Bioremediation Applications Research Articles

Combining Hard Shell with Soft Core to Enhance Enzyme Activity and Resist External Disturbances.

Immobilizing enzymes onto solid supports having enhanced catalytic activity and resistance to harsh external conditions is considered as a promising and critical method of broadening enzymatic applications in biosensing, biocatalysis, and biomedical devices; however, it is considerably hampered by limited strategies. Here, a core-shell strategy involving a soft-core hexahistidine metal assembly (HmA) is innovatively developed and characterized with encapsulated enzymes (catalase (CAT), horseradish peroxidase, glucose oxidase (GOx), and cascade enzymes (CAT+GOx)) and hard porous shells (zeolitic imidazolate framework (ZIF), ZIF-8,ZIF-67, ZIF-90, calcium carbonate, and hydroxyapatite). The enzyme-friendly environment provided by the embedded HmA proves beneficial for enhanced catalytic activity, which is particularly effective in preserving fragile enzymes that will have been deactivated without the HmA core during the mineralization of porous shells. The enzyme encapsulated within a core-shell particle exhibits noteworthy resilience against harsh external conditions, including heat, organic solvents, and proteinase K. Additionally, no significant alteration in the catalytic behavior of the enzyme is observed after multiple cycles of usage. This study offers a novel approach for immobilizing enzymes and rendering them resistant to harsh external conditions, with potential applications in diverse fields, including biocatalysis, bioremediation, and biomedical engineering.

Inhibitory effects of cadmium and hydrophilic cadmium telluride quantum dots on the white rot fungus Phanerochaete velutina.

The white rot fungus P. velutina was investigated for its ability to decolorize the reactive textile dye Reactive Black 5 (RB5) that was co-exposed to CdCl2 and quantum dots (QDs) consisting of a CdTe core capped with two different hydrophilic organic ligands (NAC and MPA). Without co-exposure, P. velutina completely decolorizes RB5 within 9 days. The highest inhibitory effect was found for soluble CdCl2 with an EC50 of 583μgl-1, followed by MPA-QDs (10,628μgl-1) and NAC-QDs (17,575μgl-1). The different EC50 values indicate that the nanoparticle coatings have a strong influence on the inhibitory effects, as the organic ligands used for surface passivation prevented the leaching of acute toxic Cd ions from the metallic QD core. Compared to CdCl2, the CdTe QDs were less inhibitory to the formation of fungal metabolites and their decolorization ability on co-exposed textile dyes. In addition, the literature comparison suggests that P. velutina is more resilient to cadmium than other microorganisms. The fungus could therefore be used for bioremediation applications of dye- or QD-contaminated wastewater from the textile or semiconductor industries.

Genome-Scale Community Model-Guided Development of Bacterial Coculture for Lignocellulose Bioconversion.

Microbial communities have shown promising potential in degrading complex biopolymers, producing value-added products through collaborative metabolic functionality. Hence, developing synthetic microbial consortia has become a predominant technique for various biotechnological applications. However, diverse microbial entities in a consortium can engage in distinct biochemical interactions that pose challenges in developing mutualistic communities. Therefore, a systems-level understanding of the inter-microbial metabolic interactions, growth compatibility, and metabolic synergisms is essential for developing effective synthetic consortia. This study demonstrated a genome-scale community modeling approach to assess the inter-microbial interaction pattern and screen metabolically compatible bacterial pairs for designing the lignocellulolytic coculture system. Here, we have investigated the pairwise growth and biochemical synergisms among six termite gut bacterial isolates by implementing flux-based parameters, i.e., pairwise growth support index (PGSI) and metabolic assistance (PMA). Assessment of the PGSI and PMA helps screen nine beneficial bacterial pairs that were validated by designing a coculture experiment with lignocellulosic substrates. For the cocultured bacterial pairs, the experimentally measured enzymatic synergisms (DES) showed good coherence with model-derived biochemical compatibility (PMA), which explains the fidelity of the in silico predictions. The highest degree of enzymatic synergisms has been observed in C. denverensis P3 and Brevibacterium sp P5 coculture, where the total cellulase activity has been increased by 53%. Hence, the flux-based assessment of inter-microbial interactions and metabolic compatibility helps select the best bacterial coculture system with enhanced lignocellulolytic functionality. The flux-based parameters (PGSI and PMA) in the proposed community modeling strategy will help optimize the composition of microbial consortia for developing synthetic microcosms for bioremediation, bioengineering, and biomedical applications.

Creating a multifunctional degrader for co-mineralization of p-nitrophenol and 1,2-dichloroethane and its application in wastewater bioremediation

Creating a multifunctional degrader for co-mineralization of p-nitrophenol and 1,2-dichloroethane and its application in wastewater bioremediation

Construction of a fusant bacterial strain simultaneously degrading atrazine and acetochlor and its application in soil bioremediation.

Application of herbicide-degrading bacteria is an effective strategy to remove herbicide in soil. However, the ability of bacteria to degrade a herbicide is often severely limited in the presence of other pesticide. In this study, the atrazine-degrading strain Klebsiella varicola FH-1 and acetochlor-degrading strain Bacillus Aryabhatti LY-4 were used as parent strains to construct the recombinant RH-92 strain through protoplast fusion technology. Compared with the parent strains, RH-92 exhibited enhanced ability to degrade herbicide mixture containing atrazine and acetochlor, exhibiting 63.16% and 68.48% higher degradation rates, respectively. RAPD analysis showed that gene rearrangement occurred during protoplast fusion, and the genetic similarity indexes of the fused strain RH-92 and the two parent strains were 0.5853 and 0.4240, respectively. HPLC-MS analysis confirmed that RH-92 shared similar degradation products and pathways with both parent strains but exhibited a novel metabolic pathway for the continuous degradation of CMEPA (degradation product of acetochlor) into MEA through amide bond hydrolysis. The activities of GSH, GST and SOD of RH-92 increased and the level of MDA decreased under the stress of compound herbicides. Strain RH-92 did not show a large number of bacterial apoptosis, and maintained good cell membrane integrity and permeability. The half-lives of atrazine and acetochlor were 4.9 d and 7.6 d when the parent strains FH-1 and LY-4 were applied in unsterilized soil containing herbicide mixture treatment,the application fusant RH-92 strain significantly reduced the half-life to 1.6 and 1.8 d, respectively. Furthermore, 16S rRNA sequencing indicated that RH-92 application effectively restored bacterial taxa with diminished relative abundances under herbicide mixture treatment, ameliorated phytotoxicity in soybean seedlings, and promoted enhanced vegetative growth in the roots and plant height. This study highlighted the application of fusant strains as a bioremediation strategy for combatting atrazine and acetochlor pollution in soil and provided theoretical insights.

Genomic insights into the probiotic potential and genes linked to gallic acid metabolism in Pediococcus pentosaceus MBBL6 isolated from healthy cow milk.

Pediococcus pentosaceus is well known for its probiotic properties, including roles in improving health, antimicrobial production, and enhancing fermented food quality. This study aimed to comprehensively analyze the whole genome of P. pentosaceus MBBL6, isolated from healthy cow milk, to assess its probiotic and antimicrobial potentials. P. pentosaceus MBBL6, isolated from a healthy cow milk at BSMRAU dairy farm, Gazipur, Bangladesh, underwent comprehensive genomic analysis, including whole genome sequencing, assembly, annotation, phylogenetic comparison, and assessment of metabolic pathways and secondary metabolites. Antimicrobial efficacy was evaluated through in-vitro and in-vivo studies, alongside in-silico exploration for potential mastitis therapy. We predicted 1,906 genes and 204 SEED sub-systems involved in carbohydrate metabolism and vitamin B complex biosynthesis, with a focus on lactose metabolism in MMBL6. Notably, 43 putative carbohydrate-active enzyme genes, including lysozymes, suggest the ability of MBBL6 for carbohydrate biotransformation and antimicrobial activity. The genome also revealed primary metabolic pathways for arginine and gallic acid metabolism and secondary metabolite gene clusters, including T3PKS and RiPP-like regions. Importantly, two bacteriocin biosynthesis gene clusters namely bovicin_255_variant and penocin_A, were identified in MBBL6. The safety assessment of MBBL6 genome revealed no virulence genes and a low pathogenicity score (0.196 out of 1.0). Several genes related to survival in gastrointestinal tract and colonization were also identified. Furthermore, MBBL6 exhibited susceptibility to a wide range of antibiotics in-vitro, and effectively suppressed mastitis pathogens in an in-vivo mouse mastitis model trial. The observed bacteriocin, particularly bovicin, demonstrated the ability to disrupt the function of an essential protein, Rho factor of mastitis pathogens by blocking transcription termination process. Taken together, our in-depth genomic analysis underscores the metabolic versatility, safety profile, and antimicrobial potential of P. pentosaceus MBBL6, suggesting its promise for applications in therapeutics, bioremediation, and biopreservation.

Potential of plants and microorganisms for bioremediation technologies for mine rehabilitation

The mining industry is one of the priority sources of environmental pollution by potentially toxic metals. The impact on the environment remains significant even after the end of mining activities. Numerous studies report the environmental impact of abandoned mines. Therefore, cleaning of mine territories from the pollution is of priority importance. Phytoremediation and microbial remediation are some of the methods. The study of plants for their possible use in phytoremediation is of great interest. Such works are of great importance in developing modern phytoremediation technologies, as they allow us to find new hyperaccumulators for possible mine reclamation. Microorganisms possessing resistance to heavy metals, such as fungi and bacteria, as well as unicellular algae, may be used to clean up tailings contaminated with potentially toxic metals. The microbiological method of tailings treatment is based on the ability of microorganisms to transform and decompose chemical compounds. Microbial remediation and phytoremediation are attracting more and more attention due to their relatively low cost and environmental friendliness. A large number of studies related to the investigation of mine plants and microorganisms and their utilization for mine cleanup demonstrate the promise of using bioremediation. Further development of bioremediation technologies will be associated with wider implementation of the research findings in practice and the possible use of biotechnology in bioremediation. The successful practical application of mine bioremediation requires a complex interdisciplinary approach associated with biological, ecological, biotechnological, and geographic-geological areas.

Temperature-responsive regulation of the polycyclic aromatic hydrocarbon-degrading mesophilic bacterium Novosphingobium pentaromativorans US6-1 with a temperature adaptation system.

Survivability and tolerance of polycyclic aromatic hydrocarbon (PAH)-degrading bacteria in harsh environments, especially under varying temperatures, are a bottleneck for the effective application of in situ bioremediation. In this study, a temperature adaptation system (TAS) was constructed by combining a customized thermotolerant system with a customized cold-resistant system to realize the temperature-responsive regulation of the PAH-degrading mesophilic bacterium Novosphingobium pentaromativorans US6-1. The innovative dual-pronged TAS strategy enabled the chassis strain to effectively tackle conditions under varying temperatures, ensuring robust biological activities across a broadened temperature spectrum and exhibiting the potential to realize the high-efficiency PAH degradation of N. pentaromativorans US6-1 in in situ bioremediation. Furthermore, the temperature-responsive regulation achieved using the TAS circuit is likely promising for creating intelligent microbial cell factories and avoiding precise temperature maintenance, making it highly useful for industrial applications.IMPORTANCEEnvironmental temperature is among the extremely important factors that determine the bioactivities of pollutant-degrading microorganisms in in situ bioremediation. Effectively maintaining the survivability and tolerance of mesophilic microorganisms under harsh conditions and varying temperatures remains a challenge in the application of pollutant bioremediation. This study, for the first time, developed a temperature adaptation system by combining a customized thermotolerant system with a customized cold-resistant system to realize the temperature-responsive regulation of the polycyclic aromatic hydrocarbon (PAH)-degrading mesophilic bacterium Novosphingobium pentaromativorans US6-1, thus diminishing the need for precise temperature control in PAH bioremediation.

Advancing environmental sustainability: a comprehensive review on alleviating carbon footprint and its application in microalgal fermentation and bioremediation

Advancing environmental sustainability: a comprehensive review on alleviating carbon footprint and its application in microalgal fermentation and bioremediation

Bibliometric Analysis of Contemporary Research on the Amelioration of Saline Soils

The decreasing availability of agricultural land, coupled with the growing global population, presents significant challenges worldwide. Reclaiming saline–alkali soil offers a promising solution to alleviate these challenges. Improving and utilizing saline soils present ecological challenges that are influenced by both technological advancements and socio-economic factors. This study presents a bibliometric analysis of the published research on saline soil remediation and reclamation from 1985 to the present, using data indexed by the Web of Science Core Collection: Science Citation Index Expanded and Social Science Citation Index. This analysis includes 16,729 publications, which indicate that, over the years, many scientists have conducted extensive research on enhancing and using sodic lands. Countries like the United States, China, Australia, Pakistan, Poland, India, Egypt, and Israel have been pioneers in this field. Furthermore, we summarize trends in this research area, highlighting how strategies for saline soil reclamation have evolved from physical and chemical remediation to salt-tolerant crop breeding and bioremediation applications. With the advancements in science and technology, more methods and strategies have become available to facilitate saline soil remediation. Consequently, management strategies combining multiple technologies will become more effective and provide powerful approaches for reclaiming arable soil from high-salinity marginal lands.

Biodegradation of various edible oils and fat by Staphylococcus petrasii sub sp. jettensis VSJK R1 for application in bioremediation of lipid rich restaurant wastewater.

The disposal of fat, oil, and grease (FOG) pollutants from various sources, including restaurants, food processing facilities, and domestic kitchens, poses significant challenges to wastewater treatment systems. In this study, we isolated and characterized a novel bacterial strain. The result of 16S rRNA gene and phylogenetic analysis showed that the isolate was Staphylococcus petrasii sub sp. jettensis and named as VSJK R1 (Fig. S1). It was tested for its biodegradation potential of FOG contaminants. Our investigation revealed that Staphylococcus petrasii sub sp. jettensis VSJK R1 effectively degraded a variety of edible oils, including soybean, sunflower, cottonseed, palm, groundnut, and butter, with notable efficiency. Optimization studies were conducted to determine the optimal conditions for biodegradation, including the effects of nitrogen, carbon, phosphorus, pH, temperature, and salt concentration. Results indicated that organic nitrogen sources and glucose as carbon source significantly enhanced biodegradation rates, while the addition of phosphorus further improved degradation efficiency within specific concentration ranges. Moreover, the optimal pH for biodegradation was found to be neutral, with temperature ranging between 22°C and 45°C favoring microbial activity. Remarkably, Staphylococcus petrasii sub sp. jettensis VSJK R1 exhibited resilience to high salt concentrations, making it suitable for treatment of wastewater with elevated salt content. Additionally, comparative studies with other microbial strains underscored the unique biodegradation capabilities of Staphylococcus petrasii sub sp. jettensis VSJK R1, particularly in degrading various edible oils. The results suggest promising applications of this novel isolate in bioremediation efforts targeting FOG pollutants in wastewater treatment plants and grease traps. Future research may focus on scaling up the bioremediation process and field testing the efficacy of Staphylococcus petrasii sub sp. jettensis VSJK R1 in real-world wastewater treatment scenarios.

Comprehensive insight into recent algal enzymes production and purification advances: Toward effective commercial applications: A review.

Algal enzymes are essential catalysts in numerous biological reactions and industrial processes owing to their adaptability and potency. The marketing of algal enzymes has recently risen due to various reasons, including the cost-efficient manner of their cultivation in photobioreactors, the eco-friendly production of high biomass contents, sources of novel enzymes that used in many sectors (biofuel and bioremediation applications), sustainability, and more renewability. Oxidoreductases and hydrolytic enzymes are among the important applied algal enzymes in industrial applications, with annually growing demand. These algal enzymes have opened up new avenues for significant health advantages in reducing and treating oxidative stress, cardiovascular illness, tumors, microbial infections, and viral outbreaks. Despite their promising uses, commercial applications of algal enzymes face many difficulties, such as stability, toxicity, and lower data availability on specific and adequate catalytic mechanisms. Therefore, this review focuses on the algal enzyme types, their uses and advantages over other microbial enzymes, downstream and upstream processing, their commercial and marketing, and their challenges. With the constant development of novel enzymes and their uses, enzyme technology provides exciting options for several industrial sectors.

Understanding the tolerance of halophilic archaea to stress landscapes.

Haloarchaea, known for their resilience to environmental fluctuations, require a minimum salt concentration of 10% (w/v) for growth and can survive up to 35% (w/v) salinity. In biotechnology, these halophiles have diverse industrial applications. This study investigates the tolerance responses of nine haloarchaea: Haloferax mediterranei, Haloferax volcanii, Haloferax gibbonsii, Halorubrum californiense, Halorubrum litoreum, Natrinema pellirubrum, Natrinema altunense, Haloterrigena thermotolerans and Haloarcula sinaiiensis, under various stressful conditions. All these archaea demonstrated the ability to thrive in the presence of toxic metals such as chromium, nickel, cobalt and arsenic, and their tolerance to significantly elevated lithium concentrations in the medium was remarkable. Among the studied haloarchaea, Hfx. mediterranei exhibited superior resilience, particularly against lithium, with an impressive minimum inhibitory concentration (MIC) of up to 4 M LiCl, even replacing NaCl entirely. Haloferax species showed specificity for conditions with maximal growth rates, while Htg. thermotolerans and Nnm. altunense displayed high resilience without losing growth throughout the ranges, although these were generally low. ICP-MS results highlighted the impressive intracellular lithium accumulation in Nnm. pellirubrum, emphasizing its potential significance in bioremediation. This research highlights a new characteristic of haloarchaea, their tolerance to high lithium concentrations and the potential for new applications in extreme industrial processes and bioremediation.

Electric stimulation: a versatile manipulation technique mediated microbial applications.

Electric stimulation (ES) is a versatile technique that uses an electric field to manipulate microorganisms individually. Over the past several decades, the capabilities of ES have expanded from bioremediation to the precise motion control of cells and microorganisms. However, there is limited information on the underlying mechanisms, latest advancement and broader microbial applications of ES in various fields, such as the production of extracellular polymers with upgraded properties. This review article summarizes recent advancements in ES and discusses it as a unique external manipulation technique for microorganisms with wide applications in bioremediation, industry, biofilm deactivation, disinfection, and controlled biosynthesis. One specific application of ES discussed in this review is the extracellular biosynthesis, regulation, and organization of extracellular polymers, such as bacterial cellulose nanofibrils, curdlan, and microbial nanowires. Overall, this review aims to provide a platform for microbial biotechnologists and synthetic biologists to leverage the manipulation of microorganisms using ES for bio-based applications, including the production of extracellular polymers with enhanced properties. Researchers can engineer, manipulate, and control microorganisms for various applications by harnessing the potential of electric fields.

Copper and chromium binding by Pseudomonas aeruginosa strain PA01 for implications of heavy metal detoxification and soil remediation: A computational approach

Heavy metal pollution poses significant environmental and health risks due to the toxic effects of metals like copper and chromium at elevated concentrations. Despite their essential roles in trace amounts, these metals can be highly toxic. Bacteria such asPseudomonas aeruginosaare promising candidates for bioremediation due to their robustness and adaptability.The objective of this study was to analyze and identify potential copper and chromium binding genes involved in metal detoxification inPseudomonas aeruginosaPA01. The heavy metal binding protein identified as ferredoxin using MALDI-TOF/PMF-MS analysis was further characterized. The structure of the ferredoxin protein was elucidated using the SWISS-MODEL tool. Metal-binding domains were validated through a pattern search against UniProtKB/Swiss-Prot and UniProtKB/TrEMBL databases using the ScanProsite tool. Comparative sequence alignments were conducted between the copper-binding NosD gene ofP. aeruginosa, the ferredoxin gene ofP. aeruginosaPA01, and the chromium-binding iron hydrogenase 1 gene ofClostridium chromiireducens. The SWISS-MODEL analysis revealed alpha helices and beta sheets with key metal-coordinating amino acids (cysteine, glutamic acid, aspartic acid, histidine, and methionine). The ScanProsite tool confirmed the presence of a 4Fe-4S ferredoxin-type iron-sulphur binding domain essential for coordinating chromium and copper ions. Sequence alignments showed a 64.29 % similarity between the NosD gene and ferredoxin gene, and a 67 % identity between the iron hydrogenase 1 gene and ferredoxin gene, with correlations in amino acid residues involved in metal binding. These findings suggest that the ferredoxin gene could effectively bind heavy metal ions, offering potential applications in bioremediation of metal-polluted soils usingPseudomonasspecies. This study contributes to sustainable agricultural productivity by facilitating the targeted remediation of heavy metal-contaminated soils through biological means.

Biorefinery and Bioremediation Strategies for Efficient Management of Recalcitrant Pollutants Using Termites as an Obscure yet Promising Source of Bacterial Gut Symbionts: A Review.

Lignocellulosic biomass (LCB) in the form of agricultural, forestry, and agro-industrial wastes is globally generated in large volumes every year. The chemical components of LCB render them a substrate valuable for biofuel production. It is hard to dissolve LCB resources for biofuel production because the lignin, cellulose, and hemicellulose parts stick together rigidly. This makes the structure complex, hierarchical, and resistant. Owing to these restrictions, the junk production of LCB waste has recently become a significant worldwide environmental problem resulting from inefficient disposal techniques and increased persistence. In addition, burning LCB waste, such as paddy straws, is a widespread practice that causes considerable air pollution and endangers the environment and human existence. Besides environmental pollution from LCB waste, increasing industrialization has resulted in the production of billions of tons of dyeing wastewater from several industries, including textiles, pharmaceuticals, tanneries, and food processing units. The massive use of synthetic dyes in various industries can be detrimental to the environment due to the recalcitrant aromatic structure of synthetic dyes, similar to the polymeric phenol lignin in LCB structure, and their persistent color. Synthetic dyes have been described as possessing carcinogenic and toxic properties that could be harmful to public health. Environmental pollution emanating from LCB wastes and dyeing wastewater is of great concern and should be carefully handled to mitigate its catastrophic effects. An effective strategy to curtail these problems is to learn from analogous systems in nature, such as termites, where woody lignocellulose is digested by wood-feeding termites and humus-recalcitrant aromatic compounds are decomposed by soil-feeding termites. The termite gut system acts as a unique bioresource consisting of distinct bacterial species valued for the processing of lignocellulosic materials and the degradation of synthetic dyes, which can be integrated into modern biorefineries for processing LCB waste and bioremediation applications for the treatment of dyeing wastewaters to help resolve environmental issues arising from LCB waste and dyeing wastewaters. This review paper provides a new strategy for efficient management of recalcitrant pollutants by exploring the potential application of termite gut bacteria in biorefinery and bioremediation processing.

The functional role of N-link glycosylation in a novel cellobiohydrolase II (LsCel6A) from a white-rot fungus Lentinus sp. WR2

White-rot fungi produce a wide spectrum of lignocellulose-degradation enzymes, which can be used in bioenergy, bioremediation, and other industrial applications. This study identified a cellobiohydrolase II (Cel6A, GH6 cellobiohydrolase, EC 3.2.1.91) with high hydrolytic activity toward crystalline cellulose from a white-rot fungus Lentinus sp. WR2. Both native (nLsCel6A) and recombinant (rLsCel6A) enzymes expressed in Pichia pastoris were purified and characterized. Three N-glycosylation sites at Asn102, Asn145, and Asn392 containing high-mannose glycans, were confirmed by mass spectrometry. To elucidate the functional role of N-linked glycans, three deglycosylated mutants of rLsCel6A, i.e., N102A, N145A, and N392A, were created and characterized for their biochemical and kinetic properties. While no discernible changes in the secondary structure of the three mutants were determined by circular dichroism spectrometry, deterioration of thermostability was revealed in N392A but not in N102A and N145A. Structure modeling and molecular dynamics analyses revealed that the N-linked glycan on Asn392 may restrict the flexibility of the C-terminal loop in LsCel6A, affecting the protein integrity and appropriate dynamics for the enzymatic function. In summary, this study identified a novel LsCel6A enzyme with high catalytic activity against insoluble forms of cellulose and demonstrated the role of N-linked glycosylation in the thermostability of the enzyme.

Roseomonas aestuarii, as a Potential In Situ Surfactin Producer During Hydrocarbon Biodegradation.

In situ biosurfactant production by hydrocarbon degrader microorganisms is an attractive approach in the bioremediation of oil contamination because of their compatibility, biodegradability, environmental safety, and stability under extreme environmental conditions. Given the high efficiency of bacteria in degrading petroleum hydrocarbons, the present work studied the detection and characterization of a biosurfactant-producing hydrocarbon degrader, Roseomonas aestuarii NB833. This strain was able to synthesize a biosurfactant during the biodegradation of crude oil, which reduced the surface tension of the aqueous system from 70 to 34 mN m-1, with a critical micelle concentration of 200 mg L-1. The emulsification ability of the biosurfactant was sustained at various temperatures, pH values, and salinities. The biosurfactant chemical structure was identified via FT-IR, LC-MS, and NMR analyses. These analyses confirmed the production of surfactin-C14 with a molecular mass of 1007 g mol-1. These results revealed the high potential of R. aestuarii NB833 as an in situ surfactin-producing bacteria for bioremediation applications under extreme environmental conditions.

Computational insights into mercuric reductase from Pseudomonas fluorescens: a bioinformatic and molecular dynamics approach for mercury detoxification

Mercury (Hg) pollution poses significant threats to human health and ecosystems worldwide due to its persistence, bioaccumulation, and toxic effects. This study focuses on mercuric reductase from Pseudomonas fluorescens (UniProt ID Q51772), a key enzyme involved in detoxifying mercury through reduction to its less toxic elemental form, Hg(0). This study aims to explore the potential of this enzyme for bioremediation applications, focusing on structural insights, functional mechanisms, and biotechnological enhancements to facilitate mercury detoxification. The protein sequence of Q51772 was analyzed using bioinformatics tools to determine its structural and functional attributes. Physiochemical properties, including molecular weight, isoelectric point, and secondary structure predictions, were assessed. Virulence prediction tools confirmed the protein’s nontoxic and nonpathogenic nature. Homology modeling and docking studies provided insights into its three-dimensional structure and binding interactions with mercury substrates. Q51772 consists of 548 amino acids and belongs to the Pyridine nucleotide-disulphide oxidoreductase family, class I. It features specific domains crucial for mercury reduction, identified through Pfam and InterPro analyses. Physiochemical analysis indicated a stable protein with hydrophilic tendencies conducive to enzymatic function. Structural modeling validated by ProQ and PROCHECK confirmed the reliability of the predicted structure. Molecular docking of organic mercury compound with wild-type and mutant mercuric reductase revealed strong binding affinities, with key hydrogen bonds involving residues Gly95, Thr122, and Asp390. Mercuric reductase Q51772 from Pseudomonas fluorescens emerges as a promising candidate for bioremediation of mercury-contaminated environments. Future research should focus on optimizing its performance under diverse environmental conditions to advance sustainable solutions for mercury pollution control.

Cohesive Living Bacterial Films with Tunable Mechanical Properties from Cell Surface Protein Display.

Engineered living materials (ELMs) constitute a novel class of functional materials that contain living organisms. The mechanical properties of many such systems are dominated by the polymeric matrices used to encapsulate the cellular components of the material, making it hard to tune the mechanical behavior through genetic manipulation. To address this issue, we have developed living materials in which mechanical properties are controlled by the cell-surface display of engineered proteins. Here, we show that engineered Esherichia coli cells outfitted with surface-displayed elastin-like proteins (ELPs, designated E6) grow into soft, cohesive bacterial films with biaxial moduli around 14 kPa. When subjected to bulge-testing, such films yielded at strains of approximately 10%. Introduction of a single cysteine residue near the exposed N-terminus of the ELP (to afford a protein designated CE6) increases the film modulus 3-fold to 44 kPa and eliminates the yielding behavior. When subjected to oscillatory stress, films prepared from E. coli strains bearing CE6 exhibit modest hysteresis and full strain recovery; in E6 films much more significant hysteresis and substantial plastic deformation are observed. CE6 films heal autonomously after damage, with the biaxial modulus fully restored after a few hours. This work establishes an approach to living materials with genetically programmable mechanical properties and a capacity for self-healing. Such materials may find application in biomanufacturing, biosensing, and bioremediation.