concentrations (ng/L to µg/L) that highlight DCF as a global emerging pollutant. While microalgae have been effective in degrading DCF in wastewater, immobilization into a matrix offers a promising approach to enhance treatment retention and efficiency. This study aimed to evaluate the efficacy of DCF removal using immobilized freshwater microalgae. Two algal species, Chlamydomonas reinhardtii (Chlamydomonas) and Scenedesmus obliquus (Scenedesmus), were tested for 6 days in both free and immobilized forms to determine if immobilized algae could degrade DCF comparably to free cells. The findings indicate that by Day 3, immobilized Chlamydomonas and Scenedesmus removed 78.0% and 80.1% of DCF, outperforming free-cell cultures. Mixed cultures demonstrated synergistic effects, with removal amounts of 91.4% for free and 92.3% for immobilized systems. By Day 6, all conditions achieved complete DCF removal (100%). Mechanistic analysis showed 80.0% biodegradation and 20.0% bioaccumulation in free Chlamydomonas and 56.8% biodegradation with 43.2% bioaccumulation in Scenedesmus. Immobilization shifted pathways slightly: in Chlamydomonas, 61.6% of DCF removal occurred via biodegradation, 18.3% via bioaccumulation, and 20.1% via abiotic degradation. For Scenedesmus, immobilization achieved 45.6% biodegradation, 36.6% bioaccumulation, and 17.8% abiotic degradation, enhancing abiotic degradation while maintaining biodegradation efficiency. This research serves as a proof of concept for utilizing immobilized algae in DCF removal and suggests an avenue for improved wastewater treatment of emerging contaminants.

Optimization of anthracene biodegradation by indigenous Trichoderma lixii and Talaromyces pinophilus using response surface methodology

Two indigenous fungal strains, Trichoderma lixii FLU1 (TlFLU1) and Talaromyces pinophilus FLU12 (TpFLU12) showed potential to biodegrade anthracene. Response Surface Methodology (RSM) employing Box-Behnken Design (BBD) and Central Composite Design (CCD) methods optimized crucial physicochemical parameters like pH, temperature, biomass, substrate concentration and media composition. BBD maximized anthracene biodegradation efficiency by predicting 98.7–103.2 %. Analysis of Variance confirmed the model's accuracy with a significant F-value of 51.0 at p<0.0001 while the quadratic regression model showed a high R² value 0.9808. CCD predicted 100 % degradation efficiency which were validated for TlFLU1 and TpFLU12 respectively on day 8 and 12 at pH 4 and 5, temperatures 30°C and 25°C, with 20 mm biomass size and 200 mg/L anthracene. 9,10-anthraquinone and phthalic acid were detected as metabolites formed during the anthracene degradation by TlFLU1 and TpFLU12 after validation of the optimization process. Acute toxicity tests showed that the degradation media toxicity reduced as evidenced by increased in survival rate (log CFU/mL) of Vibrio parahaemolyticus after 6 h exposure. Despite reduced toxicity, both strains were classified as harmful based on effective concentration (EC50) and toxicity unit (TU) (20.92±1.32 mg/L and 4.78 % for TlFLU1 and 35.29±1.55 mg/L and 2.83 % for TpFLU12). This systematic optimization approach supported by robust statistical analyses and a deep exploration of biodegradation mechanisms holds the promise of more efficient and sustainable methods for remediating PAH-contaminated environments.

Construction of versatile plastic-degrading microbial consortia based on ligninolytic microorganisms associated with agricultural waste composting

The accumulation of plastic in ecosystems is one of the most critical environmental concerns today. Plastic biodegradation using individual microbial cultures has shown limited success, which can be improved by employing microbial consortia with appropriate enzymatic capabilities. This study aims to assemble and characterize microbial consortia using ligninolytic fungi and bacteria isolated from an agricultural waste composting process, with the goal of enhancing the efficiency of plastic biodegradation. The compost microbiome demonstrated plastic-degrading functionality, particularly during the raw material and cooling phases. Ligninolytic microorganisms from compost were characterized for enzymes related to plastic degradation and their ability to colonize plastic films. The genera Bacillus, Pseudomonas, Fusarium, Aspergillus, Scedosporium, and Pseudallescheria exhibited a wide range of activities associated with plastic biodegradation, making them candidates for consortia assembly. The biodegradation of polyethylene using single and consortium cultures revealed that consortia, particularly those combining Bacillus subtilis RBM2 with Fusarium oxysporum RHM1, enhanced degradation efficiency. Additionally, consortia targeting multiple plastics, including virgin and recycled linear low-density polyethylene (LLDPE), polyethylene terephthalate (PET), and polystyrene (PS), showed varying levels of success, with bacterial-bacterial combinations such as Pseudomonas aeruginosa RBM21 and Bacillus subtilis RBM2 demonstrating broad-spectrum plastic degradation. These findings underscore the potential of compost-derived microorganisms for plastic biodegradation and suggest that utilizing microbial consortia offers a promising approach to tackling plastic pollution.

Biodegradation of Soil Contaminated with Polycyclic Aromatic Hydrocarbons PAHs through Nitrogen Biostimulation

This study evaluated the effect of nitrogen on the biostimulation of microbial load in soil mesocosms contaminated with bunker oil. Urea was used as a nitrogen source, with C/N ratios of 60:1 and 100:10 established to analyze its impact on the biodegradation of polycyclic aromatic hydrocarbons (PAHs). Experiments were conducted in plastic trays containing 2 kg of soil contaminated with 8% bunker oil. Samples were taken on days 15, 30, 60, and 90, and chemical analysis was performed using gas chromatography-mass spectrometry (GC-MS). Results indicated that the treatment with a C/N ratio of 100:10 achieved the highest PAH reduction percentage (99.27%), demonstrating the efficacy of urea biostimulation. This study highlights the importance of optimizing nutrient proportions to enhance biodegradation efficiency in hydrocarbon-contaminated soils. The addition of urea is confirmed as a viable and economical solution for soil remediation, aligning with previous studies emphasizing the crucial role of nitrogen in microbial activity and the degradation of recalcitrant contaminants. In conclusion, incorporating urea as a nitrogen source proved to be an effective strategy for biostimulation and PAH biodegradation in soil mesocosms, offering a sustainable solution to mitigate hydrocarbon contamination.

Influence of the Chemical Structure of Perylene Derivatives on the Performance of Honey-Gated Organic Field-Effect Transistors (HGOFETs) and Their Application in UV Light Detection.

Electronics based on natural or degradable materials are a key requirement for next-generation devices, where sustainability, biodegradability, and resource efficiency are essential. In this context, optimizing the molecular chemical structure of organic semiconductor compounds (OSCs) used as active layers is crucial for enhancing the efficiency of these devices, making them competitive with conventional electronics. In this work, honey-gated organic field-effect transistors (HGOFETs) were fabricated using four different perylene derivative films as OSCs, and the impact of the chemical structure of these perylene derivatives on the performance of HGOFETs was investigated. HGOFETs were fabricated using naturally occurring or low-impact materials in an effort to produce sustainable systems that degrade into benign end products at the end of their life. It is shown that the second chain of four carbons at the imide position present in perylenes N,N'-bis(5-nonyl)-perylene-3,4,9,10-bis(dicarboximide) (PDI) and N,N'-bis(5-nonyl)-1-naphthoxyperylene-3,4,9,10-bis(dicarboximide) (PDI-ONaph) reduces π-stacking interaction in the active layer, leading to lower AC conductivity and the non-functionality of HGOFETs. On the other side, the chain-on molecular orientation in the film of N,N'-dibutylperylen-3,4:9,10-bis(dicarboximide) (BuPTCD) was fundamental for the efficiency of HGOFETs, showing a better performance than the HGOFETs of N,N'-bis(2-phenylethyl)-3,4:9,10-bis(dicarboximide) (PhPTCD), which has a face-on molecular orientation. Finally, the HGOFETs of BuPTCD and PhPTCD are good candidates as UV light detectors and are used for the detection of UV radiation.

Effects of heavy metals on bioremediation of diesel by Antarctic microalga Tritostichococcus sp.

Hydrocarbon spillage has long been a concern in Antarctica as it can result in detrimental effects on Antarctic biota and ecosystems. Bioremediation, using microorganisms such as microalgae, represents one of the most effective and least damaging methods developed to remove pollutants from the environment. However, the effectiveness of bioremediation in eliminating diesel can be influenced by co-contamination of the spill area by heavy metal ions, as is often the case. This study assessed the effects of zinc (Zn), lead (Pb), copper (Cu) and cadmium (Cd) on the bioremediation of diesel by a freshwater Antarctic microalga isolated from soil, Tritostichococcus sp. WCY_AQ5_1 (GenBank accession number: OQ225631), under laboratory conditions. Toxicity testing of heavy metals (1 to 16 ppm) on Tritostichococcus sp. showed that microalgal specific growth rates and pigment ratios remained constant up till 8 ppm for all four heavy metals, an implication of toxicity at 16 ppm. In subsequent experiments, where diesel was introduced, sub-lethal Zn and Cd ion concentrations (2 to 10 ppm) did not significantly affect the biodegradation ability of Tritostichococcus sp. In contrast, sub-lethal Pb and Cu levels led to reduced diesel biodegradation at higher concentrations (8 to 10 ppm) by approximately 33% and 55%, respectively. Intriguingly, patterns of microalgal growth were not correlated with those of biodegradation efficiency as a prominent increase in growth of Zn-exposed cultures was observed at 8 and 10 ppm, and growth of Cu-exposed cultures peaked at 6 ppm. On the other hand, microalgal growth in Pb and Cd-exposed cultures (2 to 10 ppm) generally remained the same as control (0 ppm).

Hydrothermal processing of polylactic acid: Analysis of intermediate products and toxicity evaluation of anaerobically digestated residues

Polylactic acid (PLA) plastic is increasingly recognized as a sustainable alternative to petroleum-based plastics. However, its biodegradability remains a challenge, requiring substantial improvements to its biodegradation efficiency. This study explored the use of combined hydrothermal treatment (HTT) (160°C–240°C) and anaerobic digestion (AD) to improve methane yield from PLA. HTT enhanced significant structural changes in PLA, yielding 2-hydroxypropanoic acid, 1-decanol, 1-tetradecanol, pentan-2-one, and butyl 2-hydroxypropanoate, which facilitated PLA degradation. The methane yield from AD of hydrothermal-treated PLA (HTT-PLA) products at 180°C was 493 NmL/g-volatile solid, a 21.4-fold increased compared to untreated PLA. Genomic and proteomic analyses identified key genes and proteins involved in HTT-PLA products biodegradation, elucidating pathway for HTT-PLA products transformation in biodegradation process. The residues from AD of HTT-PLA products at 180°C exhibited rapeseeds germination index of approximately 90% and maintain stability locomotion and vitality in Caenorhabditis elegans, indicating their suitability for land application. Enhanced methane production offers a renewable energy source, and reduces PLA’s environmental footprint, providing significant practical implications for bioplastic waste management and sustainability.

Biodegradation of commercial polyester polyurethane by a soil-borne bacterium Bacillus velezensis MB01B: Efficiency, degradation pathway, and in-situ remediation in landfill soil

Polyurethane (PU), a widely used and durable plastic, persists in the environment, resulting in significant waste management challenges. Therefore, developing eco-friendly degradation technologies, such as screening for efficient biodegrading microorganism strains, is urgently needed to address this issue. Bacillus velezensis MB01B, an efficient polyester PU-degrading bacterium, was isolated from landfill soil and demonstrated the ability to degrade 91.4% of 0.75% Impranil DLN within 24 h under the optimal conditions (30.5 °C and initial pH 6.5). To assess the degradation capability of MB01B, three PU substrates of increasing complexity—Impranil DLN film, polyester thermoplastic polyurethane (TPU) film, and commercial PU desk mat—were tested; after 30 days, weight losses of 24.8%, 18.3%, and 5.4% were observed, respectively. In addition, SEM images showed significant morphological changes on the surface of these PU materials after treatment with MB01B. FTIR analysis of Impranil DLN films following degradation showed reductions in key functional groups (ester and urethane); and the identification of neopentyl glycol and 1,6-hexanediol as degradation intermediates suggested MB01B possesses the capability to hydrolyze ester and urethane bonds. Concurrently, genome sequencing combined with RT-qPCR identified several enzymes, including urethanases and esterases/lipases, involved in PU degradation. Based on these results, the pathway for MB01B to degrade Impranil DLN was inferred. Finally, MB01B was successfully formulated into a solid microbial inoculum with favorable storage properties and used for in-situ degradation of the commercial PU materials (Impranil DLN films, TPU films and PU desk mats) in landfill soil, underscoring its potential for the in-situ biological treatment of PU plastic wastes.

Control of membrane biofouling in MBR for wastewater treatment by biohybrid membrane with superhydrophilic self-QQ function

Quorum quenching (QQ) is an effective method for controlling MBR (membrane bioreactor) membrane biofouling by regulating the release of autoinducer during the quorum sensing (QS) process. However, the addition of QQ bacteria solution or QQ carriers inevitably leads to unpredictable effects on MBR microbial systems and operational efficiency (for example, reduced stability of nitrification and denitrification processes, reduced biodegradation efficiency and unbalanced biofilm formation etc.). Here, we present a biohybrid membrane called ES-BM (electrospinning-biohybrid membrane), which features a unique pore size structure consisting of electrospun superhydrophilic nanofiber sheaths, a self-QQ layer (active QQ bacteria are immobilized within the interlayer structure of this biohybrid membrane to inhibit the QS process of biofilm-forming associated bacteria at the source surface where membrane biofouling occurs), and a basement filter layer, which maintain the activity of QQ bacteria for an extended period. The ES-BM extends operational cycles up to 21 days at a constant flux of 24 L/m²/h, which is three times longer than conventional MBR systems. The membrane exhibits exceptional hydrophilicity (water contact angle of approximately 0° within 2 seconds) and high tensile strength (Young’s modulus of 135 MPa). Long-term bioactivity tests confirm the stability and recyclability of the ES-BM. Additionally, microbial community analysis suggests that the biohybrid membrane suppresses the growth of biofilm-related bacteria without significantly affecting the indigenous microbial population, further enhancing system performance. This work demonstrates the potential of ES-BM for improving MBR biofouling resistance and presents insights into scalable electrospinning fabrication techniques.