Turning plastics/microplastics into valuable resources? Current and potential research for future applications.

Plastics are a wide range of synthetic or semi-synthetic materials, mainly consisting of polymers. The use of plastics has increased to over 300 million metric tonnes in recent years, and by 2050, it is expected to grow to 800 million. Presently, a mere 10% of plastic waste is recycled, with approximately 75% ended up in landfills. Inappropriate disposal of plastic waste into the environment poses a threat to human lives and marine species. Therefore, this review article highlights potential routes for converting plastic/microplastic waste into valuable resources to promote a greener and more sustainable environment. The literature review revealed that plastics/microplastics (P/MP) could be recycled or upcycled into various products or materials via several innovative processes. For example, P/MP are recycled and utilized as anodes in lithium-ion (Li-ion) and sodium-ion (Na-ion) batteries. The anode in Na-ion batteries comprising PP carbon powder exhibits a high reversible capacity of ∼340 mAh/g at 0.01 A/g current state. In contrast, integrating Fe3O4 and PE into a Li-ion battery yielded an excellent capacity of 1123 mAh/g at 0.5 A/g current state. Additionally, recycled Nylon displayed high physical and mechanical properties necessary for excellent application as 3D printing material. Induction heating is considered a revolutionary pyrolysis technique with improved yield, efficiency, and lower energy utilization. Overall, P/MPs are highlighted as abundant resources for the sustainable production of valuable products and materials such as batteries, nanomaterials, graphene, and membranes for future applications.

An Overview of Crosslinked Enzyme Aggregates: Concept of Development and Trends of Applications.

Enzymes are commonly used as biocatalysts for various biological and chemical processes in industrial applications. However, their limited operational stability, catalytic efficiency, poor reusability, and high-cost hamper further industrial usage. Thus, crosslinked enzyme aggregates (CLEAs) are developed as a better enzyme immobilization tool to extend the enzymes' operational stability. This immobilization method is appealing because it is simpler due to the absence of ballast and permits the collective use of crude enzyme cocktails. CLEAs, so far, have been successfully developed using a variety of enzymes, viz., hydrolases, proteases, amidases, lipases, esterases, and oxidoreductase. Recent years have seen the emergence of novel strategies for preparing better CLEAs, which include the combi- and multi-CLEAs, magnetics CLEAs, and porous CLEAs for various industrial applications, viz., laundry detergents, organic synthesis, food industries, pharmaceutical applications, oils, and biodiesel production. To better understand the different strategies for CLEAs' development, this review explores these strategies and highlights the relevant concerns in designing innovative CLEAs. This article also details the challenges faced during CLEAs preparation and solutions for overcoming them. Finally, the trending strategies to improve the preparation of CLEAs alongside their industrial application trends are also discussed.

Comparative modeling and enzymatic affinity of novel haloacid dehalogenase from Bacillus megaterium strain BHS1 isolated from alkaline Blue Lake in Turkey.

This study presents the initial structural model of L-haloacid dehalogenase (DehLBHS1) from Bacillus megaterium BHS1, an alkalotolerant bacterium known for its ability to degrade halogenated environmental pollutants. The model provides insights into the structural features of DehLBHS1 and expands our understanding of the enzymatic mechanisms involved in the degradation of these hazardous pollutants. Key amino acid residues (Arg40, Phe59, Asn118, Asn176, and Trp178) in DehLBHS1 were identified to play critical roles in catalysis and molecular recognition of haloalkanoic acid, essential for efficient binding and transformation of haloalkanoic acid molecules. DehLBHS1 was modeled using I-TASSER, yielding a best TM-score of 0.986 and an RMSD of 0.53 Å. Validation of the model using PROCHECK revealed that 89.2% of the residues were located in the most favored region, providing confidence in its structural accuracy. Molecular docking simulations showed that the non-simulated DehLBHS1 preferred 2,2DCP over other substrates, forming one hydrogen bond with Arg40 and exhibiting a minimum energy of -2.5 kJ/mol. The simulated DehLBHS1 exhibited a minimum energy of -4.3 kJ/mol and formed four hydrogen bonds with Arg40, Asn176, Asp9, and Tyr11, further confirming the preference for 2,2DCP. Molecular dynamics simulations supported this preference, based on various metrics, including RMSD, RMSF, gyration, hydrogen bonding, and molecular distance. MM-PBSA calculations showed that the DehLBHS1-2,2-DCP complex had a markedly lower binding energy (-21.363 ± 1.26 kcal/mol) than the DehLBHS1-3CP complex (-14.327 ± 1.738 kcal/mol). This finding has important implications for the substrate specificity and catalytic function of DehLBHS1, particularly in the bioremediation of 2,2-DCP in contaminated alkaline environments. These results provide a detailed view of the molecular interactions between the enzyme and its substrate and may aid in the development of more efficient biocatalytic strategies for the degradation of halogenated compounds.Communicated by Ramaswamy H. Sarma.

Airborne microplastic/nanoplastic research: a comprehensive Web of Science (WoS) data-driven bibliometric analysis.

This paper presents the landscape of research on airborne microplastics and nanoplastics (MPs/NPs) according to the bibliometric analysis of 147 documents issued between 2015 and 2021, extracted from the Web of Science database. The publications on airborne MPs/NPs have increased rapidly from 2015 onwards, which is largely due to the existence of funding support. Science of the Total Environment is one of the prominent journals in publishing related papers. China, England, the USA, and European Countries have produced a significant output of airborne MP/NP research works, which is associated with the availability of funding agencies regionally or nationally. The research hotspot on the topic ranges from the transport of airborne MPs/NPs to their deposition in the terrestrial or aquatic environments, along with the contamination of samples by indoor MPs/NPs. Most of the publications are either research or review papers related to MPs/NPs. It is crucial to share the understanding of global plastic pollution and its unfavorable effects on humankind by promoting awareness of the existence and impact of MPs/NPs. Funding agencies are vital in boosting the research development of airborne MPs/NPs. Some countries that are lacking funding support were able to publish research findings related to the field of interest, however, with lesser research output. Without sufficient fundings, some impactful publications may not be able to carry a substantial impact in sharing the findings and discoveries with the mass public.

The first ITS2 sequence data set of eDNA from honey of Malaysian giant honeybees (Apis dorsata) and stingless bees (Heterotrigona itama) reveals plant species diversity.

OBJECTIVES: Pollen is a useful tool for identifying the provenance and complex ecosystems surrounding honey production in Malaysian forests. As native key pollinators in Malaysia, Apis dorsata and Heterotrigona itama forage on various plant/pollen species to collect honey. This study aims to generate a dataset that uncovers the presence of these plant/pollen species and their relative abundance in the honey of A. dorsata and H. itama. The information gathered from this study can be used to determine the geographical and botanical origin and authenticity of the honey produced by these two species. RESULTS: Sequence data were obtained for both A. dorsata and H. itama. The raw sequence data for A. dorsata was 5 Mb, which was assembled into 5 contigs with a size of 6,098,728 bp, an N50 of 15,534, and a GC average of 57.42. Similarly, the raw sequence data for H. itama was 6.3 Mb, which was assembled into 11 contigs with a size of 7,642,048 bp, an N50 of 17,180, and a GC average of 55.38. In the honey sample of A. dorsata, we identified five different plant/pollen species, with only one of the five species exhibiting a relative abundance of less than 1%. For H. itama, we identified seven different plant/pollen species, with only three of the species exhibiting a relative abundance of less than 1%. All of the identified plant species were native to Peninsular Malaysia, especially the East Coast area of Terengganu. DATA DESCRIPTION: Our data offers valuable insights into honey's geographical and botanical origin and authenticity. Metagenomic studies could help identify the plant species that honeybees forage and provide preliminary data for researchers studying the biological development of A. dorsata and H. itama. The identification of various flowers from the eDNA of honey that are known for their medicinal properties could aid in regional honey with accurate product origin labeling, which is crucial for guaranteeing product authenticity to consumers.

Biological and molecular approaches of the degradation or decolorization potential of the hypersaline Lake Tuz Bacillus megaterium H2 isolate.

The presence of synthetic dyes in water bodies and soil is one of the major issues affecting the global ecology, possibly impacting societal well-being adversely due to the colorants' recalcitrance and toxicity. Herein, the study spectrophotometrically monitored the ability of the Bacillus megaterium H2 azoreductase (AzrBmH2) to degrade four synthetic dyes, reactive blue 4, remazol brilliant red, thymol blue, and methyl red, followed by in-silico assessment using GROMACS. We found that the bacterium degraded as much as 60% of all four synthetic dyes at various tested concentrations. The genome analysis revealed five different azoreductase genes, which were then modeled into the AzrBmH21, AzrBmH22/3, and AzrBmH24/5 templates. The AzrBmH2-substrate complexes showed binding energies with all the dyes of between -10.6 to -6.9 kcal/mol and formed 4-6 hydrogen bonds with the predicted catalytic binding residues (His10, Glu 14, Ser 58, Met 99, Val 107, His 183, Asn184 and Gln 191). In contrast, the lowest binding energies were observed for the AzrBmH21-substrates (-10.6 to -7.9). Molecular dynamic simulations revealed that the AzrBmH21-substrate complexes were more stable (RMSD 0.2-0.25 nm, RMSF 0.05 - 0.3 nm) and implied strong bonding with the dyes. The Molecular Mechanics Poisson-Boltzmann Surface Area results also mirrored this outcome, showing the lowest azoreductase-dye binding energy in the order of AzrBmH21-RB4 (-78.18 ± 8.92 kcal/mol), AzrBmH21-RBR (-67.51 ± 7.74 kcal/mol), AzrBmH21-TB (-46.62 ± 5.23 kcal/mol) and AzrBmH21-MR (-40.78 ± 7.87 kcal/mol). In short, the study demonstrated the ability of the B. megaterium H2 to efficiently decolorize the above-said synthetic dyes, conveying the bacterium's promising use for large-scale dye remediation.Communicated by Ramaswamy H. Sarma.

Interaction of the nanobio-based reagent with sodium fluorescein and lipids via bioinformatics for forensic fingerprint visualisations.

Being commonly found at crime scenes, fingerprints are crucial for human identification, attributable to their uniqueness, persistence and systematic classification of ridge patterns. In addition to latent fingerprints being invisible to the naked eye, the escalating trends of disposing forensic evidence bearing such prints in watery bodies would further complicate criminal investigations. Taking into account the toxicity of small particle reagent (SPR) commonly used in visualising latent fingerprints on wet and non-porous objects, a greener alternative using the nanobio-based reagent (NBR) has been suggested. However, NBR only applies to white and/or relatively light-coloured objects. Thus, conjugation of sodium fluorescein dye with NBR (f-NBR) may be beneficial for increasing the contrast of fingerprint on multi-colored objects. Hence, this study was aimed at investigating the possibility of such conjugation (i.e., f-NBR) as well as proposing suitable interactions between the f-NBR and lipid constituents of fingerprints (tetra-, hexa- and octadecanoic acids) via molecular docking and molecular dynamics simulations. The binding energies between CRL with its ligands were observed at -8.1, -5.0, -4.9 and -3.6 kcal/mole for sodium fluorescein, tetra-, hexa- and octadecanoic acids, respectively. Besides, the formations of hydrogen bonds observed in all complexes (ranged between 2.6 and 3.4 Å), further supported by the stabilized root mean square deviation (RMSDs) plots in MD simulations. In short, the conjugation of f-NBR was computationally feasible, and thereby merits further investigations in the laboratory.Communicated by Ramaswamy H. Sarma.

Current perspectives of metal-based nanomaterials as photocatalytic antimicrobial agents and their therapeutic modes of action: A review.

Efforts to restrict the emergence and progression of multidrug-resistant bacterial strains should heavily involve the scientific community, including government bodies, researchers, and industries, in developing new and effective photocatalytic antimicrobial agents. Such changes warrant the modernization and upscaling of materials synthesis laboratories to support and expedite the mass production of materials at the industrial scale for the benefit of humankind and the environment. Despite the massive volume of publications reporting the potential usage of different types of metal-based nanomaterials as antimicrobial agents, reviews uncovering the similarities and differences among the various products remain lacking. This review details the basic and unique properties of metal-based nanoparticles, their use as photocatalytic antimicrobial agents, and their therapeutic modes of action. It shall be noted that compared to traditional antibiotics, the mode of action of photocatalytic metal-based nanomaterials for killing microorganisms are completely different, despite displaying promising performance against antibiotic-resistant bacteria. Besides, this review uncovers the differences in the mode of actions of metal oxide nanoparticles against different types of bacteria, as well as towards viruses. Last but not least, this review comprehensively describes previous published clinical trials and medical usages involving contemporary photocatalytic antimicrobial agents.

Desalination technologies, membrane distillation, and electrospinning, an overview.

Water is a critical component for humans to survive, especially in arid lands or areas where fresh water is scarce. Hence, desalination is an excellent way to effectuate the increasing water demand. Membrane distillation (MD) technology entails a membrane-based non-isothermal prominent process used in various applications, for instance, water treatment and desalination. It is operable at low temperature and pressure, from which the heat demand for the process can be sustainably sourced from renewable solar energy and waste heat. In MD, the water vapors are gone through the membrane's pores and condense at permeate side, rejecting dissolved salts and non-volatile substances. However, the efficacy of water and biofouling are the main challenges for MD due to the lack of appropriate and versatile membrane. Numerous researchers have explored different membrane composites to overcome the above-said issue, and attempt to develop efficient, elegant, and biofouling-resistant novel membranes for MD. This review article addresses the 21st-century water crises, desalination technologies, principles of MD, the different properties of membrane composites alongside compositions and modules of membranes. The desired membrane characteristics, MD configurations, role of electrospinning in MD, characteristics and modifications of membranes used for MD are also highlighted in this review.

Molecular interactions of trichoderma ß-1,4-glucosidase (ThBglT12) with mycelial cell wall components of phytopathogenic Macrophomina phaseolina.

Efficacy of a ß-1,4-glucosidase from Trichoderma harzianum T12 (ThBglT12) in disrupting the cell wall of the phytopathogenic fungus M. phaseolina (Macrophomina phaseolina) was studied, as the underlying molecular mechanisms of cell wall recognition remains elusive. In this study, the binding location identified by a consensus of residues predicted by COACH tool, blind docking, and multiple sequence alignment revealed that molecular recognition by ThBglT12 occurred through interactions between the α-1,3-glucan, ß-1,3-glucan, ß-1,3/1,4-glucan, and chitin components of M. phaseolina, with corresponding binding energies of -7.4, -7.6, -7.5 and -7.8 kcal/mol. The residue consensus verified the participation of Glu172, Tyr304, Trp345, Glu373, Glu430, and Trp431 in the active site pocket of ThBglT12 to bind the ligands, of which Trp345 was the common interacting residue. Root mean square deviation (RMSD), root mean square fluctuation (RMSF), total energy, and minimum distance calculation from molecular dynamics (MD) simulation further confirmed the stability and the closeness of the binding ligands into the ThBglT12 active site pocket. The h-bond occupancy by Glu373 and Trp431 instated the role of the nucleophile for substrate recognition and specificity, crucial for cleaving the ß-1,4 linkage. Further investigation showed that the proximity of Glu373 to the anomeric carbon of ß-1,3/1,4-glucan (3.5 Å) and chitin (5.5 Å) indicates the nucleophiles' readiness to form enzyme-substrate intermediates. Plus, the neighboring water molecule appeared to be correctly positioned and oriented towards the anomeric carbon to hydrolyze the ß-1,3/1,4-glucan and chitin, in less than 4.0 Å. In a nutshell, the study verified that the ThBglT12 is a good alternative fungicide to inhibit the growth of M. phaseolina.Communicated by Ramaswamy H. Sarma.

Molecular dynamics simulations reveal the inhibitory mechanism of Withanolide A against α-glucosidase and α-amylase.

Diabetes mellitus (DM) is a global chronic disease characterized by hyperglycemia and insulin resistance. The unsavory severe gastrointestinal side-effects of synthetic drugs to regulate hyperglycemia have warranted the search for alternative treatments to inhibit the carbohydrate digestive enzymes (e.g. α-amylase and α-glucosidase). Certain phytochemicals recently captured the scientific community's attention as carbohydrate digestive enzyme inhibitors due to their low toxicity and high efficacy, specifically the Withanolides-loaded extract of Withania somnifera. That said, the present study evaluated in silico the efficacy of Withanolide A in targeting both α-amylase and α-glucosidase in comparison to the synthetic drug Acarbose. Protein-ligand interactions, binding affinity, and stability were characterized using pharmacological profiling, high-end molecular docking, and molecular-dynamic simulation. Withanolide A inhibited the activity of α-glucosidase and α-amylase better, exhibiting good pharmacokinetic properties, absorption, and metabolism. Also, Withanolide A was minimally toxic, with higher bioavailability. Interestingly, Withanolide A bonded well to the active site of α-amylase and α-glucosidase, yielding the lowest binding free energy of -82.144 ± 10.671 kcal/mol and -102.1043 ± 11.231 kcal/mol compared to the Acarbose-enzyme complexes (-63.220 ± 13.283 kcal/mol and -82.148 ± 10.671 kcal/mol). Hence, the findings supported the therapeutic potential of Withanolide A as α-amylase and α-glucosidase inhibitor for DM treatment.Communicated by Ramaswamy H. Sarma.

Current and potential approaches on assessing airflow and particle dispersion in healthcare facilities: a systematic review.

An indoor environment in a hospital building requires a high indoor air quality (IAQ) to overcome patients' risks of getting wound infections without interrupting the recovery process. However, several problems arose in obtaining a satisfactory IAQ, such as poor ventilation design strategies, insufficient air exchange, improper medical equipment placement and high door opening frequency. This paper presents an overview of various methods used for assessing the IAQ in hospital facilities, especially in an operating room, isolation room, anteroom, postoperative room, inpatient room and dentistry room. This review shows that both experimental and numerical methods demonstrated their advantages in the IAQ assessment. It was revealed that both airflow and particle tracking models could result in different particle dispersion predictions. The model selection should depend on the compatibility of the simulated result with the experimental measurement data. The primary and secondary forces affecting the characteristics of particle dispersion were also discussed in detail. The main contributing forces to the trajectory characteristics of a particle could be attributed to the gravitational force and drag force regardless of particle size. Meanwhile, the additional forces could be considered when there involves temperature gradient, intense light source, submicron particle, etc. The particle size concerned in a healthcare facility should be less than 20 µm as this particle size range showed a closer relationship with the virus load and a higher tendency to remain airborne. Also, further research opportunities that reflect a more realistic approach and improvement in the current assessment approach were proposed.

Physicochemical Properties of a New Green Honey from Banggi Island, Sabah.

Green honey is exclusively available on the island of Banggi in Sabah, and its uniqueness sees the commodity being sold at a high market price. Therefore, green honey is prone to adulteration by unscrupulous individuals, possibly compromising the health of those consuming this food commodity for its curative properties. Moreover, an established standard for reducing sugar in green honey is unavailable. Ipso facto, the study aimed to profile green honey's physical and chemical properties, such as its pH, moisture content, free acidity, ash content, electroconductivity, hydroxymethylfurfural (HMF), total phenolic content, total flavonoid content, DPPH, colour, total sugar content, total protein content, and heavy metals as well as volatile organic compounds, the data of which are profoundly valuable in safeguarding consumers' safety while providing information for its quality certification for local consumption and export. The results revealed that the honey's physicochemical profile is comparable to other reported kinds of honey. The honey's naturally green colour is because of the chlorophyll from the nectar from various flowers on the island. The raw honey showed free acidity between 28 and 33 Meq/100 g, lower than the standard's 50 Meq/100 g. The hydroxymethylfurfural content is the lowest compared to other reported honey samples, with the total phenolic content between 16 and 19 mg GAE/100 g. The honey's reducing sugar content is lower (~37.9%) than processed ones (56.3%) because of water removal. The protein content ranged from 1 to 2 gm/kg, 4- to 6-fold and 2-fold higher than local and manuka honey, respectively. The exceptionally high content of trans-4-hydroxyproline in raw honey is its source of collagen and other healing agents. Interestingly, low levels of arsenic, lead, nickel, cadmium, copper, and cobalt were detected in the honey samples, presumably due to their subterranean hives. Nevertheless, the honey is fit for general consumption as the concentrations were below the maxima in the Codex Alimentarius Commission of 2001.

Effects of medical staff's turning movement on dispersion of airborne particles under large air supply diffuser during operative surgeries.

The present study examines the effect of medical staff's turning movements on particle concentration in the surgical zone and settlement on the patient under single large diffuser (SLD) ventilation. A computational domain representing the operating room (OR) was constructed using computer-aided design (CAD) software. The airflow and particle models were validated against the published data before conducting the case studies. The airflow in the OR was simulated using an RNG k-ε turbulence model, while the dispersion of the particles was simulated using a discrete phase model based on the Lagrangian approach. A user-defined function (UDF) code was written and compiled in the simulation software to describe the medical staff member's turning movements. In this study, three cases were examined: baseline, SLD 1, and SLD 2, with the air supply areas of 4.3 m2, 5.7 m2, and 15.9 m2, respectively. Results show that SLD ventilations in an OR can reduce the number of dispersed particles in the surgical zone. The particles that settled on the patient were reduced by 41% and 39% when using the SLD 1 and SLD 2 ventilations, respectively. The use of the larger air supply area of SLD 2 ventilation in the present study does not significantly reduce the particles that settle on a patient. Likewise, the use of SLD 2 ventilation may increase operating and maintenance costs.

Adverse environmental effects of disposable face masks due to the excess usage.

The widespread use of disposable face masks as a preventative strategy to address transmission of the SARS-CoV-2 virus has been a key environmental concern since the pandemic began. This has led to an unprecedented new form of contamination from improperly disposed masks, which liberates significant amounts of heavy metals and toxic chemicals in addition to volatile organic compounds (VOCs). Therefore, this study monitored the liberation of heavy metals, VOCs, and microfibers from submerged disposable face masks at different pH (4, 7 and 12), to simulate distinct environmental conditions. Lead (3.238% ppb), cadmium (0.672 ppb) and chromium (0.786 ppb) were found in the analyzed leachates. By pyrolysis, 2,4-dimethylhept-1-ene and 4-methylheptane were identified as the VOCs produced by the samples. The chemically degraded morphology in the FESEM images provided further evidence that toxic heavy metals and volatile organic compounds had been leached from the submerged face masks, with greater degradation observed in samples submerged at pH 7 and higher. The results are seen to communicate the comparable danger of passively degrading disposable face masks and the release of micro- or nanofibers into the marine environment. The toxicity of certain heavy metals and chemicals released from discarded face masks warrants better, more robust manufacturing protocols and increased public awareness for responsible disposal to reduce the adverse impact on ecology and human health.

Molecular docking and molecular dynamics simulation of Bacillus thuringiensis dehalogenase against haloacids, haloacetates and chlorpyrifos.

The high dependency and surplus use of agrochemical products have liberated enormous quantities of toxic halogenated pollutants into the environment and threaten the well-being of humankind. Herein, this study performed molecular docking, molecular dynamic (MD) simulations, molecular mechanics-Poisson Boltzmann Surface Area (MM-PBSA) calculations on the DehH2 from Bacillus thuringiensis, to identify the order of which the enzyme degrades different substrates, haloacids, haloacetate and chlorpyrifos. The study discovered that the DehH2 favored the degradation of haloacids and haloacetates (-3.3 - 4.6 kcal/mol) and formed three hydrogen bonds with Asp125, Arg201 and Lys202. Despite the inconclusive molecular docking result, chlorpyrifos was consistently shown to be the least favored substrate of the DehH2 in MD simulations and MM-PBSA calculations. Results of MD simulations revealed the DehH2-haloacid- (RMSD 0.15 - 0.25 nm) and DehH2-haloacetates (RMSF 0.05 - 0.25 nm) were more stable, with the DehH2-L-2CP complex being the most stable while the least was the DehH2-chlorpyrifos (RMSD 0.295 nm; RMSF 0.05 - 0.59 nm). The Molecular Mechanics Poisson-Boltzmann Surface Area calculations showed the DehH2-L-2CP complex (-24.27 kcal/mol) having the lowest binding energy followed by DehH2-MCA (-22.78 kcal/mol), DehH2-D-2CP (-21.82 kcal/mol), DehH2-3CP (-21.11 kcal/mol), DehH2-2,2-DCP (-18.34 kcal/mol), DehH2-2,3-DCP (-8.34 kcal/mol), DehH2-TCA (-7.62 kcal/mol), while chlorpyrifos was unable to spontaneously bind to DehH2 (+127.16 kcal/mol). In a nutshell, the findings of this study offer valuable insights into the rational tailoring of the DehH2 for expanding its substrate specificity and catalytic activity in the near future.Communicated by Ramaswamy H. Sarma.

In silico assessment of dehalogenase from Bacillus thuringiensis H2 in relation to its salinity-stability and pollutants degradation.

Increased scientific interest has led to the rise in biotechnological uses of halophilic and halotolerant microbes for hypersaline wastewater bioremediation. Hence, this study performed molecular docking, molecular dynamic (MD) simulations, and validation by Molecular Mechanic Poisson-Boltzmann Surface Area (MM-PBSA) calculations on the DehH2 from Bacillus thuringiensis H2. We aimed to identify the interactions of DehH2 with substrates haloacids, haloacetates, and chlorpyrifos under extreme salinity (35% NaCl). MD simulations revealed that DehH2 preferentially degraded haloacids and haloacetates (-6.3 to -4.7 kcal/mol) by forming three or four hydrogen bonds to the catalytic triad, Asp125, Arg201, and Lys202. Conversely, chlorpyrifos was the least preferred substrate in both MD simulations and MM-PBSA calculations. MD simulation results ranked the DehH2-L-2CP complex (RMSD □0.125-0.23 nm) as the most stable while the least was the DehH2-chlorpyrifos complex (RMSD 0.32 nm; RMSF 0.0 - 0.29). The order of stability was as follows: DehH2-L-2CP > DehH2-MCA > DehH2-D-2CP > DehH2-3CP > DehH2-2,2-DCP > DehH2-2,3-DCP > DehH2-TCA > DehH2-chlorpyrifos. The MM-PBSA calculations further affirmed the DehH2-L-2CP complex's highest stability with the lowest binding energy of -45.14 kcal/mol, followed closely by DehH2-MCA (-41.21 kcal/mol), DehH2-D-2CP (-31.59 kcal/mol), DehH2-3CP (-30.75 kcal/mol), DehH2-2,2- DCP (-29.72 kcal/mol), DehH2-2,3-DCP (-22.20 kcal/mol) and DehH2-TCA (-18.46 kcal/mol). The positive binding energy of the DehH2-chlorpyrifos complex (+180.57 kcal/mol) proved the enzyme's non-preference for the substrate. The results ultimately illustrated the unique specificity of the DehH2 to degrade the above-said pollutants under a hypersaline condition.Communicated by Ramaswamy H. Sarma.

Electrospun Magnetic Nanocellulose-Polyethersulfone-Conjugated Aspergillus oryzae Lipase for Synthesis of Ethyl Valerate.

A novel greener MNC/PES membrane was developed through an electrospinning technique for lipase immobilization to catalyze the synthesis of ethyl valerate (EV). In this study, the covalent immobilization of Aspergillus oryzae lipase (AOL) onto an electrospun nanofibrous membrane consisting of magnetic nanocellulose (MNC) and polyethersulfone (PES) to produce EV was statistically optimized. Raman spectroscopy, Fourier-transform infrared spectroscopy: attenuated total reflection, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, thermal gravimetric analysis (TGA), and differential thermal gravimetric (DTG) of MNC/PES-AOL demonstrated that AOL was successfully immobilized onto the fibers. The Taguchi design-assisted immobilization of AOL onto MNC/PES fibers identified that 1.10 mg/mL protein loading, 4 mL reaction volume, 250 rpm stirring rate, and 50 °C were optimal to yield 72.09% of EV in 24 h. The thermal stability of MNC/PES-AOL was improved by ≈20% over the free AOL, with reusability for up to five consecutive esterification cycles while demonstrating an exceptional half-life of 120 h. Briefly, the electrospun MNC/PES fibers that immobilized AOL showed promising applicability in yielding relatively good EV levels. This study suggests that using MNC as fillers in a PES to improve AOL activity and durability for a longer catalytic process could be a viable option.

Operational Stability, Regenerability, and Thermodynamics Studies on Biogenic Silica/Magnetite/Graphene Oxide Nanocomposite-Activated Candida rugosa Lipase.

Inorganic biopolymer-based nanocomposites are useful for stabilizing lipases for enhanced catalytic performance and easy separation. Herein, we report the operational stability, regenerability, and thermodynamics studies of the ternary biogenic silica/magnetite/graphene oxide nanocomposite (SiO2/Fe3O4/GO) as a support for Candida rugosa lipase (CRL). The X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field-electron scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM), and nitrogen adsorption/desorption data on the support and biocatalyst corroborated their successful fabrication. XPS revealed the Fe3O4 adopted Fe2+ and Fe3+ oxidation states, while XRD data of GO yielded a peak at 2θ = 11.67°, with the SiO2/Fe3O4/GO revealing a high surface area (≈261 m2/g). The fourier transform infrared (FTIR) spectra affirmed the successful fabricated supports and catalyst. The half-life and thermodynamic parameters of the superparamagnetic immobilized CRL (CRL/SiO2/Fe3O4/GO) improved over the free CRL. The microwave-regenerated CRL/SiO2/Fe3O4/GO (≈82%) exhibited higher catalytic activity than ultrasonic-regenerated (≈71%) ones. Lower activation (Ea) and higher deactivation energies (Ed) were also noted for the CRL/SiO2/Fe3O4/GO (13.87 kJ/mol, 32.32 kJ/mol) than free CRL (15.26 kJ/mol, 27.60 kJ/mol). A peak at 4.28 min in the gas chromatograph-flame ionization detection (GC-FID) chromatogram of the purified ethyl valerate supported the unique six types of 14 hydrogen atoms of the ester (CAS: 539-82-2) in the proton nuclear magnetic resonance (1H-NMR) data. The results collectively demonstrated the suitability of SiO2/Fe3O4/GO in stabilizing CRL for improved operational stability and thermodynamics and permitted biocatalyst regenerability.

Ternary biogenic silica/magnetite/graphene oxide composite for the hyperactivation of Candida rugosa lipase in the esterification production of ethyl valerate.

Oil palm leaves (OPL) silica (SiO2) can replace the energy-intensive, commercially produced SiO2. Moreover, the agronomically sourced biogenic SiO2 is more biocompatible and cost-effective enzyme support, which properties could be improved by the addition of magnetite (Fe3O4) and graphene oxide (GO) to yield better ternary support to immobilize enzymes, i.e., Candida rugosa lipase (CRL). This study aimed to optimize the Candida rugosa lipase (CRL immobilization onto the ternary OPL-silica-magnetite (Fe3O4)-GO (SiO2/Fe3O4/GO) support, for use as biocatalyst for ethyl valerate (EV) production. Notably, this is the first study detailing the CRL/SiO2/Fe3O4/GO biocatalyst preparation for rapid and high yield production of ethyl valerate (EV). AFM and FESEM micrographs revealed globules of CRL covalently bound to GL-A-SiO2/Fe3O4/GO; similar to Raman and UV-spectroscopy results. FTIR spectra revealed amide bonds at 3478 cm-1 and 1640 cm-1 from covalent interactions between CRL and GL-A-SiO2/Fe3O4/GO. Optimum immobilization conditions were 4% (v/v) glutaraldehyde, 8 mg/mL CRL, at 16 h stirring in 150 mM NaCl at 30 °C, offering 24.78 ± 0.26 mg/g protein (specific activity = 65.24 ± 0.88 U/g). The CRL/SiO2/Fe3O4/GO yielded 77.43 ± 1.04 % of EV compared to free CRL (48.75 ± 0.70 %), verifying the suitability of SiO2/Fe3O4/GO to hyperactivate and stabilize CRL for satisfactory EV production.