玉米浆对大肠杆菌JH-B22发酵产L-丙氨酸的影响

为了进一步降低L-丙氨酸的生产成本,以大肠杆菌JH-B22为发酵菌株,以玉米浆为氮源、葡萄糖结晶废糖液为碳源进行L-丙氨酸的发酵。结果表明,发酵培养基中玉米浆添加量为20g·L~(-1)较为适宜。在玉米浆发酵培养基中进行L-丙氨酸的发酵,L-丙氨酸产量和糖酸转化率分别为54.30g·L~(-1)和90.5%;其L-丙氨酸产量略低于无机盐发酵培养基的56.12g·L~(-1)和LB发酵培养基的56.48g·L~(-1),但玉米浆发酵培养基具有配制更简单、无需额外添加无机盐或者成本较高的酵母粉等优点,可作为L-丙氨酸发酵生产的不错选择。     

粘质沙雷氏菌G1利用玉米浆干粉和磷酸氢二铵生产2,3-丁二醇的研究

研究了几种工业氮源对粘质沙雷氏菌G1发酵生产2,3-丁二醇的影响,在确定玉米浆干粉为氮源的基础上,利用Plackett-Burman(PB)实验和响应面法(RSM)实验对玉米浆干粉和磷酸氢二铵[(NH4)2HPO4]的浓度进行了优化,确定优化培养基(g·L-1)为:蔗糖90,玉米浆干粉20.32,(NH4)2HPO47.21,NaAc 4,柠檬酸钠14,MgSO40.5,Fe-SO40.02,MnSO40.01。并以此优化培养基进行了摇瓶和分批补料发酵,结果表明,摇瓶发酵中,90g·L-1的蔗糖最终被转化成43.06g·L-1的2,3-丁二醇;分批补料发酵中,2,3-丁二醇浓度为128.28g·L-1,产率为2.67g·L-1·h-1,转化率为0.48g·g-1蔗糖。以玉米浆干粉和(NH4)2HPO4为氮源,2,3-丁二醇浓度较高,培养基的成本大幅降低,为工业化生产奠定了基础。     

玉米浆对VB_(12)发酵的影响

玉米浆质量和添加浓度对VB12发酵有很大的影响,为了选取最优玉米浆作为培养基氮源,本实验比较了3个生产厂家和5个不同浓度的玉米浆。结果表明:厂家Ⅲ的玉米浆为最优玉米浆,最适浓度为3.7%。     

以玉米为原料发酵生产L-乳酸工艺条件优化

以玉米为主要原料采用微生物发酵制备L-乳酸,可提高玉米的利用价值,降低L-乳酸的生产成本。通过正交试验,考察不同温度、p H值、加酶量、反应时间等因素对玉米液化、糖化过程的影响,确定合适的液化、糖化工艺。基于单因素实验,利用二水平设计和响应面分析法,考察不同氮源、初始糖浓度及不同接种量、温度、p H值等因素对L-乳酸发酵过程的影响,确定了L-乳酸发酵的最佳工艺,即:初始糖浓度23%,玉米浆0. 8%,接种量10%,发酵工艺条件为温度50℃,p H值6. 2,L-乳酸产量达到218. 3 g/L。     

环孢菌素A发酵中玉米浆的选择

环孢菌素A的工业生产采用真菌发酵进而分离纯化的方法,玉米浆是其发酵生产中的一种重要的培养基质.通过实验比较了液体玉米浆与固体玉米浆对其效价的影响,发现液体玉米浆优于固体玉米浆.     

实验设计法优化核酸酶P1的发酵培养基

采用实验设计法研究了碳源、氮源和磷源等因素对桔青霉(Penicillium citrinum)M02发酵产核酸酶P1的影响. 实验结果表明，含有玉米浆的复合氮源可以明显地提高核酸酶P1的产量. 同时通过两轮实验建立了一个可以较好预测实际发酵的二次模型，并依据此模型优化了碳源、氮源以及磷源的组成，优化后的产核酸酶P1的发酵培养基组成为(g/L)：葡萄糖38.73，蛋白胨1.91，玉米浆1.84, KH2PO4 0.6, K2HPO4×3H2O 0.6, MgSO4 0.4, CaCl2 0.4, ZnSO4×7H2O 0.4. 用此培养基进行发酵，实际产酶水平为648.3 U/ml，与优化前的380 U/ml相比提高了约70%. 此外，还初步探讨了玉米浆促进P1酶发酵的机理，这是因为玉米浆与蛋白胨相比含有了较多有利于P1酶发酵的氨基酸，如甘氨酸、丙氨酸以及丝氨酸等.     

一种复合阻垢剂在玉米浆蒸发器上的应用研究

通过对某淀粉厂玉米浆蒸发器上的玉米浆、垢样进行分析,并结合外在控制指标对玉米浆质量的影响,研究了该玉米浆蒸发器的结垢问题。结果表明,该玉米浆蒸发器有明显的碳酸钙、硫酸钙结垢倾向。针对玉米浆蒸发器温度较高、玉米浆中有机质含量高、粘度高的特点,开发出一种适合该环境的复合型阻垢剂。现场应用研究表明,当加药浓度为100 ppm时,成垢离子Ca~(2+)、SO_4~(2-)、CO_3~(2-)的保有率均有明显提高,玉米浆蒸发器的结垢倾向得到了有效控制。     

补料分批培养提高转氨酶发酵产酶密度的研究

转氨酶是苯丙酮酸酶法制备L-苯丙氨酸的关键酶源,为提高转氨酶的发酵产酶密度,文章采用补料分批培养方式对大肠杆菌A5发酵产酶进行了研究。优化的补料培养工艺为:初始葡萄糖质量浓度5 g/L,初始氮源体积分数为玉米浆5 mL/L、蛋白胨质量浓度1.5 g/L,控制发酵过程pH值7.5,当葡萄糖质量浓度下降为2 g/L,开始每隔2 h补加质量浓度为120 g/L的葡萄糖溶液,从8 h起每隔2 h补加20 mL/L玉米浆+6 g/L蛋白胨及0.6 g/L的4种氨基酸溶液(L-甲硫氨酸、L-缬氨酸、L-异亮氨酸和L-谷氨酸)。在此条件下发酵培养24 h,菌体干质量浓度达10.5 g/L,比优化前产酶量提高了126%。     

豆粕水解液为氮源细菌厌氧流加发酵生产L-乳酸

采用细菌厌氧发酵法生产L-乳酸,由实验确定了最佳接种量、发酵温度和pH调节剂,考察了初始葡萄糖浓度对L-乳酸生产的影响,确定初始糖浓度为70~90 g/L时得率、产率、最终生物量分别达到92.68 g/g, 3.17 g/(L×h)和8.5′107 mL-1. 为进一步降低L-乳酸生产成本,以豆粕水解液为氮源代替酵母粉,同时应用流加发酵技术,L-乳酸产量、得率、产率及转化率分别达到155 g/L, 95.5 g/g, 1.64 g/(L×h)和96.9%. 在保证L-乳酸最终浓度的同时可降低生产成本,为进一步工业化奠定了基础.     

玉米浆水解液应用于谷氨酸发酵的研究

玉米浆含有丰富的营养物质,对谷氨酸的发酵生产影响较大。实际生产中,由于玉米浆的质量波动较大,谷氨酸发酵生产深受影响。为此,我们在发酵培养基中,添加一定量的玉米浆水解液进行发酵工艺优化实验。实验结果,谷氨酸产酸率达到了18.6 g·L-1,转化率达65.1%,谷氨酸产量提高了20%。发酵培养基组成确定为:淀粉水解糖55 g/L,玉米浆30 m L/L,玉米浆水解液10 g/L,豆粕水解液10 g/L,糖蜜55 g/L,K2HPO44 g/L,Mg SO4·7H2O 1.5 g/L,Mn SO4·7H2O 30 mg/L,Fe SO4·7H2O 30 mg/L,维生素B1350μg/L,维生素H 500μg/L,消泡剂0.1 m L/L。     

Experimental evaluation of alternative fermentation media for L‐lactic acid production from apple pomace

BACKGROUND: A variety of nitrogen sources were tested for lactic acid production. Corn steep liquor is a low‐cost by‐product that could replace some of the expensive nutrients of the general lactobacilli media. This work deals with the optimisation of the composition of a low‐cost medium for lactic acid production from apple pomace by Lactobacillus rhamnosus CECT‐288. RESULTS: Corn steep liquor (CSL) and yeast extract (YE) were evaluated as nutrient sources for lactic acid production from apple pomace. In comparison with media containing CSL, experiments with YE led to higher volumetric productivities but lower lactic acid concentrations and product yields. The presence of YE increased the production of acetic acid. In media containing 0.2 g CSL g^?1 potential sugars, 29.5 g lactic acid L^?1 was obtained after 24 h, at good yield (35.5 g per 100 g dry apple pomace) and productivity (1.23 g L^?1 h^?1), with a lactic acid/acetic acid mass ratio of 98 g g^?1. CONCLUSION: The experimental results proved that CSL is a suitable nutrient source for lactic acid production from apple pomace, even though the volumetric productivity was lower than in experiments employing YE. Considered as a nutrient supplement, CSL presents advantages over YE not only in terms of cost but also in terms of product yield, final lactic acid concentration and lactic acid/acetic acid mass ratio. The utilisation of apple pomace as the raw material and CSL as the sole nutrient source (both cheap by‐products) enables the production of lactic acid by an economical, environmentally friendly process. Copyright © 2008 Society of Chemical Industry     

Downstream Processing of Lactic Acid by Membrane-Based Solvent Extraction∗

Abstract

Lactic acid has extensive use in the food and chemical industry. About half the lactic acid used in the world is produced by fermentation of carbohydrates using lactic acid bacteria. The recovery of lactic acid from the fermentation broth is more difficult than the fermentation itself. In the present work a study of membrane-based solvent extraction as a separation unit for the continuous downstream processing of lactic acid from fermentation broth was carried out. The experiments were performed using simulated fermentation broths made of lactic acid in acetate buffer or distilled water as the feed solution. The effects of membrane material, organic carrier, and pH of the feed solution on membrane extraction efficiency were investigated. A separation degree of 35% was obtained by using a polyether-etherketone (PEEK-WC 14%) membrane with 5% trioctylamine as the organic carrier in n-heptane. The experimental results obtained with the simulated system encourage the use of membrane-based solvent extraction with a real fermentation broth.

     

丙酸发酵废液中丙/乙酸的分离工艺研究

丙酸发酵生产中产生的大量废液中含有丙酸、乙酸2种有用物质。将废液直接排放不仅对环境造成污染,同时也对资源造成浪费。需要对废液进行资源化处理,寻找合理、有效利用废液,回收其中有用组分的方法,达到减少资源的浪费、提高企业经济效益、减轻有机酸对环境造成危害的目的。     

Multicomponent-liquid-membrane permeation of organic acids

The parameters of lactic acid separation from fermentation broths by Emulsion-Liquid Membranes (ELMs) have been optimized. Using these parameters, lactic acid can be separated up to 90%, concentrated up to 3 times and cleared of most of its by-products. Only about 1% of glucose and amino acids is permeated together with the lactic acid. With these parameters, not only lactic acid but also other monocarboxylic acids can be separated, the better and faster the lower the pKa-value of the acid the fewer polar side groups it carries. When separating dicarboxylic acids, the mass transfer is hindered by the second carboxylic group. The smaller the distance between the two carboxylic groups, the slower is the separation of the acid. When several organic acids are separated from the same fermentation broth, their mutual influence is not very strong, at least when the concentrations of the acids are about 100 mmol/l. However, sulphuric acid which is added to the fermentation broth throughout permeation to maintain the broth at a constant pH, does exert a strong influence. In order to reduce the competition between the organic and sulphuric acids during permeation to a minimum, as little as possible sulphuric acid is used. However, a certain quantity of sulphuric acid is necessary to maintain the pH of the fermentation broth during permeation at 4.5, otherwise organic acid separation would become too slow.     

Effect of solvent and impurity on synthesis of ethyl lactate from fermentation-derived ammonium lactate

Fermentation-derived ammonium lactate was converted into ethyl lactate by decomposition in various organic solvents followed by esterification with ethanol over Amberlyst catalyst. The ammonium lactate was decomposed more efficiently in an organic solvent with high boiling point, where the produced lactic acid was stabilized well as a monomer without oligomerization. However, only the nonreactive phosphate-type solvent such as triethyl phosphate and tributyl phosphate showed a notable ethyl lactate yield in the subsequent esterification reaction compared with dimethyl sulfoxide and N-methyl pyrolidine. The lactic acid yield in ammonium lactate decomposition and the subsequent ethyl lactate yield were also highly dependent on solvent ratio to ammonium lactate, temperature and pressure in ammonium lactate decomposition reaction. The amino acid impurity contained in the fermented ammonium lactate as well as the unreacted ammonium lactate reduced the acid strength of Amberlyst-36, which resulted in the final ethyl lactate yield.     

餐厨垃圾资源化利用及其过程污染控制研究进展

餐厨垃圾年产生量大、成分复杂,传统的焚烧、填埋处理方式易引发一系列环境问题,同时,餐厨垃圾又具有有机质含量高、营养元素丰富的特点,其资源化利用可实现价值再生,符合可持续发展的要求,因而成为国内外学者的研究热点。本文从产品利用方向的角度综述了几类餐厨垃圾资源化利用技术的研究进展,包括能源化利用方向的餐厨垃圾制生物柴油、甲烷、氢、燃料乙醇技术,农业化利用方向的餐厨垃圾制动物饲料、有机肥料技术,工业化利用方向的餐厨垃圾制还原糖、炭材料、乳酸技术;介绍了餐厨垃圾资源化过程中产生的恶臭气体、废水污染问题以及污染控制相关研究进展。最后指出,对微生物厌氧反应机制的深入研究有利于实现相关技术在工业生产规模的优化,厨垃圾资源化工艺过程的污染控制需要进一步得到关注。     

厨余垃圾的资源化技术

介绍了厨余垃圾的来源与特征,讨论了厨余垃圾的资源化技术:主要包括堆肥、厌氧发酵、真空油炸、蚯蚓生物处理、乳酸发酵以及生物制氢等,其中家庭垃圾处理机和小容量垃圾系列处理机堆肥技术具有费用低和实现源头减量化等优点。生物制氢、厌氧发酵和燃料电池发电系统的开发研究,为废物变清洁能源开辟了新的途径。此外,利用厨余垃圾制取乳酸,进而合成生物降解性塑料(聚乳酸)的技术,可为治理困扰人类的"白色污染"作出贡献。     

Process simulation for the recovery of lactic acid using thermally coupled distillation columns to mitigate the remixing effect

The objective of this study was to find process simulations of the plant-wide scale lactic acid recovery process using thermally coupled distillation columns to mitigate the remixing effect. The remixing effect has been widely discussed because in a conventional column arrangement it induces a need for a significant amount of energy for repurification in lactic acid recovery processes. One way to overcome high energy consumption is by using thermally coupled distillation columns. This paper suggests and compares two types of thermally coupled distillation columns applied to the plant-wide scale lactic acid recovery process for removing the remixing effect considering a heavy organic impurity and lactic acid oligomerization in the process. The equilibrium stage model based on the RADFRAC module of Aspen Plus was employed for simulating the thermally coupled distillation columns. Simulation results showed that thermally coupled distillation columns can eliminate the remixing effect and reduce energy consumption compared to conventional lactic acid recovery processes.     

Use of 1‐hexyl‐3‐methylimidazolium bromide ionic liquid in the recovery of lactic acid from wine

BACKGROUND: Lactic acid has many different applications in a variety of industries including the food, cosmetics, packaging, leather and chemical industries. Current methodologies for lactic acid production are lengthy and complicated and more efficient methods are being sought. Some organic wastes contain lactic acid and our work investigates the use of ionic liquids (ILs) in the efficient and selective extraction of lactic acid from organic waste using wine as a model system. The ionic liquid was chosen based on its ability to selectively solvate and separate lactic acid from the remaining bulk waste material. RESULTS: Several ILs including 1‐hexyl‐3‐methylimidazolium chloride (hmimCl), 1‐hexyl‐3‐methylimidazolium bromide (hmimBr), 1‐hexyl‐3‐methylimidazolium iodide (hmimI) and N‐hexylpyridinium iodide (hpyrI) have been synthesized in high yield (68‐95%) using microwave technology. Lactic acid is soluble in each of the ILs synthesized with optimum results achieved with hmimBr where lactic acid is miscible in all proportions. HmimBr has been used to successfully separate and extract lactic acid from wine as confirmed by FTIR spectroscopy. Furthermore, it has been possible to recover the IL for recycle in subsequent extraction cycles where the efficiency for the extraction process increases with each recycle. CONCLUSION: HmimBr has been used for the first time in a novel process for the separation and recovery of lactic acid from wine, as confirmed by FTIR spectroscopy. This work demonstrates a novel process which can be applied to the recovery of lactic acid from organic waste. Copyright © 2012 Society of Chemical Industry     

乳酸的乳化液膜萃取与有机溶剂萃取的比较

在乳酸发酵与分离耦合过程中,可以采用乳化液膜萃取法或有机溶剂萃取法提取发酵液中的乳酸。本文比较了这两种方法的传质机理和操作过程,并实验分别研究了它们的最佳工艺条件,提出：在最佳操作条件下,提取相同量的乳酸,有机溶剂萃取有机相的消耗量为乳化液膜法的３－４倍,乳化液膜法萃取率高,而且能得到浓缩的乳酸。