The oligopeptides production by the feather-degrading bacterium Bacillus methylotrophicus H0北大核心CSCD

Due to the high nutritive value of oligopeptides and the waste of feather resources, this study aimed at screening efficient strains of bacteria able to rapidly degrade feathers and produce large quantities of value-added oligopeptides. In order to assess the potential yield of oligopeptides, the promising strain H0 was selected from 16 feather-degrading microorganisms. To identify the strain, we analyzed the morphological and physiological characteristics of different strains, and carried out a gene sequence analysis of their 16S rRNAs. A single factor experiment was used to promote feather degradation and oligopeptide production, and the characteristics of the oligopeptides produced were also analyzed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). The strain was identified as Bacillus methylotrophicus. The optimal initial pH and temperature for oligopeptide production were 11 and 40 °C, respectively. After 72 h of fermentation under these optimal conditions, the feathers were almost completely degraded, with a 38.19% of oligopeptides (accounting for 67.53% of the total soluble peptides) and a 11.11% of free amino acids produced. LC-MS/MS analysis indicated that the oligopeptides were mainly short peptides containing 5-10 amino acids, with a molecular mass (Mr) of less than 1 300. Moreover, the peptides were abundant in branched-chain amino acids, that might be responsible for the antioxidant property of the feather hydrolysate. Our results demonstrate the great capability of B. methylotrophicus H0 in feather degradation and oligopeptide production. This research provides a high-quality microorganism resource, and the scientific basis for the development of feather-derived oligopeptide products. © 2018 Science Press. All rights reserved.     

An ecotoxicological view on neurotoxicity assessment

The numbers of potential neurotoxicants in the environment are raising and pose a great risk for humans and the environment. Currently neurotoxicity assessment is mostly performed to predict and prevent harm to human populations. Despite all the efforts invested in the last years in developing novel in vitro or in silico test systems, in vivo tests with rodents are still the only accepted test for neurotoxicity risk assessment in Europe. Despite an increasing number of reports of species showing altered behaviour, neurotoxicity assessment for species in the environment is not required and therefore mostly not performed. Considering the increasing numbers of environmental contaminants with potential neurotoxic potential, eco-neurotoxicity should be also considered in risk assessment. In order to do so novel test systems are needed that can cope with species differences within ecosystems. In the field, online-biomonitoring systems using behavioural information could be used to detect neurotoxic effects and effect-directed analyses could be applied to identify the neurotoxicants causing the effect. Additionally, toxic pressure calculations in combination with mixture modelling could use environmental chemical monitoring data to predict adverse effects and prioritize pollutants for laboratory testing. Cheminformatics based on computational toxicological data from in vitro and in vivo studies could help to identify potential neurotoxicants. An array of in vitro assays covering different modes of action could be applied to screen compounds for neurotoxicity. The selection of in vitro assays could be guided by AOPs relevant for eco-neurotoxicity. In order to be able to perform risk assessment for eco-neurotoxicity, methods need to focus on the most sensitive species in an ecosystem. A test battery using species from different trophic levels might be the best approach. To implement eco-neurotoxicity assessment into European risk assessment, cheminformatics and in vitro screening tests could be used as first approach to identify eco-neurotoxic pollutants. In a second step, a small species test battery could be applied to assess the risks of ecosystems.     

A dynamic study of the sorption and the transport processes of cadmium in calcareous sandy soils

The interactions of Cd2+ with silica and calcite were observed through laboratory dynamic experiments. Cd2+ sorption processes were characterised as a function of reaction kinetics in aqueous solutions saturated or not with respect to calcite. Chromatographic column experiments show that Cd2+ sorption on silica can be considered as a reversible equilibrate reaction which depends on water composition and pH. For a porous medium composed by a mixture of silica and calcite, the Cd2+ migration behaviours are predominantly controlled by calcite. The amount and the reversibility of sorbed Cd on calcite are strongly affected by kinetic limitations. Stirred flow through reactor experiments provide an original method to separate and characterise the 'fast' and 'slow' Cd sorption on calcite processes. The 'fast' Cd reversible adsorption isotherms and the rate of Cd subsequent uptake by 'slow' reactions are determined. In addition, the inhibition of calcite dissolution is observed as a function of sorbed Cd in order to provide a complete mechanistic database for coupled transport-geochemistry models.     

Single and Joint Effects of Acetochlor and Urea on Earthworm Esisenia Foelide Populations in Phaiozem

Much attention is paid to soil health and environmental safety. Earthworms are an important indicator of soil ecosystem health and safety. Ecological toxicity of acetochlor and excessive urea, in both their single and joint effects, on earthworm Esisenia foelide was thus studied using the soil-culture method. Acetochlor had an enhanced toxicity from low concentration to high concentration. The mortality of earthworms after a 6-day exposure was changed from 0 to 86.7%, and the weight change rate ranged from 7.86 to –30.43%, when the concentration of acetochlor was increased from 164 to 730 mg kg^–1. Urea expressed its positive and beneficial effects on earthworms when its concentration was lower than 500 mg kg^–1. Strongly toxic effects took place when the concentration of urea was higher than 1000 mg kg^–1. The mortality of earthworms exposed to urea reached 100% when its concentration was more than 1500 mg kg^–1. When the concentration of urea was lower than 500 mg kg^–1, there were antagonistic effects between the two agrochemicals on earthworms; when the concentration of urea was higher than 500 mg kg^–1, joint toxic effects of acetochlor and excessive urea on earthworms were synergic. In any case, excessive urea application is very harmful to the health of soil ecosystems.     

Effect of petroleum-containing wastewater irrigation on bacterial diversities and enzymatic activities in a paddy soil irrigation area

Effects of petroleum contamination on bacterial diversities and enzymatic activities in paddy soils were investigated in the Shenfu irrigation area, the largest area irrigated by oil-containing wastewater for more than 50 yr in northeastern China. Bacterial diversities were determined by conventional colony morphology typing techniques and 16S rDNA polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). Dehydrogenase, hydrogen peroxidase, polyphenol oxidase, urease, and substrate-induced respiration (SIR) were measured to evaluate the effects of petroleum-containing wastewater irrigation on soil biochemical characteristics. Results showed that paddy soil total petroleum hydrocarbon (TPH) concentration in the irrigation area varied from 277.11 to 5213.37 mg kg(-1) dry soil. Soil TPH concentration declined along the gradient of the irrigation channel from up- to downstream. At the current pollution level, the paddy soil TPH concentration was positively correlated with the colony forming units (CFU) of aerobic heterotrophic bacteria (AHB) (r = 0.928, p < 0.001) and the genetic diversity based on DGGE profiles (r = 0.655, p < 0.05). The bacterial diversities in the soils based on colony morphotypes of AHB also increased with TPH concentration (r = 0.598), but not significant statistically (p = 0.052). Analysis of soil enzyme activities indicated a significant positive correlation between soil TPH concentration and activities of dehydrogenases (r = 0.974, p < 0.001), hydrogen peroxidases (r = 0.957, p < 0.001), polyphenol oxidases (r = 0.886, p < 0.001), and SIR (r = 0.916, p < 0.001). On the contrary, the urease activity showed a negative correlation with paddy soil TPH concentration (r = -0.814, p = 0.002), and could be used as a sensitive indicator of petroleum contamination.     

Sorption and biodegradability of sludge bacterial extracellular polymers in soil and their influence on soil copper behavior

Bacterial extracellular polymers (BEP) affect the translocation and fate of organic and inorganic pollutants in terrestrial and aquatic ecosystems. In this study, BEP from activated sludge was compared with sludge dissolved organic matter (DOM) in terms of behavior and effects on the mobilization and bioavailability of Cu in a well-aged Cu-contaminated orchard sandy loam. Addition of sludge BEP (10-200 mg dissolved organic carbon [DOC] L(-1)) to the soil resulted in 1.6- to 12.8-fold-higher soil soluble Cu concentration over the control and 1.3- to 2.2-fold over sludge DOM of the same concentration. Consequently, the Cu uptake by the ryegrass (Lolium perenne L., cv. Target) grown in the soil was increased by 31% due to interval watering of 100 mg DOC L(-1) of sludge BEP solution in a 35-d period. The influence of sludge BEP on mobilizing soil Cu could be maintained as long as 60 d or more, depending on BEP biodegradation status. The findings that sludge BEP promoted Cu mobilization and bioavailability could be attributed to less adsorption of BEP by soil, slow degradation, and higher affinity with Cu. For example, after 3 wk of aerobic incubation, the soluble Cu present in the sludge DOM-treated soil was reduced to about the level of the control, while the concentration of soluble Cu in BEP-treated soil was 6.2 times higher than that in the control. Therefore, sludge BEP could act as a facilitated-transport carrier of Cu. The environmental risk of Cu should receive much attention if BEP is incorporated into soils.     

Second trimester maternal serum analytes in triploid pregnancies: correlation with phenotype and sex chromosome complement

Second trimester maternal serum alpha-fetoprotein (MS-AFP), human chorionic gonadotrophin (hCG), unconjugated estiol (uE3), and inhibin-A (INH-A) levels were evaluated in pregnancies complicated by triploidy. In addition to seven new triploid pregnancies, the results for 67 published cases were reviewed. All cases appear to fall into two major groups. First, those identifiable as screen-positive for both Down syndrome and an open neural tube defect (ONTD) with elevated MS-AFP, grossly elevated hCG, low/normal uE3, and probably elevated INH-A. Pregnancies in the second group are identifiable as screen-positive for trisomy 18 with low/normal MS-AFP, and very low hCG, uE3 and INH-A. Triploid pregnancies with high maternal serum hCG nearly always show a placenta with partial mole (25/27 or 93%), a high frequency of ONTDs or ventral wall defects (VWDs) (8/28 or 29%) and have either an XXX or XXY karyotype (observed ratio 6:10, respectively). Low hCG is infrequently associated with a molar placenta (1/11 or 9%), does not appear to be associated with ONTDs or VWDs (0/29 or 0%), and shows an excess of XXX over XXY karyotypes (observed ratio 17:2). There were 16 cases with either a molar placenta, an ONTD or a VWD that received the MS-AFP and hCG tests. All 16 were screen-positive for an ONTD (MS-AFP≥2 multiples of the median). In addition, all 31 cases that received MS-AFP, hCG, uE3 (and where available INH-A) were screen-positive for either Down syndrome or trisomy 18. The findings are discussed in the context of expected differences between digynic and diandric triploidy. It is suggested that the sex chromosome complement in triploidy is an important factor in determining risk for partial mole development and in utero survival. Copyright © 2001 John Wiley & Sons, Ltd.     

Characteristics of nitrate horizontal transport in a paddy field of the Tai Lake region,China

The characteristics of nitrate horizontal transport in a major paddy soil, Wu Shan soil in the Tai Lake region, were studied. The concentration of nitrate during horizontal movement decreased with the increasing in distance from the tracer source, the change following a logarithmic function. The concentration of the nitrate was strongly correlated with the soil moisture content, as an exponential function. The horizontal transport velocity of nitrate was significantly correlated with the distance of the tracer source as power function. Therefore, the velocity of nitrate horizontal transport was controlled by the concentration gradient of nitrate, and soil water potential gradient from beginning to the 20 cm mark in the horizontal column. However, the velocity of nitrate horizontal was stable beyond 20 cm, where it was controlled by soil matric potential.     

Validation of germination rate and root elongation as indicator to assess phytotoxicity with Cucumis sativus

Germination rate and root elongation, as a rapid phytotoxicity test method, possess several advantages, such as sensitivity, simplicity, low cost and suitability for unstable chemicals or samples. These advantages made them suitable for developing a large-scale phytotoxicity database and especially applicable for developing quantitative structure–activity relationship (QSAR) to study mechanisms of phytotoxicity. In this paper, the comparative inhibition of germination rate and root elongation of Cucumis sativus by selected halogen-substituted phenols and anilines were determined. The suitability of germination rate and root elongation as phytotoxicity endpoints was evaluated. Excellent reproducibility and stability of germination rate and root elongation in the control test, relatively greater sensitivity and similar dose–response relations for all tested compounds were observed. These results together with those of a 2-day test were used to demonstrate the suitability of this phytotoxicity test method. A QSAR was developed for the phytotoxicity mode of action of the tested compounds to C. sativus seeds. Models that combined the logarithm of 1-octanol/water partition coefficient (log K_ow) and the energy of the lowest unoccupied molecular orbital (E_lumo) were developed for both germination rate inhibition and root elongation inhibition. The results of these studies indicate that phytotoxicity of substituted phenols and anilines to C. sativus seeds could be explained by a polar narcosis mechanism. This paper will promote the application of germination rate and root elongation method and the development of large-scale phytotoxicity database, which will provide the fundamental data for QSAR and ecological risk assessment of organic pollutants.     

Comparison of two biological treatment processes using attached-growth biomass for sanitary landfill leachate treatment

The objective of this investigation was to compare two biological systems using attached-growth biomass, for treatment of leachates generated in a typical municipal solid waste sanitary landfill. A moving-bed biofilm process, which is a relatively new type of biological treatment system, has been examined. It is based on the use of small, free-floating polymeric (polyurethane) elements, while biomass is being grown and attached as biofilm on the surface of these porous carriers. A granular activated carbon (GAC) moving-bed biofilm process was also tested. This method combines both physico-chemical and biological removal mechanisms for the removal of pollutants. The presence of GAC offers a suitable porous media, which is able to adsorb both organic matter and ammonia, as well as to provide an appropriate surface onto which biomass can be attached and grown. A laboratory-scale sequencing batch reactor (SBR) was used for the examination of both carriers. The effects of different operation strategies on the efficiency of these biological treatment processes were studied in order to optimize their performance, especially for the removal of nitrogen compounds and of biodegradable organic matter. It has been found that these processes were able to remove nitrogen content almost completely and simultaneously, the removal of organic matter (expressed as BOD5 and COD), color and turbidity were sufficiently achieved.