A spectrophotometric method for the determination of nitrite ion was established based on a fading of the pyrogallol red-molybdenum(VI) complex in the presence of sodium dodecylsulfate, an anionic surfactant. This method can be used to determine 40 similar to 460 ng mL(-1) nitrite ion; the effective molar absorptivity at 535 nm and the relative standard deviation were 1.0 x 10(5) L mol(-1) cm(-1) and 1.92% (n = 6), respectively. This procedure is much more sensitive than that using a diazotization reaction. Recoveries of nitrite ion from real samples (rain water and commercial drinking water) were within 96.9 similar to 100%.

A novel spectrophotometric method was established for the determination of iodide ion and organic iodine compounds. The method is based on a color-fading reaction of the ion-association complex of adenin silver(I) ion and eosin. In the determination of iodide ion, Beer's law was obeyed in the range of 0.04 similar to 1.3 mu g mL(-1) The apparent molar absorptivity at 560 nm and the relative standard deviation were 1.38 x 10(5) dm(3) mol(-1) cm(-1) and 2.34% (n = 5), respectively. The proposed method, which requires no pretreatments, should be useful for a simple and sensitive determination of iodide ion. In addition, this method could be applied to organic iodine compounds.

The presence of the geranylgeranyl diphosphate synthase (GGS) gene is a common feature of gene clusters for diterpene biosynthesis. We demonstrated identification of a diterpene gene cluster using homology-based PCR of GGS genes and the subsequent genome walking in the fungus Phomopsis amygdali N2. Structure determination of a novel diterpene hydrocarbon phomopsene provided by enzymatic synthesis with the recombinant terpene synthase PaPS and screening of fungal broth extracts with reference to characteristic NMR signals of phomopsene allowed us to isolate a new diterpene, methyl phomopsenonate. The versatility of the gene-based screening of unidentified diterpenes is discussed in regard to fungal genomic data.

We have previously cloned a DNA fragment that contained four ORFs and was confirmed to participate in viguiepinol {3-hydroxypimara-9(11),15-diene} biosynthesis by a heterologous expression experiment, from Streptomyces sp. strain KO-3988. Of the four ORFs, ORF2 and ORF4 were confirmed to encode an ent-CDP synthase and a GGDP synthase, respectively, by experiments using recombinant enzymes. In this study, ORF3, that did not show similarities with any other known proteins was expressed in Escherichia coli and used for functional analysis. The purified ORF3 product clearly converted ent-CDP into PMD. Since ORF2 and ORF3 are the first examples of enzymes with these biosynthetic functions from prokaryotes, enzymatic properties of both enzymes were investigated. ORF2 is likely to be a dimer and requires a divalent cation such as Mg2+ and Zn2+ for its activity. The optimum pH and temperature were 5.5 and 35 degrees C. The Km value was calculated to be 13.7 +/- 1.0 microM for GGDP and the kcat value was 3.3 x 10(-2)/sec. ORF3 is likely to be a monomer and also requires a divalent cation. The optimum pH and temperature were 7.0 and 30 degrees C. The Km value for ent-CDP was estimated to be 2.6 +/- 0.2 microM and the kcat value was 1.4 x 10(-3)/sec.

To study the origin of chloroform in vegetables, a simple and sensitive method was established using a gas chromatograph equipped with an electron capture detector. The method includes solvent trapping of chloroform, and gas chromatographic separation with a detection system. The average concentrations in vegetables, tea leaves and frozen vegetables were 30.9, 62.9 and 15.7 mu /kg, respectively. Tea leaves contained the highest amount, followed by vegetables. The former was 2 times the latter. There was no significant difference between chloroform levels in vegetables grown in tap water (chloroform: 19.7-25.0 mug/L) and those in boiled distilled water. On the other hand, there was a high correlation between the number of cultivation days and chloroform levels in vegetables grown in both tap water and boiled distilled water.

A simple and sensitive method for the determination of chloroform in vegetables was established by using a gas chromatograph equipped with an electron capture detector. The proposed method includes solvent trapping of chloroform, and gas chromatographic separation with a detection system. The recoveries of added chloroform in various vegetable samples were 96.7 and 109.3%, within 8.6% of the coefficient variation. The detection limit is 1 mug/kg. The procedure can be used to determine chloroform at low levels in a variety of foods including mayonnaise, fish, oil, and cream, as well as vegetables.

Rice bran was found to effectively adsorb several organic compounds, such as dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene, and benzene. Equilibrium adsorption isotherms conformed-to the Freundlich type (log-log linear). The adsorption of dichloromethane and chloroform by rice bran was observed over the range of pH 1-11. Therefore, rice bran is applicable for treatment of wastewater over a wide pH range. Dichloromethane was successfully removed from water samples with an average removal efficiency of 70% after 60 min when rice bran was added to water samples containing from 0.006 to 100 mg/L dichloromethane. The removal of these organochlorine compounds and benzene by rice bran was attributed to the uptake by intracellular particles called spherosomes. Here, we report the results of a fundamental study of the efficiency of rice bran for removal of organochlorine compounds and benzene using a batch system on the laboratory scale, and describe elucidation of the mechanism of removal of these compounds by rice bran.

Removal efficiency of chloroform from tap water by rice bran was investigated. The adsorption rate by rice bran was similar to activated carbon. The amount of chloroform adsorbed was plotted against the equilibrium concentration of chloroform in solution on a logarithmic scale. A linear relationship was obtained, indicating that the adsorption reaction was a Freundlich type. The adsorption of chloroform by rice bran was observed in the range of pH 1-11. Chloroform was successfully removed from tap water with average removal efficiency of 70% after 60 min when rice bran was applied to tap water that contained 0.0064 mg/L chloroform.