Metabolic characteristics of ginsenosides from Panax ginseng in rat feces mediated by gut microbiota

Ginsenosides in Panax ginseng are regarded to be functional ingredients for diverse pharmacological effects and orally administrated with very low absorption in the gastrointestinal tract to be metabolized by gut microbiota. However, in vivo metabolic characteristics of ginsenosides mediated by gut microbiota are not well-known. This study aimed to explore the metabolic profiles of ginsenosides in rat feces mediated by gut microbiota. Ginsenosides and metabolites were identified and relatively quantified by ultra-performance liquid chromatography tandem/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). As a result, eighty-four metabolites were identified in the normal control rat feces, while only thirty intermediates were found with very low yields in the pseudo-germ-free (GF) group. Similarly, the main bioconversion pathways of ginsenosides in vivo were the same deglycosylation reaction mediated by gut microbiota in vitro. The findings demonstrated significant differences in metabolic profiles between the normal control and pseudo-GF rats, which implied gut microbiota played an important role in the metabolism of ginsenosides.

Fates of potentially persistent and mobile organic substances in embedded outdoor columns for artificial groundwater recharge simulation

Persistent and mobile organic micropollutants (OMP) are ubiquitously found in the aquatic environment and have a high propensity to distribute in water resources and are difficult to remediate. Managed aquifer recharge systems such as artificial groundwater recharge, produce high-quality drinking water by removing numerous OMP from the source water. In this study, the fates of selected emerging and potentially persistent and mobile OMP were investigated in outdoor columns for artificial groundwater recharge simulation. Breakthrough curves of OMP were modeled to differentiate between sorption and bio-transformation. The study showed that selected OMP were persistent in the surface water and no photo-degradation was observed, except for diclofenac. The trends of dissolved organic carbon concentrations and UV light absorption at 254 nm wavelength suggest elevated biological activity in the first 0.3 m of the columns. The study revealed that the bio-transformation of cyanoguanidine, valsartan acid and diclofenac correlated with the biological activity in the sand columns. Benzyltrimethylammonium, n-(3-(dimethylamino)-propyl)methacrylamide, 1,3-di-o-tolylguanidine, 1,3-diphenylguanidine and melamine were completely eliminated within the first 0.3 m, likely due to sorption. Less mobile compounds such as carbamazepine and adamantan-1-amine also showed sorption. Sorption was also observed for diclofenac, likely due to decreased pH along the column depth. Retardation factors of several OMP were higher in the first 0.3 m of the columns, likely due to higher organic carbon contents compared to the remaining depth. Six organic substances (for example 2-acrylamido-2-methylpropane sulfonate and dimethylbenzene sulfonate) were persistent and mobile throughout the experiment. Overall, this study reveals the vital role of pH and sand organic carbon for sorption and residence time and biological activity for OMP elimination.

Variation in photochemical properties of dissolved black carbon during bio-transformation and iron mineral fractionation process

The excellent photochemical properties of dissolved black carbon (DBC) have been proven to be a significant contributor to the removal of organic pollutants in environment. However, the photochemical properties of DBC will inevitably be changed during biotic and abiotic processes. Herein, the structures and compositions of DBC during bio-transformation and goethite adsorption processes were comprehensively studied, and their corresponding photochemical properties were also evaluated. Bio-transformed DBC (B-DBC) contained more aromatic, high molecular weight, and phenolic substances compared with pristine DBC (P-DBC). The photodegradation of 17α-ethynylestradiol (EE2) was significantly promoted by B-DBC because of its superior capacity for producing ³DBC*. Moreover, the subsequent goethite fractionation selectively reduced the parts of components with high aromaticity and carboxylic functional groups in B-DBC. The interaction between B-DBC and goethite resulted in the release of Fe²⁺ into goethite-fractionated DBC (G-DBC), which induced the photodegradation mechanism of EE2 shifting from a single-electron transfer driven by ³DBC^⁎ to the oxidation of •OH. This study provides valuable insights into the changes in photochemical behavior of DBC resulting from biotic or abiotic processes, and enhances our understanding of the role of DBC in the fate of organic pollutants.

Anticancer activity and cell death mechanism of Pt(II) complexes: Their in vitro bio-transformation to Pt(II)-DNA adduct formation and BSA binding study by spectroscopic method

Pt(II) complex cis-[Pt(PEA)(OH₂)₂] X₂, C-2 (where, PEA = 2-Pyridylethylamine and X  = ClO₄^- or NO₃^-) was synthesized by hydrolysis of cis-[Pt(PEA)Cl₂] C-1. Glutathione (GSH) and DL-penicilamine (DL-pen) substituted complexes cis-[Pt(PEA)(GSH)],C-3 and cis-[Pt(PEA)DL-pen)]X C-4 were synthesized and characterized by spectroscopic methods. Kinetic studies were traced on complex C-2 with the thiols, GSH and DL-pen. Pt(II)-Sulfur adduct formation mechanisms of the substituted products C-3 and C-4 were established from the kinetic investigation. At pH 4.0, C-2 - thiols interactions follow two consecutive steps: the first step is dependent, and the second is independent of [thiol]. The association equilibrium constant (K_E), substitution rate constants for both steps (k₁ & k₂), and activation parameters (ΔH^‡ and ΔS^‡) have been assessed to propose the mechanism. Agarose gel electrophoresis mobilization pattern of DNA with complexes was performed to visualize the interaction nature. CT-DNA and BSA binding activities of the complexes have been executed by electronic, fluorescence spectroscopy, and viscometric titration methods. Evaluation of thermodynamic parameters (ΔH⁰, ΔS⁰, and ΔG⁰) from BSA binding constants was executed to propose the driving forces of interaction between these species. A molecular docking study was performed to evaluate the binding mode of complexes with BDNA strands. Anticancer activity of the complexes C-1 to C-4 was explored on both A549 and HEp-2 cell lines, compared with approved anticancer drugs cisplatin, carboplatin, and oxaliplatin. All these complexes were tested by NBT assay on normal cell line skeletal muscle cells (L6 myotubes) to observe the adverse effects compared to recognized anticancer medications. The ultimate aim is to explore the role of anticancer agents on cell death mechanism, which has been performed by flow-cytometer on HEp-2 cell lines.

Biotransformation of adsorbed arsenic on iron minerals by coexisting arsenate-reducing and arsenite-oxidizing bacteria

Bacteria with arsenate-reducing (ars) and arsenite-oxidizing (aio) genes usually co-exist in aerobic environments, but their contrast impacts on arsenic (As) speciation and mobility remain unclear. To identify which kind of bacteria dominate As speciation under oxic conditions, we studied the biotransformation of adsorbed As on goethite in the co-existence of Pantoea sp. IMH with ars gene and Achromobacter sp. SY8 with aio gene. The incubation results show that SY8 dominated the dissolved As speciation as As(V), even though aio exhibited nearly 5 folds lower transcription levels than ars in IMH. Nevertheless, our XANES results suggest that SY8 showed a negligible effect on solid-bound As speciation whereas IMH reduced adsorbed As(V) to As(III). The change in As speciation on goethite surfaces led to a partial As structural change from bidentate corner-sharing to monodentate corner-sharing as evidenced by our EXFAS analysis. Our Mössbauer spectroscopic results suggest that the incubation with SY8 reduced the degree of crystallinity of goethite, and the reduced crystallinity can be partly compensated by IMH. The changes in As adsorption structure and in goethite crystallinity had a negligible effect on As release. The insights gained from this study improve our understanding of biotransformation of As in aerobic environment.

Bio-conversion of methane into high profit margin compounds: an innovative, environmentally friendly and cost-effective platform for methane abatement

Despite the environmental relevance of CH₄ and forthcoming stricter regulations, the development of cost-efficient and environmentally friendly technologies for CH₄ abatement is still limited. To date, one of the most promising solutions for the mitigation of this important GHG consists of the bioconversion of CH₄ into bioproducts with a high profit margin. In this context, methanotrophs have been already proven as cell-factories of some of the most expensive products synthesized by microorganisms. In the case of ectoine (1000 $ kg^-1), already described methanotrophic genera such as Methylomicrobium can accumulate up to 20% (ectoine wt^-1) using methane as the only carbon source. Moreover, α-methanotrophs, such as Methylosynus and Methylocystis, are able to store bioplastic concentrations up to 50-60% of their total cell content. More than that, methanotrophs are one of the greatest potential producers of methanol and exopolysaccharides. Although this methanotrophic factory could be enhanced throughout metabolic engineering, the valorization of CH₄ into valuable metabolites has been already consistently demonstrated under continuous and discontinuous mode, producing more than one compound in the same bioprocess, and using both, single strains and specific consortia. This review states the state-of-the-art of this innovative biotechnological platform by assessing its potential and current limitations.

Simultaneous removal of thiocyanate and nitrogen from wastewater by autotrophic denitritation process

Pollutants containing sulfur as electron donors will play an important role in the energy-saving denitritation process when organic carbon source was insufficient in wastewater. However, thiocyanate (SCN^-), a hazardous pollutant, has not been characterized in denitritation. In this study, the effects of key environmental factors on removal of thiocyanate and nitrogen were investigated in denitritation. The results showed that the maximum removal efficiency of nitrogen was observed in complete removal of thiocyanate and nitrite. The elemental sulfur was observed prior to complete depletion of thiocyanate. The efficiency of denitritation was promoted by NaHCO₃ and weakly-alkaline environment. In the sludge containing dominant Thiobacillus genus, nitrite was reduced in the conversion of thiocyanate into elemental sulfur and further into sulfate. The stoichiometric ratio of NO₂^--N to SCN^--N was close to 2.0 when thiocyanate was converted completely into sulfate, which verified complete removal of thiocyanate and nitrite at the NO₂^--N/SCN^--N ratio of 2.0.

Bio-transformation of Graphene Oxide in Lung Fluids Significantly Enhances Its Photothermal Efficacy

Rationale: Graphene oxide (GO) has shown great promises in biomedical applications, such as drug delivery and thermotherapeutics, owing to its extraordinary physicochemical properties. Nonetheless, current biomedical applications of GO materials are premised on the basis of predesigned functions, and little consideration has been given to the influence of bio-transformation in the physiological environment on the physicochemical properties and predesigned functionalities of these materials. Hence, it is crucial to uncover the possible influence on GO's physicochemical properties and predesigned functionalities for better applications. Methods: Bio-transformed GOs were characterized by X-ray diffraction (XRD) spectra, Raman spectra, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared transmission (FT-IR) spectra. The morphologies of various GO materials were assessed via transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. The photothermal (PTT) performance of different GO materials in vitro and in vivo were measured using 808 nm laser at a power density of 2 W/cm2. The PTT efficacy was determined using transplanted 4T1 cells-derived breast tumors in mice. Results: Bio-transformation of GO in the lung (a main target organ for GO to localize in vivo) can induce dramatic changes to its physicochemical properties and morphology, and consequently, its performances in biomedical applications. Specifically, GO underwent significant reduction in two simulated lung fluids, Gamble's solution and artificial lysosomal fluid (ALF), as evidenced by the increase of C/O ratio (the ratio of C content to O content) relative to pristine GO. Bio-transformation also altered GO's morphology, characterized by sheet folding and wrinkle formation. Intriguingly, bio-transformation elevated the PTT performance of GO in vitro, and this elevation further facilitated PTT-based tumor-killing efficacy in tumor cells in vitro and in a mouse model with transplanted tumors. Bio-transformation also compromised the interaction between drug with GO, leading to reduced drug adsorption, as tested using doxorubicin (DOX). Conclusions: Transformation in Gamble's solution and ALF resulted in varied degrees of improved performances of GO, due to the differential effects on GO's physicochemical properties. Our findings unveiled an overlooked impact of GO bio-transformation, and unearthed a favorable trait of GO materials in thermotherapeutics and drug delivery in the lung microenvironment.

Arsenic mobilization in spent nZVI waste residue: Effect of Pantoea sp. IMH

Nanoscale zero-valent iron (nZVI) is an effective arsenic (As) scavenger. However, spent nZVI may pose a higher environmental risk than our initial thought in the presence of As-reducing bacteria. Therefore, our motivation was to explore the As redox transformation and release in spent nZVI waste residue in contact with Pantoea sp. IMH, an arsC gene container adopting the As detoxification pathway. Our incubation results showed that IMH preferentially reduce soluble As(V), not solid-bound As(V), and was innocent in elevating total dissolved As concentrations. μ-XRF and As μ-XANES spectra clearly revealed the heterogeneity and complexity of the inoculated and control samples. Nevertheless, the surface As local coordination was not affected by the presence of IMH as evidenced by similar As-Fe atomic distance (3.32-3.36 Å) and coordination number (1.9) in control and inoculated samples. The Fe XANES results suggested that magnetite in nZVI residue was partly transformed to ferrihydrite, and the IMH activity slowed down the nZVI aging process. IMH distorted Fe local coordination without change its As adsorption capacity as suggested by Mössbauer spectroscopy. Arsenic retention is not inevitably enhanced by in situ formed secondary Fe minerals, but depends on the relative As affinity between the primary and secondary iron minerals.

Concurrent uptake and metabolism of dyestuffs through bio-assisted phytoremediation: a symbiotic approach

Manipulation of bio-technological processes in treatment of dyestuffs has attracted considerable attention, because a large proportion of these synthetic dyes enter into natural environment during synthesis and dyeing operations that contaminates different ecosystems. Moreover, these dyestuffs are toxic and difficult to degrade because of their synthetic origin, durability, and complex aromatic molecular structures. Hence, bio-assisted phytoremediation has recently emerged as an innovative cleanup approach in which microorganisms and plants work together to transform xenobiotic dyestuffs into nontoxic or less harmful products. This manuscript will focus on competence and potential of plant-microbe synergistic systems for treatment of dyestuffs, their mixtures and real textile effluents, and effects of symbiotic relationship on plant performances during remediation process and will highlight their metabolic activities during bio-assisted phytodegradation and detoxification.

Bioconversion of Iminodiacetonitrile to Iminodiacetic acid with whole cells of Lysinibacillus boronitolerans MTCC 107614 (IICT-akl252)

Biotechnological potential of nitrilases are prompting significant interest in finding the novel microbes capable of hydrolyzing nitriles. In this view, we have screened about 450 bacterial strains for nitrilase production using bioconversion of iminodiacetonitrile (IDAN) to iminodiacetic acid (IDA) through hydrolysis and obtained six nitrilase-producing isolates. Among these six isolates, IICT-akl252 was promising which was identified as Lysinibacillus boronitolerans. This is the first report on L. boronitolerans for nitrilase activity. Optimization of various medium and reaction parameters for maximizing the nitrilase production using whole cells in shake flask was carried out for L. boronitolerans IICT-akl252. Sucrose (2 %) as a carbon source attained better nitrilase yield while IDAN appeared to be the preferable inducer (0.2 %). The maximum IDA formation was achieved with 100 mM IDAN and 150 mg/ml cells at 30 °C and pH 6.5. After optimization of the culture and reaction conditions, the activity of nitrilase was increased by 2.3-fold from 27.2 to 64.5 U. The enzyme was stable up to 1 h at 50 °C. The enzyme was able to hydrolyze aliphatic, aromatic and heterocyclic nitrile substrates.

Pyrolysis of sunflower seed hulls for obtaining bio-oils

Bio-oils from pyrolysis of as received sunflower seed hulls (SSH), hulls previously washed with acid (SSHA) and hulls submitted to a mushroom enzymatic attack (BSSH) were analyzed. The concentration of lignin, hemicellulose and cellulose varied with the pre-treatment. The liquid corresponding to SSH presented a relatively high concentration of acetic acid and a high instability to storage. The bio-oil from SSHA showed a high concentration of furfural and an appreciable amount of levoglucosenone. Lignin was degraded upon enzymatic activity, for this reason BSSH led to the highest yield of bio-oil, with relative high concentration of acetic acid and stability to storage.