Exploring the substrate spectrum of phylogenetically distinct bacterial polyesterases.

The rapid escalation of plastic waste accumulation presents a significant threat of the modern world, demanding an immediate solution. Over the last years, utilization of the enzymatic machinery of various microorganisms has emerged as an environmentally friendly asset in tackling this pressing global challenge. Thus, various hydrolases have been demonstrated to effectively degrade polyesters. Plastic waste streams often consist of a variety of different polyesters, as impurities, mainly due to wrong disposal practices, rendering recycling process challenging. The elucidation of the selective degradation of polyesters by hydrolases could offer a proper solution to this problem, enhancing the recyclability performance. Towards this, our study focused on the investigation of four bacterial polyesterases, including DaPUase, IsPETase, PfPHOase, and Se1JFR, a novel PETase-like lipase. The enzymes, which were biochemically characterized and structurally analyzed, demonstrated degradation ability of synthetic plastics. While a consistent pattern of polyesters' degradation was observed across all enzymes, Se1JFR stood out in the degradation of PBS, PLA, and polyether PU. Additionally, it exhibited comparable results to IsPETase, a benchmark mesophilic PETase, in the degradation of PCL and semi-crystalline PET. Our results point out the wide substrate spectrum of bacterial hydrolases and underscore the significant potential of PETase-like enzymes in polyesters degradation.

Gelatin-/Alginate-Based Hydrogel Scaffolds Reinforced with TiO2 Nanoparticles for Simultaneous Release of Allantoin, Caffeic Acid, and Quercetin as Multi-Target Wound Therapy Platform.

This study proposes synthesis and evaluation of gelatin-/alginate-based hydrogel scaffolds reinforced with titanium dioxide (TiO2) nanoparticles which, through their combination with allantoin, quercetin, and caffeic acid, provide multi-target therapy directed on all phases of the wound healing process. These scaffolds provide the simultaneous release of bioactive agents and concurrently support cell/tissue repair through the replicated structure of a native extracellular matrix. The hydrogel scaffolds were synthesized via a crosslinking reaction using EDC as a crosslinker for gelatin. Synthesized hydrogel scaffolds and the effect of TiO2 on their properties were characterized by structural, mechanical, morphological, and swelling properties, and the porosity, wettability, adhesion to skin tissue, and simultaneous release features. The biocompatibility of the scaffolds was tested in vitro on fibroblasts (MRC5 cells) and in vivo (Caenorhabditis elegans) in a survival probe. The scaffolds revealed porous interconnected morphology, porosity of 88.33 to 96.76%, elastic modulus of 1.53 to 4.29 MPa, full hydrophilicity, favorable skin adhesivity, and biocompatibility. The simultaneous release was investigated in vitro indicating dependence on the scaffold's composition and type of bioactive agents. The novel scaffolds designed as multi-target therapy have significant promise for improved wound healing in a beneficial and non-invasive manner.

Proteomic examination of polyester-polyurethane degradation by Streptomyces sp. PU10: Diverting polyurethane intermediates to secondary metabolite production.

Global plastic waste accumulation has become omnipresent in public discourse and the focus of scientific research. Ranking as the sixth most produced polymer globally, polyurethanes (PU) significantly contribute to plastic waste and environmental pollution due to the toxicity of their building blocks, such as diisocyanates. In this study, the effects of PU on soil microbial communities over 18 months were monitored revealing that it had marginal effects on microbial diversity. However, Streptomyces sp. PU10, isolated from this PU-contaminated soil, proved exceptional in the degradation of a soluble polyester-PU (Impranil) across a range of temperatures with over 96% degradation of 10 g/L in 48 h. Proteins involved in PU degradation and metabolic changes occurring in this strain with Impranil as the sole carbon source were further investigated employing quantitative proteomics. The proposed degradation mechanism implicated the action of three enzymes: a polyester-degrading esterase, a urethane bond-degrading amidase and an oxidoreductase. Furthermore, proteome data revealed that PU degradation intermediates were incorporated into Streptomyces sp. PU10 metabolism via the fatty acid degradation pathway and subsequently channelled to polyketide biosynthesis. Most notably, the production of the tri-pyrrole undecylprodigiosin was confirmed paving the way for establishing PU upcycling strategies to bioactive metabolites using Streptomyces strains.

Silver(I) complexes containing antifungal azoles: significant improvement of the anti-Candida potential of the azole drug after its coordination to the silver(I) ion.

Inspired by the emergence of resistance to currently available antifungal therapy and by the great potential of metal complexes for the treatment of various diseases, we synthesized three new silver(I) complexes containing clinically used antifungal azoles as ligands, [Ag(ecz)2]SbF6 (1, ecz is econazole), {[Ag(vcz)2]SbF6}n (2, vcz is voriconazole), and [Ag(ctz)2]SbF6 (3, ctz is clotrimazole), and investigated their antimicrobial properties. The synthesized complexes were characterized by mass spectrometry, IR, UV-vis and 1H NMR spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction analysis. In the mononuclear complexes 1 and 3 with ecz and ctz, respectively, the silver(I) ion has the expected linear geometry, in which the azoles are monodentately coordinated to this metal center through the N3 imidazole nitrogen atom. In contrast, the vcz-containing complex 2 has a polymeric structure in the solid state in which the silver(I) ions are coordinated by four nitrogen atoms in a distorted tetrahedral geometry. DFT calculations were done to predict the most favorable structures of the studied complexes in DMSO solution. All the studied silver(I) complexes have shown excellent antifungal and good to moderate antibacterial activities with minimal inhibitory concentration (MIC) values in the ranges of 0.01-27.1 and 2.61-47.9 µM on the selected panel of fungi and bacteria, respectively. Importantly, the complexes 1-3 have exhibited a significantly improved antifungal activity compared to the free azoles, with the most pronounced effect observed in the case of complex 2 compared to the parent vcz against Candida glabrata with an increase of activity by five orders of magnitude. Moreover, the silver(I)-azole complexes 2 and 3 significantly inhibited the formation of C. albicans hyphae and biofilms at the subinhibitory concentration of 50% MIC. To investigate the impact of the complex 3 more thoroughly on Candida pathogenesis, its effect on the adherence of C. albicans to A549 cells (human adenocarcinoma alveolar basal epithelial cells), as an initial step of the invasion of host cells, was studied.

Bacillus and Streptomyces spp. as hosts for production of industrially relevant enzymes.

The application of enzymes is expanding across diverse industries due to their nontoxic and biodegradable characteristics. Another advantage is their cost-effectiveness, reflected in reduced processing time, water, and energy consumption. Although Gram-positive bacteria, Bacillus, and Streptomyces spp. are successfully used for production of industrially relevant enzymes, they still lag far behind Escherichia coli as hosts for recombinant protein production. Generally, proteins secreted by Bacillus and Streptomyces hosts are released into the culture medium; their native conformation is preserved and easier recovery process enabled. Given the resilience of both hosts in harsh environmental conditions and their spore-forming capability, a deeper understanding and broader use of Bacillus and Streptomyces as expression hosts could significantly enhance the robustness of industrial bioprocesses. This mini-review aims to compare two expression hosts, emphasizing their specific advantages in industrial surroundings such are chemical, detergent, textile, food, animal feed, leather, and paper industries. The homologous sources, heterologous hosts, and molecular tools used for the production of recombinant proteins in these hosts are discussed. The potential to use both hosts as biocatalysts is also evaluated. Undoubtedly, Bacillus and Streptomyces spp. as production hosts possess the potential to take on a more substantial role, providing superior (bio-based) process robustness and flexibility. KEY POINTS: • Bacillus and Streptomyces spp. as robust hosts for enzyme production. • Industrially relevant enzyme groups for production in alternative hosts highlighted. • Molecular biology techniques are enabling easier utilization of both hosts.

Exploring Microorganisms from Plastic-Polluted Sites: Unveiling Plastic Degradation and PHA Production Potential.

The exposure of microorganisms to conventional plastics is a relatively recent occurrence, affording limited time for evolutionary adaptation. As part of the EU-funded project BioICEP, this study delves into the plastic degradation potential of microorganisms isolated from sites with prolonged plastic pollution, such as plastic-polluted forests, biopolymer-contaminated soil, oil-contaminated soil, municipal landfill, but also a distinctive soil sample with plastic pieces buried three decades ago. Additionally, samples from Arthropoda species were investigated. In total, 150 strains were isolated and screened for the ability to use plastic-related substrates (Impranil dispersions, polyethylene terephthalate, terephthalic acid, and bis(2-hydroxyethyl) terephthalate). Twenty isolates selected based on their ability to grow on various substrates were identified as Streptomyces, Bacillus, Enterococcus, and Pseudomonas spp. Morphological features were recorded, and the 16S rRNA sequence was employed to construct a phylogenetic tree. Subsequent assessments unveiled that 5 out of the 20 strains displayed the capability to produce polyhydroxyalkanoates, utilizing pre-treated post-consumer PET samples. With Priestia sp. DG69 and Neobacillus sp. DG40 emerging as the most successful producers (4.14% and 3.34% of PHA, respectively), these strains are poised for further utilization in upcycling purposes, laying the foundation for the development of sustainable strategies for plastic waste management.

Polyurethane-Degrading Potential of Alkaline Groundwater Bacteria.

Plastic waste is a global environmental burden and long-lasting plastic polymers, including ubiquitous and toxic polyurethanes (PUs), rapidly accumulate in the water environments. In this study, samples were collected from the three alkaline groundwater occurrences in the geotectonic regions of the Pannonian basin of northern Serbia (Torda and Slankamen Banja) and Inner Dinarides of western Serbia (Mokra Gora) with aim to isolate and identify bacteria with plastic- and lignocellulose-degrading potential, that could be applied to reduce the burden of environmental plastic pollution. The investigated occurrences belong to cold, mildly alkaline (pH: 7.6-7.9) brackish and hyperalkaline (pH: 11.5) fresh groundwaters of the SO4 - Na + K, Cl - Na + K and OH, Cl - Ca, Na + K genetic type. Full-length 16S rDNA sequencing, using Oxford Nanopore sequencing device, was performed with DNA extracted from colonies obtained by cultivation of all groundwater samples, as well as with DNA extracted directly from one groundwater sample. The most abundant genera belong to Pseudomonas, Acidovorax, Kocuria and Methylotenera. All screened isolates (100%) had the ability to grow on at least 3 of the tested plastic and lignocellulosic substrates, with 53.9% isolates degrading plastic substrate Impranil® DLN-SD (SD), a model compound for PUs degradation. Isolates degrading SD that were identified by partial 16S rDNA sequencing belong to the Stenotrophomonas, Pseudomonas, Paraburkholderia, Aeromonas, Vibrio and Acidovorax genera. Taking into account that plastics, including commonly produced PUs, are widespread in groundwater, identification of PUs-degrading bacteria may have potential applications in bioremediation of groundwater polluted with this polymer.

Novel Quinoline-Based Thiosemicarbazide Derivatives: Synthesis, DFT Calculations, and Investigation of Antitubercular, Antibacterial, and Antifungal Activities.

The discovery of new antimicrobial agents as a means of treating drug-resistant microbial pathogens is of utmost significance to overcome their immense risk to human well-being. The current investigation involves the development, synthesis, and assessment of the antimicrobial efficacy of novel quinoline derivatives incorporating a thiosemicarbazide functionality. To design the target compounds (QST1-QST14), we applied the molecular hybridization approach to link various thiosemicarbazides to the quinoline core with a sulfonyl group. Upon the synthesis and completion of structural characterization via spectroscopic techniques (1H NMR, 13C NMR, 15N NMR, IR, and HRMS), the title molecules were extensively evaluated for their potential antitubercular, antibacterial, and antifungal activities. N-(3-Chlorophenyl)-2-(quinolin-8-ylsulfonyl)hydrazine-1-carbothioamide (QST4), the most effective compound against Mycobacterium tuberculosis H37Rv, was also tested on isoniazid-resistant clinical isolates with katG and inhA promoter mutations. Based on molecular docking studies, QST4 was also likely to demonstrate its antimycobacterial activity through inhibition of the InhA enzyme. Furthermore, three derivatives (QST3, QST4, and QST10) with preferable antimicrobial and drug-like profiles were also shown to be nontoxic against human embryonic kidney (HEK) cells. All compounds were optimized by the density functional theory method using B3LYP with the 6-31+G(d,p) basis set. Structural analysis, natural bond orbital calculations of donor-acceptor interactions, molecular electrostatic potential analysis, and frontier molecular orbital analysis were carried out. Quantum chemical descriptors and charges on the atoms were determined to compare the strengths of the intramolecular hydrogen bonds formed and their stabilities. We determined that the sulfur atom forms a stronger intramolecular hydrogen bond than the nitrogen, oxygen, and fluorine atoms in these sulfonyl thiosemicarbazide derivatives.

Upcycling of food waste streams to valuable biopigments pyocyanin and 1-hydroxyphenazine.

Phenazines, including pyocyanin (PYO) and 1-hydroxyphenazine (1-HP) are extracellular secondary metabolites and multifunctional pigments of Pseudomonas aeruginosa responsible for its blue-green color. These versatile molecules are electrochemically active, involved in significant biological activities giving fitness to the host, but also recognized as antimicrobial and anticancer agents. Their wider application is still limited partly due to the cost of carbon substrate for production, which can be solved by the utilization of carbon from food waste within the biorefinery concept. In this study, a variety of food waste streams (banana peel, potato peel, potato washing, stale bread, yoghurt, processed meat, boiled eggs and mixed canteen waste) was used as sole nutrient source in submerged cultures of P. aeruginosa BK25H. Stale bread was identified as the most suitable substrate to support phenazine biopigments production and bacterial growth. This was further increased in 5-liter fermenter when on average 5.2 mg L-1 of PYO and 4.4 mg L-1 of 1-HP were purified after 24 h batch cultivations from the fermentation medium consisting of homogenized stale bread in tap water. Purified biopigments showed moderate antimicrobial activity, and showed different toxicity profiles, with PYO not being toxic against Caenorhabditis elegans, a free-living soil nematode up to 300 µg mL-1 and 1-HP showing lethal effects at 75 µg mL-1. Therefore, stale bread waste stream with minimal pretreatment should be considered as suitable biorefinery feedstock, as it can support the production of valuable biopigments such as phenazines.

Synthesis, Stereochemical Determination, and Antimicrobial Evaluation of Myxocoumarin A.

The myxobacterial natural product myxocoumarin A from Stigmatella aurantiaca MYX-030 has remarkable antifungal activity against agriculturally relevant pathogens. To broaden the initial evaluation of its biological potential, we herein completed the first total synthesis of myxocoumarin A. This synthetic access facilitated stereochemical investigations on the natural product structure, revealing its (R)-configuration. Biological activity profiling showed a lack of activity against Candida spp. and Gram-negative bacteria but revealed strong antibiotic activities against Bacillus subtilis and Staphylococcus aureus, including MRSA.

Antibiotic Potential of the Ambigol Cyanobacterial Natural Product Class and Simplified Synthetic Analogs.

The ambigols are cyanobacterial natural products characterized by three polychlorinated aromatic building blocks connected by biaryl and biaryl ether bridges. All ambigols known to date possess promising biological activities. Most significantly, ambigol A was reported to have antibacterial activity against Gram-positive bacteria, such as Bacillus megaterium and B. subtilis. We established a diverse compound library for in-depth biological evaluation building on our previous bio- and total synthetic research on this natural product family. To explore the antimicrobial potential in detail and to determine initial structure-activity relationships of this product class, a large set of dimeric and trimeric compounds were screened against selected bacterial and Candida target strains. Our results reveal exceptional antibiotic activity of the ambigols, especially against challenging clinical isolates.

Two-Step Upcycling Process of Lignocellulose into Edible Bacterial Nanocellulose with Black Raspberry Extract as an Active Ingredient.

(1) Background: Bacterial nanocellulose (BNC) has gained in popularity over the years due to its outstanding properties such as renewability, biocompatibility, and bioavailability, and its use as an eco-friendly material of the future for replacing petrochemical products. (2) Methods: This research refers to the utilization of lignocellulose coming from wood waste via enzymatic hydrolysis to produce biopolymer BNC with an accumulation rate of 0.09 mg/mL/day. Besides its significant contribution to the sustainability, circularity, and valorization of biomass products, the obtained BNC was functionalized through the adsorption of black raspberry extract (BR) by simple soaking. (3) Results: BR contained 77.25 ± 0.23 mg GAE/g of total phenolics and 27.42 ± 0.32 mg CGE/g of total anthocyanins. The antioxidant and antimicrobial activity of BR was evaluated by DPPH (60.51 ± 0.18 µg/mL) and FRAP (1.66 ± 0.03 mmol Fe2+/g) and using a standard disc diffusion assay, respectively. The successful synthesis and interactions between BNC and BR were confirmed by FTIR analysis, while the morphology of the new nutrient-enriched material was investigated by SEM analysis. Moreover, the in vitro release kinetics of a main active compound (cyanidin-3-O-rutinoside) was tested in different release media. (4) Conclusions: The upcycling process of lignocellulose into enriched BNC has been demonstrated. All findings emphasize the potential of BNC-BR as a sustainable food industry material.

Biological and physiochemical studies of electrospun polylactid/polyhydroxyoctanoate PLA/P(3HO) scaffolds for tissue engineering applications.

Polyhydroxyoctanoate, as a biocompatible and biodegradable biopolymer, represents an ideal candidate for biomedical applications. However, physical properties make it unsuitable for electrospinning, currently the most widely used technique for fabrication of fibrous scaffolds. To overcome this, it was blended with polylactic acid and polymer blend fibrous biomaterials were produced by electrospinning. The obtained PLA/PHO fibers were cylindrical, smaller in size, more hydrophilic and had a higher degree of biopolymer crystallinity and more favorable mechanical properties in comparison to the pure PLA sample. Cytotoxicity evaluation with human lung fibroblasts (MRC5 cells) combined with confocal microscopy were used to visualize mouse embryonic fibroblasts (MEF 3T3 cell line) migration and distribution showed that PLA/PHO samples support exceptional cell adhesion and viability, indicating excellent biocompatibility. The obtained results suggest that PLA/PHO fibrous biomaterials can be potentially used as biocompatible, biomimetic scaffolds for tissue engineering applications.

Brackish Groundwaters Contain Plastic- and Cellulose-Degrading Bacteria.

The selected brackish groundwater occurrences in the geotectonic regions of Inner Dinarides of western Serbia (Obrenovacka Banja) and Serbian crystalline core (Lomnicki Kiseljak and Velika Vrbnica) were sampled for isolation and identification of plastic- and lignocellulose-degrading bacteria, as well as for the assessment of their enzymatic potential. The examined occurrences belong to the cold and warm (subthermal), weakly alkaline, neutral, and weakly acidic groundwater, and their genetic types are HCO3-Na + K and HCO3-Ca, Mg. The most abundant genera identified by next-generation 16S sequencing of cultivated groundwater samples belong to Aeromonas and Exiguobacterium. Of isolates screened on plastic and lignocellulosic substrates, 85.3% demonstrated growth and/or degrading activity on at least one tested substrate, with 27.8% isolates degrading plastic substrate Impranil® DLN-SD (SD), 1.9% plastic substrate bis(2-hydroxyethyl)terephthalate, and 5.6% carboxymethyl cellulose (CMC). Isolates degrading SD that were identified by 16S rDNA sequencing belonged to genera Stenotrophomonas, Flavobacterium, Pantoea, Enterobacter, Pseudomonas, Serratia, Acinetobacter, and Proteus, while isolates degrading CMC belonged to genera Rhizobium and Shewanella. All investigated brackish groundwaters harbor bacteria with potential in degradation of plastics or cellulose. Taking into account that microplastics contamination of groundwater resources is becoming a significant problem, the finding of plastic-degrading bacteria may have potential in bioremediation treatments of polluted groundwater. Subterranean ecosystems, which are largely untapped resources of biotechnologically relevant enzymes, are not traditionally considered the environment of choice for screening for plastic- and cellulose-degrading bacteria and therefore deserve a special attention from this aspect.

Enzymatic functionalization of liquid phase exfoliated graphene using horseradish peroxidase and laccase.

We present a novel approach for the enzymatic functionalization of graphene, utilizing horseradish peroxidase (HPO) and laccase (LC) from Trametes versicolor. This study demonstrates, for the first time, the covalent modification of non-homogeneous graphene with a low surface-to-volume ratio, both in solution and on solid support. Through thermogravimetry analysis, we estimate the degree of functionalization to be 11% with HPO and 4% with LC, attributed to the varying redox potentials of the enzymes. This work highlights the potential of enzymatic reactions for tailored functionalization of graphene under mild conditions.

2-Hydroxyethyl Methacrylate/Gelatin/Alginate Scaffolds Reinforced with Nano TiO2 as a Promising Curcumin Release Platform.

The idea of this study was to create a new scaffolding system based on 2-hydroxyethyl methacrylate, gelatin, and alginate that contains titanium(IV) oxide nanoparticles as a platform for the controlled release of the bioactive agent curcumin. The innovative strategy to develop hybrid scaffolds was the modified porogenation method. The effect of the scaffold composition on the chemical, morphology, porosity, mechanical, hydrophilicity, swelling, degradation, biocompatibility, loading, and release features of hybrid scaffolds was evaluated. A porous structure with interconnected pores in the range of 52.33-65.76%, favorable swelling capacity, fully hydrophilic surfaces, degradability to 45% for 6 months, curcumin loading efficiency above 96%, and favorable controlled release profiles were obtained. By applying four kinetic models of release, valuable parameters were obtained for the curcumin/PHEMA/gelatin/alginate/TiO2 release platform. Cytotoxicity test results depend on the composition of the scaffolds and showed satisfactory cell growth with visible cell accumulation on the hybrid surfaces. The constructed hybrid scaffolds have suitable high-performance properties, suggesting potential for further in vivo and clinical studies.

Study of PLA pre-treatment, enzymatic and model-compost degradation, and valorization of degradation products to bacterial nanocellulose.

It is well acknowledged that microplastics are a major environmental problem and that the use of plastics, both petro- and bio- based, should be reduced. Nevertheless, it is also a necessity to reduce the amount of the already spread plastics. These cannot be easily degraded in the nature and accumulate in the food supply chain with major danger for animals and human life. It has been shown in the literature that advanced oxidation processes (AOPs) modify the surface of polylactic acid (PLA) materials in a way that bacteria more efficiently dock on their surface and eventually degrade them. In the present work we investigated the influence of different AOPs (ultrasounds, ultraviolet irradiation, and their combination) on the biodegradability of PLA films treated for different times between 1 and 6 h. The pre-treated samples have been degraded using a home model compost as well as a cocktail of commercial enzymes at mesophilic temperatures (37 °C and 42 °C, respectively). Degradation degree has been measured and degradation products have been identified. Excellent degradation of PLA films has been achieved with enzyme cocktail containing commercial alkaline proteases and lipases of up to 90% weight loss. For the first time, we also report valorization of PLA into bacterial nanocellulose after enzymatic hydrolysis of the samples.

Alginate-Based Hydrogels and Scaffolds for Biomedical Applications.

Alginate is a natural polymer of marine origin and, due to its exceptional properties, has great importance as an essential component for the preparation of hydrogels and scaffolds for biomedical applications. The design of biologically interactive hydrogels and scaffolds with advanced, expected and required properties are one of the key issues for successful outcomes in the healing of injured tissues. This review paper presents the multifunctional biomedical applications of alginate-based hydrogels and scaffolds in selected areas, highlighting the key effect of alginate and its influence on the essential properties of the selected biomedical applications. The first part covers scientific achievements for alginate in dermal tissue regeneration, drug delivery systems, cancer treatment, and antimicrobials. The second part is dedicated to our scientific results obtained for the research opus of hydrogel materials for scaffolds based on alginate in synergy with different materials (polymers and bioactive agents). Alginate has proved to be an exceptional polymer for combining with other naturally occurring and synthetic polymers, as well as loading bioactive therapeutic agents to achieve dermal, controlled drug delivery, cancer treatment, and antimicrobial purposes. Our research was based on combinations of alginate with gelatin, 2-hydroxyethyl methacrylate, apatite, graphene oxide and iron(III) oxide, as well as curcumin and resveratrol as bioactive agents. Important features of the prepared scaffolds, such as morphology, porosity, absorption capacity, hydrophilicity, mechanical properties, in vitro degradation, and in vitro and in vivo biocompatibility, have shown favorable properties for the aforementioned applications, and alginate has been an important link in achieving these properties. Alginate, as a component of these systems, proved to be an indispensable factor and played an excellent "role" in the optimal adjustment of the tested properties. This study provides valuable data and information for researchers and demonstrates the importance of the role of alginate as a biomaterial in the design of hydrogels and scaffolds that are powerful medical "tools" for biomedical applications.

Investigation of Antimicrobial, Anti-Quorum Sensing, and Cytotoxic Activities of Flavonoids Isolated from Pulicaria armena Boiss. & Kotschy ex Boiss. (Asteraceae).

This is the first report on the separation and biological assessment of all metabolites derived from Pulicaria armena (Asteraceae) which is an endemic species narrowly distributed in the eastern part of Turkey. The phytochemical analysis of P. armena resulted in the identification of one simple phenolic glucoside together with eight flavon and flavonol derivatives whose chemical structures were elucidated by NMR experiments and by the comparison of the spectral data with the relevant literature. The screening of all molecules for their antimicrobial, anti-quorum sensing, and cytotoxic activities revealed the biological potential of some of the isolated compounds. Additionally, quorum sensing inhibitory activity of quercetagetin 5,7,3' trimethyl ether was supported by molecular docking studies in the active site of LasR which is the primary regulator of this cell-to-cell communication system in bacteria. Lastly, the critical molecular properties indicating drug-likeness of the compounds isolated from P. armena were predicted. As microbial infections can be a serious problem for cancer patients with compromised immune systems, this comprehensive phytochemical research on P. armena with its anti-quorum sensing and cytotoxic compounds can provide a new approach to the treatment.

Triggering and identifying the polyurethane and polyethylene-degrading machinery of filamentous fungi secretomes.

The uncontrollable disposal of plastic waste has raised the concern of the scientific community, which tries to face this environmental burden by discovering and applying new techniques. Regarding the biotechnology field, several important microorganisms possessing the necessary enzymatic arsenal to utilize recalcitrant synthetic polymers as an energy source have been discovered. In the present study, we screened various fungi for their ability to degrade intact polymers, such as ether-based polyurethane (PU) and low-density polyethylene (LDPE). For this, ImpranIil® DLN-SD and a mixture of long-chain alkanes were used as sole carbon sources, indicating not only the most promising strains in agar plate screening but also inducing the secretion of depolymerizing enzymatic activities, useful for polymer degradation. The agar plate screening revealed three fungal strains belonging to Fusarium and Aspergillus genera, whose secretome was further studied for its ability to degrade the aforementioned non-treated polymers. Specifically for ether-based PU, the secretome of a Fusarium species reduced the sample mass and the average molecular weight of the polymer by 24.5 and 20.4%, respectively, while the secretome of an Aspergillus species caused changes in the molecular structure of LDPE, as evidenced by FTIR. The proteomics analysis revealed that the enzymatic activities induced in presence of Impranil® DLN-SD can be associated with urethane bond cleavage, a fact which was also supported by the observed degradation of the ether-based PU. Although, the mechanism of LDPE degradation was not completely elucidated, the presence of oxidative enzymes could be the main factor contributing to polymer modification.