A versatile tag for simple preparation of cutinase towards enhanced biodegradation of polyethylene terephthalate

Engineering dual-functional and thermophilic BMHETase for efficient degradation of polyethylene terephthalate

Polyethylene terephthalate (PET) biodegradation is hindered by the intermediates bis (2-hydroxyethyl) terephthalate (BHET) and mono (2-hydroxyethyl) terephthalate (MHET). BMHETase, a thermophilic hydrolase identified from the UniParc database, exhibits degradation activity towards both BHET and MHET. BMHETase showed higher activity on BHET than LCCICCG and FASTPETase at temperatures ranging from 50 to 70℃. To enhance its activity in degrading MHET, BMHETase was engineered to mimic Ideonella sakaiensis MHETase. The resulting 6-point mutant's activities on MHET and BHET were 8 and 2 times those of the WT, with both optimal temperatures increased by 5℃. This enhancement may be attributed to the BMHETase6M's intensified binding ability with MHET and enlarged binding pocket. When combined with LCCICCG, BMHETase6M achieved complete degradation of MHET in PET films to terephthalic acid, indicating broad application potential. These findings suggest that BMHETase6M holds promise as a candidate for enhancing PET biodegradation efficiency and plastic waste management.

Review of key issues and potential strategies in bio-degradation of polyolefins

Polyolefins are the most widely used plastic product and a major contributor to white pollution. Currently, studies on polyolefin degradation systems are mainly focused on microorganisms and some redox enzymes, and there is a serious black-box phenomenon. The use of polyolefin-degrading enzymes is limited because of the small number of enzymes; in addition, the catalytic efficiency of these enzymes is poor and their catalytic mechanism is unclear, which leads to the incomplete degradation of polyolefins to produce microplastics. In this review, three questions are addressed: the generation and degradation of action targets that promote the degradation of polyolefins, the different modes by which enzymes bind substrates and their application scenarios, and possible multienzyme systems in a unified system. This review will be valuable for mining or modifying polyolefin degradation enzymes and constructing polyolefins degradation systems and may provide novel ideas and opportunities for polyolefin degradation.

Magnetic silica-coated cutinase immobilized via ELPs biomimetic mineralization for efficient nano-PET degradation

The proliferation of nano-plastic particles (NPs) poses severe environmental hazards, urgently requiring effective biodegradation methods. Herein, a novel method was developed for degrading nano-PET (polyethylene terephthalate) using immobilized cutinases. Nano-PET particles were prepared using a straightforward method, and biocompatible elastin-like polypeptide-magnetic nanoparticles (ELPs-MNPs) were obtained as magnetic cores via biomimetic mineralization. Using one-pot synthesis with the cost-effective precursor tetraethoxysilane (TEOS), silica-coated magnetically immobilized ELPs-tagged cutinase (ET-C@SiO2@MNPs) were produced. ET-C@SiO2@MNPs showed rapid magnetic separation within 30 s, simplifying recovery and reuse. ET-C@SiO2@MNPs retained 86 % of their initial activity after 11 cycles and exhibited superior hydrolytic capabilities for nano-PET, producing 0.515 mM TPA after 2 h of hydrolysis, which was 96.6 % that of free enzymes. Leveraging ELPs biomimetic mineralization, this approach offers a sustainable and eco-friendly solution for PET-nanoplastic degradation, highlighting the potential of ET-C@SiO2@MNPs in effective nanoplastic waste management and contributing to environmental protection and sustainable development.

The evolution of cutinase Est1 based on the clustering strategy and its application for commercial PET bottles degradation

The rapid increase in global plastic consumption, especially the worldwide use of polyethylene terephthalate (PET), has caused serious pollution problems. Due to the low recycling rate of PET, a substantial amount of waste accumulates in the environment, which prompts a growing focus on enzymatic degradation for its efficiency and environmentally friendliness. This study systematically designed and modified a cutinase, Est1 from Thermobifida alba AHK119, known for its potential of plastic-degradation at high temperatures. Additionally, the introduction of clustering algorithms provided the ability to understand and modify biomolecules, to accelerate the process of finding the optimal mutations. K-means was further proceeded based on the positive mutations. After comprehensive screening for thermostability and activity mutation sites, the dominant mutation Est1_5M (Est1 with the mutations of N213M, T215P, S115P, Q93A, and L91W) exhibited satisfying degradation ability for commercial PET bottles. The results showed that Est1_5M achieved a degradation rate of 90.84% in 72 h, 65-fold higher than the wild type. This study offers reliable theoretical and practical support for the development of efficient PET-degrading enzymes, providing a reference for plastic pollution management.

Microbial Immobilized Enzyme Biocatalysts for Multipollutant Mitigation: Harnessing Nature's Toolkit for Environmental Sustainability

The ever-increasing presence of micropollutants necessitates the development of environmentally friendly bioremediation strategies. Inspired by the remarkable versatility and potent catalytic activities of microbial enzymes, researchers are exploring their application as biocatalysts for innovative environmental cleanup solutions. Microbial enzymes offer remarkable substrate specificity, biodegradability, and the capacity to degrade a wide array of pollutants, positioning them as powerful tools for bioremediation. However, practical applications are often hindered by limitations in enzyme stability and reusability. Enzyme immobilization techniques have emerged as transformative strategies, enhancing enzyme stability and reusability by anchoring them onto inert or activated supports. These improvements lead to more efficient pollutant degradation and cost-effective bioremediation processes. This review delves into the diverse immobilization methods, showcasing their success in degrading various environmental pollutants, including pharmaceuticals, dyes, pesticides, microplastics, and industrial chemicals. By highlighting the transformative potential of microbial immobilized enzyme biocatalysts, this review underscores their significance in achieving a cleaner and more sustainable future through the mitigation of micropollutant contamination. Additionally, future research directions in areas such as enzyme engineering and machine learning hold immense promise for further broadening the capabilities and optimizing the applications of immobilized enzymes in environmental cleanup.

An antifouling epoxy coated metal surface containing silica-immobilized carbonic anhydrase supraparticles for CO2 capture through microalgae

Carbonic anhydrase (CA) has a promising application as a green and efficient biocatalyst for CO2 capture, and many successful cases of immobilizing CA have been reported. However, CA antifouling coatings on metal for CO2 sequestration have rarely been reported. Herein, dimeric CA from Sulfurihydrogenibium azorense (SazCA) with a ferritin tag, which was prepared by low-speed centrifugation with high yield, was adopted as a free enzyme and encapsulated in the sol-gel silica. The silica-immobilized CAs were dispersed into the commercialized metal-antifouling epoxy resin paint to obtain CA coated nickel foams, which had excellent stability, with 90 % and 67 % residual activity after 28 days of incubation at 30 °C and 60 °C, respectively. The CA coated nickel foams remained 60 % original activity after 6 cycles of use within 28 days. Then, a CA-microalgae carbon capture device was constructed using the CA coated nickel foams and Chlorella. The growth rate of Chlorella was significantly increased and the biomass of Chlorella increased by 29 % compared with control after 7 days of incubation. Due to the simple and cost-effective preparation process, sustainable and efficient CO2 absorption, this easy-to-scale up CA coated nickel foam has great potential in CA assisted microalgae-based CO2 capture and carbon neutrality.

Biodegradation strategies of veterinary medicines in the environment: Enzymatic degradation

One Health closely integrates healthy farming, human medicine, and environmental ecology. Due to the ecotoxicity and risk of transmission of drug resistance, veterinary medicines (VMs) are regarded as emerging environmental pollutants. To reduce or mitigate the environmental risk of VMs, developing friendly, safe, and effective removal technologies is an important means of environmental remediation for VMs. Many previous studies have proved that biodegradation has significant advantages in removing VMs, and biodegradation based on enzyme catalysis presents higher operability and specificity. This review focused on biodegradation strategies of environmental pollutants and reviewed the enzymatic degradation of VMs including antimicrobial drugs, insecticides, and disinfectants. We reviewed the sources and catalytic mechanisms of peroxidase, laccase, and organophosphorus hydrolases, and summarized the latest research status of immobilization methods and bioengineering techniques in improving the performance of degrading enzymes. The mechanism of enzymatic degradation for VMs was elucidated in the current research. Suggestions and prospects for researching and developing enzymatic degradation of VMs were also put forward. This review will offer new ideas for the biodegradation of VMs and have a guide significance for the risk mitigation and detoxification of VMs in the environment.

Nature-inspired material binding peptides with versatile polyester affinities and binding strengths

Biodegradable polyesters, such as polyhydroxyalkanoates (PHAs), are having a tremendous impact on biomedicine. However, these polymers lack functional moieties to impart functions like targeted delivery of molecules. Inspired by native GAPs, such as phasins and their polymer-binding and surfactant properties, we generated small material binding peptides (MBPs) for polyester surface functionalization using a rational approach based on amphiphilicity. Here, two peptides of 48 amino acids derived from phasins PhaF and PhaI from Pseudomonas putida, MinP and the novel-designed MinI, were assessed for their binding towards two types of PHAs, PHB and PHOH. In vivo, fluorescence studies revealed selective binding towards PHOH, whilst in vitro binding experiments using the Langmuir-Blodgett technique coupled to ellipsometry showed KD in the range of nM for all polymers and MBPs. Marked morphological changes of the polymer surface upon peptide adsorption were shown by BAM and AFM for PHOH. Moreover, both MBPs were successfully used to immobilize cargo proteins on the polymer surfaces. Altogether, this work shows that by redesigning the amphiphilicity of phasins, a high affinity but lower specificity to polyesters can be achieved in vitro. Furthermore, the MBPs demonstrated binding to PET, showing potential to bind cargo molecules also to synthetic polyesters.

Revealing the role of tunable amino acid residues in elastin-like polypeptides (ELPs)-mediated biomimetic silicification

Elastin-like polypeptides (ELPs) are attractive materials for the green preparation of silica nanoparticles via biomimetic silicification. However, the critical factors affecting the ELP-mediated silicification remain unclear. Herein, the role of tunable amino acid residues of ELPs in silicification was studied using three ELPs (ELPs[V9F-40], ELPs[KV8F-40], and ELPs[K5V4F-40]) and their fusion proteins (ELPs[V9F-40]-SpyCatcher, ELPs[KV8F-40]-SpyCatcher, and ELPs[K5V4F-40]-SpyCatcher) with different contents of lysine residues. Bioinformatics methods were employed for the first time to reveal the key physicochemical parameters correlated with silicification. The specific activity of ELPs was increased with the promotion of lysine content with a high correlation coefficient (R = 0.899). Furthermore, exogenous acidic protein SpyCatcher would hinder the interactions between the silica precursors and ELPs, leading to the significantly decrease in specific activity. The isoelectric point (pI) of ELPs presented the highest correlation to silicification with a coefficient of 0.963. The charges of the ELPs [K5V4F-40] at different pH were calculated based on the sequence or structure. Interestingly, the excellent correlation between charges based on structure and specific activity was obtained. Collectively, the novel methods developed here may pave a new way for rational design of ELPs or other peptides for efficient and green preparation of silica nanomaterials for biomedicine, biocatalysis, and biosensor.