节瓜抗镰刀菌酸突变体的筛选和特性研究

枯萎病是节瓜的主要病害之一。为了创新节瓜抗枯萎病资源,利用枯萎病毒素镰刀菌酸(FA)为胁迫剂,以节瓜不定芽为筛选材料,进行了节瓜抗镰刀菌酸变异体离体筛选研究。试验结果表明,FA胁迫的适宜浓度为60～80mg/L。筛选出的抗性细胞系继代培养后仍保持对FA抗性,其再生植株的R1、R3代株系亦具有对枯萎病的抗性;与供体材料相比,再生系后代株系除枯萎病抗性增强外,其他主要农艺性状没有明显变化。表明利用抗FA细胞系离体筛选技术改良和创新节瓜抗枯萎病材料是可行的。

梅花鹿梭菌性气性坏疽的诊断

1990年5月中旬,江西中医学院药用动植物实验部3头雄鹿先后发生急性死亡,经临床观察、剖检、病理组织学及细菌学检查,诊断为梭菌性气性坏疽,现报告如下。

Comparison of electrochemical dissolution of chalcopyrite and bornite in acid culture medium

The electrochemical dissolution process of chalcopyrite and bornite in acid bacteria culture medium was investigated by electrochemical measurements and X-ray photoelectron spectroscopy（XPS） analysis. Bornite was much easier to be oxidized rather than to be reduced, and chalcopyrite was difficult to be both oxidized and reduced. The relatively higher copper extraction of bornite dissolution can be attributed to its higher oxidation rate. Covellite（CuS） was detected as the intermediate species during the dissolution processes of both bornite and chalcopyrite. Bornite dissolution was preferred to be a direct oxidation pathway, in which bornite was directly oxidized to covellite（CuS） and cupric ions, and the formed covellite（CuS） may inhibit the further dissolution. Chalcopyrite dissolution was preferred to be a continuous reduction-oxidation pathway, in which chalcopyrite was initially reduced to bornite, then oxidized to covellite（CuS）, and the initial reduction reaction was the rate-limiting step.

Research on Oxidative Stress Induced by Tenuazonic Acid from Alternaria augustiovoide and Changes in Antioxidant Enzyme Activities in Leaves of Echinochloa crus-galli

[Objective] The aim of the study was to determine whether phytotoxicity of TeA against Echinochloa crus-galli leaves was correlated with oxidative stress caused by generation of reactive oxygen and the changes of antioxidant enzymes activity.[Method] The changes of malondialdehyde（MDA）content,hydrogen peroxide（H2O2）,and activities of superoxide dismutase（SOD）,glutathione reductase（GR）and catalase（CAT）were studied by leaf segment method in vitro.[Result] After the treatment of 500 μmol/L TeA,the content of MDA and H2O2 increased by 247.86% and 67.00%,respectively,indicating that the accumulation of MDA and H2O2 in E.crus-galli leaves was due to the reactive oxygen burst induced by TeA.TeA induced a significant increase in activities of SOD,GR and CAT.At 500 μmol/L TeA,activities of SOD,GR and CAT increased more than one fold compared with the control.[Conclusion] TeA could not only cause oxidative stress in leaves of E.crus-galli through the induction of reactive oxygen,but also induce the increasing of antioxidant enzyme activity.

Reconstruction of a Food-grade Expression Vector in Lactococcus Lactis

[Objective]In order to improve expression vector of L.lactis at food grade and widen application range of original system.[Method] Taking pNZ8149 as basis,the promoter PnisA of pNZ8149 was inserted L.lactis MG1363 and SPusp45 of unknown secretory protein in downstream.Through PCR technology,specific primers were used to delete restriction sites between promoter sequence and signal peptide gene sequence and ensure better distance between SD sequence and start codon to construct secreting expression vector pNZS.The reporter gene gus was recombined into multiple cloning site of pNZS to construct pNZS-gus and L.lactis was transformed by electroporation.10 ng/ml nisin was used for induction culture,then culture solution was conducted GUS staining test.[Result]The new constructed L.lactis N3900/pNZS-gus system could express active GUS protein and GUS protein could be secreted out of cell.[Conclusion]The successful construction of this system lays foundation for secretion expression study of protein and oral vaccine research.

Triterpenoid Saponins from Eclipta prostrata L.

Five triterpenoid saponins were isolated from the Chinese traditional medicine Eclipta prostrata L.. On the basis of their chemical properties and spectral data, they were identified as eclalbasaponins II(1), I(2), III(3), 3-O-[b-D-glucopyranosyl(12)-b-D-glucopyranosyl]-16a-ethoxy-olean-12-ene-28-oic acid-28-O-b-D-glu-copyranoside(4) and 3-O-[(2-O-sulfuryl-b-D-glucopyranosyl)(12)-b-D-glucopyranosyl]-echinocystic acid-28-O-b-D-glucopyranoside(5). Compounds 4 and 5 are new compounds and named eclalbasaponins XI and XII, respectively. Compounds 1 and 5 induced morphological deformation of Pyricularia oryzae mycelia.

Diversity and Phylogenetic Analysis of Lactic Acid in Forage of Xinjiang Uigur Autonomous Region

[Objective] The aim was to conduct preliminary investigation and diversity analysis of lactic acid bacteria resources in forage from Turpan of Xinjiang. [Method] The lactic acid bacteria in the three kinds of forage ingredients in Xinjiang were isolated by using plate separation method and screened by MRS＋CaCO3 solid medium. Morphological, physiological and biochemical identification and 16S rDNA gene sequence analysis were carried out to the isolated eighty strains of lactic acid bacteria, to explore its taxonomic status. [Result] Twenty strains of lactic acid bacteria were obtained from alfalfa, forty-one from wheat, and nineteen from corn. The physiological and biochemical identification and 16S rDNA gene sequence analysis results showed that the eighty strains of lactic acid bacteria belonged to two genera, namely, Lactobacillus, Enterococcus; 7 species, Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus paracasei, Entercoccus faecium, Entercoccus durans, Lactobacillus plantarum, Entercoccus hirae. Lactobacillus casei and Entercoccus faecium were ubiquitous in the three kinds of forage ingredients. Besides these two lactic acid bacteria, there were Lactobacillus rhamnosus, Lactobacillus paracasei, Lactobacillus plantarum in wheat, Lactobacillus plantarum, Lactobacillus paracasei, Entercoccus hirae, Entercoccus durans in alfalfa, Lactobacillus plantarum, Entercoccus durans in corn. [Conclusion] There is a big diversity of lactic acid bacteria in different forage from Turpan of Xinjiang, in which Lactobacillus casei, Entercoccus faecium are the key bacteria for forage fermentation.

Preservation efficiency of new cryoprotectant used for Acidithiobacillus ferrooxidans in liquid nitrogen

The efficiency of a new cryoprotectant,GP,for the preservation of Acidithiobacillus ferrooxidans（A.ferrooxidans） strain DC in liquid nitrogen was investigated.The optimal concentration of this new cryoprotectant for the maximal viable cell recovery and the highest ferrous ion oxidation activity was determined.The results show that 30%（volume fraction） GP is optimal for the cryopreservation with 84.4% of cells surviving,completely oxidizing ferrous ions within 120 h,and growing to a final density of 5.8×107 cell/mL after 6 d in the culture.Furthermore,the optimal residual GP concentration for viable cell recovery after culture of thawed cells in 9K medium for 6 d is 0.6%（volume fraction）.At this concentration,strain DC completely oxidizes ferrous ions within 108 h and grows to a final cell density of 6.8×107 mL-1.Thus,GP is a simple,effective cryoprotectant for the preservation of A.ferrooxidans strain DC in liquid nitrogen.

Antimicrobial Expanded Polytetrafluoroethylene Film Prepared by 3-ray Radiation Induced Grafting of Poly（acrylic acid）

The simultaneous γ-ray-radiation-induced grafting polymerization of acrylic acid on ex- panded polytetrafluoroethylene （ePTFE） film was investigated. It was found that the degree of grafting （DG） of poly（acrylic acid） （PAA） can be controlled by the monomer concentration, absorbed dose, and dose rate under an optimal inhibitor concentration of [Fe2＋]=18 mmol/L. SEM observation showed that the macroporous structure in ePTFE films would be covered gradually with the increase of the DG of PAA. The prepared ePTFE-g-PAA film was im- mersed in a neutral silver nitrate solution to fabricate an ePTFE-g-PAA/Ag hybrid film after the addition of NaBH4 as a reduction agent of Ag＋ to Ag atom. SEM, XRD, and XPS results proved that Ag nanoparticles with a size of several tens of nanometers to 100 nanometers were in situ immobilized on ePTFE film. The loading capacity of Ag nanoparticles could be tuned by the DG of PAA, and determined by thermal gravimetric analysis. The quart- titative antibacterial activity of the obtained ePTFE-g-PAA/Ag hybrid films was measured using counting plate method. It can kill all the Escherichia coli in the suspension in 1 h. Moreover, this excellent antibacterial activity can last at least for 4 h. This work provides a facile and practical way to make ePTFE meet the demanding antimicrobial requirement in more and more practical application areas.

Isolation of an acid producing Bacillus sp. EEEL02: Potential for bauxite residue neutralization

Bauxite residue deposit area(BRDA)is a typical abandoned mining wasteland representing extreme hostile environment with increased alkalinity.Microbially-driven neutralization of bauxite residue,based on the microbial acid producing metabolisms,is a novel strategy for achieving rapid pH neutralization and thus improving its environmental outcomes.The hypothesis was that these extreme conditions promote microbial communities which are capable of novel ecologically relevant functions.Several alkaliphilic acid producing bacteria were isolated in this study.One strain was selected for its superior growth pattern and acid metabolism(termed EEEL02).Based on the phylogenetic analysis,this strain was identified as Bacillus thuringiensis.The optimized fermentation conditions were as follows:pH 10;NaCl concentration 5%;temperature 25℃;EEEL02 preferred glucose and peptone as carbon and nitrogen sources,respectively.Based on optimal fermentation conditions,EEEL02 induced a significant pH reduction from 10.26 to 5.62 in 5-day incubation test.Acetic acid,propionic acid and CO2(g)were the major acid metabolites of fermentation,suggesting that the pH reduction in bauxite residue may be caused by acid neutralization derived from microbial metabolism.This finding provided the basis of a novel strategy for achieving rapid pH neutralization of bauxite residue.

Isolation and characterization of Acidithiobacillus caldus from several typical environments in China

Six strains of moderately thermophilic sulfur-oxidizing bacteria were isolated from several different typical environments in China. The identities of the isolates were confirmed by analyses of their 16S rRNA genes, and some key physiological traits. The isolates are Gram negative, rod-shaped bacteria, their optimal temperature and pH value for growth are 45-50℃ and 2.5-3.5 respectively. They are autotrophic and used elemental sulfur, sodium thiosulfate and potassium tetrathionate as electron donor, while a little glucose stimulated their growth. 16S rDNA sequences analysis reveals that the strains are phylogenetically clustered to Acidithiobacillus caldus.

New therapeutic opportunities for Hepatitis C based on small RNA

Hepatitis C virus （HCV） infection is one of the major causes of chronic liver disease, including cirrhosis and liver cancer and is therefore, the most common indication for liver transplantation. Conventional antiviral drugs such as pegylated interferon-alpha, taken in combination with ribavirin, represent a milestone in the therapy of this disease. However, due to different viral and host factors, clinical success can be achieved only in approximately half of patients, making urgent the requirement of exploiting alternative approaches for HCV therapy. Fortunately, recent advances in the understanding of HCV viral replication and host cell interactions have opened new possibilities for therapeutic intervention. The most recent technologies, such as small interference RNA mediated gene-silencing, antisense oligonucleotides （ASO）, or viral vector based gene delivery systems, have paved the way to develop novel therapeutic modalities for HCV. In this review, we outline the application of these technologies in the context of HCV therapy. In particular, we will focus on the newly defined role of cellular microRNA （miR-222） in viral replication and discuss its potential for HCV molecular therapy.

Antifungal Activity of Lactic Acid Bacteria, Isolated from Bulgarian Wheat and Rye Flour

The economic losses and the health hazards of the mycotoxins produced by spoilage fungi are the main concerns of the food industry. The spoilage of bakery products by fungi is more common in countries with a high humidity and temperature. About 5-10% of food production is spoiled by the growth of yeast and fungi in food materials. Similarly, in Western Europe, the growth of the spoilage fungi of bread is estimated to reach more than 200 million Euros per year. The history conditions of the food can be a major factor in determining any fungal spoilage--for example, stored and processed foods are more sensitive to spoilage when compared with fresh and prepared foods. Lactic acid bacteria isolated from Bulgarian wheat and rye flour were used in the present study to check their antifungal properties against pathogenic yeast and fungi imperfecta using standard disc diffusion method in vitro. A broad spectrum of antifungal activity of the six newly identified as L. plantarum strains e Tsl, Ts2, Ts3,Ts4 and Ts5, and L. helveticus Ts6 was estimated. Our in vitro studies were performed with wheat and rye sourdough, in order to simulate a real product and to assess the bio-protective potential of the tested lactobacilli. The used test-cultures are representatives of carcinogenic, toxigenic, deteriorative and allergenic fungi from the genera .4spergillus and Penicillium. The all tested strains completely suppress the growth of against C. glabrata 72. Strains L. plantarum Tsl and Ts3 completely suppress the growth against S. cerevisae. While, in the sample with L. plantarum strains e Tsl, Ts2, Ts3,Ts4 and Ts5, and L. helveticus Ts6, a retarded and weak growth of A. niger and P. claviforme was observed. However, the spore germination and the colony growth started only on the fifth day of the mould lactobacilli co-cultivation, which also should be considered as a good result. In this study six isolates Tsl,Ts2, Ts3, Ts4, Ts5 and Ts6, from the traditional Bulgarian wheat and rye flour have been identified as L. plantarum and L. helveticus and characterized as cultures with promising antifungal activity. Obtained results from the combined molecular identification （16S rRNA gene sequencing） approach contribute to give new data on the microbial biodiversity of this not well-studied niche. The antifungal activity of our new isolates, identified as L. plantarum and L. helveticus, seems to be a promising advantage of these six strains, suggesting their potential applications in different food technologies. However, more experiments have to be conducted to clarify the nature and the mechanisms of the reported antifungal activity and they are still in progress. The combination of dairy origin and strong inhibitory activity of the lactobacillus strains is a prerequisite for their possible application as starters and/or bioprotective antifungal adjuncts.

Plant Enzymes, Root Exudates, Cluster Roots and Mycorrhizal Symbiosis are the Drivers of P Nutrition in Native Legumes Growing in P Deficient Soil of the Cape Fynbos in South Africa

The Cape fynbos is characterised by highly leached, sandy, acidic soils with very low nutrient concentrations. Plant-available P levels range from 0.4 μg P g-1 to 3.7 μg P g-I soil, and 1-2 mg N gl soil. Despite these low nutrient concentrations, the fynbos is home to 9,030 vascular plant species with 68.7% endemicity. How native plant species survive such low levels of available P is intriguing, and indeed the subject of this review. In the fynbos soils, P is easily precipitated with cations such as Fe and Al, forming AI-P and Fe-P in acidic soils, or Ca-P in neutral-to-alkaline soils. The mechanisms for promoting P availability and enhancing P nutrition include the development of mycorrhizal symbiosis （with 80%-90% of higher plants, e.g., Cyclopia, Aspalathus, Psoralea and Leucadendron etc.） which exhibits 3-5 times much greater P acquisition than non-mycorrhizal roots. Formation of cluster roots by the Leguminosae （Fabaceae） and their exudation of Kreb cycle intermediates （organic acids） for solubilizing P, secretion of root exudate compounds （organic acids, phenolics, amino acids, etc.） that mobilize P. The synthesis and release of acid and alkaline phosphatase enzyme that catalyze the cleavage of mineral P from organic phosphate esters in acidic and alkaline soils, and the development of deep tap roots as well as massive secondary roots within the uppermost 15 cm of soil for capturing water and nutrients. Some fynbos legumes employ all these adaptive mechanisms for enhancing P nutrition and plant growth. Aspalathus and Cyclopia species typically form mycorrhizal and rhizobial symbiosis for improving P and N nutrition, produce cluster roots and acid phosphatases for increasing P supply, and release root exudates that enhance P solubilisation and uptake.

Purification and Characterization of Glutamate Decarboxylase of Lactobacillus brevis CGMCC 1306 Isolated from Fresh Milk

A Lactobacillus brevis CGMCC 1306 isolated from fresh milk without pasteurization was found to have higher glutamate decarboxylase （GAD） activity. An effective isolation and purification procedure of GAD from a cell-free extract of Lactobacillus brevis was developed, and the procedure included four steps： 30%-90% saturation （NH4）2SO4 fractional precipitation, Q sepharose FF anion-exchange chromatography, sephacryl S-200 gel filtration, and resource Q anion-exchange chromatography. Using this protocol, the purified GAD was demonstrated to possess electrophoretic homogeneity via SDS-PAGE. The purification fold and activity recovery of GAD were 43.78 and 16.95%, respectively. The molecular weight of the purified GAD was estimated to be approximately 62 kDa via SDS-PAGE. The optimum pH and temperature of the purified GAD were 4.4 and 37℃, respectively. The purified GAD had a half-life of 50rain at 45℃ and the Km value of the enzyme from Lineweaver-Burk plot was found to be 8.22.5＇-pyridoxal phosphate （PLP） had little effect on the regulation of its activity.

Catalytic effect of visible light and Cd^2+on chalcopyrite bioleaching

The effects of visible light and Cd^2+ion on chalcopyrite bioleaching in the presence of Acidithiobacillus ferrooxidans(A.ferrooxidans)were studied by scanning electron microscopy(SEM),synchrotron radiation X-ray diffraction(SR-XRD),and X-ray photoelectron spectroscopy(XPS).The results of bioleaching after 28 days showed that the copper dissolution increased by 4.96%with only visible light,the presence of Cd2+alone exerted slight inhibition effect on chalcopyrite dissolution and the concentration of dissolved copper increased by 14.70%with visible light and 50 mg/L Cd^2+.The results of chemical leaching showed that visible light can promote the circulation of iron.SEM results showed that Cd^2+promoted the attachment of A.ferrooxidans on chalcopyrite surface under visible light.SR-XRD and XPS results indicated that visible light and Cd^2+promoted chalcopyrite dissolution,but did not inhibit the formation of passivation.Finally,a model of synergistic catalysis mechanism of visible light and Cd2+on chalcopyrite bioleaching was proposed.

Diversity of microbial community at acid mine drainages from Dachang metals-rich mine, China

Two acid mine drainage(AMD)samples TS and WK,which were from the Dachang metals-rich mine in Guangxi province,China,were studied using PCR-based cloning approach.A total of 44 operational taxonomic units(OTUs)were obtained from the two AMD samples.However,only three OTUs(GXDC-9,GXDC-19 and GXDC-50)detected in sample TS can also be observed in sample WK.Phylogenetic analysis revealed that the bacteria in the two samples fell into four putative divisions,which were Nitrospira,Alphaproteobacteria,Gamaproteobacteria,and Acidobacteria.Organisms of genuses Acidithiobacillus and Leptospirillum,which were in gamaproteobacteria class and Nitrospira family,were dominant in two samples,respectively.In sample TS,which was characterized by low pH,high sulfate,high iron,and high arsenide,two species(Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans)constituted 98.22% of the entire microbial community.Compared with sample TS,the microbial community in sample WK was more diversified according to the observation.Interestedly,the Legionella species,which was rarely observed in the low-pH environment,was detected in sample WK.This work helps us to further understand the diversity of microbial community living in extreme acid mine drainages with unique geochemistry and the tolerance capability of acidophiles to heavy metal.

Antibacterial Activity of Extracts from Zostera marina Against Pathogens of Apostichopus japonicus Skin Ulceration Disease

The purpose of this study was to investigate the antibacterial activity of extracts from Zostera marina against the pathogens of Apostichopus japonicus skin ulceration disease.When 95% ethanol (v/v) solvent was used to extract Zostera marina at 50℃,aqueous extract (ZA) showed obvious bacteriostatic effects on the tested bacterial strains (inhibition halo diameters between 8.23 mm and 13.62 mm),whereas the ethyl acetate extract (ZE) was almost inactive.The minimal inhibitory concentration (MIC) of ZA against four pathogens were homogeneous at 12.8 g L-1.ZA components were analyzed by thin layer chromatography (TLC) assay and six fractions were obtained.In another study,the six fractions showed inhibitory effects against the tested bacteria while their functions seemed to counteract the ZA activity.

Lactobacilli Improve the Antioxidant Activity in Fermented Coriolus versicolor Extract

Coriolus versicolor has been reported to have biological activities such as anticancer, antibacterial, antibiotics and immunopotentiation. The authors tried to ferment using lactobacilli associated with various biological functions and expected that fermented extract by lactobacilli will be superior to non-fermented extract in antioxidant activity. C. versicolor was extracted with 70% ethanol and then it was fermented by Lactobacillus acidophilus KCTC3164 and Lactobacillus plantarum KCTC3099, respectively. 1,l-dipheny｜-2-picrylhydrazyl （DPPH） scavenging activity, superoxide dismutase （SOD）-like activity and tetrazolium salt 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） assays were performed. DPPH scavenging activity of fermented extract by L. acidophilus was higher than fermented extract by L. plantarum and antioxidant effect of fermented extract was 20%-30% higher than non-fermented extract. SOD-like activity was represented 18% in fermented extract by L. acidophilus, and was 27% in fermented extract by L. plantarum higher than non-fermented extract. As a result, this study suggests that it may need an efficient protocol for dominant bio-physiological activities such as extract volume or appropriate working volume of cultured cell or mixture condition. The fermented C. versicolor extract should provide with useful antioxidant agent in the human skin.

Species of Inorganic Phosphate Solubilizing Bacteria in Red Soil and the Mechanism of Solubilization

INTRODUCTION The insoluble phosphates which can not be directly absorbed by plants are the mai forms of inorganic phosphate in soil. These kinds of phosphates can be solubilized by several species of bacteria which are widely spread in soil especially in rhizosphere where70% of the bacteria are capable of solubilizing inorganic phosphate. Many researchers re-