Enhancement of hydrogen production from palm oil mill effluent via cell immobilisation technique

Clostridium sp. LS2 was immobilised by entrapment in polyethylene glycol (PEG) gel beads to improve the biohydrogen production rate from palm oil mill effluent (POME). We sought to explore and optimise the hydrogen production capability of the immobilised cells by studying the conditions for cell immobilisation, including PEG concentration, cell loading and curing times, as well as the effects of temperature and K₂HPO₄ (500–2000 mg/L), NiCl₂ (0.1–5.0 mg/L), FeCl₂ (100–400 mg/L) MgSO₄ (50–200 mg/L) concentrations on hydrogen production rate. The results showed that by optimising the PEG concentration (10% w/v), initial biomass (2.2 g dry weight), curing time (80 min) and temperature (37 °C), as well as the concentrations of K₂HPO₄ (2000 mg/L), NiCl₂ (1 mg/L), FeCl₂ (300 mg/L) and MgSO₄ (100 mg/L), a maximum hydrogen production rate of 7.3 L/l ‐POME/day and a yield of 0.31 L H₂/g chemical oxygen demand were obtained during continuous operation. We believe that this process may be potentially expanded for sustained and large‐scale hydrogen production. Copyright © 2014 John Wiley & Sons, Ltd.     

Aspergillus niger CGMCC No.6640全细胞生物转化制备蔗果低聚糖

蔗果低聚糖（FOS）作为一种益生元物质,由于其具有极好的生物和功能性质,受到人们极大的关注。具有独立知识产权的菌株Aspergillus niger CGMCC No. 6640被发现能利用蔗糖制备FOS。为利用A. niger 6640的全细胞制备FOS,以蔗糖为底物,利用高效液相法对该菌株的全细胞生物转化参数进行了研究。利用色谱柱Rezex RCM-Monosaccharife Cat的高效液相法能同时检测催化产物中蔗果四糖（或蔗果五糖）、蔗果三糖、蔗糖、葡萄糖和果糖的浓度,其保留时间分别为8.403 min,8.853 min,9.705 min,11.473 min和14.683 min。全细胞生物催化剂浓度和底物浓度对FOS产量有正面的影响。而CaCl2浓度对FOS含量有负面影响。当全细胞生物催化剂浓度,初始反应pH、反应温度、反应时间、蔗糖浓度分别为60 g/L、7.0、33 ℃、40 h和600 g/L的最佳条件下,FOS含量为314.60 g/L。总之,Aspergillus niger CGMCC No.6640全细胞生物催化剂能有效地制备FOS,为其工业化提供依据。     

Effect of immobilised cell concentration on beer quality in continuous fermentation

Abstract

We studied the influence of immobilised yeasts on fermentation parameters and beer quality using a continuous gas‐lift bioreactor system with Saccharomyces warum entrapped in calcium pectate beads. The higher the amount of biomass, the shorter the fermentation time. At an immobilised biomass volume to wort ratio of 0.35:1 (v/v), productivity began to fall and the specific rate of saccharide utilisation decreased. The optimum level for productivity and beer quality was obtained at the ratio of 0.27:1 (v/v) biocatalyst volume to the wort volume. Beer with suitable flavour, low level of diacetyl (less than 0.1 mg/1) and an optimum ratio of the higher alcohols to esters content (4.53:1) has been produced with a residence time of 13.16 h and maximum specific rate of saccharide utilisation of I.106 g/g.h. Except for higher nitrogen and lower amyl alcohols contents, the parameters characterising the beer quality produced in this bioreactor were close to the parameter values of classically produced beer.     

人工合成膜──生物催化剂固定化的新载体

合成膜在生化工程中最新应用是作为生物催化剂固定化的新载体。人工膜用于固定化生物催化剂近年来引起了人们的极大关注并获得了广泛地研究。不同的膜体系及运行方式与生物催化剂相结合构成了多种膜生化反应器。本文介绍并综述了膜固定化生物催化剂的原理、方法分类和应用。     

生物催化与生物转化的研究进展

生物催化与生物转化是生物学、化学、过程工程科学的交叉领域,其核心目标是大规模采用微生物或酶为催化剂生产化学品、医药、能源、材料等。本文指出生物催化与生物转化研究重新崛起,并已成为发达国家的重要科技与产业发展战略,概述了生物催化与生物转化技术的发展现状与趋势,介绍了我国重大基础研究项目生物催化与生物转化的研究动态,该项目的关键问题及主要研究方向是：(1)生物催化多样性理论及其实现方法;(2)催化剂改造的方法学;(3)生物系统催化的理论和方法;(4)生物催化剂适应性原理和方法问题;(5)重要生物催化体系的催化机理。     

Lipase‐catalysed esterification of oleic acid and ethanol in a continuous packed bed reactor,using supercritical CO2 as solvent: approximation of system kinetics

This work investigated the immobilised lipase kinetics of esterification of oleic acid and ethanol. The reaction was conducted under supercritical conditions (13 × 10⁶ Pa and 40 °C) using carbon dioxide as solvent in a continuous packed bed (plug flow) reactor. Biocatalyst Lypozyme^TM IM60, which is lipase from Rhizomucor miehei (EC.3.1.1.3), immobilised on Duolite (anionic exchange resin) was used as biocatalyst. Kinetically, with regard to oleic acid, the reaction was successfully modelled by the Michaelis–Menten mechanism. The reaction rate constants K_m and V_max were evaluated. Furthermore, it was found to undergo competitive inhibition by ethanol, and the inhibition constant K_i was evaluated. © 2000 Society of Chemical Industry     

表达细胞色素b562及分子改造L-氨基酸脱氨酶提高全细胞转化法合成丙酮酸效率

丙酮酸广泛用于制药、农业化学和化学工业.通过两种策略提高生物转化合成丙酮酸效率.首先,通过表达细胞色素b562提高黄素腺嘌呤二核苷酸(FAD)合成的效率,使反应时间由27h减少到21 h,生产率提高了28.5％.其次,通过饱和突变技术对L-氨基酸脱氨酶(pm1)进行定向进化提高其催化能力,三突变体E418A/V438I...     

Enhanced nitrogen removal from pharmaceutical wastewater using SBA-ANAMMOX process

Efficient biological nitrogen removal from pharmaceutical wastewater has been focused recently. The present study dealt with the treatment of colistin sulfate and kitasamycin manufacturing wastewater through anaerobic ammonium oxidation (ANAMMOX). The biotoxicity assay on luminescent bacterium Photobacterium phosphoreum (T3 mutation) showed that the pharmaceutical wastewater imparted severe toxicity with a relative luminosity of 3.46% ± 0.45%. During long-term operation, the cumulative toxicity from toxic pollutants in wastewater resulted in the performance collapse of conventional ANAMMOX process. A novel ANAMMOX process with sequential biocatalyst (ANAMMOX granules) addition (SBA-ANAMMOX process) was developed by combining high-rate ANAMMOX reactor with sequential biocatalyst addition (SBA). At biocatalyst addition rate of 0.025 g VSS (L wastewater)⁻¹ day⁻¹, the nitrogen removal rate of the process reached up to 9.4 kg N m⁻³ day⁻¹ in pharmaceutical wastewater treatment. The effluent ammonium concentration was lower than 50 mg N L⁻¹, which met the Discharge Standard of Water Pollutants for Pharmaceutical Industry in China (GB 21903-2008). The application of SBA-ANAMMOX process in refractory ammonium-rich wastewater is promising.     

生物催化剂固定化技术的研究进展

综述了近年来在生物催化剂固定化技术研究中的一些最新方法，在此基础上提出了新的用于评价固定化技术优劣性的标准，并对所阐述各种固定化方法进行了比较，为研究和发展出更有效。更具有普适性的生物催化剂固定化技术提供必要的参考。     

Enzymatically-mediated uranium accumulation and uranium recovery using a Citrobacter sp. Immobilised as a biofilm within a plug-flow reactor

Biofilm-immobilised Citrobacter sp. removed uranyl ion from flows supplemented with glycerol 2-phosphate. The metal uptake mechanism was mediated by the activity of a cell-surface bound phosphatase that precipitated liberated inorganic phosphate with uranyl ion as HUO₂PO₄·4H₂O at the bacterial surface. A modified integrated form of the Michaelis–Menten equation is proposed to describe the removal of metal ion by a columnar bioreactor, where the efficiency of metal removal is semi-quantitatively related to the input flow rate, the total enzyme loading (E₀) and the bioreactor activity. With biofilm-immobilised bacteria, E₀ was further divisible (split) into subparameters of phosphatase titre per bacterium and total biomass surface area. Varying the split E₀ and the reaction temperature modified the bioreactor performance. The immobilised bacteria retained high metal loads without loss in steady-state activity. Accumulated metal was recovered as a concentrated solution.