Medium optimization for the production of anti-cyanobacterial substances by Streptomyces sp. HJC-D1 using response surface methodology

Bioremediation using isolated anti-cyanobacterial microorganism has been widely applied in harmful algal blooms (HABs) control. In order to improve the secretion of activated anti-cyanobacterial substances, and lower the cost, a sequential optimization of the culture medium based on statistical design was employed for enhancing the anti-cyanobacterial substances production and chlorophyll a (Chl a) removal by Streptomyces sp. HJC-D1 in the paper. Sucrose and KNO₃ were selected as the most suitable carbon and nitrogen sources based on the one-at-a-time strategy method, and sucrose, KNO₃ and initial pH were found as major factors that affected the anti-cyanobacterial ability of the isolated stain via the Plackett–Burman design. Based on the response surface and canonical analysis, the optimum condition of culture medium was obtained at 22.73 g l^-1 of sucrose, 0.96 g l^-1 of KNO₃, and initial pH 8.82, and the Chl a removal efficiency by strain HJC-D1 increased from 63?±?2 % to 78?±?2 % on the optimum conditions.     

Heterogeneous photocatalytic degradation of pesticides using decatungstate intercalated macroporous layered double hydroxides

Decatungstate W₁₀O₃₂ ^4? was efficiently intercalated between the layers of three-dimensionally ordered macroporous Mg₂Al-layered double hydroxide. The structural and textural properties of as-prepared intercalated compound were characterized using different solid-state characterization techniques such as X-ray powder diffraction, FTIR and Raman spectroscopies and electronic microscopy. The photocatalytic properties of immobilized W₁₀O₃₂ ^4? within Mg₂Al structure were investigated using 2-(1-naphthyl) acetamide (NAD) as a model of pesticide. The influence of different parameters such as amount of catalyst, pH and oxygen concentration were investigated. An optimal NAD degradation was obtained for a photocatalyst concentration of 60 mg l^?1. Under our experimental conditions, this heterogeneous photocatalyst induces photodegradation of 60 % of NAD after 17 h of irradiation at 365 nm and at pH 6.6. Interestingly, pesticide photodegradation leads to the mineralization of substrates to H₂O and CO₂ and the photocatalyst can be recycled and reused without any loss of activity over four cycles.     

Reproductive toxicity of lead,cadmium, and phthalate exposure in men

Environmental toxicants viz lead or cadmium and phthalate esters (di(2-ethylhexyl) phthalate [DEHP], dibutyl phthalate [DBP], and diethyl phthalate [DEP]) widely found in different environmental strata are linked to deteriorating male reproductive health. The objective was to assess the relationships between the seminal lead, cadmium, and phthalate (DEHP, DBP, DEP) concentrations at environmental level and serum hormone levels and semen quality in non-occupationally exposed men and specify the effect of individual and combined exposure of toxicants on semen quality. A study of 60 male partners of couples attending the Andrology Laboratory of the Reproductive Biology Department, All India Institute of Medical Sciences (AIIMS), New Delhi, India for semen analysis to assess their inability to achieve a pregnancy was selected for the study. The results of univariate and stepwise multiple regression analysis in the unadjusted model showed a significant correlation between lead or cadmium and phthalates DEHP/DBP/DEP and sperm motility, sperm concentration, and DNA damage. After adjusting for potential confounders, an association with lead or DEHP was only observed. The present data shows that lead (Pb) or cadmium (Cd) or phthalates might independently contribute to decline in semen quality and induce DNA damage. Phthalates might influence reproductive hormone testosterone. These findings are significant in light of the fact that men are exposed to a volley of chemicals; however, due to the small sample size, our finding needs to be confirmed in a larger population.     

Oxidative stress response in dye degrading bacterium Lysinibacillus sp. RGS exposed to Reactive Orange 16, degradation of RO16 and evaluation of toxicity

Lysinibacillus sp. RGS degrades sulfonated azo dye Reactive Orange 16 (RO16) efficiently. Superoxide dismutase and catalase activity were tested to study the response of Lysinibacillus sp. RGS to the oxidative stress generated by RO16. The results demonstrated that oxidative stress enzymes not only protect the cell from oxidative stress but also has a probable role in decolorization along with an involvement of oxidoreductive enzymes. Formation of three different metabolites after degradation of RO16 has been confirmed by GC-MS analysis. FTIR analysis verified the degradation of functional groups of RO16, and HPTLC confirmed the removal of auxochrome group from the RO16 after degradation. Toxicity studies confirmed the genotoxic, cytotoxic, and phytotoxic nature of RO16 and the formation of less toxic products after the treatment of Lysinibacillus sp. RGS. Therefore, Lysinibacillus sp. RGS has a better perspective of bioremediation for textile wastewater treatment.     

Chemical and spectroscopic characterization of organic matter during the anaerobic digestion and successive composting of pig slurry

In this work, anaerobic digestion of pig slurry and successive composting of the digestate after centrifugation were studied by means of chemical analysis, FTIR and fluorescence spectroscopy as excitation–emission matrix (EEM). Chemical analysis highlighted the organic matter transformation occurring during the processes. A decrease of volatile solids and total organic carbon were observed in the digestate with respect to the fresh pig slurry as a consequence of the consumption of sugars, proteins, amino acids and fatty acids used by microorganisms as a C source. Water Extractable Organic Matter (WEOM) was obtained for all samples and fractionated into a hydrophilic and a hydrophobic fraction. The highest WEOM value was found in the pig slurry indicating a high content of labile organic C. The digestate centrifuged and the digestate composted showed lower hydrophilic and higher hydrophobic contents because of the decrease of labile C. Total phenolic content was lower in the digestate with respect to fresh pig slurry sample (36.7%) as a consequence of phenolic compounds degradation. The strong decrease of total reducing sugars in the digestate (76.6%) as compared to pig slurry confirmed that anaerobic process proceed mainly through consumption of sugars which represent a readily available energy source for microbial activity. FTIR spectra of pig slurry showed bands indicative of proteins and carbohydrates. A drop of aliphatic structures and a decrease of polysaccharides was observed after the anaerobic process along with the increase of the peak in the aromatic region. The composted substrate showed an increase of aromatic and a relative decrease of polysaccharides. EEM spectra provided tryptophan:fulvic-like fluorescence ratios which increased from fresh substrate to digestate because of the OM decompostion. Composted substrate presented the lowest ratio due to the humification process.     

不同运行模式对同步脱氮除磷CAST工艺快速启动及其稳定维持的影响

以实际生活污水为处理对象,考察了传统进水/曝气和改良型分段进水的交替缺氧-好氧(A/O)2种运行模式对CAST工艺的快速启动及脱氮除磷性能稳定维持的影响。结果表明,传统进水/曝气运行模式下,系统达到最佳营养物去除性能所需启动时间30 d,稳定运行阶段TN平均去除80.66%,磷的去除率维持在66.30%左右;采用改良型交替运行模式,反应器达到稳定运行状态仅需18 d,系统稳定运行时TN平均去除81.36%,磷去除率稳定维持在90%以上,出水磷浓度在0.3 mg/L以下,出水水质达到国家污水综合排放标准一级A(GB8978-2002)。研究还发现,传统运行模式下,由低温引起的污泥沉降性能变差导致系统污泥严重流失,反应器几乎丧失污染物去除性能;而低温对交替运行模式下的反应器除磷性能几乎没有影响,总氮去除则因氨氮不完全硝化而大大降低。     

Growth Inhibition by Nitrocompounds of Selected Uric Acid-Utilizing Microorganisms Isolated from Poultry Manure

The overall objective of this study was to evaluate the potential ability of nitrocompounds to reduce ammonia volatilization by inhibiting uric acid–utilizing microorganisms. Experiment I was conducted to evaluate the effects of nitrocompounds on the growth of uric acid–utilizing microorganisms isolated from poultry manure during six-hour incubation. There were five treatments: (1) control, (2) 50 mM nitroethane, (3) 50 mM nitroethanol, (4) 50 mM nitropropanol, and (5) 50 mM nitropropionic acid. Optical density values of nitrocompounds were significantly lower than that of control at two, four, and six hours. Plate counts of uric acid–utilizing microorganisms after six-hour incubation exhibited that nitrocompounds greatly reduced the growth of these microorganisms except for the nitroethane (P < 0.05). The nitropropanol and nitropropionic acid treatments showed significantly higher inhibitory effects compared to the nitroethanol. Experiments II and III were conducted to evaluate inhibitory effects of nitrocompounds on growth of uric acid–utilizing microorganisms compared to non-nitrocompounds such as ethanol, propanol, and propionic acid. Experiments II and III consisted of seven treatments: (1) control, (2) nitroethanol, (3) nitropropanol, (4) nitropropionic acid, (5) ethanol, (6) propanol, and (7) propionic acid. The incubation times of Experiments II and III were 6 and 24 h, respectively. The nitrocompounds were significantly more successful in inhibiting growth of uric acid–utilizing microorganisms compared to those non-nitrocompounds. These results suggest that nitrocompounds exhibit potential to reduce ammonia volatilization in poultry manure by inhibiting growth of uric acid–utilizing microorganisms.     

2,4-D Mineralization in soil profiles of a cultivated hummocky landscape in Manitoba,Canada

The objective of this study was to quantify 2,4-D (2,4-dichlorophenoxyacetic acid) mineralization in soil profiles characteristic of hummocky, calcareous-soil landscapes in western Canada. Twenty-five soil cores (8 cm inner diameter, 50 to 125 cm length) were collected along a 360 m transect running west to east in an agricultural field and then segmented by soil-landscape position (upper slopes, mid slopes, lower slopes and depressions) and soil horizon (A, B, and C horizons). In the A horizon, 2,4-D mineralization commenced instantaneously and the mineralization rate followed first-order kinetics. In both the B and C horizons, 2,4-D mineralization only commenced after a lag period of typically 5 to 7 days and the mineralization rate was biphasic. In the A horizon, 2,4-D mineralization parameters including the first-order mineralization rate constant (k ₁), the growth-linked mineralization rate constant (k ₂) and total 2,4-D mineralization at the end of the experiment at 56 days, were most strongly correlated to parameters describing 2,4-D sorption by soil, but were also adequately correlated to soil organic carbon content, soil pH, and carbonate content. In both B and C horizons, there was no significant correlation between 2,4-D mineralization and 2,4-D sorption parameters, and the correlation between soil properties and 2,4-D mineralization parameters was very poor. The k ₁ significantly decreased in sequence of A horizon (0.113% day^?1) > B horizon (0.024% day^?1) = C horizon (0.026% day^?1) and in each soil horizon was greater than k ₂. Total 2,4-D mineralization at 56 days also significantly decreased in sequence of A horizon (42%) > B horizon (31%) = C horizon (27%). In the A horizon, slope position had little influence on k ₁ or k ₂, except that k ₁ was significantly greater in upper slopes (0.170% day^?1) than in lower slopes (0.080% day^?1). Neither k ₁ nor k ₂ was significantly influenced by slope position in the B or C horizons. Total 2,4-D mineralization at 56 days was not influenced by slope positions in any horizon. Our results suggest that, when predicting 2,4-D transport at the field scale, pesticide fate models should consider the strong differences in 2,4-D mineralization between surface and subsurface horizons. This suggests that 2,4-D mineralization is best predicted using a model that has the ability to describe a range of non-linear mineralization curves. We also conclude that the horizontal variations in 2,4-D mineralization at the field scale will be difficult to consider in predictions of 2,4-D transport at the field scale because, within each horizon, 2,4-D mineralization was highly variable across the twenty-five soil cores, and this variability was poorly correlated to soil properties or soil-landscape position.     

Use of cholinesterase activity in monitoring chlorpyrifos exposure of steer cattle after topical administration

The aim of this work was to study the pharmacokinetic behavior and the inhibitory effect of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities of chlorpyrifos (CPF) in steer cattle after pour-on administration. Determination of cholinesterase activity in plasma and erythrocyte was carried out according to Ellman kinetic method. CPF was analyzed by gas chromatography. AChE was the predominant form of cholinesterase analyzed, with low levels of BChE in plasma. Following the treatment with CPF, the maximum inhibitory effect on AChE or BChE were 50.88 ± 11.57 and 42.66 ± 12.01%, respectively. The chlorpyrifos plasma concentrations observed were low and they presented a high variability. Chlorpyrifos peak plasma concentration (10.42 ± 4.76 μ g/L) was reached at 8.42 ± 13.97 h. The pesticide was not detected in plasma after 48 h post treatment. The values of area under the curve (AUC) were 118.48 ± 87.46 μ g· h/L and mean resistance time (MRT) were 13.38 ± 10.41 h. The pour-on exposure to the organophosphate chlorpyrifos significantly reduced AChE and BChE activity in steer cattle and the recovery was not reached on 50 days post-treatment.     

Manure placement depth impacts on crop yields and N retained in soil

The objective of this study was to determine the impact of manure placement depth on crop yield and N retention in soil. Experimental treatments were deep manure injection (45 cm), shallow manure injection (15 cm), and conventional fertilizer-based management with at least three replications per site. Water infiltration, and changes in soil N and P amounts were measured for up to 30 months and crop yield monitored for three seasons following initial treatment. Deep and shallow manure injections differed in soil inorganic N distributions. For example, in the manure slot the spring following application, NO₃-N in the surface 60 cm was higher (p < .01) when injected 15 cm (21.4 μ g/g) into the soil than 45 cm (11.7 μ g/g), whereas NH₄-N had opposite results with shallow injection having less (p = 0.045) NH₄-N (102 μ g/g) than deep (133 μ g/g) injection. In the fall one year after the manure was applied, NO₃-N and NH₄-N were lower (p = 0.001) in the shallow injection than the deep injection. The net impact of manure placement on total N was that deep injection had 31, 59, and 44 more kg N ha^{? 1} than the shallow injection treatment 12, 18, and 30 months after application, respectively. Deep manure injection did not impact soybean (Glycine max L.) yield, however corn (Zea mays L.) yield increased if N was limiting. The higher corn yield in the deep injected treatment was attributed to increased N use efficiency. Higher inorganic N amounts in the deep injection treatment were attributed to reduced N losses through ammonia volatilization, leaching, or denitrification. Results suggest that deep manure placement in glacial till soil may be considered a technique to increase energy, N use efficiency, and maintain surface and ground water quality. However, this technique may not work in glacial outwash soils due to the inability to inject into a rocky subsurface.