固定化生物硅藻土强化CAST工艺处理含盐污水研究

采用9%聚乙烯醇+0.5%海藻酸钠包埋耐盐菌群的固定化生物硅藻土小球投加到循环式活性污泥(CAST)反应器中,对比传统CAST工艺和投加固定化小球的CAST工艺对含盐污水COD和氨氮的去除效果,考察固定化生物硅藻土小球强化CAST工艺处理含盐污水性能。试验结果表明:在相同运行条件下,投加固定化生物硅藻土小球的CAST工艺出水COD、氨氮去除率基本维持在88%和90%以上,与传统CAST工艺相比分别提高了15%和10%。同时,向CAST工艺添加固定化生物硅藻土有助于维持反应器中微生物浓度稳定,提高出水水质及其稳定性。     

固定化脱氮硫杆菌净化硫化氢气体的研究

以海藻酸钙包埋脱氮硫杆菌制成的固定化微生物颗粒填充生物固定床,用以净化低浓度H2S废气。实验研究了温度、pH值、进气浓度及流速对反应体系中的H2S脱除率的影响,测定了生物固定床中代谢物的种类及其含量。结果表明当进气口的质量浓度低于6×10-5mg/L、25～40℃、pH值在6.0～7.5范围时,生物固定床对废气中H2S的脱除率可达90%以上,在反应过程中pH值保持不变;进气口的流速对不同浓度的H2S的影响较大,当进气口H2S质量浓度为3×10-5mg/L且流速在35L/h时,脱除率高达95%以上。元素硫作为主要产物防止了生物固定床的酸化,并保证脱硫装置的稳定性。     

A novel microbial BOD biosensor developed by the immobilization of P. Syringae in micro‐cellular polymers

BACKGROUND: A biochemical oxygen demand (BOD) sensor, based on an immobilized Pseudomonas syringae in highly porous micro‐cellular polymer (MCP) in combination with a dissolved oxygen electrode, has been developed for the analysis of biodegradable organic compounds in aqueous samples. Microorganisms were immobilized in a molded MCP disk and a wastewater sample was injected into the biocomposite disk by a flow injection system. Dissolved oxygen (DO) changes as a measure of soluble BOD was read with a DO probe placed into a flow cell carrying biocatalytically activated disk. RESULTS: Optimal response of the MCP BOD sensor was obtained at pH 6.8 and 25 °C with a typical response time of 3–5 min for a 2 mm thick molded polymeric disk. The sensor showed detection linearity over the range 5–100 mg L^?1 BOD₅ (r² > 0.99) at a flow rate of 0.6 mL min^?1. The repeatability and reproducibility of the sensor response were found to be 3.08% and 7.77%, respectively. BOD values produced with this biosensor for various municipal and industrial wastewaters correlated well with those determined by the conventional 5‐day BOD test. CONCLUSION: This new biosensor was different from present amperometric BOD biosensor configurations in which the biocatalyst (microbial/enzymatic) is placed between cellulose and Teflon membranes installed on a DO probe. The use of a molded MCP disk coniainng microbial activity offers better stability and lifetime for commercial use in environmental monitoring. Copyright © 2008 Society of Chemical Industry     

Immobilization of polyphenol oxidase on alginate–SiO2 hybrid gel: stability and preliminary applications in the removal of aqueous phenol

An organic/inorganic hybrid gel of alginate–SiO₂ (ALG–SiO₂) was used to immobilize the partially purified potato polyphenol oxidase (PPO) for the treatment of phenolic wastewater. The influences of alginate concentration, quantity of both enzyme and tetramethoxysilane (TMOS) on immobilization were investigated. The Michaelis constant for immobilized PPO was determined as 14.7 mmol L⁻¹ at 25 °C, and the highest activity of immobilized PPO was achieved at pH 7.0. The ALG–SiO₂ immobilized PPO was more stable than the free PPO or ALG(alone) immobilized PPO. This study suggests that ALG–SiO₂ immobilized PPO might be a potential tool for the removal of phenolic compounds from industrial wastewater. Copyright © 2008 Society of Chemical Industry     

Effect of different fermentation parameters on bioethanol production from corn meal hydrolyzates by free and immobilized cells of Saccharomyces cerevisiae var. ellipsoideus

BACKGROUND: Bioethanol produced from renewable biomass, such as corn meal, is a biofuel that is both renewable and environmentally friendly. Significant scientific and technological investments will be needed to achieve substitution of conventional fossil fuels with alternative fuels. The ethanol fermentation of enzymatically obtained corn meal hydrolyzates by free and immobilized cells of Saccharomyces cerevisiae var. ellipsoideus yeast in a batch system was studied. The initial glucose and inoculum concentration and the time required for the efficient ethanol production were optimized taking into account parameters such as ethanol concentration, ethanol yield, percentage of the theoretical yield of ethanol and volumetric productivity in both immobilized and free cell systems. RESULTS: The yeast cells were immobilized in Ca–alginate by an electrostatic droplet generation method. An optimal initial inoculum concentration of 2% (v/v) and optimal fermentation time of 38 h for both immobilized and free yeasts were determined. An optimal initial glucose concentration of 150 g L^?1 for free system was achieved. At the initial glucose concentration of 176 g L no substrate or product inhibition were achieved with immobilized yeast. CONCLUSION: By immobilization of the yeast into Ca–alginate using the method of electrostatic droplet generation a superior system was realized, which exhibited lower substrate inhibition and higher tolerance to ethanol. The cells of S. cerevisiae var. ellipsoideus yeast entrapped in Ca–alginate showed good physical and chemical stability, and no substrate and product diffusion restrictions were noticed. Copyright © 2008 Society of Chemical Industry     

Antioxidative/Antimicrobial Effects and TBARS in Aerobically Refrigerated Beef as Related to Microbial Growth

Ground beef muscle-pretreated (PT) with 60 ppm chlortetracycline/0.2% potassium sorbate or nonpretreated (NPT)-was mixed with sodium lactate (3%), ascorbate (0.05%), tripolyphosphate (0.5%), citrate (0.5%), or water only and aerobically refrigerated for 0–18 days. More TBA-reactive substances (TBARS) were accumulated in PT than in NPT samples. Only lactate was antimicrobial and resulted in higher TBARS in the NPT. Ascorbate and citrate resulted in lower TBARS in both PT and NPT meat. TBARS correlated with 18:2 fatty acid losses only in microbially controlled (PT) samples. Ascorbate and citrate reduced overall off-odor scores in the PT and discoloration in both NPT and PT samples.     

固定化酶荧光毛细分析法测定乳酸

基于乳酸脱氢酶(LDH)和烟酰胺腺嘌呤二核苷酸(NADH)氧化还原体系,提出了乳酸的液态酶荧光毛细分析方法(IE-FCA)。在激发波长350nm、发射波长460nm条件下,用LE-FCA法成功的对乳酸样品中的乳酸进行了测定;其线性范围为1.0-5.0mmol/L,r>0.9930,检出限为0.38mmol/L,RSD<1.3%。IE-FCA重现性好、操作简便、能节省贵重的酶试剂、样品用量仅为18μL,测定成本低;可实现乳酸的微量化、快速化测定。     

固定化猴头菌细胞的研究

利用海藻酸钠对深层发酵的猴头菌细胞进行固定化培养 ,就包埋剂的最佳浓度、发酵条件及固定化猴头菌细胞在深层发酵中应用的可能性进行了探讨。结果表明 ,最佳海藻酸钠的质量分数为 2 % ,CaCl2 质量分数为 2 % ,固定化猴头菌细胞在发酵培养基内的代谢与游离细胞的代谢基本一致 ,发酵液中氨基酸含量最高可达 80 0mg/L ,多糖含量最高可达 14 0 0mg/L ,固定化细胞可以连续使用 3 2～ 48d ,在工业生产中是可行的     

SUPPRESSION OF α-ACETOLACTATE FORMATION IN BREWING WITH IMMOBILIZED YEAST

Immobilized yeast cells extensively produced the diacetyl precursor, α-acetolactate, during alcohol fermentation. The activity of acetohydroxy acid synthetase, which is responsible for the formation of α-acetolactate from pyruvic acid, was high in cell-free extracts of immobilized yeast cells compared with that of free yeast cells. It was suggested that the expression of AHA synthase of immobilized yeast cells was increased during growth in the carrier as compared with free yeast cells. When the initial immobilizing yeast cell concentration was changed from 1.0 × 10⁶ cells/ml to 1.0 × 10⁹ cells/ml, production of α-acetolactate was reduced from 0.94 mg/l to 0.30 mg/l. Furthermore, during continuous fermentation for 10 d, the concentration of α-acetolactate in beer was 0.30 mg/l.