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Abstract The objective of this study was to discuss the phytoremediation potential of Leersia hexandra Swartz in Cu contaminated soil and its enhancement by agronomic management practices. The results showed that L. hexandra had a high extraction capacity for copper (Cu), and Cu concentration was found maximum in shoots (755.4 mg/kg), which is very close to the Cu-hyperaccumulators. Three successive harvests did not reduce the biomass and Cu level in shoots of L. hexandra (p > 0.05), indicating that sequential harvest was feasible for the increase of total biomass and Cu extraction amount. Fertilization could obviously increase the tissue dry weight, resulting in the total amount of extracted-Cu up to 52.3%. 3-Indole acetic acid (IAA) also significantly increased biomass, causing the efficiency of Cu phytoextraction up to 204.6%. These suggested that fertilization and IAA were effective for enhancing Cu phytoextraction by L. hexandra. [ABSTRACT FROM AUTHOR]

Constructed wetlands planted with Leersia hexandra Swartz can effectively remove Cr(VI) from water. This work aims to assess the function of L. hexandra in constructed wetlands that treat Cr(VI)-contaminated water. Cr(VI) removal performance of planted and unplanted mesocosms were compared under two different temperatures (25 °C and 5 °C). Results indicated that the Cr(VI) removal performance of the planted mesocosm was more efficient and stable than that of the unplanted mesocosm. The planted mesocosm showed enhanced Cr(VI) removal even in cold season (5 °C) when the shoots were wilted. Therefore, L. hexandra played important roles in enhancing Cr(VI) removal. However, direct Cr uptake by plants only accounted for 9.3% of the total amount of Cr loading in the wetlands. This finding suggested that L. hexandra indirectly improved Cr(VI) removal by influencing other removal processes. Organic content and microbial abundance in the sediments of the planted mesocosm were significantly higher than those in the sediments of the unplanted mesocosm ( p < 0.05). The major functions of L. hexandra as an ecosystem engineer include producing organic matter and facilitating microbial growth, which are the key factors that influence Cr(VI) reduction and sequestration. A small proportion of Cr accumulated in biomass (4.7–8.6%) was released during plant litter decomposition, indicating that the effect of litter decomposition on water quality was negligible. [ABSTRACT FROM AUTHOR]

Hydroponic experiments were conducted with rice seedlings to determine parameters involved in phytotoxicity and transport of Cadmium (Cd). Results showed that a linear decrease in relative growth rate and water use efficiency was observed in rice seedlings with increasing Cd concentrations. More severe inhibitory effects on both parameters were found at the 4-d treatment. The effective concentrations (EC) were estimated using the Levenberg–Marquardt Algorithm. The EC values obtained from the relative growth rate were always smaller than these from water use efficiency, indicating that the former was more sensitive to change of Cd than the latter. Phyto-transport of Cd was apparent, but the distribution of Cd in different parts of rice seedlings was different and roots were the dominant sink for Cd accumulation ( p < 0.05). Although the translocation of Cd into shoots was detectable, more Cd was detected in shoots at the 4-d treatments than that at the 2-d treatments ( p < 0.05). The partial correlation analysis suggested that the total accumulation rate of Cd was highly related to the doses of Cd supplied ( p < 0.05). In conclusion, Cd is problematic at relatively low concentrations for rice seedlings, and inhibitory effects are highly dependent on the selected response endpoints and the duration of exposure periods. [ABSTRACT FROM AUTHOR]

Hexavalent chromium [Cr(VI)] is considered a hazardous water pollutant. Thus, the removal of Cr(VI) is necessary for the protection of the environment. In this study, two lab-scale constructed wetlands vegetated with Leersia hexandra Swartz (CWL) were set up to purify Cr(VI)-contaminated water. X-ray absorption near-edge spectroscopy (XANES) and X-ray photoelectron spectroscopy (XPS) were employed to determine the speciation of chromium (Cr) in plant tissues and substrates, respectively. Results showed that the CWL efficiently removed Cr(VI) from water. XANES analysis revealed that Cr was predominantly trivalent in plant tissues, although minimal Cr(VI) was observed in roots. In substrates, the majority of chromium existed as trivalent chromium [Cr(III)], whereas only 5.9% of chromium existed as Cr(VI). Therefore, CWL is capable of detoxifying through the reduction of Cr(VI) to Cr(III). We propose that CWL has a great potential for decontaminating and detoxifying water contaminated with Cr(VI). [ABSTRACT FROM AUTHOR]

Abstract: Natural phenazines in secondary metabolites of bacteria have been receiving increasing attention in recent years due to their potential usage as antibiotics. In the present study, a rapid and reliable capillary zone electrophoresis (CZE) method was developed and validated for monitoring for the first time dynamic phenazine-1-carboxylic acid (PCA) and the 2-hydroxyphenazine (2-OH-PHZ) production of Pseudomonas chlororaphis GP72 during the entire fermentation cycle. The paper begins with the optimization of separate conditions for 2-OH-PHZ and PCA together with phenazine (PHZ), which is used as internal standard. The optimized conditions are: 10mM, pH 7.3 phosphate buffer, a fused-silica capillary with a total length of 49cm×75μmID, 375μmOD with an effective length of 40cm, 25kV, 13mbar 10s pressure sample injection and 25°C air-cooling. The three compounds could be separated within 2min under optimized conditions. The validation of the newly developed study shows the linear response of 2-OH-PHZ and PCA ranging from 10 to 250μgmL−1 with high correlation coefficient (r =0.9997 and 0.9993, n =7), low limits of detection (0.47 and 0.38μgmL−1) and quantification (1.56 and 1.28μgmL−1), respectively. Good precision values for intra- and inter-day detection and acceptable individual recovery ranges for 2-OH-PHZ and PCA are indicated. The newly developed method was also validated through monitoring dynamic PCA and 2-OH-PHZ production of P. chlororaphis GP72 during an 84h growth cycle. [Copyright &y& Elsevier]

Leersia hexandra Swartz (Gramineae), which occurs in Southern China, has been found to be a new chromium hyperaccumulator by means of field survey and pot-culture experiment. The field survey showed that this species had an extraordinary accumulation capacity for chromium. The maximum Cr concentration in the dry leaf matter was 2978mgkg−1 on the side of a pond near an electroplating factory. The average concentration of chromium in the leaves was 18. 86 times as that in the pond sediment, and 297. 41 times as that in the pond water. Under conditions of the nutrient solution culture, it was found that L. Hexandra had a high tolerance and accumulation capacity to Cr(III) and Cr(VI). Under 60mgl−1 Cr(III) and 10mgl−1 Cr(VI) treatment, there was no significant decrease of biomass in the leaves of L. Hexandra (p >0. 05). The highest bioaccumulation coefficients of the leaves for Cr(III) and Cr(VI) were 486. 8 and 72. 1, respectively. However, L. Hexandra had a higher accumulation capacity for Cr(III) than for Cr(VI). At the Cr(III) concentration of 10mgl−1 in the culture solution, the concentration of chromium in leaves was 4868mgkg−1, while at the same Cr(VI) concentration, the concentration of chromium in leaves was only 597mgkg−1. These results confirmed that L. Hexandra is a chromium hyperaccumulator which grows rapidly with a great tolerance to Cr and broad ecological amplitude. This species could provide a new plant resource that explores the mechanism of Cr hyperaccumulation, and has potential for usage in the phytoremediation of Cr-contaminated soil and water. [Copyright &y& Elsevier]

Natural phenazines are important secondary metabolites that generally exhibit broad antimicrobial bioactivities. However, the bioactivity diversity of phenazines is relatively narrow due to the limited substitution of side groups. In this study, Streptomyces lomondensis S015 was confirmed with capability of catalyzing phenazine-1-carboxylic acid (PCA) to 5-(2-hydroxyacetyl)− 5,10-dihydrophenazine-1-carboxylic acid (HDPCA) based on substrate feeding, UPLC-MS and NMR analysis. Besides antimicrobial activity, HDPCA exhibited potent antioxidant activity compared with PCA and the antioxidant butylated hydroxytoluene (BHT). Furthermore, an efficient whole cells biotransformation system was developed by screening carbon sources and optimizing reaction conditions. Using S. lomondensis S015 cells prepared from glucose as the biocatalyst, the production of HDPCA achieved 1.38 mM (392.0 mg/L) under a rotation rate of 220 rpm, 32 °C, pH 7.0, and 3.6 g/L dry cell weight for 36 h. This work not only identified the intriguing bioactivity of HDPCA but provide an environmentally friendly strategy for the biocatalysis of phenazines. [Display omitted] • Phenazine-1-carboxylic acid (PCA) can be biotransformed to 5-(2-hydroxyacetyl)-5,10-dihydrophenazine-1-carboxylic acid (HDPCA). • HDPCA exhibit potent antioxidative activity. • An efficient whole cells biotransformation system was developed. [ABSTRACT FROM AUTHOR]

Abstract: Ionic liquid (IL) based ultrasonic assisted extraction (ILUAE) was developed for the effective extraction of puerarin from Radix Puerariae Lobatae (RPL). The ILUAE parameters including the type of ILs, IL concentration, RPL amount, ultrasonic power and time were optimized by single-factor experiment and response surface methodology. Under the optimized experimental conditions, the best results were obtained using RPL amount 0.43g in 10mL 1.06molL−1 1-butyl-3-methylimidazolium bromide aqueous solution, ultrasonic time 27.43min and ultrasonic power 480W. Scanning electron microscope images of RPL samples were obtained to provide visual evidence of the sonication effect. Compared with the conventional ultrasonic assisted extraction and refluent extraction, the proposed ILUAE offered shorter extraction time and remarkable higher efficiencies due to the higher penetration ability and solubility of IL and the cavitation phenomenon produced in the solvent by the passage of an ultrasonic wave, which further supported the suitability of the proposed approach. [Copyright &y& Elsevier]

Abstract: Characteristics of Cr(III) uptake by roots of hyperaccumulator Leersia hexandra Swartz were studied using pot-culture experiment. The results showed that the uncoupler, 2,4-dinitrophenol (DNP), and low temperature significantly limited the Cr(III) uptake (p <0.05), which indicated an active uptake of Cr(III) in the roots. The calcium channel blocker “LaCl3” and the kalium channel blocker “tetraethyl ammonium chloride (TEA)” did not inhibit the Cr(III) uptake, i.e., the Cr(III) uptake was not related to the K+ or Ca2+ ion channels. However, an inhibiting effect of Fe(III) on the Cr(III) uptake was observed in the roots of L. hexandra. The Cr(III) uptake followed Michaelis–Menten kinetics with a Michaelis constant (K m) of 123.9μmol/L, which was increased by 2-fold in the presence of 300μmol/L Fe(III). The Fe-deficiency increased the maximum uptake velocity (V max) by 33.5% and decreased the Michaelis constant by 23.2%. The antagonistic effect of Fe(III) on Cr(III) uptake suggest that the Cr(III) uptake by the roots of L. hexandra may be mediated partly via transporters for the Fe(III)–phytosiderophore complex. [Copyright &y& Elsevier]

In this work, a superparamagnetic Fe 3 O 4 -graphene oxide (MGO) nanocomposite was prepared by one-step chemical co-precipitation method, and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), powder X-ray diffraction (PXRD), Raman spectroscopy and nitrogen adsorption–desorption curve. The as-prepared MGO was used to adsorb nuciferine, and the adsorption kinetic, isotherm and reusability of MGO were also investigated. The results showed that the adsorption of nuciferine on MGO reached its equilibrium very quickly (within 10 min) due to the two-dimensional carbon nanostructure of GO. In comparison with MGO, five conventional sorbents, i.e., macroporous resin D-101, silica gel, reverse phase silica gel (RP-C18) and cation exchange resin and polyamide, were also used to evaluate their adsorption capabilities. Therefore, MGO combined the advantages of both superparamagnetic particle and GO, i.e., easy separation and high absorption capacity. Finally, MGO was successfully applied to enrichment and separation of nuciferine in the extract of Nelumbinis Folium (Lotus leaf). [ABSTRACT FROM AUTHOR]

Highlights: [•] The novel molecularly imprinted polymers (MIP) can be used in methanol–water media. [•] The specific ionic liquid (IL) was used as the functional monomer to prepare MIP. [•] ILs are easily designable. [•] A larger quantity of ILs are facile to be designed as functional monomer for MIP. [Copyright &y& Elsevier]