Yeasts as a model for assessing the toxicity of the fungicides Penconazol, Cymoxanil and Dichlofluanid

In the present work the sensitivity of yeast strains of Kluyveromyces marxianus, Pichia anomala, Candida utilis, Schizosaccharomyces pombe and Saccharomyces cerevisiae, to the fungicides cymoxanil, penconazol, and dichlofluanid, was evaluated. Dichlofluanid induced the most negative effects, whereas penconazol in general was not very toxic. Overall, our results show that the parameters IC50 for specific respiration rates of C. utilis and S. cerevisiae and C(D) for cell viability of S. cerevisiae can be applied to quantify the toxicity level of the above compounds in yeast. Hence, could be explored as an alternative or at least as a complementary test in toxicity studies and, therefore, its potential for inclusion in a tier testing toxicity test battery merits further research.     

Isolation and characterization of biarylic structure-degrading yeasts: hydroxylation potential of dibenzofuran

Yeast communities from heavily polluted sediments that received the discharge from oil refineries and other industries were studied. Yeast species were isolated from these sediments and their ability to degrade dibenzofuran were determined. Twenty-four different yeast strains were isolated and cultured on aromatic medium; two Candida krusei strains. Candida tenuis, Candida tropicalis, two Pichia anomala strains, Pichia haplophila, two Rhodotorula glutinis strains, Rhodotorula mucilaginosa, two Trichosporon pullulans strains and Yarrowia lipolytica were able to hydroxylate dibenzofuran. Three metabolites were identified by HPLC analysis: 3-hydroxydibenzofuran was in all the cases the most abundant isomer, and while 4-hydroxydibenzofuran was also common, 2-hydroxydibenzofuran was detected in very small quantities and with few species. In the R. glutinis and Y. lipolytica cultures a ring cleavage product was also found. While in the R. gluttinis assays the hydroxydibenzofuran was detected earlier, at 2 days' incubation time, in the other yeast experiments they were observed at the 4-5th incubation days with the maximum amounts at the 7th day. Our results confirmed the ability of autochthonous yeast species to hydroxylate dibenzofuran and to cleave the rings, and it is the first report for C. krusei, C. tenuis, P. anomala, P. haplophila and R. mucilaginosa. The ecological relevance of this study is based on the fact that dibenzofuran is a xenobiotic not easily transformed, so the catabolic activities observed in authochonous yeasts contribute to broadening the biodegradable substrate spectrum.     

非固定化和固定化啤酒酵母对Cd^2＋和Cu^2＋的吸附特性研究

对比了不同吸附剂对重金属的吸附效果，同时研究了啤酒酵母的固定化方法、菌体用量对吸附效果的影响、非同定化和固定化啤酒酵母吸附热力学特性。研究结果表明，非固定化死啤酒酵母对Cd^2＋的单位菌体吸附量是常用吸附剂活性炭的3倍；由1：3的海藻酸钠与碱处理啤酒酵母（w／w）制得的固定化颗粒吸附效果最好；菌体用量的增加会降低单位菌体对重金属的吸附量；啤酒酵母对重金属的吸附位点有限，Cd^2＋的实际最大吸附量为13．95mg／g，Cu^2＋为7．67μg／g。非固定化和固定化啤酒酵母对Cu^2＋和Cd^2＋的等温吸附过程均可用Linear方程、Langmuir方程和Freundlich方程来进行拟合，但非同定化啤酒酵母以Langmuir方程最优，其拟合计算的最大吸附量qmzxCd和qmxxCu分别为13．96mg／g和8．01mg／g；固定化啤酒酵母以Freundlich方程最优，实际最大吸附量Cd为75．41mg／g，Cu为66．58mg／g。     

Biodegradation of C.I. Acid Red 1 by indigenous bacteria <Emphasis Type="Italic">Stenotrophomonas</Emphasis> sp. BHUSSp X2 isolated from dye contaminated soil

A significant proportion of xenobiotic recalcitrant azo dyes are being released in environment during carpet dyeing. The bacterial strain Stenotrophomonas sp. BHUSSp X2 was isolated from dye contaminated soil of carpet industry, Bhadohi, India. The isolated bacterial strain was identified morphologically, biochemically, and on the basis of 16S rRNA gene sequence. The isolate decolorized 97 % of C.I. Acid Red 1 (Acid RED G) at the concentration of 200 mg/l within 6 h under optimum static conditions (temperature ?35 °C, pH 8, and initial cell concentration 7?×?10⁷ cell/ml). Drastic reduction in dye degradation rate was observed beyond initial dye concentration from 500 mg/l (90 %), and it reaches to 25 % at 1000 mg/l under same set of conditions. The analysis related to decolorization and degradation was done using UV-Vis spectrophotometer, HPLC, and FTIR, whereas the GC-MS technique was utilized for the identification of degradation products. Phytotoxicity analysis revealed that degradation products are less toxic as compared to the original dye.     

Kinetics of basic dye (methylene blue) biosorption by giant duckweed (Spirodela polyrrhiza)

Wastewater containing pigments and/or dyes can cause serious water pollution problems in the form of reduced light penetration and photosynthesis, and the toxicity from heavy metals associated with pigments and/or dyes. Laboratory investigations, of the potential use of dried Spirodela polyrrhiza biomass as an adsorbent for the removal of the basic dye methylene blue from aqueous solution were conducted. A series of experiments were undertaken in an agitated batch adsorber to assess the effect of the system variables, i.e. sorbent dosage, pH, and contact time. The results showed that as the amount of the dried S. polyrrhiza increased, the percentage of dye sorption increased accordingly. At pH 2.0 the sorption of dye was not favorable, while the sorption at other pHs (3.0-11.0) was remarkable. There was no significant difference in the dye concentration remaining when the pH was increased from 3.0 to 11.0. The dye removal time was influenced by the initial dye concentration, and the process followed the first-order rate kinetics. The rate constants for intraparticle diffusion were 1.00 and 3.27 mg/g/min1/2 for 300 and 500 mg/l of dye, respectively.     

Biosorption of alpacide blue from aqueous solution by lignocellulosic biomass: <Emphasis Type="Italic">Luffa cylindrica</Emphasis> fibers

The aim of the present work is to develop an effective and inexpensive pollutant-removal technology using lignocellulosic fibers: Luffa cylindrica, for the biosorption of an anionic dye: alpacide blue. The influence of some experimental parameters such as pH, temperature, initial concentration of the polluted solution, and mass of the sorbent L. cylindrica on the biosorption of alpacide blue by L. cylindrica fibers has been investigated. Optimal parameters for maximum quantity of biosorption dye were achieved after 2 h of treatment in a batch system using an initial dye concentration of 20 mg/L, a mass of 1 g of L. cylindrica fibers, and pH 2. In these conditions, the quantity of dye retained is 2 mg/g and the retention rate is 78 %. Finally, a mathematical modeling of kinetics and isotherms has been used for mathematical modeling; the model of pseudo-second order is more appropriate to describe this phenomenon of biosorption. Concerning biosorption isotherms, the Freundlich model is the most appropriate for a biosorption of alpacide blue dye by L. cylindrica fibers.     

Phytoremediation potential of Spirulina (Arthrospira) platensis: biosorption and toxicity studies of cadmium

This study examines the possibility of using Spirulina (Arthrospira) platensis TISTR 8217 to remove low concentrations of cadmium (less than 100 mg/l) from wastewater. The cyanobacteria were exposed to six different cadmium concentrations for 96 h, and the growth rate was determined using an optical density at 560 nm. The inhibiting concentration (IC50) was estimated using probit analysis. The IC50 at 24, 48, 72, and 96 h were 13.15, 16.68, 17.28, and 18.35 mg/l Cd, respectively. Cellular damage was studied under a light microscope and a transmission electron microscope. Swollen cells and fragmented filaments were observed. Cell injury increased with increasing concentrations of cadmium. Ultrastructural changes were observed in the algae exposed to cadmium concentrations both close to IC50 (14.68 mg/l) and at IC50 (18.35 mg/l). The alterations induced by cadmium were disintegration and disorganization of thylakoid membranes, presence of large intrathylakoidal space, increase of polyphosphate bodies, and cell lysis. In addition, the cadmium adsorption by algal cells was studied. Environmental factors were found to have an effect on biosorption. The uptake of cadmium was not affected by the temperature of the solution, but the sorption was pH dependent. The optimum pH for biosorption of algal cells was 7. The cadmium uptake process was rapid, with 78% of metal sorption completed within 5 min. The sorption data fit well to the Langmuir isotherm. The maximum adsorption capacity for S. platensis was 98.04 mg Cd per g biomass.     

Thermal and spectroscopic studies on sorption of nickel(II) ion on protonated baker's yeast

Protonated form (Hy) of yeast was subjected to thermal analysis (TGA and DTG) in the temperature range 60–800 °C. Chemically bound water volatilizes around 200 °C and the matrix undergoes extensive oxidative decomposition at 450 °C, the weight loss reaching 75% at 800 °C. The sorption capacity of the matrix for nickel(II) ion increases on heat treatment from 60 to 200 °C (from 16.9 to 25.0 mg/g), but was reduced on heating to higher temperatures at an initial nickel(II) ion concentration of 1200 mg/g. The FTIR spectra of Hy and nickel(II) ion saturated yeast, indicated that biosorption occurs on the sugar and nucleic acid regions, possibly involving –COOH and –NH groups.     

Biosorption of synthetic dyes (Direct Red 89 and Reactive Green 12) as an ecological refining step in textile effluent treatment

With the use of cost-effective natural materials, biosorption is considered as an ecological tool that is applied worldwide for the remediation of pollution. In this study, we proposed Lemna gibba biomass (LGB), a lignocellulosic sorbent material, for the removal of two textile dyes, Direct Red 89 (DR-89) and Reactive Green 12 (RG-12). These azo dyes commonly used in dying operations of natural and synthetic fibres are the most important pollutants produced in textile industry effluents. For this purpose, batch biosorption experiments were carried out to assess the efficacy of LGB on dye treatment by evaluating the effect of contact time, biomass dosage, and initial dye concentration. The results indicated that the bioremoval efficiency of 5 mg?L^?1 DR-89 and RG-12 reached approximately 100 % after 20 min of the exposure time; however, the maximum biosorption of 50 mg?L^?1 DR-89 and 15 mg?L^?1 RG-12 was determined to be about 60 and 47 %, respectively. Fourier transform infrared spectroscopy used to explain the sorption mechanism showed that the functional groups of carboxylic acid and hydroxyl played a major role in the retention of these pollutants on the biomass surface. The modelling results using Freundlich, Langmuir, Temkin, Elovich, and Dubini Radushkevich (D-R) isotherms demonstrated that the DR-89 biosorption process was better described with the Langmuir theory (R ²?=?0.992) while the RG-12 biosorption process fitted well by the D-R isotherm equation (R ²?=?0.988). The maximum biosorption capacity was found to be 20.0 and 115.5 mg?g^?1 for DR-89 and RG-12, respectively, showing a higher ability of duckweed biomass for the bioremoval of the green dye. The thermodynamic study showed that the dye biosorption was a spontaneous and endothermic process. The efficacy of using duckweed biomass for the bioremoval of the two dyes was limited to concentrations ≤50 mg?L^?1, indicating that L. gibba biomass may be suitable in the refining step of textile effluent treatment.     

从矿区土壤中筛选微生物对Pb^2＋、Zn^2＋吸附的研究

从铅锌矿区土壤中分离到12株细菌和10株真菌,通过其干菌体对Pb^2＋和Zn^2＋的吸附试验,筛选出具有较强生物吸附能力的细菌菌株B6和真菌菌株F1。探讨了pH值、吸附时间、菌量和Pb^2＋、Zn^2＋的初始浓度对B6和F1菌株的吸附影响,结果表明：2株菌对Pb^2＋、Zn^2＋吸附是一个快速的过程,pH值为5.0-6.0是菌体吸附的较适范围。Pb^2＋、Zn^2＋初始浓度在150-300 mg/L内,B6和F1菌株吸附效果明显。当B6菌株的菌量超过0.1 g,F1菌株的菌量超过0.2 g后吸附率趋于平缓。应用Langmuir和Freundlich吸附等温线研究,Langmuir吸附等温线更为适合模拟B6和F1菌株的吸附过程。B6和F1菌株吸附Pb^2＋、Zn^2＋的动力学过程都可以用准二级动力学方程进行描述。16S rDNA基因序列分析表明,B6菌株属于里拉微球菌（Micrococcus lylae）。用形态及理化特征鉴定,F1菌株属于镰刀霉菌属（Fusarium sp.）。     

产朊假丝酵母处理马铃薯淀粉废水

研究了pH、接种量、无机盐(通过加入磷酸二氢钾进行无机盐补充)及DO等对产朊假丝酵母处理马铃薯淀粉废水的影响.结果表明.在pH为5.0、产朊假丝酵母接种量为10%(体积分数)、磷酸二氢钾(质量分散为0.1%)加入量为0.5 g/L、废水不灭菌的条件下,废水处理效果和产朊假丝酵母生长最佳.且当废水COD为5 074 mg/L时,COD去除率达到74.86%,同时可获得2.23g/L的单细胞蛋白.产朊假丝酵母处理马铃薯淀粉废水的最佳条件的实验研究对实现马铃薯淀粉废水资源化利用提供了理论参考.     

Characterization of a simple bacterial consortium for effective treatment of wastewaters with reactive dyes and Cr(VI)

A microbial consortia consisting of three bacteria isolated from tanning and textile wastewaters revealed high capacity to simultaneously bioaccumulate dye and Cr(VI). The identity of the bacteria were determined by 16S rRNA gene analysis to be closely related to Ochrobactrium sp., Salmonella enterica and Pseudomonas aeruginosa. Dependence of initial pH values and range of concentrations of the dye Reactive Black B (33.2-103.1 mg l(-1)) and Cr(VI) (19.9-127.6 mg l(-1)) were examined to find the effect of pH on the dye and Cr(VI) bioaccumulation. Optimal pH for growth of the consortia in media containing 35 mg l(-1) dye and 50 mg l(-1) Cr(VI) was determined to be around 8. The Cr(VI) bioaccumulation by the consortia was rapid in media containing molasses with or without reactive dye with a maximum Cr(VI) bioaccumulation yield ranging from 90% to 99% within a 2-4d period. A slightly lower yield for the dye bioaccumulation was measured with a maximum dye bioaccumulation of 80% at 59.3 mg l(-1) dye and 69.8 mg l(-1) Cr(VI). The highest specific Cr uptake value was obtained as 76.7 mg g(-1) at 117.1 mg l(-1) Cr(VI) and 50.8 mg l(-1) dye concentration. This ability to bioaccumulate dye and Cr(VI) was more efficient than the enriched sludge from which they were isolated.     

固定化啤酒酵母菌对锶的吸附机制及热力学研究

以聚乙烯醇和海藻酸钠作为载体,制备了固定化啤酒酵母菌颗粒。研究了固定化啤酒酵母菌对锶的吸附机制和吸附热力学。结果表明:(1)吸附Sr2+后的固定化啤酒酵母菌的内部结构更松散,更有利于固定化啤酒酵母菌对Sr2+的吸附。(2)固定化啤酒酵母菌吸附Sr2+后,部分-OH参与了吸附,使形成的氢键部分断开,振动峰发生蓝移。另外,由于-NH2和-CO-NH-中的N原子可提供孤对电子与有空轨道的Sr2+配位,从而改变了基团的极性。(3)当Sr2+初始质量浓度为10～200mg/L时,固定化啤酒酵母菌对Sr2+的吸附同时符合Freundlich和Langmuir吸附模型,但符合Langmuir吸附模型的程度更优,这说明固定化啤酒酵母菌与Sr2+之间主要通过分子间引力产生吸附,是以单分子层吸附为主的物理吸附。     

Biosorption of strontium from aqueous solution by fungus Aspergillus terreus

INTRODUCTION: The biosorption characteristics of strontium ions using fungus Aspergillus terreus were investigated. Experimental parameters affecting the biosorption process such as pH, contact time, initial metal concentration, and temperature were studied. MATHEMATICAL DESCRIPTION: Fungus A. terreus exhibited the highest strontium uptake capacity at 15°C at an initial strontium ion concentration of 876 mg L(-1) and an initial pH of 9. Biosorption capacity increased from 219 to 308 mg g(-1) with a decrease in temperature from 45°C to 15°C at this initial strontium concentration. The equilibrium data fitted very well to the Langmuir adsorption model in the concentration range of strontium ions and at all the temperatures studied. CONCLUSION: Evaluation of the experimental data in terms of biosorption dynamics showed that the biosorption of strontium onto fungus followed the pseudo-second-order dynamics well (R(2)?>?0.985). The calculated thermodynamics parameters (-1.64?相似文献   

Biological decolourisation of simulated azo dye in aqueous phase by algae Spirogyra species

Biological decolourisation of two azo dye effluents (direct and reactive dye) were investigated using a commonly available green algae Spirogyra sp. in viable form. Batch studies revealed the potential of algal species in removing the dye colour and dye removal was dependant on initial algal inoculum, concentration and application class of the dye. Maximum dye uptake was noticed on the third day for both the dyes. Higher dye uptake was observed in the case of direct red 28 compared to reactive red 2. Dye colour removal by the algal species may be attributed to biosorption of the dye molecules onto the surface of algal cell and subsequent diffusion and participation in metabolism (bioconversion). The remaining dye molecules could be further removed from the aqueous phase by adsorption and/or chelation reaction of the exopolymers released by the algae (biocoagulation). The results of the present study reveal the potential nature of algae in treating azo dyes which in turn can be extended to oxidation pond system of wastewater treatment.     

Removal of cationic dyes from aqueous solutions using microspherical particles of fly ash

Batch sorption experiments were carried out for the removal of cationic dyes (methylene blue and malachite green) from their aqueous solutions using sorbent made from fly ash-a waste material. Effects of various experimental parameters: initial dye concentration, contact time, pH, adsorbent dosage, solution temperature, surfactant addition and ionic strength on the fly ash sorption of dyes were evaluated. The isothermal data for sorption followed the Langmuir model. The maximum sorption capacity obtained for methylene blue and malachite green was 36.05 mg/g and 40.65 mg/g, respectively. Kinetic studies indicate that sorption on fly ash follows the pseudo-second order kinetics. Present research suggests that fly ash could be an appropriate adsorbent for the removal of basic dyes from aqueous solutions.     

Comparative performance evaluation of Aspergillus lentulus for dye removal through bioaccumulation and biosorption

Dyes used in various industries are discharged into the environment and pose major environmental concern. In the present study, fungal isolate Aspergillus lentulus was utilized for the treatment of various dyes, dye mixtures and dye containing effluent in dual modes, bioaccumulation (employing growing biomass) and biosorption (employing pre-cultivated biomass). The effect of dye toxicity on the growth of the fungal isolate was studied through phase contrast and scanning electron microscopy. Dye biosorption was studied using first and second-order kinetic models. Effects of factors influencing adsorption and isotherm studies were also conducted. During bioaccumulation, good removal was obtained for anionic dyes (100 mg/l), viz. Acid Navy Blue, Fast Red A and Orange-HF dye (99.4 %, 98.8 % and 98.7 %, respectively) in 48 h. Cationic dyes (10 mg/l), viz. Rhodamine B and Methylene Blue, had low removal efficiency (80.3 % [48 h] and 92.7 % [144 h], respectively) as compared to anionic dyes. In addition to this, fungal isolate showed toxicity response towards Methylene Blue by producing larger aggregates of fungal pellets. To overcome the limitations of bioaccumulation, dye removal in biosorption mode was studied. In this mode, significant removal was observed for anionic (96.7–94.3 %) and cationic (35.4–90.9 %) dyes in 24 h. The removal of three anionic dyes and Rhodamine B followed first-order kinetic model whereas removal of Methylene Blue followed second-order kinetic model. Overall, fungal isolate could remove more than 90 % dye from different dye mixtures in bioaccumulation mode and more than 70 % dye in biosorption mode. Moreover, significant color removal from handmade paper unit effluent in bioaccumulation mode (86.4 %) as well as in biosorption mode (77.1 %) was obtained within 24 h. This study validates the potential of fungal isolate, A. lentulus, to be used as the primary organism for treating dye containing wastewater.     

Degradation of azo dye Procion Red MX-5B by photocatalytic oxidation

The photocatalytic oxidation (PCO) of a monoazo dye Procion Red MX-5B under various physico-chemical conditions was investigated. Degradation of the dye by PCO was enhanced by augmentation in UV intensity, titanium dioxide and hydrogen peroxide concentrations but was inhibited by increase in initial dye concentration. The PCO process was affected by pH in a peculiar way. In the presence of 100 mg/l of TiO2 and the absence of H2O2, the highest reaction rate was observed when the initial pH was 10. With 500 mg/l of TiO2 and 10 mM of H2O2, the reaction was the fastest at initial pH of 3-5. The optimal conditions for the degradation of the dye, at an UV intensity of 17 mW/cm2, were determined to be: TiO2 concentration, 500 mg/l; initial H2O2 concentration, 10 mM; initial pH, 5.0. Monitoring of TOC loss showed that the dye was mineralized by 90% within 80 min under these conditions. Nevertheless, the persistence of a low level of TOC indicated that mineralization was not complete and dead-end product(s) which was (were) resistant to PCO might have accumulated.     

Activated carbon from industrial solid waste as an adsorbent for the removal of Rhodamine-B from aqueous solution: kinetic and equilibrium studies

The activated carbon was prepared using industrial solid waste called sago waste and physico-chemical properties of carbon were carried out to explore adsorption process. The effectiveness of carbon prepared from sago waste in adsorbing Rhodamine-B from aqueous solution has been studied as a function of agitation time, adsorbent dosage, initial dye concentration, pH and desorption. Adsorption equilibrium studies were carried out in order to optimize the experimental conditions. The adsorption of Rhodamine-B onto carbon followed second order kinetic model. Adsorption data were modeled using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacity Q0 was 16.12 mg g(-1) at initial pH 5.7 for the particle size 125-250 microm. The equilibrium time was found to be 150 min for 10, 20 mg l(-1) and 210 min for 30, 40 mg l(-1) dye concentrations, respectively. A maximum removal of 91% was obtained at natural pH 5.7 for an adsorbent dose of 100mg/50 ml of 10 mg l(-1) dye concentration and 100% removal was obtained when the pH was increased to 7 for an adsorbent dose of 275 mg/50 ml of 20 mg l(-1) dye concentration. Desorption studies were carried out in water medium by varying the pH from 2 to 10. Desorption studies were performed with dilute HCl and show that ion exchange is predominant dye adsorption mechanism. This adsorbent was found to be both effective and economically viable.