Microbial community dynamics during the bioremediation process of chlorimuron-ethyl-contaminated soil by Hansschlegelia sp. strain CHL1.

Long-term and excessive application of chlorimuron-ethyl has led to a series of environmental problems. Strain Hansschlegelia sp. CHL1, a highly efficient chlorimuron-ethyl degrading bacterium isolated in our previous study, was employed in the current soil bioremediation study. The residues of chlorimuron-ethyl in soils were detected, and the changes of soil microbial communities were investigated by phospholipid fatty acid (PLFA) analysis. The results showed that strain CHL1 exhibited significant chlorimuron-ethyl degradation ability at wide range of concentrations between 10μg kg-1 and 1000μg kg-1. High concentrations of chlorimuron-ethyl significantly decreased the total concentration of PLFAs and the Shannon-Wiener indices and increased the stress level of microbes in soils. The inoculation with strain CHL1, however, reduced the inhibition on soil microbes caused by chlorimuron-ethyl. The results demonstrated that strain CHL1 is effective in the remediation of chlorimuron-ethyl-contaminated soil, and has the potential to remediate chlorimuron-ethyl contaminated soils in situ

Dynamic changes in microbial communities during the bioremediation of herbicide (chlorimuron-ethyl and atrazine) contaminated soils by combined degrading bacteria.

Chlorimuron-ethyl and atrazine are two herbicides with long half-lives in soil; their long-term and excessive application has led to a series of environmental problems. In this study, the strains Chenggangzhangella methanolivorans CHL1 and Arthrobacter sp. ART1 were combined and used for the remediation of chlorimuron-ethyl, atrazine and combined contaminated soils in a microcosm experiment. Changes in chlorimuron-ethyl and atrazine concentrations in soils were monitored, and variations in the soil microbial community were studied by phospholipid fatty acid (PLFA) analysis. The two inoculated degrading strains accelerated the degradation of chlorimuron-ethyl and atrazine in soil, especially in the combined contaminated soil. Addition of the two herbicides and their combination generally decreased the concentrations of total PLFAs, total bacterial PLFAs, Gram-negative and Gram-positive bacterial PLFAs and Shannon-Wiener indices, and changed microbial community composition, whilst stimulating fungal PLFA concentrations. In addition, the combined herbicide treatment had more impact on microbial biomass than the single herbicide treatments. Inoculation treatments significantly relieved the effects of herbicides on soil microbial biomass, diversity and community structure. This study demonstrated that strains CHL1 and ATR1 have the potential to remediate chlorimuron-ethyl, atrazine and combined contaminated soils, and provided valuable information for remediation of chlorimuron-ethyl, atrazine and combined contaminated soils in situ

A Facile Electrochemical Sensor Labeled by Ferrocenoyl Cysteine Conjugate for the Detection of Nitrite in Pickle Juice

Simple and facile electrochemical sensors for nitrite detection were fabricated by directly depositing ferrocenoyl cysteine conjugates Fc[CO-Cys(Trt)-OMe]2 [Fc(Cys)2] or Fc[CO-Glu-Cys-Gly-OH] [Fc-ECG] on screen-printed electrodes (SPEs). The modified carbon electrodes were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Results indicated that Fc-ECG/SPE sensor showed enhanced current response and a lower overpotential than Fc(Cys)2/SPE sensor for nitrite detection. Optimal operating conditions were estimated for nitrite detection by DPV. The concentration of nitrite showed a good linear relationship with the current response in the range of 1.0–50 μmol·L−1 and with 0.3 μmol·L−1 as the concentration for limit of detection. There were no interferences from most common ions. The development of this electrochemical sensor was used for nitrite detection in pickled juice with a R.S.D. lower than 2.1% and average recovery lower than 101.5%, which indicated that disposable electrochemical sensor system can be applied for rapid and precise nitrite detection in foods

Comparison of Physicochemical Properties and Immunomodulatory Activity of Polysaccharides from Fresh and Dried Litchi Pulp

Drying is commonly used for preservation and processing of litchi. However, its polysaccharide structure may be altered by the drying process, resulting in biological activity changes. Polysaccharides from fresh and dried litchi pulp (denoted as LPF and LPD, respectively) were isolated, investigated by GC-MS, GPC and UV/IR spectrum analysis and their antitumor and immunomodulatory activities were evaluated in vitro. LPD, the molecular weight of which was lower than that of LPF, contained more protein, uronic acid, arabinose, galactose and xylose. Compared with LPF, LPD exhibited a higher inhibitory effect on the proliferation of HepG2, Hela and A549 cells from 50–750 μg/mL. LPD was also a better stimulator of spleen lymphocyte proliferation, NK cells cytotoxicity and macrophage phagocytosis from 50–400 μg/mL. In summary, drying could change the physicochemical properties and enhance the bioactivity of polysaccharides from litchi pulp. This finding is supported by the fact that dried litchi pulps are used in Traditional Chinese Medicine

Multivariate analysis of variance by three-way ANOVA of the sum of all PLFAs, ratios of GN/GP and bacteria/fungi, the stress level and the Shannon index.

<p>*The categorical factors are inoculation with strain CHL1, treatment (S₀, S₁₀, S₃₀, S₅₀, S₁₀₀, S₁₀₀₀), incubation time (1, 7, 15, 30, 45, 60 days). Presented are the F-values with the level of significance.</p><p>Multivariate analysis of variance by three-way ANOVA of the sum of all PLFAs, ratios of GN/GP and bacteria/fungi, the stress level and the Shannon index.</p

Values of the Shannon-Wiener index of microbes in treated soils inoculation with strain CHL1 (b) or not (a).

<p>Symbols represent the mean of triplicate samples and error bars indicate the standard deviation. S₁₀, S₃₀, S₅₀, S₁₀₀, S₁₀₀₀ mean 10, 30, 50, 100, 1000μg kg^-1 chlorimuron-ethyl treatment group, respectively. ‘-’ indicates without strain CHL1 inoculation; ‘+’ indicates inoculation with strain CHL1.</p

The degradation of chlorimuron-ethyl in treated soils.

<p>Values represent the mean (±SD) of three replicates.</p><p>*S₁₀, S₃₀, S₅₀, S₁₀₀, S₁₀₀₀ mean 10, 30, 50, 100, 1000μg kg^-1 chlorimuron-ethyl treatment group, respectively. ‘-’ indicates without strain CHL1 inoculation; ‘+’ indicates inoculation with strain CHL1.</p><p>The degradation of chlorimuron-ethyl in treated soils.</p

Values of total PLFAs biomass in treated soils inoculation with strain CHL1 (b) or not (a).

<p>Symbols represent the mean of triplicate samples and error bars indicate the standard deviation. S₁₀, S₃₀, S₅₀, S₁₀₀, S₁₀₀₀ mean 10, 30, 50, 100, 1000μg kg^-1 chlorimuron-ethyl treatment group, respectively. ‘-’ indicates without strain CHL1 inoculation; ‘+’ indicates inoculation with strain CHL1.</p

Values of Gram negative bacteria (GN), Gram positive bacteria (GP) and the rate of GN and GP in treated soils inoculation with strain CHL1 (b, d, f) or not (a, c, e).

<p>Symbols represent the mean of triplicate samples and error bars indicate the standard deviation. S₁₀, S₃₀, S₅₀, S₁₀₀, S₁₀₀₀ mean 10, 30, 50, 100, 1000μg kg^-1 chlorimuron-ethyl treatment group, respectively. ‘-’ indicates without strain CHL1 inoculation; ‘+’ indicates inoculation with strain CHL1.</p

PCA plot of the microbial community structure of all treatments on days 7, 30 and 60.

<p>S₀, S₁₀, S₃₀, S₅₀, S₁₀₀ and S₁₀₀₀ mean 0, 10, 30, 50, 100 and 1000μg kg^-1 chlorimuron-ethyl treatment group, respectively. ‘-’ indicates without strain CHL1 inoculation; ‘+’ indicates inoculation with strain CHL1.</p