Haplotype diversity of Heterodera koreana (Tylenchida: Heteroderidae), affecting bamboo in Korea.

In a survey of plant-parasitic nematodes in agricultural fields, cyst-forming nematodes were found in soil planted bamboo in Korea. The aim of this study was to identify the cyst nematodes based on morphological and molecular characteristics. As the results, the morphology and morphometrics of cysts and second-stage juveniles (J2s) were consistent with those of previous descriptions of Heterodera koreana. In phylogenetic analyses based on DNA sequences, these cyst nematodes were clustered together with clade of H. koreana in internal transcribed spacer (ITS) region, and large subunit D2-D3 segments (LSU D2-D3). These nematodes were clustered together with clade of H. koreana in cytochrome c oxidase subunit I (COI) gene, but a haplotype was different when compared with previous reported haplotypes (haplotype A-C) in Japan. This study showed these cyst nematodes were identified as H. koreana, and a new haplotype of H. koreana is distributed in Korea. We suggest that the new haplotype of H. koreana name as haplotype D.

Effect of HCl and H2SO4 treatment of TiO2 powder on the photosensitized degradation of aqueous rhodamine B under visible light.

The acid treatments of TiO2 nanopowder with HCI or H2SO4 solution increase the concentration of the hydroxyl group on TiO2 surfaces compared to bare TiO2, which acts as a Brønsted acid site. For the case of the HCl-treated TiO2, the dissociation of Brønsted acid (proton donor) sites on TiO2 leads to a drop in the pH levels of rhodamine B (RhB) dye solutions (leading to the protonation of the RhB molecule), which allows the physisorption of the uncharged carboxyl acid group on the positively charged TiO2 surface. The carboxyl acid group is believed to afford a more efficient charge injection from the Visible-light-excited RhB to the conduction band of TiO2 compared to the N-ethyl group, yielding a significantly enhanced photodegradation of RhB mainly via the N-de-ethylation pathway. For the case of the H2SO4-treated TiO2, although the dissociation of Brønsted acid sites on TiO2 is also achieved, its photoactivity is much lower than that of the HCl-treated TiO2. It seems that the presence of SO4(2-) on the H2SO4-treated TiO2 behaves as an *OH scavenger to prevent the photodegradation of the dye.

Assessment of the extent of bacterial growth in reverse osmosis system for improving drinking water quality.

This study was carried out to assess reverse osmosis (RO) treatment efficacy of drinking water in terms of biological stability in the distribution system. Two flat-sheet RO membranes were used in this study. Experiments were designed to investigate the growth of biofilm and bulk phase bacteria for the RO-treated water flowing through a model distribution system under controlled conditions without disinfectants. RO membranes improved the water quality of drinking water in terms of inorganic, organic and bacterial contents. Organic matter including the fraction available for microbes was efficiently removed by the RO membranes tested. More than 99% of bacterial cells in the tap water was retained by the RO membranes, leaving <50 cells/mL in the permeate water. In spite of the low nutrient contents and few cells in the RO permeates, monitoring of the model distribution systems receiving the RO permeates showed that remarkable biofilm accumulation and bulk cell growth occurred in the RO permeate water. In quasi-steady state, the total cell numbers in the biofilm and bulk water were of order 10(3) cells/cm(2) and 10(3) cells/mL, respectively, which were about 2 orders of magnitude lower than those grown in the tap water produced from conventional water treatment. The culturable heterotrophic bacteria constituted a significant part of the total cells (20.7-32.1% in biofilms and 21.3-46.3% in bulk waters). Biofilm maximum density and production rate were of the order 10(4) cells/cm(2) and 10(2) cells/cm(2)/day, respectively. The specific cell growth rate of bacteria in the biofilms was found to be much lower than those in the bulk waters (0.04-0.05 day(-1) versus 0.28-0.36 day(-1)). The overall specific cell growth rate which indicates the growth potential in the whole system was calculated as 0.07-0.08 day(-1), representing a doubling time of 9.1-10.1 days. These observations can be indicative of possibilities for bacterial growth in the RO permeate water with easily assimilable organic carbon concentrations below values proposed for biostability. RO permeate water does not appear to be biologically stable water. Therefore, efforts to minimize bacterial growth in the RO permeate water and in the distribution system must consider post-disinfection.

Response of microbial growth to orthophosphate and organic carbon influx in copper and plastic based plumbing water systems.

Consequences of orthophosphate addition for corrosion control in water distribution pipes with respect to microbial growth were investigated using batch and dynamic tests. Batch tests showed that the release of copper in either low or high organic carbon content water was decreased by 69% and 56% with addition 206 microg PO(4)-P, respectively. Dosing of orthophosphate against corrosion did not increase microbial growth potential in the water and in the biofilm in both corroded and uncorroded systems receiving tap water with a low content of organic carbon and of biodegradable organic fraction. However, in tap water having a high concentration of organic carbon from acetate addition, orthophosphate addition promoted the growth of bacteria, allowed more bacteria to assemble on corroded and uncorroded surfaces, and increased the consumption of organic carbon. Orthophosphate consumption did not exceed 1% of the amount of easily biodegradable organic carbon required for microbial growth, and the orthophosphate demand for corrosion control greatly exceeded the nutritional requirement of microbial growth. The results of the dynamic tests demonstrated that there was a significant effect of interaction between biodegradable organic carbon and orthophosphate on biofilm growth, whereby the effect of orthophosphate flux on microbial growth was dependent on the levels of biodegradable organic carbon. Controlling an easily biodegradable organic carbon would be therefore necessary to minimize the microbial growth potential induced by orthophosphate-based anticorrosion treatment.

Maternal alcohol administration suppresses expression of nitric oxide synthase in the hippocampus of offspring rats.

Maternal alcohol consumption during pregnancy can produce teratogenic effects and has a detrimental effect on the development of the fetus. In this study, the dose-dependent effect of maternal alcohol administration on the expression of nitric oxide synthase (NOS) in the hippocampus of the offspring rats was investigated. From the present result, it was shown that expression of NOS is decreased following treatment with maternal alcohol in a dose-dependent fashion. The present results suggest that suppression of NOS expression in the hippocampus of offspring rats with maternal alcohol mediates the associated developmental retardation and/or anomalies.

Evaluation of bioassays for analyzing biodegradable dissolved organic carbon in drinking water.

Three different bioassays for analysis of biodegradable dissolved organic carbon (BDOC) were evaluated to identify which method is most applicable to analysis of drinking water. The determination of BDOC is primarily based on the differences between initial and final DOC levels during a certain incubation period using indigenous bacterial consortium as an inoculum. The assay procedures basically differ in the preparation method of inoculum. Inoculum was added in the form of suspended bacteria in one assay. In the other two assays, bacterial inoculum attached to either sand or inert media was used in a continuous reactor column. Standard solutions containing sodium acetate, sodium oxalate, or glucose at 1 mg C/L, and tap water were tested. The bioassay using bacteria attached to sand was shown to be superior to the two other methods for BDOC determination in terms of its incubation period, recovery, and reproducibility. Tap water samples, when analyzed by this assay, could not be guaranteed for biological stability due to their high BDOC concentrations (0.17 to 0.23 mg/L) that corresponded to 26-36% of the initial DOC level.