酿酒酵母菌对重金属的生物吸附作用研究进展

结合最近的研究成果,总结了酿酒酵母菌作为生物吸附材料的优点、表现形式和吸附性能,重点讨论了酿酒酵母菌的生物吸附机理,提出今后的研究方向。     

固定化啤酒酵母对锶离子的吸附

用2%海藻酸钠(SA),4%氯化钙(CaCl2)包埋法制备了固定啤酒废酵母。考察了菌体含量对固定化菌体强度的影响,研究了pH值、温度、Sr2+初始浓度、吸附时间等外界因素对固定化啤酒酵母吸附溶液中Sr2+的影响。结果表明:菌体含量为10%时,制备的固定化菌体具有较好的机械强度。固定化啤酒废酵母对Sr2+最佳吸附条件为:pH=4.5,温度30℃,Sr2+起始浓度50 mg/L,吸附时间4 h。Sr2+浓度在10～150 mg/L范围内,固定化啤酒废酵母对Sr2+的吸附符合Langmuir模型和Freundlich模型,但符合Freundlich模型的程度更优。     

啤酒酵母吸附去除水中Cd~(2+)的影响因素

生物吸附法是一种经济有效的处理大规模低浓度重金属废水的生物技术,其中啤酒酵母(Saccharomyces cerevisiae)是具有实用潜力的生物吸附剂。本文研究了啤酒酵母对Cd2+吸附效果的主要影响因素,结果表明pH值对Cd2+会产生较大的影响,非固定化和固定化啤酒酵母对Cd2+吸附的最佳pH值都为4,过高和过低均不利于吸附的进行。水中常见的K+、Ca2+、Na+、Mg2+四种离子在低浓度时对Cd2+的吸附无显著影响,但当其浓度高于5mg/L时会影响吸附,其影响顺序为K+Na+Ca2+Mg2+;Zn2+、Fe2+、Cu2+、Pb2+对Cd2+的吸附效果影响顺序为Pb2+Zn2+Fe2+Cu2+;当Cu2+浓度≥50mg/L时,啤酒酵母对Cd2+不产生性吸附,而对Cu2+产生专性吸附。     

Biosorption of heavy metals by chemically‐activated alga Fucus vesiculosus

The sorption capacity of the brown alga Fucus vesiculosus for copper, cadmium, lead and nickel was investigated. Metal sorption yields were modified using different kinds of pretreatment reagents: HCl, CaCl₂, formaldehyde, Na₂CO₃ and NaOH. The Langmuir isotherm was applied to both the non‐treated and all treated biomass tests. Calcium chloride was the only chemical that improved the maximum sorption capacity of the biomass. Copyright © 2005 Society of Chemical Industry     

Factors affecting silver biosorption by an industrial strain of Saccharomyces cerevisiae

Factors affecting silver biosorption by Saccharomyces cerevisiae biomass, obtained as a waste product from industry, were examined. Maximum removal of silver from solution was achieved within 5 min. Increasing the concentration of biomass in experimental flasks from 1 to 8 mg cm⁻³ decreased both silver accumulation, from 224·7 to 89·5 μmol Ag g⁻¹ dry wt, and associated H⁺ ion release, from 109·4 to 31·7 μmol H⁺ g⁻¹ dry wt. The presence of 1·0 mol dm⁻³ cadmium or methionine decreased silver biosorption by 40% and 93% respectively. Boiling in 100 mmol dm⁻³ NaOH or 10 mmol dm⁻³ sodium dodecyl sulphate decreased silver biosorption by 54% and 25% respectively. A temperature increase from 4°C to 55°C decreased silver biosorption by 9%. The metabolic state of the yeast had no effect on silver biosorption. Decreasing the pH of the silver solution caused a reduction in metal removal by the biomass.     

Biosorption of heavy metals from aqueous solution using modified activated carbon: comparison of linear and nonlinear methods

BACKGROUND: Biosorption of heavy metals from aqueous solution by modified activated carbon with Phanerochaete chrysosporium immobilised in Ca‐alginate beads was investigated using a batch system and comparison of linear and nonlinear methods. RESULTS: The amount of Cu(II), Zn(II) and Pb(II) ion sorption by the beads was as follows: activated carbon with P. chrysosporium immobilised in Ca‐alginate beads (ACFCA) (193.4, 181.8, 136.6 mg g^?1) > activated carbon immobilised in Ca‐alginate beads (ACCA) (174.8, 162.0, 130.7 mg g^?1) > P. chrysosporium (F) (148.8, 125.6, 120.4 mg g^?1) > activated carbon (AC) (138.8, 112.3, 109.3 mg g^?1) > plain Ca‐alginate beads (PCA) (125.4, 105.2, 98.2 mg g^?1). The widely used Langmuir and Freundlich isotherm models were utilised to describe the biosorption equilibrium process. CONCLUSION: The results of this study suggest that the immobilisation of modified activated carbon with P. chrysosporium in Ca‐alginate beads is suitable for a batch system. The isotherm parameters were estimated using linear and nonlinear regression analyses. The surface charge density of the biosorbents varied with the pH of the medium; the maximum biosorption of heavy metal ions on the biosorbents was obtained when the pH was between 5.6 and 7.4. Copyright © 2008 Society of Chemical Industry     

化学修饰啤酒酵母菌对铀的吸附特性

以甲醛为交联剂, 将胱氨酸修饰到啤酒酵母菌(SC)上, 并采用海藻酸钠和明胶固定化, 得到一种新型的生物吸附剂--修饰啤酒酵母菌(MSC)。通过红外光谱(IR)分别表征了两种吸附剂的结构, 考察了其吸附铀的主要影响因素即溶液pH值、吸附时间等。结果表明: MSC细胞表面具有大量吸附铀的基团, MSC和SC吸附铀的最佳条件是: pH值为6.0, 相似文献   

Removal of heavy metals using a brewer's yeast strain of Saccharomyces cerevisiae: application to the treatment of real electroplating effluents containing multielements

BACKGROUND: Yeast cells have been recognized as an effective type of biomass for the treatment of wastewaters containing heavy metals. However, its capability to treat efficiently complex effluents loaded with several metals ions (Cr, Cu, Ni and Zn) has never been reported. The aim of this work was to study the feasibility of a hybrid technology, which combines chemical precipitation at pH 6.0 with a subsequent biotechnological‐based process (using heat‐killed cells of a flocculent brewing strain of Saccharomyces cerevisiae), to remove simultaneously several metals from real electroplating effluents. RESULTS: Two effluents containing Cu, Ni and Zn (effluent A) or Cr, Cu and Ni (effluent B) were treated. In both effluents, pH was adjusted to 6.0; in effluent B, Cr(VI) was previously reduced to Cr(III). Chemical speciation studies allowed defining the amount of biomass to be employed with a minimum number of batches. Subsequently to pH adjustment to 6.0, effluents were fully treated with a serial batch of biomass. After the third batch, metal concentrations were lowered to below the legal limits of discharge; removals ≥ 89, 91, 92 and 94% were attained for Ni, Cu, Cr and Zn, respectively. CONCLUSIONS: In the present work, the usefulness of using flocculent brewing yeast cells to treat complex industrial effluents loaded with several heavy metals was demonstrated. The hybrid process developed was shown to be an efficient alternative for the treatment of real electroplating effluents. Copyright © 2010 Society of Chemical Industry     

真菌对重金属生物吸附机理的研究进展

对真菌生物吸附重金属的吸附机理进行了综述。从是否消耗能量和吸附作用发生的位置2方面对吸附机理做出简单分类,依据吸附作用发生在吸附剂细胞的不同位置,分别从细胞表面、细胞外和细胞内3个方面对吸附机理展开探讨。同时指出了真菌吸附重金属机理研究中存在的问题,并对今后的研究方向提出展望。     

非活性藻类吸附重金属的研究

藻类对重金属有很好的吸附作用，并具有成本低，选择性好，吸附量大，浓度适用范围广等众多优点，而且带来的环境污染小，可作为一种廉价吸附剂。但目前存在机械强度低，可操作条件差等特点，限制了在实际中的应用。本文在综述和分析藻类吸附重金属研究机理基础上，着重介绍了吸附剂的改性处理方式及吸附特点和效果的分析，并探讨了进一步改性处理方式和应用前景。     

酿酒酵母在硅橡胶膜生物反应器中连续发酵的生长动力学

实验研究了酿酒酵母在硅橡胶膜生物反应器中的细胞生长速率与操作参数之间的关系。在三水平正交实验基础上,用Gauss Newton非线性最小二乘法拟合了细胞比生长率与葡萄糖浓度、乙醇浓度和细胞浓度3变量之间的关系式,得到硅橡胶膜生物反应器乙醇连续发酵的细胞最大比生长率、饱和常数、产物抑制常数和群聚抑制常数等基本动力学参数,表明当细胞浓度达到15g/L或乙醇浓度达到70g/L时细胞生长受到完全抑制。连续发酵实验验证了硅橡胶膜生物反应器中的细胞生长动力学满足拟合模型的规律。     

不同非氧化磷酸戊糖途径基因的过表达对酿酒酵母木糖发酵性能的影响

以双拷贝过表达木糖代谢上游途径关键酶(木糖还原酶XR、木糖醇脱氢酶XDH和木酮糖激酶XKS)的酿酒酵母菌株为背景,在过表达非氧化磷酸戊糖(PP)途径中转醛酶基因TAL1的基础上,对途径中其他基因TKL1(转酮酶)、RPE1(核酮糖-5-磷酸差向异构酶)和RKI1(核酮糖-5-磷酸异构酶)进行了不同程度的过表达,以研究PP途径基因过表达对酿酒酵母木糖代谢的影响。在不同培养基条件下对重组菌株木糖代谢进行研究,结果显示,在过表达TAL1的基础上不同组合过表达PP途径其他基因不同程度改善了酿酒酵母木糖发酵性能,重组菌株能在36~48 h耗完质量分数(下同)为5%的木糖。其中,过表达PP途径全部基因比其他过表达基因组合表现出明显的优势,在8%木糖发酵条件下其乙醇产量达到了每1 g木糖0.337 g,较对照菌株提高了7.86%。这说明同步过表达PP途径基因更有利于酿酒酵母木糖发酵。     

钠基膨润土对重金属离子的吸附特征

探讨了在不同振荡时间、不同溶液重金属离子浓度、不同矿物颗粒细度和不同pH值条件下,钠基膨润土对Cu2+、Zn2+和Cd2+的吸附效果,讨论了钠基膨润土对重金属离子吸附的影响因素。结果表明:重金属离子在钠基膨润土表面的吸附是个迅速的过程,钠基膨润土对重金属的吸附在10 min内即可达最大值。钠基膨润土不同颗粒细度对重金属离子的去除率有所不同,但并非颗粒越细吸附量越大。就试验的3种重金属离子而言,钠基膨润土对其吸附效果均很好。较高的pH值有助于钠基膨润土对溶液中重金属离子的吸附,但考虑到实际操作的其它因素,不能把pH值调得过高。     

Utilization of raffinose and melibiose by a mutant of Saccharomyces cerevisiae

The mutant Saccharomyces cerevisiae ATCC 36858 was used in the production of ethanol and/or fructose from synthetic media in batch processes with raffinose, melibiose or sucrose. The mutant was able to hydrolyze all the sugars used and to selectively ferment glucose and galactose to ethanol while fructose accumulated in the fermentation medium. The fructose yield was above 89% of the theoretical value in the media with either raffinose or sucrose, when initial concentrations were between 131.5 g dm^?3 and 242.0 g dm^?3. The ethanol yields were 82% and 77% of the theoretical values in the media with melibiose and sucrose, respectively, and about 72% of the theoretical value when raffinose was used. The fructose fraction in the carbohydrate content of the produced syrups was more than 96% when raffinose concentration was below 189.1 g dm^?3. However, even at a sucrose concentration of 187.9 g dm^?3, the produced syrup contained 100% fructose. Some oligosaccharides were also produced in all tested media. The produced oligosaccharides were consumed by the end of the fermentation process. These findings can be useful in the production of ethanol and high fructose syrups using raw materials based on sucrose and raffinose such as molasses. Copyright © 2003 Society of Chemical Industry     

Increasing isobutanol yield by double-gene deletion of PDC6 and LPD1 in Saccharomyces cerevisiae

As a new biofuel, isobutanol has received more attentions in recent years. Because of its high tolerance to higher alcohols, Saccharomyces cerevisiae has potential advantages as a platform microbe to produce isobutanol. In this study, we investigated integration effects of enhancing valine biosynthesis by overexpression of ILV2 and BAT2 with eliminating ethanol formation by deletion of PDC6 and decreasing acetyl-Co A biosynthesis by deletion of LPD1 on isobutanol titers. Our results showed that deletion of LPD1 in strains overexpressing BAT2 and ILV2 increased isobutanol titer by 5.3-fold compared with control strain. Additional deletion of PDC6 in lpd1Δ strains carrying overexpressed BAT2 and ILV2 further increased isobutanol titer by 1.5 fold. Overexpression of BAT2 and ILV2 in lpd1Δ strains and pdc6Δ strains decreased ethanol titers. Glycerol titers of the engineered strains did not have greater changes than that of control strain, while their acetic acid titers were higher, perhaps due to the imbalance of cofactors in isobutanol synthesis. Our researches suggest that double-gene deletion of PDC6 and LPD1 in strains overexpressing BAT2 and ILV2 could increase isobutanol production dramatically than single-gene deletion of PDC6 or LPD1. This study reveals the integration effects of overexpression of ILV2/BAT2 and double-gene deletion of LPD1 and PDC6 on isobutanol production, and helps understanding future developments of engineered strains for producing isobutanol.     

泥炭吸附法去除废水中重金属

介绍了天然廉价矿物泥炭的物理化学性质,综述了泥炭的改性方法及其对多种重金属离子的吸附容量．分析了pH、改性方法、竞争离子浓度等因素的影响。并对泥炭吸附重金属离子的机理和规律进行了总结．其吸附机理有离子交换、络合、表面吸附、化学吸附等四种,吸附一般符合Langmuir吸附等温式或Freundlich吸附等温式。最后展望了泥炭在重金属废水处理中的应用前景,提出了一些建议。     

Removal of toxic metals from aqueous mixtures. Part 1: Biosorption

The biosorption of toxic metals from an aqueous mixture containing zinc, copper and nickel, in the presence of calcium and sodium ions (usual co‐existing cations in related systems) has been investigated. Industrial biomass samples of different origin have been examined batchwise as effective sorbents, including bacteria (Streptomyces rimosus), fungi (Penicillium chrysogenum) and yeasts (Saccharomyces carlsbergensis and Saccharomyces cerevisiae). The effect of solution pH was evaluated in the range of 3–11.5. Selectivity was observed, particularly for the removal of copper. The observed removal of metals by the application of biosorption was also compared in laboratory experiments with other more conventional separation techniques (filtration, centrifugation and flotation). © 1999 Society of Chemical Industry     

Improvement of ethanol production in Saccharomyces cerevisiae by hetero‐expression of GAPN and FPS1 deletion

BACKGROUND: During anaerobic bioethanol fermentation of Saccharomyces cerevisiae, the main byproduct glycerol is essential to regulate redox balance (reoxidize NADH to NAD⁺), which is necessary to maintain cell growth and fermentation. Hetero‐expression of a NADP⁺‐dependent glyceraldehydes‐3‐phosphate dehydrogenase (GAPN) [EC.1.2.1.9] in S. cerevisiae could redirect the carbon flux from glycerol to ethanol involving a net oxidation of NADH. The present study investigates whether combination of GAPN hetero‐expression and glycerol exporter Fps1p disruption would result in less glycerol and more ethanol production without affecting growth rate during anaerobic fermentations. RESULTS: The results of anaerobic fermentations showed that the fps1Δ mutant with GAPN (named 4FG) produced 21.47% less glycerol and 9.18% more ethanol compared with a parental strain with a control plasmid, while the rates of growth and fermentation were not changed. Moreover, the engineered strain 4FG yielded less glycerol and acetic acid, and more ethanol than the control, fps1Δ mutant or with GAPN only. CONCLUSIONS: During anaerobic fermentations, hetero‐expression of GAPN restored the reduced grow rate of the fps1Δ mutant, and led to less byproducts and more ethanol production. This combination strategy could be used to modulate glycerol metabolism and optimize the anaerobic fermentation of S. cerevisiae. Copyright © 2011 Society of Chemical Industry