Showing papers by "Nanchang University published in 2010"

Cultivation of green algae Chlorella sp. in different wastewaters from municipal wastewater treatment plant.

Abstract: The objective of this study was to evaluate the growth of green algae Chlorella sp. on wastewaters sampled from four different points of the treatment process flow of a local municipal wastewater treatment plant (MWTP) and how well the algal growth removed nitrogen, phosphorus, chemical oxygen demand (COD), and metal ions from the wastewaters. The four wastewaters were wastewater before primary settling (#1 wastewater), wastewater after primary settling (#2 wastewater), wastewater after activated sludge tank (#3 wastewater), and centrate (#4 wastewater), which is the wastewater generated in sludge centrifuge. The average specific growth rates in the exponential period were 0.412, 0.429, 0.343, and 0.948 day(-1) for wastewaters #1, #2, #3, and #4, respectively. The removal rates of NH4-N were 82.4%, 74.7%, and 78.3% for wastewaters #1, #2, and #4, respectively. For #3 wastewater, 62.5% of NO3-N, the major inorganic nitrogen form, was removed with 6.3-fold of NO2-N generated. From wastewaters #1, #2, and #4, 83.2%, 90.6%, and 85.6% phosphorus and 50.9%, 56.5%, and 83.0% COD were removed, respectively. Only 4.7% was removed in #3 wastewater and the COD in #3 wastewater increased slightly after algal growth, probably due to the excretion of small photosynthetic organic molecules by algae. Metal ions, especially Al, Ca, Fe, Mg, and Mn in centrate, were found to be removed very efficiently. The results of this study suggest that growing algae in nutrient-rich centrate offers a new option of applying algal process in MWTP to manage the nutrient load for the aeration tank to which the centrate is returned, serving the dual roles of nutrient reduction and valuable biofuel feedstock production.

Lactic acid bacterial cell factories for gamma-aminobutyric acid.

Abstract: Gamma-aminobutyric acid is a non-protein amino acid that is widely present in organisms. Several important physiological functions of gamma-aminobutyric acid have been characterized, such as neurotransmission, induction of hypotension, diuretic effects, and tranquilizer effects. Many microorganisms can produce gamma-aminobutyric acid including bacteria, fungi and yeasts. Among them, gamma-aminobutyric acid-producing lactic acid bacteria have been a focus of research in recent years, because lactic acid bacteria possess special physiological activities and are generally regarded as safe. They have been extensively used in food industry. The production of lactic acid bacterial gamma-aminobutyric acid is safe and eco-friendly, and this provides the possibility of production of new naturally fermented health-oriented products enriched in gamma-aminobutyric acid. The gamma-aminobutyric acid-producing species of lactic acid bacteria and their isolation sources, the methods for screening of the strains and increasing their production, the enzymatic properties of glutamate decarboxylases and the relative fundamental research are reviewed in this article. And the potential applications of gamma-aminobutyric acid-producing lactic acid bacteria were also referred to.

Abundance of SSR Motifs and Development of Candidate Polymorphic SSR Markers (BARCSOYSSR_1.0) in Soybean

Abstract: Simple sequence repeat (SSR) genetic markers, also referred to as microsatellites, function in map-based cloning and for marker-assisted selection in plant breeding. The objectives of this study were to determine the abundance of SSRs in the soybean genome and to develop and test soybean SSR markers to create a database of locus-specific markers with a high likelihood of polymorphism. A total of 210,990 SSRs with di-, tri-, and tetranucleotide repeats of five or more were identified in the soybean whole genome sequence (WGS) which included 61,458 SSRs consisting of repeat units of di-(≥10), tri- (>8), and tetranucleotide (>7). Among the 61,458 SSRs, (AT)n, (ATT)n and (AAAT)n were the most abundant motifs among di-, tri-, and tetranucleotide SSRs, respectively. After screening for a number of factors including locus-specificity using e-PCR, a soybean SSR database (BARCSOYSSR_1.0) with the genome position and primer sequences for 33,065 SSRs was created. To examine the likelihood that primers in the database would function to amplify locus-specific polymorphic products, 1034 primer sets were evaluated by amplifying DNAs of seven diverse Glycine max (L.) Merr. and one wild soybean (Glycine soja Siebold & Zucc.) genotypes. A total of 978 (94.6%) of the primer sets amplified a single polymerase chain reaction (PCR) product and 798 (77.2%) amplified polymorphic amplicons as determined by 4.5% agarose gel electrophoresis. The BARCSOYSSR1.0 SSR markers can be found in Soy-Base (http://soybase.org; verified 21 June 2010) the USDA-ARS Soybean Genome Database.

Review of biological and engineering aspects of algae to fuels approach

Abstract: Current biofuel production relies on limited arable lands on the earth, and is impossible to meet the biofuel demands. Oil producing algae are alternative biofuel feedstock with potential to meet the world's ambitious goal to replace fossil fuels. This review provides an overview of the biological and engineering aspects in the production and processing technologies and recent advances in research and development in the algae to fuels approach. The article covers biology, selection and genetic modification of algae species and strains, production systems design, culture media and light management, harvest and dewatering, downstream processing, and environment and economic assessment. Despite the many advances made over several decades, commercialization of algal fuels remains challenging chiefly because of the techno-economic constraints. Technological breakthroughs in all major aspects must take place before commercial production of algal fuels becomes economically viable. Keywords: algae, microalgae, open pond, enclosed photobioreactor, light, harvest, dewatering, extraction, hydrothermal liquefaction, gasification, pyrolysis, fermentation DOI: 10.3965/j.issn.1934-6344.2009.04.001-030 Citation: Paul Chen, Min Min, Yifeng Chen, Liang Wang, Yecong Li, Qin Chen, et al. Review of the biological and engineering aspects of algae to fuels approach. Int J Agric & Biol Eng, 2009; 2(4): 1

Peptide fractionation and free radical scavenging activity of zein hydrolysate

Abstract: Alcalase-treated zein hydrolysate (ZH) was separated by gel filtration, ultrafiltration, and reversed-phase HPLC, and the scavenging activities for 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+), 1,1-diphenyl-2-picrylhydrazyl (DPPH*), and superoxide anion (O2*-) radicals of different peptide fractions were measured to establish the antioxidant efficacy. Results showed that the ability to stabilize water-soluble free radicals (ABTS*+) by ZH components was insensitive to the peptide size, whereas that against ethanol-soluble free radicals (DPPH*) and O2*- was molecular weight dependent. Antioxidative peptides of <1 kDa were further separated by HPLC into 30 components, of which those with great hydrophobicity exhibited strong DPPH* and O2*- scavenging ability and those with intermediate hydrophobicity displayed the maximum ABTS*+ scavenging activity. Two dominant components (fractions 8 and 17) were further purified and identified by LC-PDA-ESI-MS to be Tyr-Ala and Leu-Met-Cys-His, respectively. The results demonstrated that the free radical scavenging activity of ZH depended on the radical species and was strongly related to the molecular weight and hydrophobicity of the constituting peptides.

Supplementing l-leucine to a low-protein diet increases tissue protein synthesis in weanling pigs

Abstract: Recent work with young pigs shows that reducing dietary protein intake can improve gut function after weaning but results in inadequate provision of essential amino acids for muscle growth. Because acute administration of L-leucine stimulates protein synthesis in piglet muscle, the present study tested the hypothesis that supplementing L-leucine to a low-protein diet may maintain the activation of translation initiation factors and adequate protein synthesis in multiple organs of post-weaning pigs. Eighteen 21-day pigs (Duroc×Landrace×Yorkshire) were fed low-protein diets (16.9% crude protein) supplemented with 0, 0.27 or 0.55% L-leucine (total leucine contents in the diets being 1.34, 1.61 or 1.88%, respectively). At 35 days of age, protein synthesis was determined using the [2H] phenylalanine flooding-dose technique. Additionally, total and phosphorylated levels of mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase 1 (S6K1), and eIF4E-binding protein-1 (4E-BP1) were measured in longissimus muscle and liver. Compared with the control group, dietary supplementation with 0.55% L-leucine for 2 weeks increased (P<0.05): (1) the phosphorylated levels of S6K1 and 4E-BP1; (2) protein synthesis in skeletal muscle, liver, the heart, kidney, pancreas, spleen, and stomach; and (3) daily weight gain by 61%. Dietary supplementation with 0.27% L-leucine enhanced (P<0.05) protein synthesis in proximal small intestine, kidney and pancreas. These novel findings provide a molecular basis for designing effective nutritional means to increase the efficiency of nutrient utilization for protein accretion in neonates.

Dietary supplementation with l-arginine or N-carbamylglutamate enhances intestinal growth and heat shock protein-70 expression in weanling pigs fed a corn- and soybean meal-based diet

Abstract: This study determined effects of dietary supplementation with l-arginine (Arg) or N-carbamylglutamate (NCG) on intestinal health and growth in early-weaned pigs. Eighty-four Landrace × Yorkshire pigs (average body weight of 5.56 ± 0.07 kg; weaned at 21 days of age) were fed for 7 days one of the three isonitrogenous diets: (1) a corn- and soybean meal-based diet (CSM), (2) CSM + 0.08% NCG (0.08%), and (3) CSM + 0.6% Arg. There were four pens of pigs per diet (7 pigs/pen). At the end of a 7-day feeding period, six piglets were randomly selected from each treatment for tissue collections. Compared with the control group, Arg or NCG supplementation increased (P < 0.05): (1) Arg concentrations in plasma, (2) small-intestinal growth, (3) villus height in duodenum, jejunum and ileum, (4) crypt depth in jejunum and ileum, (5) goblet cell counts in intestinal mucosae, and (6) whole-body weight gain in pigs. Real-time polymerase chain reaction and western blotting analyses revealed that both mRNA and protein levels for heat shock protein-70 (HSP70) were higher (P < 0.05) in the intestinal mucosae of Arg- or NCG-supplemented pigs than in the control group. Furthermore, the incidence of diarrhea in the NCG group was 18% lower (P < 0.01) than that in the control group. Collectively, these results indicate that dietary supplementation with 0.6% Arg or 0.08% NCG enhances intestinal HSP70 gene expression, intestinal growth and integrity, and the availability of dietary nutrients for whole-body weight gain in postweaning pigs fed a CSM-based diet. Thus, Arg or NCG is a functional ingredient in the weaning diet to improve nutrition, health, and growth performance of these neonates.

Production of gamma-aminobutyric acid by Lactobacillus brevis NCL912 using fed-batch fermentation

Abstract: Background: Gamma-aminobutyric acid is a major inhibitory neurotransmitter in mammalian brains, and has several well-known physiological functions. Lactic acid bacteria possess special physiological activities and are generally regarded as safe. Therefore, using lactic acid bacteria as cell factories for gamma-aminobutyric acid production is a fascinating project and opens up a vast range of prospects for making use of GABA and LAB. We previously screened a high GABA-producer Lactobacillus brevis NCL912 and optimized its fermentation medium composition. The results indicated that the strain showed potential in large-scale fermentation for the production of gamma-aminobutyric acid. To increase the yielding of GABA, further study on the fermentation process is needed before the industrial application in the future. In this article we investigated the impacts of pyridoxal-5’phosphate, pH, temperature and initial glutamate concentration on gamma-aminobutyric acid production by Lactobacillus brevis NCL912 in flask cultures. According to the data obtained in the above, a simple and effective fed-batch fermentation method was developed to highly efficiently convert glutamate to gamma-aminobutyric acid. Results: Pyridoxal-5’-phosphate did not affect the cell growth and gamma-aminobutyric acid production of Lb. brevis NCL912. Temperature, pH and initial glutamate concentration had significant effects on the cell growth and gamma-aminobutyric acid production of Lb. brevis NCL912. The optimal temperature, pH and initial glutamate concentration were 30-35°C, 5.0 and 250-500 mM. In the following fed-batch fermentations, temperature, pH and initial glutamate concentration were fixed as 32°C, 5.0 and 400 mM. 280.70 g (1.5 mol) and 224.56 g (1.2 mol) glutamate were supplemented into the bioreactor at 12 h and 24 h, respectively. Under the selected fermentation conditions, gamma-aminobutyric acid was rapidly produced at the first 36 h and almost not produced after then. The gamma-aminobutyric acid concentration reached 1005.81 ± 47.88 mM, and the residual glucose and glutamate were 15.28 ± 0.51 g L -1 and 134.45 ± 24.22 mM at 48 h. Conclusions: A simple and effective fed-batch fermentation method was developed for Lb. brevis NCL912 to produce gamma-aminobutyric acid. The results reveal that Lb. brevis NCL912 exhibits a great application potential in large-scale fermentation for the production of gamma-aminobutyric acid.

Wave and particle characteristics of earthward electron injections associated with dipolarization fronts

Abstract: [1] A comprehensive examination of particle and wave data from multiple Thermal Emission Imaging System (THEMIS) satellites has been made of an electron injection structure in the magnetotail as it propagated earthward from −20 RE to −11 RE on 27 February 2009. The electron injection, which was closely associated with a dipolarization front and bursty bulk flows, occurred within a thin plasma boundary layer and had both perpendicular and parallel energization, with very little energy dispersion. The thin plasma boundary layer had a thickness comparable to the ion inertial length and displayed different plasma characteristics at different locations. Strong electromagnetic waves between the lower hybrid frequency and the electron gyrofrequency, as well as electrostatic waves up to the electron plasma frequency, were observed within the thin plasma boundary layers. The two outermost spacecraft at X = −20.1 RE and X = −16.7 RE detected intense whistler waves, most likely driven by an observed electron temperature anisotropy with T⊥/T∥ > 1. Closer to Earth at X = −11.1 RE, whistlers were not seen, consistent with the observed electron distribution having T⊥/T∥ < 1. Near the electron injection region, nonlinear electrostatic structures such as electrostatic solitary waves and double layers were also observed. These nonlinear electrostatic structures can interact with the electron distribution and accelerate electrons; high energy distributions could be generated if the electrons encountered a large number of these structures. The observations show that nonideal MHD, nonlinear, and kinetic behavior is intrinsic to the electron injections with multiscale coupling.

Eshelby's problem of non-elliptical inclusions

Abstract: The Eshelby problem consists in determining the strain field of an infinite linearly elastic homogeneous medium due to a uniform eigenstrain prescribed over a subdomain, called inclusion, of the medium. The salient feature of Eshelby's solution for an ellipsoidal inclusion is that the strain tensor field inside the latter is uniform. This uniformity has the important consequence that the solution to the fundamental problem of determination of the strain field in an infinite linearly elastic homogeneous medium containing an embedded ellipsoidal inhomogeneity and subjected to remote uniform loading can be readily deduced from Eshelby's solution for an ellipsoidal inclusion upon imposing appropriate uniform eigenstrains. Based on this result, most of the existing micromechanics schemes dedicated to estimating the effective properties of inhomogeneous materials have been nevertheless applied to a number of materials of practical interest where inhomogeneities are in reality non-ellipsoidal. Aiming to examine the validity of the ellipsoidal approximation of inhomogeneities underlying various micromechanics schemes, we first derive a new boundary integral expression for calculating Eshelby's tensor field (ETF) in the context of two-dimensional isotropic elasticity. The simple and compact structure of the new boundary integral expression leads us to obtain the explicit expressions of ETF and its average for a wide variety of non-elliptical inclusions including arbitrary polygonal ones and those characterized by the finite Laurent series. In light of these new analytical results, we show that: (i) the elliptical approximation to the average of ETF is valid for a convex non-elliptical inclusion but becomes inacceptable for a non-convex non-elliptical inclusion; (ii) in general, the Eshelby tensor field inside a non-elliptical inclusion is quite non-uniform and cannot be replaced by its average; (iii) the substitution of the generalized Eshelby tensor involved in various micromechanics schemes by the average Eshelby tensor for non-elliptical inhomogeneities is in general inadmissible.

Using the concept of Chou's pseudo amino acid composition to predict enzyme family classes: an approach with support vector machine based on discrete wavelet transform.

Abstract: The early determination of family for a newly found enzyme molecule becomes important because it is directly related to the detail information about which specific target it acts on, as well as to its catalytic process and biological function. Unfortunately, it is still a hard work to distinguish enzyme classes by experiments. With an enormous amount of protein sequences uncovered in the genome research, it is both challenging and indispensable to develop an automatic method for fast and reliably classifying the enzyme family. Using the concept of Chous pseudo amino acid composition, we developed a new method that coupled discrete wavelet transform with support vector machine based on the amino acid hydrophobicity to predict enzyme family. The overall success rate obtained by the 10-cross-validation for the identification of the six enzyme families was 91.9%, indicating the current method could be an effective and promising highthroughput method in the enzyme research.

Chemical characteristics and antioxidant activities of polysaccharide purified from the seeds of Plantago asiatica L.

Abstract: BACKGROUND: A water-soluble polysaccharide from the seeds of Plantago asiatica L. (P. asiatica L. polysaccharide, PLP) was extracted with hot water and purified by gel filtration chromatography. The chemical characteristics of PLP were determined by high-performance gel permeation chromatography (HPGPC) and Fourier transform infrared (FTIR) spectroscopy. In addition, the antioxidant activities of PLP in vitro were evaluated using various test systems, including scavenging of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals, scavenging of superoxide radicals generated by 1,2,3-phentriol autoxidation, scavenging of hydroxyl radicals and inhibition of lipid peroxidation. RESULTS: The molecular weight of PLP was determined by HPGPC to be about 1894 kDa. PLP contained 29.2 g kg−1 protein and 145.8 g kg−1 uronic acid. The FTIR spectrum of PLP also revealed typical characteristics of a polysaccharide containing protein and uronic acid. Moreover, the results showed that PLP possessed antioxidant activities, but lower than those of ascorbic acid. CONCLUSION: PLP is an acid protein-bound polysaccharide of high molecular weight, but its structure needs further study. The present results suggest that PLP could potentially be used as a natural antioxidant. Copyright © 2009 Society of Chemical Industry

Medium optimization for production of gamma-aminobutyric acid by Lactobacillus brevis NCL912.

Abstract: Production of gamma-aminobutyric acid (GABA) was carried out in Erlenmeyer flasks by Lactobacillus brevis NCL912. Traditional methods were first adopted to select the key factors that impact the GABA production to preliminarily determine the suitable concentration ranges of the key factors. It was found that glucose, soya peptone, Tween-80 and MnSO4·4H2O were the key factors affecting GABA production. Then, response surface methodology was applied to analyze the optimum contents of the four key factors in the medium, and the production of GABA was predicted as 349.69 mM under the optimized conditions with this model. Afterward, the experiment was performed under the optimized conditions, and the yield of GABA reached 345.83 mM, which was 130% higher than the initial medium. The results showed that experimental yield and predicted values of GABA yield were in good agreement.

Mupirocin for preventing exit-site infection and peritonitis in patients undergoing peritoneal dialysis

Abstract: OBJECTIVES Recently, there have been increasing concerns about the emergence of mupirocin resistance and increased infections due to lowered inhibition of Staphylococcus aureus. We conducted this systemic analysis to find out whether the application of mupirocin was effective for the prevention of exit-site infection (ESI) and peritonitis in patients undergoing peritoneal dialysis (PD). METHODS Recruited studies met the following criteria: they were randomized controlled trials or historical cohort studies; subjects consisted of adults (age, >or= 18 years) undergoing PD; mupirocin treatment was administered to the therapy group and placebo or no treatment was administered to the control group. The primary extracted data were the difference in the episodes of ESI and peritonitis S. aureus or other organisms among treatment and control groups. Results. Fourteen studies described in 13 articles and a total of 1,233 patients versus 1,217 controls were included in the analysis. Of the 13 articles, 6 were newly published articles that had not been analysed previously and 3 were randomized controlled trials. The application of mupirocin decreased the risk by 72% [95% confidence interval (CI): 0.60-0.81] in ESI and by 70% (95% CI 0.52-0.81) in peritonitis due to S. aureus among all patients undergoing PD. Treatment of mupirocin reduced the risks of ESI and peritonitis due to all organisms by 57% (95% CI: 0.46-0.66) and 41% (95% CI: 0.24-0.54), respectively. Based on the six newly published articles, the reduced risk rate for mupirocin therapy was found to be 80% (95% CI: 0.39-0.93, P = 0.004) in ESI and 91% (95% CI: 0.72-0.97, P < 0.0001) in peritonitis due to S. aureus; 70% (95% CI: 0.47-0.82, P < 0.0001) in ESI and 42% (95% CI: 0.25-0.55, P < 0.0001) in peritonitis due to all organisms among mupirocin-treated and -untreated subjects. Based on the three randomized controlled trials, ESI and peritonitis due to S. aureus were found to be reduced by 73% (95% CI: 0.63-0.80, P < 0.0001) and 40% (95% CI: 0.17-0.56, P = 0.002), respectively. Interestingly, although mupirocin treatment can reduce the risk rate of ESI by 46% (95% CI: 0.35-0.55, P < 0.00001), it cannot decrease the risk rate of peritonitis due to all organisms (P = 0.56). CONCLUSIONS Mupirocin prophylaxis was effective on preventing ESI and peritonitis due to S. aureus and other organisms in PD patients.

A new technique for dispersion of carbon nanotube in a metal melt

Abstract: A major issue in achieving the best potential of carbon nanotube (CNT)-reinforced metal matrix composites is to disperse homogeneously CNTs within the matrix of magnesium–aluminum alloys. In order to address this issue, we have developed a new approach by adding multi-walled CNTs (MWCNTs) into a magnesium–aluminum alloy matrix. This could trigger significant de-bundling of the nanotubes within the molten alloy. Also, we have characterized mechanical properties of the CNT-blended matrix, such as microstructure, matrix/nanotube interface, and dispersion of the nanotubes, by employing optical microscopy, scanning electron microscopy, atomic force microscopy and X-ray diffractometer. This method remarkably facilitated a uniform dispersion of nanotubes within the magnesium alloy matrix as well as a refinement of grain size. No significant reaction was observed between the nanotubes and the metallic matrix. Finally, we observed a maximum tensile strength at 210.3 MPa and an elongation rate of 8.56%, which represents an increase of 30.8% and 124.1%, respectively, over the parental alloy. Together, our study establishes a new approach to disperse carbon nanotubes in a metal matrix, which could be applicable for CNT materials with higher potential.

Study of interaction between kaempferol–Eu3+ complex and DNA with the use of the Neutral Red dye as a fluorescence probe

Abstract: The interaction between kaempferol–Eu 3+ complex and calf thymus DNA was investigated in physiological buffer (pH 7.4) using the Neutral Red (NR) dye as a spectral probe by UV–vis absorption and fluorescence spectroscopy, as well as viscosity measurements and DNA melting techniques. The results indicated that kaempferol–Eu 3+ complex can bind to DNA and the major binding mode is intercalative binding. The binding constants K and number of binding sites n of kaempferol–Eu 3+ complex with DNA were obtained by fluorescence quenching method. The thermodynamic parameters (Δ H θ , Δ S θ and Δ G θ ) were calculated from the fluorescence data measured at three different temperatures, which showed that the binding of kaempferol–Eu 3+ complex to DNA was driven mainly by hydrophobic interaction. Furthermore, the alternative least squares (ALS) method was applied to resolve a complex two-way array of the absorption spectra data, which provided simultaneously the concentration information for the three reaction components, NR, kaempferol–Eu 3+ and DNA–NR. This ALS analysis indicated that the intercalation of the kaempferol–Eu 3+ complex into the DNA proceeds by exchanging with the NR probe.