Zeolitic imidazolate framework-8 (ZIF-8) doped TiZSM-5 and Mesoporous carbon for antibacterial characterization

Drug resistant bacteria affects millions worldwide and remains a serious threat to health care system. The study reports the first application of hybrid nanocomposites based on zeolitic imidazolate framework-8 (ZIF-8) with MFI structured zeolite Ti-ZSM-5 (TiZ5) and mesoporous carbon (MC). The composite was designated as TiZ5/ZIF-8 and MC/ZIF-8 was studied for antibacterial activity. Bioactive components Zn²⁺ and 2-methyl imidazole present in ZIF-8 was found to exert significant antibacterial effect on Escherchia. coli and Staphyloccocus. No other antibiotic drugs are required. For comparative purpose, Fe-BTC MOF (BTC = 1,3,5‐benzenetricarboxylate) was used as second set of nanoformulations (TiZ5/Fe-BTC and MC/Fe-BTC) but showed a lower antibacterial activity. The phase (X-ray diffraction), texture (BET surface area), coordination (DRS-UV–Vis), and morphology (TEM) was investigated. XRD showed the presence of nanosized ZIF-8 over TiZ5 and MC. Surface area calculation using N₂ adsorption isotherm showed a reduction in the micropore surface area of ZIF-8 from 1148 m²/g to 224 m²/g (80%) and an increased meso surface area from 31 m²/g to 59 m²/g (90%). The mesopore pore volume increased significantly from 0.05 cm³/g to 0.12 m²/g. MC/ZIF-8 showed similar textural modifications. FT-IR spectra and DRS-UV–Vis spectra showed distinct composite formation with TiZ5, while a weak absorption of ZIF-8 observed over MC. TEM revealed the presence of nanocomposite MC/ZIF-8 and TiZ5/ZIF-8 distributed in nanosize ranging between 25 and 50 nm. TiZ5/ZIF-8 showed the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of 0.5 and 1 mg/ml, respectively against E. coli. The MIC and MBC of TiZ5/ZIF-8 against S. aureus were 1 and 2 mg/ml, respectively. MC/ZIF-8 composite had second best antibacterial activity. This study shows that ZIF-8 based composite holds a great potential against E. coli and S. aureus.     

Efficient adsorptive removal of Congo red from aqueous solution by synthesized zeolitic imidazolate framework-8

Dyes exposure in aquatic environment creates risks to human health and biota due to their intrinsic toxic mutagenic and carcinogenic characteristics. In this work, a metal-organic frameworks materials, zeolitic imidazolate framework-8 (ZIF-8), was synthesized through hydrothermal reaction for the adsorptive removal of harmful Congo red (CR) from aqueous solution. Results showed that the maximum adsorption capacity of CR onto ZIF-8 was ultrahigh as 1250 mg g^?1. Adsorption behaviors can be successfully fitted by the pseudo-second order kinetic model and the Langmuir isotherm equation. Solution conditions (pH condition and the co-exist anions) may influent the adsorption behaviors. The adsorption performance at various temperatures indicated the process was a spontaneous and endothermic adsorption reaction. The enhanced adsorption capacity was determined due to large surface area of ZIF-8 and the strong interactions between surface groups of ZIF-8 and CR molecules including the electrostatic interaction between external active sites Zn?OH on ZIF-8 -and ?SO₃ or –N=N– sites in CR molecule, and the π–π interaction.     

Biosorption of Methylene Blue by De-Oiled Algal Biomass: Equilibrium,Kinetics and Artificial Neural Network Modelling

The main objective of the present study is to effectively utilize the de-oiled algal biomass (DAB) to minimize the waste streams from algal biofuel by using it as an adsorbent. Methylene blue (MB) was used as a sorbate for evaluating the potential of DAB as a biosorbent. The DAB was characterized by SEM, FTIR, pH_PZC, particle size, pore volume and pore diameter to understand the biosorption mechanism. The equilibrium studies were carried out by variation in different parameters, i.e., pH (2–9), temperature (293.16–323.16 K), biosorbent dosage (1–10 g L⁻¹), contact time (0–1,440 min), agitation speed (0–150 rpm) and dye concentration (25–2,500 mg L⁻¹). MB removal was greater than 90% in both acidic and basic pH. The optimum result of MB removal was found at 5–7 g L⁻¹ DAB concentration. DAB removes 86% dye in 5 minutes under static conditions and nearly 100% in 24 hours when agitated at 150 rpm. The highest adsorption capacity was found 139.11 mg g⁻¹ at 2,000 mg L⁻¹ initial MB concentration. The process attained equilibrium in 24 hours. It is an endothermic process whose spontaneity increases with temperature. MB biosorption by DAB follows pseudo-second order kinetics. Artificial neural network (ANN) model also validates the experimental dye removal efficiency (R² = 0.97) corresponding with theoretically predicted values. Sensitivity analysis suggests that temperature and agitation speed affect the process most with 23.62% and 21.08% influence on MB biosorption, respectively. Dye adsorption capacity of DAB in fixed bed column was 107.57 mg g⁻¹ in preliminary study while it went up to 139.11 mg g⁻¹ in batch studies. The probable mechanism for biosorption in this study is chemisorptions via surface active charges in the initial phase followed by physical sorption by occupying pores of DAB.     

Molecularly imprinted electrochemiluminescence sensor based on ZIF-8 doped with CdSe quantum dots for the detection of trace estriol

A composite of the metal–organic framework compound ZIF-8 doped with CdSe quantum dots (QDs) with sensitive and stable luminescence was synthesized, and a molecularly imprinted electrochemiluminescence (ECL) sensor was constructed based on this composite. The ZIF-8@CdSe molecularly imprinted ECL sensor combines the high sensitivity of ECL and the high selectivity of molecular imprinting to realize the sensitive and specific detection of estriol. CdSe QDs and gold nanoparticles were encapsulated within ZIF-8 to obtain the ZIF-8@CdSe QDs/GNP (ZIF@CdSe/GNP) composite. Subsequently, the GNPs were further loaded on the surface of this composite to obtain the GNP/ZIF@CdSe/GNP composite. l -Cysteine was used to immobilize the GNP/ZIF@CdSe/GNP composite on the surface of a gold electrode to obtain the GNP/ZIF@CdSe/GNP-modified gold electrode. A molecularly imprinted polymer (MIP) film was prepared on the surface of the modified electrode by electropolymerization with o-phenylenediamine as the functional monomer and estriol as the template molecule. After elution, estriol could be specifically recognized by the cavities. The readsorption of estriol by the MIP can prevent the coreactant from reaching the electrode surface through the cavities, thereby weakening ECL. A good linear relationship existed between the ∆ECL and lg C of estriol concentrations of 1 × 10⁻¹⁴ to 1 × 10⁻⁹ mol·L⁻¹. The detection limit was as low as 8.9 × 10⁻¹⁶ mol·L⁻¹. The sensor was applied in the determination of estriol in serum samples with a recovery of 97.0–102%.     

Preparation,Characterization and Application of Magnetic Fe3O4-CS for the Adsorption of Orange I from Aqueous Solutions

Fe₃O₄ (Fe₃O₄-CS) coated with magnetic chitosan was prepared as an adsorbent for the removal of Orange I from aqueous solutions and characterized by FTIR, XRD, SEM, TEM and TGA measurements. The effects of pH, initial concentration and contact time on the adsorption of Orange I from aqueous solutions were investigated. The decoloration rate was higher than 94% in the initial concentration range of 50–150 mg L⁻¹ at pH 2.0. The maximum adsorption amount was 183.2 mg g⁻¹ and was obtained at an initial concentration of 400 mg L⁻¹ at pH 2.0. The adsorption equilibrium was reached in 30 minutes, demonstrating that the obtained adsorbent has the potential for practical application. The equilibrium adsorption isotherm was analyzed by the Freundlich and Langmuir models, and the adsorption kinetics were analyzed by the pseudo-first-order and pseudo-second-order kinetic models. The higher linear correlation coefficients showed that the Langmuir model (R² = 0.9995) and pseudo-second-order model (R² = 0.9561) offered the better fits.     

Production of astaxanthin by Haematococcus pluvialis in a sequential heterotrophic-photoautotrophic culture

Production of astaxanthin by sequential heterotrophic-photoautotrophiccultivation of a green alga, Haematococcus pluvialis was investigated.This involved cultivating the cells heterotrophically to high cellconcentration, followed by illumination of the culture for astaxanthinaccumulation. The optimum pH and temperature for heterotrophic biomassproduction were 8 and 25 ^°C, respectively. There was no significantdifference in the specific growth rate of the cells when acetateconcentration was varied between 10 mM and 30 mM. However, cellgrowth was inhibited at higher acetate concentrations. A pH stat methodwas then used for fed-batch heterotrophic culture, using acetate as theorganic carbon source. A cell concentration of 7 g L^-1 wasobtained. Higher cell concentration could not be obtained because the cellschanged from vegetative to cyst forms during the heterotrophic cultivation.However, by using repeated fed-batch processes, the cells could bemaintained in the vegetative form, leading to more than two times increasein cell number output rate. When the vegetative cells were transferred tophotoautotrophic phase, there was a sharp decrease in the cell number andonly very few cells encysted and accumulated astaxanthin. On the otherhand, when the shift from heterotrophic to photoautotrophic condition wasdone when most of the cells had encysted, there was still a decrease in cellnumber but astaxanthin accumulation was very high. The astaxanthinconcentration (114 mg L^-1) and productivity (4.4 mg L^-1d^-1) obtained by this sequential heterotrophic-photoautotrophiccultivation method are very high compared to the data in the literature.     

菜心组织培养技术初探

为建立菜心(Brassica campestris ssp.chinensis var.utilis)的快繁技术体系,以花药和子叶-子叶柄为外植体进行组织培养研究。结果表明,花药培养以选取未开放的花蕾为宜,且花柱略高于花瓣,此时小孢子多数处于单核靠边期。菜心花粉的萌发率不高,且秋冬季的花粉比夏季的萌发率高。菜心花药愈伤组织诱导培养基为:MS+1.0 mg L–1 KT+1.0 mg L–1 2,4-D+3%糖+6 g L–1琼脂+8%椰乳,不定芽诱导培养基为:MS+2.0 mg L–1 6-BA+0.5 mg L–1 NAA+1.0 g L–1活性炭+2%糖+6 g L–1琼脂或MS+2.0 mg L–1 ZT+0.5 mg L–1 IAA+0.5 g L–1 AgNO3+1.0 g L–1活性炭+2%糖+6 g L–1琼脂。花药培养的不定芽诱导率为36.7%,不定芽培养出现褐化现象,不能形成再生植株;而以子叶-子叶柄为外植体培养获得的植株再生率可达80%。     

Study on russet-related enzymatic activity and gene expression in ‘Shine Muscat’ grape treated with GA3 and CPPU

Physiological (metabolite analysis) and molecular (gene expression) approaches were used to understand the mechanism underlying russet formation in response to the application of GA₃ and CPPU (Forchlorfenuron) in a Japanese table grape cultivar ‘Shine Muscat’. Several different concentrations of GA₃ and GA₃?+?CPPU [25?mg?L^?1 GA₃ (A), 25?mg?L^?1 GA₃?+?5?mg?L^?1 CPPU (B), 25?mg?L^?1 GA₃?+?10?mg?L^?1 CPPU (C), and 25?mg?L^?1 GA₃?+?15?mg?L^?1 CPPU (D)] were applied to grape berry clusters at two weeks after flowering (WAF). No russet was observed on the berries treated with the ‘C’ combination. Lower levels of phenylalanine ammonia-lyase (PAL) activity was observed in the treated samples, relative to the untreated material. Reduced peroxide (POD) activity was also observed in response to different treatments, while the expression of Peroxidase 17 and Phenylalanine ammonia-lyase G1 genes mirrored lignin content. Increased activity of 4-coenzyme A ligase (4CL) may contribute to decreasing the level of russet and help to improve grape berry quality.     

镉与萘复合胁迫对红树植物白骨壤幼苗萌芽及生长的影响

为探讨白骨壤(Avicennia marina)幼苗对重金属镉(Cd)和多环芳烃萘(Nap)复合胁迫的响应,采用砂基栽培,对其幼苗的萌芽和生长进行了研究。结果表明,Cd、Nap复合胁迫对白骨壤萌芽的抑制效应较单一胁迫明显,胁迫前期幼苗成活率提高,胁迫后期则降低。胁迫栽培45 d,10 mg L~(–1)的Nap在叶形态、茎高及各器官生物量上能够减轻Cd胁迫的影响,但增强对根长的抑制作用,10 mg L~(–1) Nap-25 mg L~(–1) Cd处理的叶面积、叶长、叶宽、茎高及全株生物量分别比25 mg L~(–1) Cd处理的提高9.6%、7.9%、7.4%、5.1%和20.2%,但根长则比150 mg L~(–1) Cd处理的下降11.1%。至胁迫栽培90 d,各处理间幼苗器官及全株生物量无显著影响,复合胁迫对叶形态、茎高和根长等的抑制作用要强于单一Cd胁迫。因此,随着复合胁迫时间的延长,Cd和Nap对白骨壤幼苗的生长由拮抗效应转变为协同效应。     

速生白榆的组织培养与快速繁殖

该文以速生白榆半木质化枝条为外植体,使用75%的酒精和0.1%HgCl_2消毒处理,外植体经过启动培养后,在增殖培养基中进行丛生芽诱导,将丛生芽切成单株进行生根诱导,最终建立起成熟的速生白榆组培快繁体系。结果表明:外植体最佳消毒处理组合为75%的酒精处理50 s+0.1%HgCl_2处理8 min,外植体污染率为17.3%,成活率为78%;将消毒处理过的外植体接种到启动培养基中,培养25 d,最终筛选出最适白榆外植体启动的培养基为MS+1.0 mg·L~(-1)6-BA+0.1 mg·L~(-1)IBA+30 g·L~(-1)蔗糖+6.5 g·L~(-1)琼脂,启动率高达87.5%;将经过启动培养后的外植体腋芽切下,接种到增殖培养基中进行丛生芽诱导,最终筛选出最佳增殖培养基为MS+0.5 mg·L~(-1)6-BA+0.1 mg·L~(-1)KT+0.1 mg·L~(-1)IBA+30 g·L~(-1)蔗糖+6.5 g·L~(-1)琼脂,继代周期25 d,增殖系数达6.2;将丛生芽切成单株,接种到生根诱导培养基中,筛选出最佳生根培养基为1/2 MS+0.1 mg·L~(-1)IBA+0.1 mg·L~(-1)IAA+30 g·L~(-1)蔗糖+6.5 g·L~(-1)琼脂,生根诱导30 d,生根率达97%。将生根苗在室外炼苗后,移栽到珍珠岩∶蛭石∶泥炭土体积比为1∶1∶1的混合基质中,成活率在90%以上。较高的增殖系数、生根率和移栽成活率可以降低生产成本,进而实现工厂化育苗。     

Factors controlling eicosapentaenoic acid production in semicontinuous cultures of marine microalgae

Three marine microalgal species with a high content of eicosapentaenoic acid (EPA), Phaeodactylum tricornutum, Isochrysis galbana and Porphyridium cruentum, were cultured semicontinuously in order to study the effect of renewal rate on EPA productivity. The percentage of EPA in total fatty acids increased with increasing renewal rates in nitrogen limited cultures, but while for Phaeodactylum tricornutum and Isochrysis galbana a plateau around 20–25% of total fatty acids was reached with renewal rates that were not nitrogen-limiting, in Porphyridium cruentum EPA percentage increased continuously with increasing renewal rate even for those cultures that were nitrogen sufficient. Maximal EPA productivities of4.6 mg L^-1 day^-1 for Isochrysis galbana and 5.2 mg L^-1 day^-1 for Phaeodactylum tricornutum were achieved with renewal rates of 20% and 30% respectively. On the other hand for Porphyridium cruentum maximal EPA productivity, 5.3 mg L^-1 day^-1, was obtained with the maximal renewal rate tested. Results indicate that different culture strategies should be adopted for the production of a particular polyunsaturated fatty acid depending on the microalgal species being used. This revised version was published online in August 2006 with corrections to the Cover Date.     

牛角瓜离体快繁技术

该文选用牛角瓜茎段为外植体,通过组织培养方法探索牛角瓜组织培养和种苗快繁技术。结果表明:最佳外植体表面消毒方法是以0.1%HgCl_2处理7 min,外植体存活率为32.3%;初代培养基为MS+蔗糖30 g·L~(-1)+琼脂3.5 g·L~(-1),培养20 d后形成3～4 cm高的再生芽。增殖培养前期筛选的较为适宜的增殖培养基为MS+6-BA 1.5 mg·L~(-1)+NAA 0.05 mg·L~(-1)+蔗糖30 g·L~(-1)+琼脂3.5 g·L~(-1),增殖系数4.6。但在后续的培养过程中发现,牛角瓜组培苗易玻璃化,且随着世代更迭,玻璃化程度加重,到了第四代几乎全部玻璃化。因此在上述增殖培养的基础上,以AgNO_3作为玻璃化抑制剂,筛选出最终的增殖培养基为MS+6-BA1.5 mg·L~(-1)+NAA 0.05 mg·L~(-1)+AgNO_31.0 g·L~(-1)+蔗糖30 g·L~(-1)+琼脂3.5 g·L~(-1)。用此增殖培养基,培养25 d,苗高5～8 cm,增殖系数5.8,玻璃化率低于10%,且连续培养多代,玻璃化率维持在10%以下。生根壮苗培养基为1/2MS+NAA 1.0 mg·L~(-1)+蔗糖20 g·L~(-1)+琼脂3.6 g·L~(-1),培养14 d,生根率98%;将生根苗移栽于70%遮阴度的大棚中,30 d后,苗高20 cm左右,成活率85%。利用该方法可对牛角瓜优良种苗进行规模化生产。     

Effects of Plant Growth Regulators on Seed Filling,Endogenous Hormone Contents and Maize Production in Semiarid Regions

In this study, we determined whether the application of uniconazole alone or combined with ethephon could enhance the seed-filling rates in maize by regulating the endogenous hormone contents. Uniconazole was applied to the foliage at concentrations of 0 (CK), 25 (U₂₅), 50 (U₅₀) and 75 (U₇₅) mg L⁻¹ at the 12-leaf stage. In addition, uniconazole was applied to the foliage at the 12-leaf stage and ethephon at 10 days after silking stage at concentrations of 0 (CK), 25 mg L⁻¹ uniconazole + 100 mg L⁻¹ ethephon (U₂₅ + E₁₀₀), 50 mg L⁻¹ uniconazole + 200 mg L⁻¹ ethephon (U₅₀ + E₂₀₀) and 75 mg L⁻¹ uniconazole + 300 mg L⁻¹ ethephon (U₇₅ + E₃₀₀). Uniconazole applied alone or in combination with ethephon significantly improved ear characters and grain yield. Uniconazole applied alone or combination with ethephon significantly improved the dry matter accumulation in seeds and seed-filling rates. Uniconazole significantly increased the abscisic acid (ABA) and zeatin (Z) + zeatin riboside (ZR) contents of seeds, but reduced the gibberellic acid (GA) contents. The application of uniconazole combined with ethephon decreased the ABA, Z + ZR and GA contents in seeds. The ABA and Z + ZR contents were significantly positively correlated, whereas the GA content was negatively correlated with the maximum seed weight, maximum seed-filling rate and mean seed-filling rate. The application of uniconazole alone significantly improved the seed-filling rates in maize by regulating the endogenous hormone contents. Thus, we conclude that uniconazole application at 50 mg L⁻¹ in the 12-leaf stage can enhance the maize production.

     

Mineralization of pentachlorophenol in a contaminated soil by Pseudomonas sp UG30 cells encapsulated in κ-carrageenan

A fermentation process in Escherichia coli for production of supercoiled plasmid DNA for use as a DNA vaccine was developed using an automated feed-back control nutrient feeding strategy based on dissolved oxygen (DO) and pH. The process was further automated through a computer-aided data processing system to regulate the cell growth rate by controlling interactively both the nutrient feed rate and agitation speed based on DO. The process increased the total yield of the plasmid DNA by approximately 10-fold as compared to a manual fed-batch culture. The final cell yield from the automated process reached 60 g L⁻¹ of dry cell weight (OD₆₀₀ = 120) within 24 h. A plasmid DNA yield of 100 mg L⁻¹ (1.7 mg g⁻¹ cell weight) was achieved by using an alkaline cell lysis method. Plasmid yield was confirmed using High Performance Liquid Chromatography (HPLC) analysis. Because cells had been grown under carbon-limiting conditions in the automated process, acetic acid production was minimal (below 0.01 g L⁻¹) throughout the fed-batch stage. In contrast, in the manual process, an acid accumulation rate as high as 0.36 g L⁻¹ was observed, presumably due to the high nutrient feed rates used to maintain a maximum growth rate. The manual fed-batch process produced a low cell density averaging 10–12 g L⁻¹ (OD₆₀₀ = 25–30) and plasmid yields of 5–8 mg L⁻¹ (approximately 0.7 mg g⁻¹ cells). The improved plasmid DNA yields in the DO- and pH-based feed-back controlled process were assumed to be a result of a combination of increased cell density, reduced growth rate (μ) from 0.69 h⁻¹ to 0.13 h⁻¹ and the carbon/nitrogen limitation in the fed-batch stage. The DO- and pH-based feed-back control, fed-batch process has proven itself to be advantageous in regulating cell growth rate to achieve both high cell density and plasmid yield without having to use pure oxygen. The process was reproducible in triplicate fermentations at both 7-L and 80-L scales. Received 22 March 1996/ Accepted in revised form 20 September 1996     

Copper biosorption in an aerobic bioreactor

Abstract

This study evaluates the biosorption of copper by aerobic biomass that was selected from surface waters of the San Pedro River in Sonora, Mexico. Using a batch system, 73% biosorption of copper was obtained in 75 minutes. Continuous biosorption assays were carried out for 133 days in an ascending flow aerobic reactor packed with zeolite (AFAR-PZ) that was inoculated with a bacterial consortium. Strains were grown until 1g L^?1 of biomass was obtained. Tests using continuous biosorption were performed as follows: (i) the addition of 50 mg Cu²⁺ L^?1 without recirculation of biomass; (ii) the addition of 20 mg Cu²⁺ L^?1without recirculation of biomass; and (iii) the biomass were recirculated with the addition of 20 mg Cu²⁺ L^?1 to pH 3 to 4. The fourth and fifth assays varied pH between 4 and 5, with 20 mg Cu²⁺ L^?1and the biomass recirculated. Biosorption capacity of the first and second assays was 96% on the first day of experimentation. During the third trial 97% of biosorption was obtained during 6 days and the process was improved by varying the pH. Copper biosorption equilibrium was investigated under the same operating conditions. Langmuir adsorption isotherms were used to fit experimental data. The biosorption capacity of aerobic biomass was 3.08 mmol g^?1. It was demonstrated that this biomass is capable of biosorbing copper and this method has potential for the treatment of industrial effluents contaminated with heavy metals.     

An efficient selection and regeneration protocol for Agrobacterium-mediated transformation of oriental melon (Cucumis melo L. var. makuwa)

An efficient selection and plant regeneration protocol for Agrobacterium-mediated transformation using cotyledon explants of oriental melon (Cucumis melo L. var. makuwa) has been developed. All six oriental melon cultivars evaluated in the study showed a >90?% shoot regeneration frequency and produced 1.8?C3.6 shoots per cotyledon explant when cultured on Murashige and Skoog (MS) medium supplemented with 1.0?mg?L^?1 benzyladenine and 0.01?mg?L^?1 indoleacetic acid. Kanamycin (Km) and geneticin (Gt) in the shoot induction medium (SIM) were compared both qualitatively and quantitatively for their efficiency as a selection agent for the selection and regeneration of transgenic plants after Agrobacterium-mediated transformation. Shoot formation was completely inhibited at 50?mg?L^?1 Km and 10?mg?L^?1 Gt. Relatively high concentrations of both Gt and Km (>100?mg?L^?1 Km and >25?mg?L^?1 Gt) were necessary because large numbers of non-transgenic shoots survived during the selection process. The incorporation of a selectable marker (neomycin phosphotransferase II) into the genome of transgenic plants was confirmed using ??-glucuronidase (GUS), PCR and Southern blot analysis. Shoot regeneration frequencies were 41.2?% at 100?mg?L^?1 Km and 15.2?% at 30?mg?L^?1 Gt 8?weeks after transformation, whereas the transformation frequencies based on the PCR were 2.9 and 7.1?%, respectively, 16?weeks after transformation. These results demonstrate that a large portion of the regenerated shoots on SIM supplemented with 100?mg?L^?1 Km consisted of non-transformed or escaped shoots, indicating that 30?mg?L^?1 Gt is the more suitable for the selection and regeneration of transgenic plants in oriental melon.     

Genotype Screening of Recipient Resources with High Regeneration and Transformation Efficiency in Chrysanthemum

Genetic transformation is one of the key steps in the molecular breeding of chrysanthemum, which relies on an optimal regeneration and transformation system. However, the regeneration system of different chrysanthemum cultivars varies, and the regeneration time of most cultivars is long. To screen cultivars with highly efficient regeneration, leaves and shoot tip thin cell layers (tTCL) from eight chrysanthemum cultivars with different flower colors and flower types were cultured on Murashige and Skoog media (MS) supplemented with 1.0–5.0 mg L⁻¹ 6-benzylaminopurine (6-BA) and 0.1–1.0 mg L⁻¹ α-naphthaleneacetic (NAA). The results showed that the most efficient regeneration media were MS + 6-BA 1.0 mg L⁻¹ + NAA 0.5 mg L⁻¹ for leaf explants and MS + 6-BA 5.0 mg L⁻¹ + NAA 0.1 mg L⁻¹ for tTCL explants. Subsequently, another 13 chrysanthemum cultivars were screened by using the media, and finally, three cultivars with high regeneration efficiency were obtained from 21 cultivars. Among these, C1 had the highest regeneration efficiency: the regeneration rate of leaf explants reached 80.0% after 42 days of culture, and the regeneration rate of tTCL explants reached 100% after 31 days of culture. Furthermore, we also established the transformation system for C1 as follows: preculturing for one day, infecting with Agrobacterium suspension (OD₆₀₀ = 0.6) for 10 min, and cultivating in the regeneration medium with 350 mg L⁻¹ carbenicillin and 10 mg L⁻¹ kanamycin, thus ultimately achieving a transformation rate of 4.0%. In this study, a new chrysanthemum cultivar with an efficient regeneration and transformation system was screened, which is beneficial to enrich the flower color of chrysanthemum transgenic plant recipients and to the functional research of flower color or type-related genes.     

Physostigmine production byStreptomyces griseofuscus NRRL 5324: Process development and scale-up studies

A reliable and scalable fermentation process was developed for production of the acetylcholine esterase inhibitor physostigmine employingStreptomyces griseofuscus NRRL 5324. Initial fermentation in small-scale bioreactors reached physostigmine levels of approximately 60 mg L^–1 after 139 h. Optimization of both process operating parameters and production medium composition rapidly yielded a seven-fold increase in physostigmine titer. The scaled up process routinely produced physostigmine titers of approximately 400 mg L^–1 during a fermentation cycle of 180 h, and supported the rapid production of large amounts of physostigmine. A physostigmine production of 500 mg L^–1 representing an eight-fold improvement over the original performance, was achieved using a glucose/ammonium fed-batch process.     

Sorption of Glyphosate on Soil Components: The Roles of Metal Oxides and Organic Materials

Predicting the behavior, fate, and transport potential of a herbicide in any soil involves understanding the sorption characteristics. The sorption characteristics of glyphosate (GPS) on soil and their main components were investigated, indicating that the mineral phase is more important than the organic carbon in adsorption of GPS. Sorption isotherms were determined from each component using the batch equilibrium method at various concentrations (5, 10, 15, 20, 25, and 30 mg L^?1) and sorption affinity of GPS was approximated by the Freundlich equation. The sorption strength K _f [mg kg^?1 (L mg^?1)^?n] across the various components ranged from 2.1–134.9 while the organic carbon-normalized Freundlich sorption capacity values, K _foc, ranged from 1.28–3.53 mg kg^?1-OC/(mg L^?1)ⁿ. Infrared Fourier transform spectroscopy (FTIR) of the components showed significant structural differences. The results suggest that the presence of the oxides and hydroxides iron, in particular in soil solutions, enhanced GPS adsorption. They also suggest that reduction in OC% due to various treatments may enhance the remobilization of GPS into the aqueous phase (i.e., groundwater), though at different rates. Comparatively, contribution of surface area to the adsorption of GPS on the various components proved more significant than contents of organic carbon.     

Effects of humic acid-herbicide interactions on the growth of Pisum sativum in nutrient solution

Slight increases in root length and dry matter production were measured in roots and shoots of Pisum sativum seedlings, when germinated seeds were grown for eight days in a controlled environment chamber, on Nitch nutrient solution to which 10 mg L^-1 soil humic acid (HA) had been added. A concentration of 100 mg L^-1 of HA produced a small reduction in dry matter production of shoots. In the presence of herbicides, 10 mg L^-1 cycluron or 100 mg L^-1 prometone, root elongation and shoot growth was reduced by varying degrees with respect to the control. Nutrient solutions containing 100 mg L^-1 cycluron, 10 or 100 mg L^-1 alachlor, or as little as 0.1 mg L^-1 of 2,4-D resulted in an almost complete suppression of the growth of pea seedlings. The addition of 10 or 100 mg L^-1 of HA to nutrient solution containing the herbicide was found to be either ineffective in enhancing growth, or even further reduced growth, compared to samples grown in the presence of the herbicide alone. The results of this preliminary study suggest that the generally accepted view that humic substances exert a positive effect on plant growth may not occur when humic substances interact with herbicides.