Surface modification of orthodontic wires with photocatalytic titanium oxide for its antiadherent and antibacterial properties.

OBJECTIVE: To test the antiadherent and antibacterial properties of surface modification of orthodontic wires with photocatalytic titanium oxide (TiO(2)). MATERIALS AND METHODS: TiO(2) was coated on the surface of the orthodontic wires by a sol-gel thin film dip-coating method. Bacterial adhesion to the wires was evaluated by the weight change of the wires. The antibacterial activity of the surface-modified orthodontic wires was demonstrated by the dilution agar plate method for Streptococcus mutans and spectrophotometry for Porphyromonas gingivalis. RESULTS: The orthodontic wires coated with the photocatalytic TiO(2) showed an antiadherent effect against S. mutans compared with the uncoated wires. The bacterial mass that bound to the TiO(2)-coated orthodontic wires remained unchanged, whereas that of the uncoated wires increased by 4.97%. Furthermore, the TiO(2)-coated orthodontic wires had a bactericidal effect on S. mutans and P. gingivalis, which cause dental caries and periodontitis, respectively. The antiadherent and antibacterial mechanisms of TiO(2) to break down the cell wall of those bacteria were revealed by scanning electron microscopy. CONCLUSION: The surface modification of orthodontic wires with photocatalytic TiO(2) can be used to prevent the development of dental plaque during orthodontic treatment.

Activation of protein kinase C by 1-beta-D-arabinofuranosylcytosine conjugates of phospholipid.

1-beta-D-arabinofuranosylcytosine (ara-C) conjugates of phospholipid were shown to be highly antineoplastic against various tumor cells. In this study, we report that these conjugates are potent activators of protein kinase C (PKC, EC) in vitro. Although required Ca2+, PKC activation by the conjugates occurred even in the absence of phospholipid and diacylglycerol. Among the conjugates, 1-beta-D-arabino-furanosylcytosine 5'-diphosphate-rac-1-O-octadecyl-2-O-palmitoylglycerol [(ara-CDP-DL-PBA); ara-C conjugate of ether phospholipid], was employed to investigate its mode of activation, since ether phospholipid has been reported to be a regulator of the PKC. When PKC was activated by ara-CDP-DL-PBA, diacylglycerol enhanced its activity with 3-fold reduction of an apparent Ka value for ara-CDP-DL-PBA and no change in the Vmax. During the PKC activation by phosphatidylserine, ara-CDP-DL-PBA exhibited a synergistic effect on the activation. Studies on the relationship between the structures of ara-CDP-DL-PBA and their effects on PKC activity showed that phosphate group of ether lipid was important for its activation of PKC, and that conjugation of ara-C and ether lipid further enhanced the enzyme activity. These results suggest that the ara-C conjugate of phospholipid activates PKC in a co-operative manner with diacylglycerol and/or phosphatidylserine, however, the exact mechanism of the antineoplastic effect of ara-CDP-DL-PBA through PKC activation still remains speculative.

Metabolite Profiling during Fermentation of Makgeolli by the Wild Yeast Strain Saccharomyces cerevisiae Y98-5.

Makgeolli is a traditional Korean alcoholic beverage. The flavor of makgeolli is primarily determined by metabolic products such as free sugars, amino acids, organic acids, and aromatic compounds, which are produced during the fermentation of raw materials by molds and yeasts present in nuruk, a Korean fermentation starter. In this study, makgeolli was brewed using the wild yeast strain Saccharomyces cerevisiae Y98-5, and temporal changes in the metabolites during fermentation were analyzed by ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry. The resultant data were analyzed by partial least squares-discriminant analysis (PLS-DA). Various metabolites, including amino acids, organic acids, sugar alcohols, small peptides, and nucleosides, were obviously altered by increasing the fermentation period. Changes in these metabolites allowed us to distinguish among makgeolli samples with different fermentation periods (1, 2, 3, 6, 7, and 8 days) on a PLS-DA score plot. In the makgeolli brewed in this study, the amounts of tyrosine (463.13 µg/mL) and leucine (362.77 µg/mL) were high. Therefore, our results indicate that monitoring the changes in metabolites during makgeolli fermentation might be important for brewing makgeolli with good nutritional quality.

Oceanobacillus gochujangensis sp. nov., isolated from gochujang a traditional Korean fermented food.

A Gram-stain-positive, polar flagella-containing, rod-shaped, obligate aerobic, endospore-forming bacterium, strain TK1655(T), was isolated from the traditional Korean food gochujang. The 16S rRNA sequence of strain TK1655(T) was a member of the genus Oceanobacillus similar to that of the type strain of Oceanobacillus oncorhynchi subsp. incaldanensis DSM 16557(T) (97.2%), O. oncorhynchi subsp. oncorhynchi JCM 12661(T) (97.1%), O. locisalsi KCTC 13253(T) (97.0%), and O. sojae JCM 15792(T) (96.9%). Strain TK1655(T) was oxidase and catalase positive. Colonies were circular, smooth, low convex, cream in colour, and measured about 0.5-1.0 mm in diameter. The range for growth was 20-40°C (optimal, 30°C), pH 6.0-10.0 (optimal, 7.0), and 2-16% (w/v) NaCl (optimal, 2%). Additionally, the cells contained meso-DAP, and the predominant isoprenoid quinone was MK-7. The complex polar lipids were consisted of diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylcholine (PC). The major cellular fatty acid components were iso-C15:0, anteiso-C15:0, iso-C16:0, and anteiso-C17:0, and the DNA G+C content was 40.5%. DNA-DNA relatedness of our novel strain and reference strain O. locisalsi KCTC 13253(T), O. oncorhynchi subsp. incaldanensis DSM 16557(T), O. oncorhynchi subsp. oncorhynchi JCM 12661(T) was 45.7, 43.8, and 41.9%. From the results of phenotypic, chemotaxonomic, and phylogenetic analyses of strain TK1655(T), we propose the novel species Oceanobacillus gochujangensis sp. nov. The type strain is TK1655(T) (=KCCM 101304(T) =KCTC 33014(T) =CIP 110582(T) =NBRC 109637(T)).

Bioconversion of Ginsenosides from Red Ginseng Extract Using Candida allociferrii JNO301 Isolated from Meju.

Red ginseng (Panax ginseng), a Korean traditional medicinal plant, contains a variety of ginsenosides as major functional components. It is necessary to remove sugar moieties from the major ginsenosides, which have a lower absorption rate into the intestine, to obtain the aglycone form. To screen for microorganisms showing bioconversion activity for ginsenosides from red ginseng, 50 yeast strains were isolated from Korean traditional meju (a starter culture made with soybean and wheat flour for the fermentation of soybean paste). Twenty strains in which a black zone formed around the colony on esculin-yeast malt agar plates were screened first, and among them 5 strains having high ß-glucosidase activity on p-nitrophenyl-ß-D-glucopyranoside as a substrate were then selected. Strain JNO301 was finally chosen as a bioconverting strain in this study on the basis of its high bioconversion activity for red ginseng extract as determined by thin-layer chromatography (TLC) analysis. The selected bioconversion strain was identified as Candida allociferrii JNO301 based on the nucleotide sequence analysis of the 18S rRNA gene. The optimum temperature and pH for the cell growth were 20~30℃ and pH 5~8, respectively. TLC analysis confirmed that C. allociferrii JNO301 converted ginsenoside Rb1 into Rd and then into F2, Rb2 into compound O, Rc into compound Mc1, and Rf into Rh1. Quantitative analysis using high-performance liquid chromatography showed that bioconversion of red ginseng extract resulted in an increase of 2.73, 3.32, 33.87, 16, and 5.48 fold in the concentration of Rd, F2, compound O, compound Mc1, and Rh1, respectively.

Microbiological Characteristics of Wild Yeast Strain Pichia anomala Y197-13 for Brewing Makgeolli.

Makgeolli is a traditional cloudy-white Korean rice wine with an alcohol content of 6~7%. The present study investigated the morphological characteristics, carbon-utilizing ability, fatty acid composition, alcohol resistance, glucose tolerance, and flocculence of Saccharomyces cerevisiae Y98-5 and Pichia anomala Y197-13, non-S. cerevisiae isolated from Nuruk, which is used in brewing Makgeolli. Similar morphological characteristics were observed for both isolated wild yeast strains; and the carbon source assimilation of Y197-13 differed from that of other P. anomala strains. Strain Y197-13 was negative for D-trehalose, mannitol, arbutin, I-erythritol, and succinic acid. The major cellular fatty acids of strain Y197-13 included C18:2n6c (33.94%), C18:1n9c (26.97%) and C16:0 (20.57%). Strain Y197-13 was Crabtree-negative, with 60% cell viability at 12% (v/v) ethanol. The flocculation level of strain Y197-13 was 8.38%, resulting in its classification as a non-flocculent yeast.

Analysis of microflora profile in Korean traditional nuruk.

A variety of nuruk were collected from various provinces in Korea, and their microflora profiles were analyzed at the species level. A total of 42 nuruk samples were collected and when the viable cell numbers in these nuruk were enumerated, the average cell numbers of bacteria, fungi, yeast, and lactic acid bacteria from all nuruk were 7.21, 7.91, 3.49, and 4.88 log CFU/10 g, respectively. There were no significant differences in viable cell numbers of bacteria or fungi according to regions collected. Bacillus amyloliquefaciens and B. subtilis were the predominant bacterial strains in most samples. A significant portion, 13 out of 42 nuruk, contained foodborne pathogens such as B. cereus or Cronobacter sakazakii. There were various species of lactic acid bacteria such as Enterococcus faecium and Pediococcus pentosaceus in nuruk. It was unexpectedly found that only 13 among the 42 nuruk samples contained Aspergillus oryzae, the representative saccharifying fungi in makgeolli, whereas a fungi Lichtheimia corymbifera was widely distributed in nuruk. It was also found that Pichia jadinii was the predominant yeast strain in most nuruk, but the representative alcohol fermentation strain, Saccharomyces cerevisiae, was isolated from only 18 out of the 42 nuruk. These results suggested that a variety of species of fungi and yeast were distributed in nuruk and involved in the fermentation of makgeolli. In this study, a total of 64 bacterial species, 39 fugal species, and 15 yeast species were identified from nuruk. Among these strains, 37 bacterial species, 20 fungal species, and 8 yeast species were distributed less than 0.1%.

Feasibility of brewing makgeolli using Pichia anomala Y197-13, a non-Saccharomyces cerevisiae.

Makgeolli is a traditional rice wine favored by the general public in Korea. This study investigated the fermentation and sensory characteristics of using wild yeast strains for brewing makgeolli. A non-Saccharomyces cerevisiae strain was isolated from nuruk and termed Y197-13. It showed 98% similarity to Pichia anomala and had an optimal growth temperature of 25 degrees C. Makgeolli was manufactured using koji, jinju nuruk, and improved nuruk as fermentation agents. Y197-13 makgeolli brewed with koji had alcohol and solids contents of 11.1% and 13.9%, respectively. Sweet sensory characteristics were attributed to residual sugars in makgeolli with 6% alcohol. The makgeolli had a fresh sour taste and carbonated taste. Volatile component analysis showed the isoamyl alcohol, phenylethyl alcohol, isoamyl acetate, and fatty acid, including ethyl oleate and ethyl linoleate, relative peak area was higher in Y197-13 makgeolli than in makgeolli with Saccharomyces cerevisiae. These results suggest the wild yeast, Y197-13, as a candidate for brewing makgeolli.

Identification and Characterization of Useful Fungi with α-Amylase Activity from the Korean Traditional Nuruk.

The objective of this study was to find useful fungi with α-amylase activity from the Korean traditional nuruk for the quality of traditional Korean alcoholic beverage. In this study, 165 samples of traditional nuruk were collected from 170 regions throughout Korea and the fungi were isolated to a total of 384 strains. In order to investigate the effect of microflora on nuruk, α-amylase activity, saccharogenic power (SP), starch hydrolysis activity and acid producing activity were evaluated. Ten strains were selected by α-amylase activity, which ranged from 458.47 to 1,202.75 U/g. The size of the discolored zone for the starch hydrolysis activity of each fungus ranged from 0.3 to 2 cm. The SP of the 10 strains ranged from 228.8 to 433.4 SP. Of the 10 stains, three were identified as Aspergillus oryzae, two as Aspergillus flavus, two as Lichtheimia sp., one as Rhizopus oryzae and two as other strains. The total aflatoxins present in the nuruks were examined using enzyme-linked immunosorbent assay. The 10 nuruks had less than 1.11 ppb of aflatoxins.

Characteristics of the squalene synthase inhibitors produced by a Streptomyces species isolated from soils.

Microorganisms producing squalene synthase inhibitors were screened from soils. A high producer was selected and identified as a Streptomyces species. Two active inhibitors were obtained from culture broths via a series of purification processes involving solvent extraction, WK-10 cation-exchange column chromatography, HP-20 adsorption column chromatography, silica-gel column chromatography, preparative HPLC, and crystallization. The inhibitors were confirmed as macrolactins A and F with molecular weights of 402 by UV-absorption spectrometry, fast atom bombardment mass spectometry, and 13C- and 1H-NMR analyses. Kinetic results for macrolactins A and F showed that they appear to be noncompetitive inhibitors of rat liver squalene synthase with IC50 values of 1.66 and 1.53 micromol/L, respectively. Since mammalian squalene synthase was used, these inhibitors have significant potential as therapeutic agents for hyperlipemia and suppression of cholesterol biosynthesis.