Cornmeal-induced resistance to ciprofloxacin and erythromycin in enterococci

Triclosan is used as an antibacterial agent in household items and personal care products. Since this compound is found in maternal milk of humans and bodies of wild animals, there is growing concern among some consumer groups and scientific community that triclosan is adverse for humans and wild animals. In order to estimate adverse actions of triclosan, the effects of triclosan on intracellular Zn²⁺ concentration and cellular thiol content were studied in rat thymocytes by the use of flow cytometer with appropriate fluorescent probes. Triclosan at 1-3 μM (sublethal concentrations) increased the intensity of FluoZin-3 fluorescence (intracellular Zn²⁺ concentration) and decreased the intensity of 5-chloromethylfluorescein (5-CMF) fluorescence (cellular thiol content). Negative correlation (r = −0.985) between triclosan-induced changes in FluoZin-3 and 5-CMF fluorescences was found. Removal of external Zn²⁺ did not significantly affect the triclosan-induced augmentation of FluoZin-3 fluorescence, suggesting an intracellular Zn²⁺ release by triclosan. These actions of triclosan were similar to those of H₂O₂ and triclosan significantly potentiated the cytotoxicity of H₂O₂. Therefore, the results may suggest that triclosan at sublethal concentrations induces oxidative stress that decreases cellular thiol content, resulting in an increase in intracellular Zn²⁺ concentration by Zn²⁺ release from intracellular store(s). Since recent studies show many physiological roles of intracellular Zn²⁺ in cellular functions, the triclosan-induced disturbance of cellular Zn²⁺ homeostasis may induce adverse actions on the cells.     

Anaerobic degradation of microcrystalline cellulose: kinetics and micro-scale structure evolution

The degradation kinetics and micro-scale structure change of microcrystalline cellulose during anaerobic biodegradation were investigated. A modified Logistic model was established to properly describe the kinetics, which showed good fitness and wide applicability for cellulose degradation. A maximum degradation rate of 0.14 g L⁻¹ h⁻¹ was achieved after cultivating for 51.5 h. This result was in good agreement with the scanning electron microscope and X-ray diffraction analysis. Channels of 400-500 nm size started to occur on the crystalline surface of cellulose at around the inflexion time. Accordingly, the crystallinity significantly decreased at this point, indicating a degradation of the crystalline structure zones by anaerobic bacteria. This study offers direct morphological evidence and quantitative analysis of the biodegradation process of cellulose, and is beneficial to a better understanding of the cellulose degradation mechanism.     

Chromium exhibits adverse effects at environmental relevant concentrations in chronic toxicity assay system of nematode Caenorhabditis elegans

Here we investigated whether the assay system (10-d) in Caenorhabditis elegans can be used to evaluate chronic toxicity of chromium (Cr(VI)) at environmental relevant concentrations ranging from 5.2 μg L⁻¹ to 260 μg L⁻¹. The results indicated that lethality, locomotion behavior as revealed by head thrash, body bend, and forward turn, metabolism as revealed by pumping rate and mean defecation cycle length, intestinal autofluorescence, and ROS production were severely altered in Cr chronically exposed nematodes at environmental relevant concentrations. The most surprising observations were that head thrash, body bend, intestinal autofluorescence, and ROS production in 13 μg L⁻¹ Cr exposed nematodes were significantly influenced. The observed adverse effects of Cr on survival, locomotion behavior, and metabolism were largely due to forming severe intestinal autofluorescence and ROS production. Therefore, our findings demonstrate the usefulness of chronic toxicity assay system in C. elegans in evaluating the chronic toxicity of toxicants at environmental relevant concentrations.     

Historical change of mercury pollution in remote Yongle archipelago, South China Sea

We collected three ornithogenic coral sand sedimentary profiles from Jinyin Island, Jinqing Island and Guangjin Island of Yongle archipelago, South China Sea and reconstructed the deposition flux of anthropogenic Hg over the past 700 years in the study area. On the whole, the anthropogenic Hg flux is relatively low; it remained at a low level before the Industrial Revolution with a small peak at about 1450-1550 AD, which may record the enhanced metallurgy activity in Ming Dynasty of China. During the 20th century, the deposition flux of anthropogenic Hg increased rapidly, but two troughs occurred during the periods around 1940s and 1970s, corresponding to the economic depression caused by World War II, Civil War in China (1945-1949), and the Culture Revolution (1966-1976) in China. Since the 1970s the deposition flux of anthropogenic Hg has been persistently increasing, apparently the result of fast economic development in East and Southeast Asia countries around South China Sea.     

Textural and chemical properties of swine-manure-derived biochar pertinent to its potential use as a soil amendment

Biochars have received increasing attention in recent years because of their properties pertaining to soil fertility and contaminant immobilization as well as serving as carbon sinks. In this work, a series of biochars were produced from dried swine manure waste by slow pyrolysis at different temperatures (i.e., 673-1073 K). The characterization of the resulting biochars was examined for its relevance to its potential use as soil amendment. It was found that the pore properties, ash contents and pH values of all swine-manure-derived biochars basically increased as temperature increased, while the yield and nitrogen/oxygen contents decreased with increasing temperature as a result of pyrolytic volatilization during pyrolysis. From the organic and inorganic elements analyses, the manure-derived biochar was rich in soil nutrients such as N, P, Ca, Mg, and K. Furthermore, the pore, surface and chemical properties were also consistent with the observations of the SEM-EDS, XRD and FTIR. This result suggested that the mesoporous manure-derived biochar could be used as an excellent medium to soil environment.     

Interaction between BSM-contaminated soils and Italian ryegrass

The interaction among the bensulfuron-methyl, growth of Italian ryegrass, and soil chemical/biochemical/microbiological parameters was investigated in a microcosm experiment. The bensulfuron-methyl added to the soil can be rapidly degraded by certain fungi and actinomycetes present in the original paddy rice soil. The growth of Italian ryegrass significantly accelerated the in-soil degradation of bensulfuron-methyl in its rhizosphere. The uptake of bensulfuron-methyl by ryegrass increased with increasing dosage level of bensulfuron-methyl. However, the phytoextraction of bensulfuron-methyl by ryegrass contributed insignificantly to the total removal of the soil bensulfuron-methyl. Within the dosage range set in this study, the root development of ryegrass was not adversely affected by the presence of the soil bensulfuron-methyl although the fresh biomass of shoot was slightly reduced in the higher dosage treatments. This can be attributed to the adsorption of the added bensulfuron-methyl by soil colloids and consequently the reduction of bensulfuron-methyl level in the soil pore water to a concentration sufficiently lower than the toxic level. The growth of ryegrass significantly increased soil pH and the activities of phosphatase and peroxidase but reduced the EC and the activities of urease in the rhizospheric soil.     

Cosorption of organic chemicals with different properties: their shared and different sorption sites

Complementary sorption of different chemicals was expected and investigating the relationship between the sorption inhibition of primary sorbate (ΔQ(pri)) and sorption of secondary sorbate (Q(sec)) could provide a new angle to understand coadsorption of different chemicals. This study used bisphenol A (BPA) as the primary adsorbate, sulfamethoxazole (SMX) as the competitor, and carbon nanotubes as model adsorbents to study their complementary and competitive adsorption. At low BPA concentrations, the sorption of SMX (Q(sec)) exceeded BPA sorption inhibition (ΔQ(pri)), indicating that these two chemicals complementarily adsorbed on their respectively preferred sorption sites. At high BPA concentrations, higher ΔQ(pri) was observed in comparison to Q(sec), which may be resulted from different packing efficiencies of the adsorbed SMX and BPA. This study emphasized that both competitive and complementary sorption should be discussed in binary sorption system.     

VOC amounts in ambient areas of a high-technology science park in Taiwan: their reciprocal correlations and impact on inhabitants

Introduction  

This study presents bihourly, seasonal, and yearly concentration changes in volatile organic compounds (VOCs) in the inlet and effluent water of the wastewater treatment plant (WWTP) of a high-technology science park (HTIP) in Taiwan, with the VOC amounts at different sites correlated geologically.     

Harvesting of Chlorella sp. using hollow fiber ultrafiltration

Introduction

The suitability of the application of ultrafiltration (UF) to harvest Chlorella sp. from the culture medium was examined. We investigated the effects of two improved UF system, forward air?Cwater flushing and backwash with permeate, on the concentration process.

Materials and methods

Backwash with permeate was selected as an optimization of the improved UF system, which was more effective for permeate flux recovery. Moreover, the hollow fiber UF system by adding periodical backwash with permeate was examined for Chlorella sp. harvesting.

Results and discussion

It was found that Chlorella sp. could be concentrated with high recovery in a lab-scale experiment. An overall algal biomass recovery of above 90% was achieved when the volume concentration factor was 10. For an original biomass of 1.3?±?0.05?g/L, 1?min backwash followed by 20?min forward concentrating was more effective, which resulted in a recovery of 94% and a high average flux of 30.3?L/m²/h. In addition, the algal recovery was highly correlated to the volume concentration factor and the initial biomass. A high concentration factor or a high initial biomass resulted in a low biomass recovery.