Biodegradation of heptachlor and heptachlor epoxide-contaminated soils by white-rot fungal inocula

The ability of certain white-rot fungi (WRF) inocula to transform heptachlor and heptachlor epoxide and its application in artificially contaminated soil were investigated. Fungal inoculum of Pleurotus ostreatus eliminated approximately 89 % of heptachlor after 28 days of incubation, and chlordene was detected as the primary metabolite. The fungal inoculum of Pleurotus ostreatus had the highest ability to degrade heptachlor epoxide; approximately 32 % were degraded after 28 days of incubation, and heptachlor diol was detected as the metabolite product. Because Pleurotus ostreatus transformed heptachlor into a less toxic metabolite and could also effectively degrade heptachlor epoxide, it was then selected to be applied to artificially contaminated soil. The spent mushroom waste (SMW) of Pleurotus ostreatus degraded heptachlor and heptachlor epoxide by approximately 91 and 26 %, respectively, over 28 days. This finding indicated that Pleurotus ostreatus SMW could be used to bioremediate heptachlor- and heptachlor epoxide-contaminated environments.     

Effects of ozone on growth, yield and leaf gas exchange rates of two Bangladeshi cultivars of wheat (Triticum aestivum L.)

To clarify the effects of O₃ on crop plants cultivated in Bangladesh, two Bangladeshi wheat cultivars (Sufi and Bijoy) were grown in plastic boxes filled with Andisol and exposed daily to charcoal-filtered air or O₃ at 60 and 100 nl l⁻¹ (10:00-17:00) from 13 March to 4 June 2008. The whole-plant dry mass and grain yield per plant of the two cultivars at the final harvest were significantly reduced by the exposure to O₃. Although there was no significant effect of O₃ on stomatal diffusive conductance to H₂O of flag leaf, net photosynthetic rate of the leaf was significantly reduced by the exposure to O_3. The sensitivity of growth, yield, yield components and leaf gas exchange rates to O₃ was not significantly different between the two cultivars. The results obtained in the present study suggest that ambient levels of O₃ may detrimentally affect wheat production in Bangladesh.     

Zinc tolerance and uptake by <Emphasis Type="Italic">Arabidopsis halleri ssp. gemmifera</Emphasis> grown in nutrient solution

Background, aim, and scope  

Zinc is an essential micronutrient element but its concentrations found in contaminated soils frequently exceed those required by the plant and soil organisms, and thus create danger to animal and human health. Phytoremediation is a technique, often employed in remediation of contaminated soils, which aims to remove heavy metals or other contaminants from soils or waters using plants. Arabidopsis (A.) halleri ssp. gemmifera is a plant recently found to be grown vigorously in heavy metal contaminated areas of Japan and it contained remarkably high amount of heavy metals in its shoots. However, the magnitude of Zn accumulation and tolerance in A. halleri ssp. gemmifera need to be investigated for its use as a phytoremediation plant.     

Inception of formation and early morphogenesis of the bacterial light organ of the sea urchin cardinalfish, <Emphasis Type="Italic">Siphamia versicolor</Emphasis>

The cardinalfish Siphamia versicolor (Perciformes: Apogonidae) forms a bioluminescent symbiosis with the marine luminous bacterium Photobacterium mandapamensis, harboring the bacteria in a ventral, disc-shaped light organ and using the bacterial light apparently for counterillumination and attracting prey. Little definitive information has been available on the developmental and microbiological events surrounding the initiation of symbiosis, a critical stage in the life history of the fish, in S. versicolor or any of the many other species of bacterially luminous fish. To identify the stage at which light organ formation begins, to determine the origin of cells forming the light organ, and to characterize its bacterial colonization status during development, early developmental stages of S. versicolor obtained and reared from wild-caught mouth-brooding males were examined with histological and microbiological methods. A light organ primordium was not evident in embryos, post-embryos, or pre-release larvae, whereas the light organ began to form within 1 day of release of full-term pre-flexion larvae from the mouths of male fish. Analysis of post-release larvae revealed that the light organ arises from a proliferation and differentiation of intestinal epithelial cells, and that it quickly develops structural complexity, including the formation of chambers and gaps contiguous with the intestinal epithelium. However, the nascent light organ remained uncolonized by the symbiotic bacteria through several days of post-release development, even in the presence of high numbers of the symbiotic bacteria. These results demonstrate that the inception of light organ formation in S. versicolor occurs independently of its symbiotic bacteria and that receptivity to bacterial colonization apparently requires substantial post-release development of the light organ. Larvae therefore most likely acquire their symbiotic bacteria from seawater, during or shortly after the transition from the pre-flexion to the flexion developmental stage.     

Conversion of concentrated solar thermal energy into chemical energy

When a concentrated solar beam is irradiated to the ceramics such as Ni-ferrite, the high-energy flux in the range of 1500-2500 kW/m(2) is absorbed by an excess Frenkel defect formation. This non-equilibrium state defect is generated not by heating at a low heating-rate (30 K/min), but by irradiating high flux energy of concentrated solar beam rapidly at a high heating rate (200 K/min). The defect can be spontaneously converted to chemical energy of a cation-excess spinel structure (reduced-oxide form) at the temperature around 1773 K. Thus, the O(2) releasing reaction (α-O(2) releasing reaction) proceeds in two-steps; (1) high flux energy of concentrated solar beam absorption by formation of the non-equilibrium Frenkel defect and (2) the O(2) gas formation from the O(2-) in the Frenkel defect even in air atmosphere. The 2nd step proceeds without the solar radiation. We may say that the 1st step is light reaction, and 2nd step, dark reaction, just like in photosynthesis process.     

Utilization of Triacetylcellulose Waste for the Production of Carbonaceous Adsorbents

Triacetylcellulose(TAC)-based globular activated carbons having the adsorption capacity comparable with commercial ones have been derived using a carbonization system developed for this purpose. The carbonization of TAC proceeds through a liquid phase causing bubbling due to the emission of the decomposition gases. The phosphorus compounds resulting from the starting material of TAC waste promote the activation reactions to produce micro-pores.     

Conversion of Concentrated Solar Thermal Energy into Chemical Energy

When a concentrated solar beam is irradiated to the ceramics such as Ni-ferrite, the high-energy flux in the range of 1500–2500 kW/m² is absorbed by an excess Frenkel defect formation. This non-equilibrium state defect is generated not by heating at a low heating-rate (30 K/min), but by irradiating high flux energy of concentrated solar beam rapidly at a high heating rate (200 K/min). The defect can be spontaneously converted to chemical energy of a cation-excess spinel structure (reduced-oxide form) at the temperature around 1773 K. Thus, the O₂ releasing reaction (α-O₂ releasing reaction) proceeds in two-steps; (1) high flux energy of concentrated solar beam absorption by formation of the non-equilibrium Frenkel defect and (2) the O₂ gas formation from the O^2? in the Frenkel defect even in air atmosphere. The 2nd step proceeds without the solar radiation. We may say that the 1st step is light reaction, and 2nd step, dark reaction, just like in photosynthesis process.     

Simultaneous degradation of commercially produced CNP herbicide and of contaminated dioxin by treatment using the white-rot fungus Phlebia brevispora

An experiment was carried out to study the degradation of commercially produced chlornitrofen (2,4,6-trichlorophenyl p-nitrophenyl ether; CNP) herbicide contaminated with 1,3,6,8-tetrachlorodibenzo-p-dioxin (1,3,6,8-tetraCDD) by means of the white rot fungus Phlebia brevispora TMIC33929. Recently, we reported that 1,3,6,8-tetraCDD was degraded by P. brevispora. In the degradation experiment using CNP standard compounds, CNP was transformed into several metabolites including monomethoxylated compounds and 2,4,6-trichlorophenol by P. brevispora. When the mixture of CNP and 1,3,6,8-tetraCDD was treated with P. brevispora, each substrate was degraded and metabolites were detected. The treatment of the commercially produced CNP herbicide by P. brevispora led to the degradation of CNP and contaminated 1,3,6,8-tetraCDD as a result. These results indicate that P. brevispora can degrade CNP and 1,3,6,8-tetraCDD at the same time, and that biological treatment of commercially produced CNP herbicide is possible.     

Distribution of Poly(β-propiolactone) Aerobic Degrading Microorganisms in Different Environments

The distribution of degading microorganisms of high molecular weight poly(-propiolactone) (PPL), whose individual structural units are similar to those of poly(-hydroxybutyrate) (PHB) and poly(€-caprolactone) (PCL), was examined. Despite the fact that PPL is a chemosynthetic polymer, many kinds of PPL-degrading microorganisms were found to be distributed as resident populations widely in natural environments. A total of 77 strains of PPL-degrading microorganisms was isolated. From standard physiological and biochemical tests, at least 41 strains were referred to as Bacillus species. Microbial degradation of fibrous PPL proceeded rapidly in some enrichment cultures but was not as complete as that of PHB. Most of the isolated PPL-degrading microorganisms were determined to be PCL degraders and/or PHB degraders. Therefore, it can be assumed that mostly PPL is recognized by the microorganisms as PHB or another natural substrate of the same type as which PCL is regarded. Microbial degradation of PPL was confirmed by some Bacillus strains from type culture collections. The similarity of microbial degradation between PPL and PCL was found to be very close.     

Effects of bacterial counts and temperature on the biodegradation of bisphenol A in river water

Total 15 surface river waters were collected from thirteen different rivers to investigate a relationship of bacterial counts and temperature to the degradation of bisphenol A (BPA). Autoclaved and non-autoclaved river water samples were spiked with 0.2 mg/l BPA. The spiked samples were placed at temperatures of 4, 20, and 30 degrees C and analyzed by high performance liquid chromatography. BPA was degraded at all temperatures in the non-autoclaved samples. However, BPA in the autoclaved samples was not changed at all temperatures for 20 d. These results show that the primary factor of BPA degradation in river water is bacteria. Moreover, three groups [group A (> 10000 CFU/ml), group B (2000-10000 CFU/ml), and group C (< 2000 CFU/ml)], were made on the basis of bacterial counts of the samples. Half-lives for BPA degradation in groups A, B, and C were 2, 3, and 6 d at 30 degrees C and were 4, 5, and 7 d at 20 degrees C, respectively. But at 4 degrees C, the loss of BPA was about 40%, 20%, and 10% in groups A, B, and C for 20 d, respectively. Bacterial counts exerted an influence on BPA degradation in river water with temperature. Our results also show that BPA-degrading bacteria are widely distributed in river waters.