Biofilm formation and lipopeptide antibiotic iturin A production in different peptone media

Biofilm fermentation is a newly developed promising technique in fermentation technology. In this study no.3 and no.3S media have been used for the lipopeptide antibiotic iturin A production by Bacillus subtilis RB14. The main component of no.3 and no.3S media is Polypepton and Polypepton S, respectively. B. subtilis RB14 produces thick stable biofilm and high amount of iturin A in no.3S medium. Whereas, impaired biofilm formation and lower iturin A production was observed in no.3 medium. From the analytical information it was observed that the amounts of metal ions, such as K⁺, Ca²⁺ and Mn²⁺, cysteine and cellulose are lower in Polypepton compared to the Polypepton S. To investigate their effect on biofilm formation and iturin A production cysteine, cellulose, K⁺, Ca²⁺ and Mn²⁺ were added respectively into the no.3 medium at similar amount that Polypepton S contains. It was observed that individual addition of K⁺, Ca²⁺, cysteine and cellulose had no effect on biofilm formation, cellular growth induction or iturin A production. However, when Mn²⁺ was supplemented in no.3 medium, biofilm development was restored with an improved production of iturin A. Finally, combined addition of investigated substances into the no.3 medium resulted with highly folded, thick biofilm with high cellular growth and iturin A production compared to the original no.3 medium.     

Evaluation of an electrolysis apparatus for inactivating antineoplastics in clinical wastewater

We recently reported a system for inactivating antineoplastics in which sodium hypochlorite is supplied by the electrolysis of sodium chloride solution. In this study, we designed an electrolysis apparatus for inactivating the cytotoxicity of antineoplastics in clinical wastewater using the system. The apparatus consists of an electrolysis cell with platinum-iridium electrodes, a pool tank, a circulating system for wastewater, a safety system for explosive gas and overflow, and an exhaust duct. The free chlorine concentration increased linearly up to 6500 mg l(-1), and pH also increased to 9.0-10.0 within 2h, when 0.9% sodium chloride solution was electrolyzed. We examined its efficacy with model and clinical wastewaters. The reciprocal of dilution factor for disappearance of cytotoxicity using Molt-4 cells was compared before and after electrolysis. In the model wastewater, that was 9.10 x 10(4) before electrolysis, and 3.56 x 10(2) after 2h of electrolysis. In the clinical wastewater (n=26), that was 6.90 x 10(3)-1.02 x 10(6) before electrolysis, and 1.08 x 10(2)-1.45 x 10(4) after 2h of electrolysis. Poisonous and explosive gases released by the electrolysis were measured; however, they were found to be negligible in terms of safety. The environmental load was evaluated by carbon dioxide generation as an index and it was found that the carbon dioxide generated by the electrolysis method was 1/70 lower than that by the dilution method with tap water. Moreover, the cost of the electrolysis method was 1/170 lower than that of the dilution method. This method was found to be both effective and economically valuable.     

Seasonal variability of 1-chloropyrene on atmospheric particles and photostability in toluene

The occurrence of a mutagenic compound, 1-chloropyrene (Cl-Py), in extracts of ambient particulate matter at an urban site in Japan has been investigated. Samples were collected with a high-volume air sampler for 24 h periods over the course of 1 week in winter (February), spring (May), summer (August), and autumn (November) 2002. The Cl-Py levels showed seasonal variation, ranging from 2.4 pg/m(3) (summer) to 18.9 pg/m(3) (winter). This variation would indicate that the lower temperatures in winter results in an increased distribution of Cl-Py from vapor phase to the particle phase. In addition, there is also the possibility that ambient Cl-Py is emitted from seasonal sources or is susceptible to photodegradation by sunlight, or both. The photodegradation of Cl-Py in a laboratory experiment was conducted to simulate the compound's fate on airborne particle surfaces. The degradation of Cl-Py proceeded by a first-order reaction with a rate constant of 0.72 h(-1). In the presence of a radical sensitizer, 9,10-anthraquinone (AQ), the photodegradation rate of Cl-Py was elevated in comparison with the rate in the absence of AQ. In addition, the dechlorination of Cl-Py (i.e., the formation of Py) occurred in the presence of AQ.     

Human factors and tidal influences on water quality of an urban river in Can Tho, a major city of the Mekong Delta, Vietnam

In this study, we focused on water quality in an urban canal and the Mekong River in the city of Can Tho, a central municipality of the Mekong Delta region, southern Vietnam. Water temperature, pH, electrical conductivity, BOD₅, COD_Cr, Na⁺, Cl^?, NH₄ ⁺?N, SO₄ ^2??S, NO₃ ^??N, and NO₂ ^??N for both canal and river, and tide level of the urban canal, were monitored once per month from May 2010 to April 2012. The urban canal is subject to severe anthropogenic contamination, owing to poor sewage treatment. In general, water quality in the canal exhibited strong tidal variation, poorer at lower tides and better at higher tides. Some anomalies were observed, with degraded water quality under some high-tide conditions. These were associated with flow from the upstream residential area. Therefore, it was concluded that water quality in the urban canal changed with a balance between dilution effects and extent of contaminant supply, both driven by tidal fluctuations in the Mekong River.     

Radiostrontium monitoring of bivalves from the Pacific coast of eastern Japan

In early April 2011, radiostrontium was accidentally released from the Fukushima Daiichi Nuclear Power Plant to the Pacific coast of eastern Japan. We developed a simple procedure to analyze radiostrontium levels in marine mussels (Septifer virgatus) and seawater using crown ether (Sr Resin; Eichrom). Then, we used our method to describe the spatial and temporal distribution of radiostrontium in mussels and seawater on the Pacific coast of eastern Japan from 2011 to 2013 and for 2015. Activity of ⁹⁰Sr in mussels and seawater decreased with distance from the Fukushima Daiichi Nuclear Power Plant and between 2011 and 2013 tended to be higher in areas south of the Fukushima Daiichi Nuclear Power Plant than to the north of it. Activity in mussels and seawater also tended to decrease from 2011 to 2013 and by 2015 had reached levels experienced prior to the Fukushima accident. Our results suggest that radiostrontium discharged from the Fukushima Daiichi Nuclear Power Plant was dispersed by coastal currents in a southerly direction along the Pacific coast of eastern Japan from 2011 to 2013, following which its activity decreased to background levels by 2015.     

Improvement of reporter gene assay for highly sensitive dioxin detection using protoplastic yeast with inactivation of CWP and PDR genes

Environmental Science and Pollution Research - A yeast reporter gene assay system with improved performance for dioxin detection was established. Since yeast reporter gene assays are relatively...     

Application of a Larval Medaka Assay to Evaluate the Fish Safety Level in Sagami River, Japan

Physico-chemical characteristics of some river and hand-dug well waters used for drinking and domestic purposes in the oil rich Niger Delta area of Nigeria were assessed using standard methods. The concentrations of the parameters in the river water samples ranged in the following order: pH (5.6–6.9), temperature (26.90–28.60°C), turbidity (23–63 NTU), electrical conductivity (52–184 μs/cm), DO (5.4–7.2 mg/l), BOD (21–57 mg/l), TDS (6.0–217 mg/l), PO₄ ³⁻ (0.19–1.72 mg/l), SO₄ ²⁻ (25–36.8 mg/l), NO₃ ⁻ (20.3–28 mg/l), Fe (6.07–15.71 mg/l), Zn (0.04–0.24 mg/l), Pb (0.01–0.17 mg/l), Ni (0.01–0.13 mg/l), Vn (0.01–0.20 mg/l) and Hg (0.001–0.002 mg/l). The concentrations of these parameters in the hand-dug well water ranged in the following order: pH (5.7–6.8) temperature (26–30°C), turbidity (134–171 NTU), electrical conductivity (160–340 μs/cm), DO (5.4–6.4 mg/l), BOD (13–34 mg/l), TDS (110–190 mg/l), PO₄ ³⁻ (0.84–1.84 mg/l), SO₄ ²⁻ (10.6–28.1 mg/l), NO₃ ⁻ (11.3–23 mg/l), Fe (13.17–16.31 mg/l), Ni (0.01–0.02 mg/l), Vn (0.01–0.04 mg/l) and Hg (0.001–0.004 mg/l). The concentrations of BOD, turbidity, NO₃ ⁻ and Fe in the water samples were above WHO and FMENV permissible limits for safe drinking water. The results suggest that the use of such waters for drinking and domestic purposes pose a serious threat to the health of the users and calls for the intervention of government agencies.     

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in rice plants: possible contaminated pathways

Uptake of dioxins was confirmed in rice plants. We determined (i) dioxin concentrations and isomer profiles in leaf+stem samples of rice plants grown in three soils with different dioxin concentrations and isomer profiles and (ii) temporal changes in dioxin concentrations and isomer profiles in rice grown in a paddy field on which agricultural chemicals containing dioxin impurities had been used in previous years. Principal-component and chemical mass-balance analyses of the data showed that dioxin concentrations and isomer profiles in the rice grown in the different soils were similar, even though the dioxin concentrations and isomer profiles of the soils were different. However, the dioxin concentrations in the rice were influenced by dioxin levels in the atmospheric gas phase. Changes in dioxin levels during the growing period of the rice were also strongly influenced by adhesion of the soil to plant components during the early stage of growth, but gradually the influence of the atmospheric gas phase became predominant. Calculated dietary uptake estimates indicated that, even in rice grown in Japan on soil contaminated with high concentrations of dioxins, the amount of dioxins ingested by humans from rice is extremely small, and the amount of dioxins ingested by livestock from forage rice is similar to that for other forage crops.