Yool-Jin Park

Phenolic Compound Concentration and Antioxidant Activities of Edible and Medicinal Mushrooms from Korea

A study was conducted to determine the content of phenolic compounds and the antioxidative activity of five edible and five medicinal mushrooms commonly cultivated in Korea. Phenolic compounds were analyzed using high performance liquid chromatography, and antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide dismutase activity. A total of 28 phenolic compounds were detected in the mushrooms studied. The average total concentration of phenolic compounds was 326 microg/g, the average being of 174 microg/g in edible mushrooms and 477 microg/g in medicinal mushrooms. The average total flavonoids concentration was 49 microg/g, with averages of 22 and 76 microg/g in edible and medicinal mushrooms, respectively. The DPPH radical scavenging activities ranged between 15 (Pleurotus eryngii) and 70% (Ganoderma lucidum) when reaction time was for 1 min. When reaction time was 30 min, the values ranged between 5 (Pleurotus eryngii) and 78% (Agaricus bisporus). The SOD activity averaged 28% among the 10 mushroom species, averages for edible and medicinal mushrooms being comparable. DPPH activities was significantly correlated (p < 0.01) with total content of phenolic compounds in edible mushrooms, while in medicinal mushrooms there was a significant correlation (p < 0.01) between SOD activity and total concentration of phenolic compounds. Numerous significant positive correlations were observed between phenolic compounds detected and antioxidative potential.

Photobiologic-mediated fabrication of silver nanoparticles with antibacterial activity

We present the simple, eco-friendly synthesis of silver nanoparticles (AgNPs) using sunlight or green, red, blue, or white LED light together with Dryopteris crassirhizoma rhizome extract (DCRE) as the reducing and capping agent. The preliminary indication of AgNP production was a color change from yellowish green to brown after light exposure in the presence of DCRE. Optimization of parameters such as pH, inoculum dose, and metal ion concentration played an important role in achieving nanoparticle production in 30min. The spectroscopic and morphological properties of AgNPs were characterized using UV-Vis spectroscopy through the presence of a characteristic surface plasmon resonance (SPR) band for AgNPs, Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). The FT-IR results indicated that the phytochemical present in DCRE was the probable reducing/capping agent involved in the synthesis of AgNPs, and light radiation enhanced nanoparticle production. HR-TEM revealed that the AgNPs were almost spherical with an average size of 5-60nm under all light sources. XRD studies confirmed the face cubic center (fcc) unit cell structure of AgNPs. The synthesized AgNPs showed good antimicrobial activity against Bacillus cereus and Pseudomonas aeruginosa. This study will bring a new insight in ecofriendly production of metal nanoparticles.

Lead biotransformation potential of allochthonous Bacillus sp. SKK11 with sesame oil cake extract in mine soil

The potential of allochthonous Bacillus sp. SKK11 and sesame oil cake extract for the immobilization of Pb in mine soil was investigated in this study. The isolate SKK11, isolated from a brackish environment and identified as Bacillus sp. based on partial 16S rDNA sequencing, exhibited maximum resistance to Pb (750 mg L−1). Growth kinetic studies revealed that the presence of oil cake extract (2%) increased the biomass of the isolate SKK11. Transmission electron microscopy and X-ray diffraction studies showed that isolate SKK11 transformed Pb either intracellularly or extracellularly. Selective sequential extraction studies showed that the bioremediation decreased 24.9% of the exchangeable fraction in the mine soil in 3 days. However, 75.1% of the exchangeable fraction was not immobilized in the soil. An X-ray diffractogram of the bioremediated soil showed a major decrease (79.0%) in the intensity of the plagioclase mineral peak. Urease, dehydrogenase, amylase, invertase, cellulase, and alkaline phosphatase enzyme activities were increased in the bioremediated mine soil. These results suggest that the isolate Bacillus sp. SKK11 in combination with sesame oil cake extract could be employed for the immobilization of bioavailable Pb in contaminated soil.

Effects of immunotoxic activity of the major essential oil of Angelica purpuraefolia Chung against Aedes aegypti L.

RETRACTED

Characterization of ACC deaminase gene in Pseudomonas entomophila strain PS-PJH isolated from the rhizosphere soil

The enzyme 1‐aminocyclopropane‐1‐carboxylate (ACC) deaminase cleaves the ethylene precursor ACC into α‐ketobutyrate and ammonia. The decreased level of ethylene allows the plant to be more resistant to a wide environmental stress including plant pathogens. In the present study, we characterized the ACC deaminase activity of a Pseudomonas entomophila strain PS‐PJH isolated from the red pepper rhizosphere region of red pepper grown at Jinan, Korea. The isolate produced 23.8 ± 0.4 μmol of α‐ketobutyrate/mg of protein/h during ACC deamination under in vitro conditions. Polymerase chain reaction for acdS gene showed that the isolated P. entomophila strain PS‐PJH carry sequences similar to the known acdS genes. Results of the multiple sequence alignment revealed >99% identity (nucleotide and amino acid) with acdS gene of Pseudomonas putida strains AM15 and UW4. The isolated bacteria promoted 43.3 and 34.1% of growth in Raphanus sativus and Lactuca sativa plants, respectively. Based on the 16S–23S internal transcribed spacer region sequences, the isolate was identified as P. entomophila. To the best of our knowledge this is the first study to report the acdS gene in P. entomophila. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Antiplasmodial procyanidins derivatives from Chinese Hawthorn.

RETRACTED

Characterization and assessment of two biocontrol bacteria against Pseudomonas syringae wilt in Solanum lycopersicum and its genetic responses

Pseudomonas and Bacillus species are attractive due to their potential bio-control application against plant bacterial pathogens. Pseudomonas aeruginosa strain D4 and Bacillus stratosphericus strain FW3 were isolated from mine tailings in South Korea. In these potent bacterial strains, we observed improved antagonistic activity against Pseudomonas syringae DC3000. These strains produced biocatalysts for plant growth promotion, and in vivo examination of Solanum lycopersicum included analysis of disease severity, ion leakage, chlorophyll content, and H2O2 detection. In addition, regulation of the defense genes pathogen-related protein 1a (PR1a) and phenylalanine ammonia lyase (PAL) was compared with treated plants and untreated control plants. The results suggest that these two bacterial strains provide protection against plant pathogens via direct and indirect modes of action and could be used as a bio-control agent.

Potential for plant biocontrol activity of isolated Pseudomonas aeruginosa and Bacillus stratosphericus strains against bacterial pathogens acting through both induced plant resistance and direct antagonism

Phytopathogenic bacteria have caused significant damage to agricultural crops in both controlled and open cultivation practices, imposing heavy losses to farmers. Thereby, the goal of this study was to evaluate Pseudomonas aeruginosa and Bacillus stratosphericus isolated from soil has antagonistic activity against bacterial phytopathogens with the potential to control plant diseases. Isolated novel strains of P. aeruginosa and B. stratosphericus showed broad spectrum of antagonistic activity against five bacterial phytopathogens. Antagonistic activity was examined under optimized pH (8 and 7), carbon sources (lactose and starch), nitrogen sources (ammonium chloride, peptone and ammonium nitrate) for P. aeruginosa and B. stratosphericus, respectively, and biocatalyst production (chitinase, protease and amylase) was studied. Additionally, up-regulation of defense-related genes (PR-1a and PAL) was studied in tomato plants treated with P. aeruginosa and B. stratosphericus. The induction of defense-related genes in tomato plant was triggered after 12 h treatment with a cell concentration of 0.20 O.D. for P. aeruginosa and 0.21 O.D. for B. stratosphericus during treatment period. Broad spectrum antagonistic activity was observed due to antibiotic and siderophore production by P. aeruginosa and B. stratosphericus.

Complex nanostructures of ZnO: growth and properties

Variety of complex ZnO nanostructures such as flower-shaped structures, hierarchical and star-shaped nanostructures have been grown by the novel cyclic feeding chemical vapour deposition (CFCVD) process on various substrates at low-temperatures of 475°C to 550°C. Metal organic source, diethyl zinc (DEZn) and oxygen gas was used as source materials for zinc and oxygen, respectively for the growth of ZnO nanostructures synthesised by CFCVD process. The selected area electron diffraction (SAED) pattern of the flower-shaped structures confirmed that the grown products are single-crystalline ZnO. In addition to the ZnO nanostructures grown CFCVD process, comb-like ZnO structures were also synthesised, in a high density, via simple thermal evaporation process by using metallic zinc powder and oxygen as source materials for zinc and oxygen, respectively. The X-ray diffraction pattern of the synthesised comb-like structures exhibited that these structures are possessing single-crystallinity and wurtzite hexagonal phase of ZnO.

Extraction of natural colorant from purple sweet potato and dyeing of fabrics with silver nanoparticles for augmented antibacterial activity against skin pathogens

The main objective of this study was to extract natural colorant from purple sweet potato powder (PSPP) via a water bath and ultrasound water bath using acidified ethanol (A. EtOH) as the extraction solvent. When optimizing the colorant extraction conditions of the solvents, acidified ethanol with ultrasound yielded a high extraction capacity and color intensity at pH2, temperature of 80°C, 20mL of A. EtOH, 1.5g of PSPP, time of 45min, and ultrasonic output power of 75W. Subsequently, the colorant was extracted using the optimized conditions for dyeing of textiles (leather, silk, and cotton). This natural colorant extraction technique can avoid serious environmental pollution during the extraction and is an alternative to synthetic dyes, using less solvent and simplified abstraction procedures. The extracted purple sweet potato natural colorant (PSPC) was used to dye leather, silk, and cotton fabrics in an eco-friendly approach with augmented antibacterial activity by in situ synthesis of silver nanoparticles (AgNPs) and dyeing. The optimal dyeing conditions for higher color strength (K/S) values were pH2 and 70°C for 45min. The colorimetric parameters L∗, a∗, b∗, C, and H were measured to determine the depth of the color. The Fourier transform infrared spectroscopy (FTIR) spectra of undyed control, dyed with PSPC and dyed with blend of PSPC and AgNPs treated leather, silk and cotton fabric were investigated to study the interaction among fiber type, nanoparticles, and dye. The structural morphology of leather and silk and cotton fabrics and the anchoring of AgNPs with elemental compositions were investigated by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS). The dry and wet rubbing fastness for dye alone and dye with nanoparticles were grade 4-5 and 4, respectively. Thus, the results of the present study clearly suggest that in situ synthesis of AgNPs along with dyeing should be considered in the development of antimicrobial textile finishes.