Enrichment of vermicomposts prepared from cow dung spiked solid textile mill sludge using nitrogen fixing and phosphate solubilizing bacteria

Textile mill waste can be vermicomposted if it is mixed in the range of 20–30% with cow dung. This article reports the effect of inoculation, of nitrogen fixing Azotobacter chroococcum strain; Azospirillum brasilense strain and phosphate solubilizing Pseudomonas maltophila, on nitrogen and phosphorus content of vermicomposts prepared from cow dung (CD) and cow dung spiked textile mill sludge (CD + STMS). The CD vermicompost was more supportive to the growth and multiplication of all the three bacteria than CD + STMS vermicompost. In Azotobacter chroococcum treated vermicomposts maximum nitrogen content was recorded between 45 and 60 days [CD␣vermicompost (25.9 ± 0.45 g kg⁻¹) and CD + STMS vermicompost (20.6 ± 0.62 g kg⁻¹)] followed by Azospirillum brasilense inoculation [CD vermicompost (19.4 ± 0.60 g kg⁻¹) and CD + STMS vermicompost (18.6 ± 0.17 g kg⁻¹)]. Phosphorus content in Pseudomonas maltophila inoculated CD vermicompost was 20.8 ± 0.20 g kg⁻¹ and CD + STMS vermicompost was 13.4 ± 0.45 g kg⁻¹ after 75th day of inoculation.     

应用FISH法对污水生物处理系统中细菌数量的计数

近年来,FISH(Fluorescence in Situ Hybridization,荧光原位杂交)法作为一种应用分子生物学技术对细胞及细菌等微生物进行定性以及定量分析的研究方法,在国际上得到广泛的应用。本文介绍了应用FISH法对污水处理工艺中细菌数量的计数方法。同时介绍了活性污泥试样制作、FISH法观测试样的制作以及各种试剂的配制、作用以及使用方法,基因探针的选择原则、杂交方法等实际操作方法与过程。     

Effects of surfactants on the combined toxicity of TiO2 nanoparticles and cadmium to Escherichia coli

The combined ecological toxicity of TiO₂ nanoparticles (nano-TiO₂) and heavy metals has been paid more attention. As the common pollutants in water environment, surfactants could affect the properties of nanoparticles and heavy metals, and thus further influence the combined toxicity of nano-TiO₂ and heavy metals. In this study, the effects of sodium dodecyl benzene sulfonate (SDBS) and Tween 80 on the single and combined toxicities of Cd^2 + and nano-TiO₂ to Escherichia coli (E. coli) were examined, and the underlying influence mechanism was further discussed. The results showed both SDBS and Tween 80 enhanced the toxicity of Cd^2 + to E. coli in varying degrees. The reaction of SDBS and Cd^2 + could increase the outer membrane permeability and the bioavailability of Cd, while Tween 80 itself could enhance the outer membrane permeability. The combined toxicity of nano-TiO₂ and Cd^2 + to E. coli in absence of surfactant was antagonistic because of the adsorption of Cd^2 + to nano-TiO₂ particles. However, in the presence of SDBS, both SDBS and nano-TiO₂ influenced the toxicity of Cd^2 +, and also SDBS could adsorb to nano-TiO₂ by binding to Cd^2 +. The combined toxicity was reduced at Cd^2 + lower than 4 mg/L and enhanced at Cd^2 + higher than 4 mg/L under multiple interactions. Tween 80 enhanced the combined toxicity of nano-TiO₂ and Cd^2 + by increasing the outer membrane permeability. Our study firstly elucidated the effects of surfactants on the combined toxicity of nano-TiO₂ and Cd^2 + to bacteria, and the underlying influencing mechanism was proposed.     

Self-purification ability of a resurgence stream

The self-purification ability of a resurgence stream has been investigated by taking samples along the course of a channeled tract made up of a first part in beaten soil (3.3 km) and a second in concrete (7.2 km). The study has been conducted by statistically processing pre-existent data, acquired monthly by analyzing waters at the beginning and at the end of the whole canal for 6 years, from 1995 to 2000 (historic data), and by performing specific experiments (recent data) to evaluate differently the self-purification capacity of the beaten soil section and that in concrete. A significant abatement of concentrations has been observed from historic data for ammonium, phosphates, turbidity, heavy metals and bacteria. From the recent data, all these parameters seem to decrease in the beaten soil tract. Whereas significant further decreases in the concrete tract were observed only for ammonium, phosphates and bacteria. For other parameters, e.g. pH, dissolved oxygen, chlorides, fluorides, sodium, and sulfates, a significant increase was observed from the historic data.     

高效工程菌的构建及其降解有机农药的研究进展

综述了目前环境治理保护中构建高效工程菌常用的质粒转移、原生质体融合和基因重组等方法。介绍了工程菌在处理有机农药污染方面的降解性能及其固定化研究,并简要阐述了工程菌改造及应用方面所存在的问题及未来的研究展望。     

Bioelectricity generation from three ornamental plants: Chlorophytum comosum,Chasmanthe floribunda and Papyrus diffusus

In the present study, bioelectricity generation using a living plant in soil was achieved by converting solar energy into electricity on the principles of plant photosynthesis. The plants Chlorophytum comosum, Chasmanthe floribunda and Papyrus diffuses were used in microbial fuel cells (MFCs) and produced, respectively, a maximum current of 25, 31 and 19 mA/m², without the use of any nutrient or membrane. In this study, the importance of light was demonstrated by the high current values generated during daytime, and the microorganisms at the anode-rhizosphere interface were examined.     

Cell concentration, viability and culture composition of airborne bacteria during a dust event in Beijing

Airborne bacteria were measured when a dust storm passed Beijing in spring 2012 with a focus on cell concentration,viability and TSA-and R2A-cultured strain composition.The concentration varied at an order of 10~7 cells/m~3 with dust loading(demonstrated with PM_(10))and they had a very close correlation(R_T~2 = 0.91,p 0.01).At the time of highest PM_(10) of652 μg/m~3,the bacterial concentration reached 1.4 × 10~8 cells/m~3,which was larger than that before and after the dust event by one order.Bacterial viability,the ratio of number concentration of viable cells to total cells,was 32%-64%and smaller in the dust plume than that before the dust arrival.Bacterial strains from the culture ranged between 2.5 x 104 and4.6×10~5 CFU/m~3 and no correlation with PM_(10) was determined.Their composition was different before and after the dust arrival according to 16SrRNA gene sequences and strains belong to Actinomycetes and Firmicutes were the majority in the dust samples.     

Hydroxyquinol Pathway for Microbial Degradation of Halogenated Aromatic Compounds

Several peripheral metabolic pathways can be used by microorganisms to degrade toxic aromatic compounds that are known to pollute the environment. Hydroxyquinol (1,2,4-trihydroxybenzene) is one of the central intermediates in the degradative pathway of a large variety of aromatic compounds. The present review describes the microorganisms involved in the degradative pathway, the key enzymes involved in the formation and splitting of the aromatic ring of (chloro)hydroxyquinol as well as the central intermediates formed. An attempt was also made to provide some estimation for genetic basis of the hydroxyquinol pathway.     

Bacterial resistance to lead: Chemical basis and environmental relevance

Natural bacterial isolates from heavily contaminated sites may evolve diverse tolerance strategies, including biosorption, efflux mechanism, and intracellular precipitation under the continually increased stress of toxic lead (Pb) from anthropogenic activities. These strategies utilize a large variety of functional groups in biological macromolecules (e.g., exopolysaccharides (EPSs) and metalloproteins) and inorganic ligands, including carboxyl, phosphate and amide groups, for capturing Pb. The amount and type of binding sites carried by biologically originated materials essentially determines their performance and potential for Pb removal and remediation. Many factors, e.g., metal ion radius, electronegativity, the shape of the cell surface sheath, temperature and pH, are thought to exert significant influences on the abovementioned interactions with Pb. Conclusively, understanding the chemical basis of Pb-binding in these bacteria can allow for the development of effective microbial Pb remediation technologies and further elucidation of Pb cycling in the environment.     

焦化废水生物脱氮工艺反硝化段菌相分析

对焦化废水反硝化段的试样进行了细菌数量及菌相分析研究，对反硝化细菌在反硝化段生态环境中的分布进行了探讨。试验共分离出２３株菌株，分别属于７个属，其中假单胞菌和芽孢杆菌为主要优势菌，分别占总鉴定菌数的３９．１％和２１．７％，反硝化细菌共有１１株，占总鉴定菌数４７．８％。