包埋法固定微生物细胞技术的新进展

自六十年代固定化酶技术问世以来,固定化细胞技术随之迅速发展。到了七十年代,作为酶源的微生物菌体本身的固定化又引起人们极大兴趣,其研究和应用已涉及食品、化工、医药、环境保护等领域。目前,工业化生产上采用的固定化方法主要有两大类:吸附法和包埋法。微生物菌体的固定化一般采用包埋法。其优点是:(1)微生物菌体包埋在聚合物中不易漏出;(2)操作条件温和、对外界环境的缓冲作用大;(3)可防止微生物菌体的机械损伤,易于再生,产物分离提取容易。 载体的性能影响固定化细胞的机械强度、细胞活性、工作稳定性,因此,载体的选择及其制备方法一直     

包埋法固定化微生物技术的载体选择

微生物技术具有处理效果理想、适用范围广泛、成本优势明显的优点。自20世纪70、80年代以来，微生物技术一直是水处理研究领域的热点，文章综述了固定化微生物载体材料的种类和特点以及琼脂、海藻酸钠、聚乙烯醇三种常用包埋载体的特点；最后对微生物固定化载体的发展方向进行了展望。     

酒精酵母固定化后强化技术的研究

固定化酵母生产酒精是近年来迅速发展起来的一项新技术,与传统的游离酵母生产酒精的技术相比,具有很多优点。然而,目前固定化酵母在酒精生产中的应用仍处于实验室阶段,其主要原因是固定微生物细胞的载体机械强度不够;另一原因是载体价格昴贵,不适合大规模工业化生产。包埋法是固定化细胞应用最广泛的一种方法,常用的载体有琼脂、海藻酸盐、K-角叉菜等。琼脂凝胶的优点是生活细胞在凝胶基质中生长得快,但在葡萄糖的酒精发酵期     

生物固定化技术及其应用研究进展

生物固定化技术具有小型高效、稳定性好、操作简便、易实现连续化、自动化控制等优点,在生物、医药、农业、食品、化工、能源开发、环境保护等方面得到了广泛应用.当前生物固定化的材料已由单一的酶发展到含酶菌体或菌体碎片.固定化方法主要包括载体结合法、交联法和包埋法,这些方法近年来都通过发展新型材料和技术得到了长足发展,生物固定化技术在有机污染物净化、土壤重金属污染修复、真菌毒素降解、生物能源开发等方面都取得了重要进展.今后应在开发固定化生物资源、提高固定化微生物活性、固定化机理和应用等方面加强研究.     

微贮用植物乳杆菌固定化菌剂的制备

乳酸菌与纤维素降解菌因其可防止微贮饲料酸败、增加秸秆饲料的营养价值等优点,在秸秆微贮过程中起重要作用。但由于乳酸菌的繁殖会抑制纤维素降解菌的活性,如何实现微贮过程中两种微生物分时发挥功能是解决上述问题的关键。文中利用固定化技术将乳酸菌制备成含有玉米秸秆粉的固定化菌剂以达到缓释的目的。首先制作固定化空白小球得出复合固定化载体成球的最佳浓度,利用玉米芯吸附植物乳杆菌S1得到复合固定化载体,以对S1的包埋率、成球效果等为指标,通过对比两种固定化方法 (包埋法与包埋-交联法),得到固定化植物乳杆菌S1的最佳条件。研究表明,使用6%PVA+0.4%SA+0.3%CMC-Na进行包埋-交联时成球效果最好,使用1.2%SA+0.5%CMC-Na进行直接包埋时成球效果最好。通过对比5种固定化工艺,将1.2%SA+0.5%CMC-Na和吸附玉米粉组成的固定化载体混合物逐滴滴入4%氯化钙中直接包埋24 h得到的固定化小球其机械强度以及包埋率均优于其他工艺。因此,利用玉米芯吸附-海藻酸钠包埋的方法可以有效提高植物乳杆菌包埋效率,为使用固定化技术制备微贮饲料菌剂奠定基础。     

固定化微生物技术在处理高浓度有机废水中的应用进展

本为首先概述了微生物固定化的主要特点和主要方法:吸附法、包埋法、包络法、交联法以及共价结合法;其次,介绍了目前固化微生物技术所采用载体选择的主要要求;最后,对当前固化微生物技术在高浓度有机废水中的应用进行了简单的说明,并对未来发展提出了展望。     

固定化微生物在废水处理中的研究及进展

微生物固定化是一种比一般生物处理法更为优越的方法,它具有处理效率高、稳定性强、耐负荷、产污泥量少等优点。作者对固定化技术方法以及不同载体的选择进行了介绍和对比,分析评价了国内外微生物固定化在废水控制中最新研究进展,并对其发展问题做了探讨。     

发酵技术中新的生物催化剂—联合固定化系统

常用的固定化生物催化剂是将一种酶或一种微生物固定化,制成固定化酶或固定化细胞。近年来,德国、丹麦等科学家报道了一种新的联合固定化方法。该法是将一种微生物与另一种来源的酶固定在同一载体上,以形成联合固定化系统。目前已报道了两种联合固定化方法,一是将酶首先固定在载体上,再将微生物细胞包埋到固定酶中;二是将一种酶溶液与一种微生物混合,再经戊二醛或单宁等处理得到联合固定化物。丹麦Godtfzedson等人报道了将一种酶交联在葡聚糖凝胶上,再将不溶性的固定化葡聚     

L(+)-酒石酸发酵法生产工艺改进的研究

虽然具有广泛用途的Ｌ( ) 酒石酸的生产方法有 4种[1 ] ,但目前研究最多 ,最具工业生产前景的方法 ,是应用化学合成的前体为底物 ,发酵生产Ｌ( ) 酒石酸的方法。该法中的微生物发酵转化适宜在弱碱性的条件下进行 ,通常都是把顺式环氧琥珀酸制备成相应的二钠盐来作为前体 ,再进行微生物转化生成Ｌ( ) 酒石酸。张建国[2 ] 、黄腾华等人[3 ] 在实验室按以上路线生产Ｌ( ) 酒石酸 ;孙志浩等人[4] 以明胶为载体固定化微生物细胞生产Ｌ( ) 酒石酸 ;张建国等人[5 ]在他们自己工作的基础上进一步探讨了细胞固定化的方法 ,找到了一种…     

固定化酶和细胞中应用的新载体

自固定化技术兴起以来 ,其载体的研究就广受关注 ,也取得了不少成就 ,但在实际应用中还有许多问题需要解决 ,如使用寿命较短 ,操作半衰期不够长 ;载体价格较高 ,而且对底物和产物存在扩散阻力 ,所以许多学者仍一直在致力于新载体的研制和应用。固定化技术中所使用的载体可分为有机高分子载体、无机载体和复合载体[1] 。1　有机高分子载体材料1 1　天然高分子凝胶载体此类载体材料一般无毒性 ,传质性能好 ,但强度较低 ,在厌氧条件下易被微生物分解 ,寿命短。常见的有琼脂、海藻酸钠等 ,近来研究的比较热门的新载体是甲壳素和壳聚糖。1 1 1　…     

Removal of toxic chromate using free and immobilized Cr(VI)-reducing bacterial cells of Intrasporangium sp. Q5-1

Chromate-reducing microorganisms with the ability of reducing toxic chromate [Cr(VI)] into insoluble trivalent chromium [Cr(III)] are very useful in treatment of Cr(VI)-contaminated water. In this study, a novel chromate-reducing bacterium was isolated from Mn/Cr-contaminated soil. Based on morphological, physiological/biochemical characteristics and 16S rRNA gene sequence analyses, this strain was identified as Intrasporangium sp. strain Q5-1. This bacterium has high Cr(VI) resistance with a MIC of 17 mmol l⁻¹ and is able to reduce Cr(VI) aerobically. The best condition of Cr(VI) reduction for Q5-1 is pH 8.0 at 37°C. Strain Q5-1 is also able to reduce Cr(VI) in resting (non-growth) conditions using a variety of carbon sources as well as in the absence of a carbon source. Acetate (1 mmol l⁻¹) is the most efficient carbon source for stimulating Cr(VI) reduction. In order to apply strain Q5-1 to remove Cr(VI) from wastewater, the bacterial cells were immobilized with different matrices. Q5-1 cells embedded with compounding beads containing 4% PVA, 3% sodium alginate, 1.5% active carbon and 3% diatomite showed a similar Cr(VI) reduction rates to that of free cells. In addition, the immobilized Q5-1 cells have the advantages over free cells in being more stable, easier to re-use and minimal clogging in continuous systems. This study provides potential applications of a novel immobilized chromate-reducing bacterium for Cr(VI) bioremediation.     

Characterization of the nitrobenzene-degrading strain Pseudomonas sp. a3 and use of its immobilized cells in the treatment of mixed aromatics wastewater

A bacterial strain Pseudomonas sp. a3 capable of degrading nitrobenzene, phenol, aniline, and other aromatics was isolated and characterized. When nitrobenzene was degraded, the release of NH(4) (+) was detected, but not of NO(2) (-). This result implied that nitrobenzene might have a partial reductive metabolic pathway in strain a3. However, aniline appeared as one of the metabolites during the aerobic degradation of nitrobenzene. Moreover, the appearance of 2-aminophenol during aniline degradation by strain a3 indicated that novel initial reactions existed during the degradation of nitrobenzene and aniline by strain a3. Strain a3 was immobilized in the mixed carrier of polyvinyl alcohol and sodium alginate to improve its degrading efficiency. The optimal concentrations of polyvinyl alcohol and sodium alginate in the mixed carrier were 9 and 3 %, respectively. The immobilized cells had stable degradation activity and good mechanical properties in the recycling tests. The immobilized cells also exhibited higher tolerances in acidic (pH 4-5) and highly saline (10 % NaCl) environments than those of free cells. The biodegradation of nitrobenzene mixed with aniline and phenol using immobilized cells of Pseudomonas sp. a3 was also greatly improved compared with those of free cells. The immobilized cells could completely degrade 300 mg L(-1) nitrobenzene within 10 h with 150 mg L(-1) aniline and 150 mg L(-1) phenol. This result revealed that the immobilized cells of Pseudomonas sp. a3 could be a potential candidate for treating nitrobenzene wastewater mixed with other aromatics.     

Cross-induction of pyrene and phenanthrene in a Mycobacterium sp. isolated from polycyclic aromatic hydrocarbon contaminated river sediments.

A polycyclic aromatic hydrocarbon (PAH)-degrading culture enriched from contaminated river sediments and a Mycobacterium sp. isolated from the enrichment were tested to investigate the possible synergistic and antagonistic interactions affecting the degradation of pyrene in the presence of low molecular weight PAHs. The Mycobacterium sp. was able to mineralize 63% of the added pyrene when it was present as a sole source of carbon and energy. When the enrichment culture and the isolated bacterium were exposed to phenanthrene, de novo protein synthesis was not required for the rapid mineralization of pyrene, which reached 52% in chloramphenicol-treated cultures and 44% in the absence of the protein inhibitor. In the presence of chloramphenicol, < 1% of the added pyrene was mineralized by the mixed culture after exposure to anthracene and naphthalene. These compounds did not inhibit pyrene utilization when present at the same time as pyrene. Concurrent mineralization of pyrene and phenanthrene after exposure to either compound was observed. Cross-acclimation between ring classes of PAHs may be a potentially important interaction influencing the biodegradation of aromatic compounds in contaminated environments.     

Cr(VI) reduction by Pseudomonas aeruginosa immobilized in a polyvinyl alcohol/sodium alginate matrix containing multi-walled carbon nanotubes

Pseudomonas aeruginosa (P. aeruginosa) was immobilized with polyvinyl alcohol (PVA), sodium alginate and multiwalled carbon nanotubes (MCNTs). After immobilization, the beads were subjected to freeze-thawing to enhance mechanical strength. When exposed to 80 mg/L Cr(VI), the immobilized bacteria were able to reduce 50% of them in 84 h, however the free cells were deactivated at this concentration. The beads were used to reduce 50 mg/L Cr(VI) for nine times, with the reduction efficiency above 90% in the first five times and 65% in the end.     

Degradation of phenanthrene, fluorene, fluoranthene, and pyrene by a Mycobacterium sp.

Mycobacterium sp. strain BB1 was isolated from a former coal gasification site. It was able to utilize phenanthrene, pyrene, and fluoranthene as sole sources of carbon and energy and to degrade fluorene cometabolically. Exponential growth with solid phenanthrene, pyrene, and fluoranthene was obtained in fermentor cultures. The growth rates were 0.069, 0.056, and 0.040 h-1, respectively. Several metabolites of phenanthrene and fluorene metabolism were identified.     

Phenanthrene stimulates the degradation of pyrene and fluoranthene by <Emphasis Type="Italic">Burkholderia</Emphasis> sp. VUN10013

Pyrene and fluoranthene, when supplied as the sole carbon source, were not degraded by Burkholderia sp. VUN10013. However, when added in a mixture with phenanthrene, both pyrene and fluoranthene were degraded in liquid broth and soil. The amounts of pyrene and fluoranthene in liquid media (initial concentrations of 50 mg l⁻¹ each) decreased to 42.1% and 41.1%, respectively, after 21 days. The amounts of pyrene and fluoranthene in soil (initial concentrations of 75 mg kg⁻¹ dry soil each) decreased to 25.8% and 12.1%, respectively, after 60 days. None of the high molecular weight (HMW) polycylic aromatic hydrocarbons (PAHs) tested adversely affected phenanthrene degradation by this bacterial strain and the amount of phenanthrene decreased rapidly within 3 and 15 days of incubation in liquid broth and soil, respectively. Anthracene also stimulated the degradation of pyrene or fluoranthene by Burkholderia sp. VUN10013, but to a lesser extent than phenanthrene. The extent of anthracene degradation decreased in the presence of these HMW PAHs.     

Degradation of polycyclic aromatic hydrocarbons by an immobilized mixed bacterial culture

The mixed bacterial culture MK1 was capable of degrading a wide spectrum of aromatic compounds both as free and as immobilized cells. By offering anthracene oil or a defined mixture of phenol, naphthalene, phenanthrene, anthracene and pyrene (in concentrations of 0.1–0.2 mm, respectively) as sources of carbon and energy, a specific degradation pattern correlating with the condensation degree was observed. Regarding the defined mixture of aromatic hydrocarbons, complete metabolism was reached for phenol (0.1 mm) after 1 day, for naphthalene (0.1 mm) after 2 days and for phenanthrene (0.1 mm) after 15 days of cultivation. The conversion of anthracene (0.1 mm) and pyrene (0.1 mm) resulted in minimal residual concentrations, analogous to fluoranthene and pyrene of the anthracene oil (0.1%). Maximal total degradation for the tricyclic compounds dibenzofurane, fluorene, dibenzothiophene, phenanthrene and anthracene of the anthracene oil (0.1%) occurred after 5 days. In general, a significant metabolisation of the tetracyclic aromatic hydrocarbons fluoranthene and pyrene was observed after the degradation of phenol, naphthalene and most of the tricyclic compounds. Doubling the start concentrations of the polycyclic aromatic hydrocarbons effected higher degradation rates. Cell growth occurred simultaneously with the conversion of phenol, naphthalene and the tricyclic compounds. The immobilized cells showed stable growth and, compared to freely suspended cells, the same degradation sequence as well as an equivalent degradation potential — even in a model soil system. Correspondence to: I. Wiesel     

Immobilization of Rhizopus oryzae in a modified polyvinyl alcohol gel for L(+)-lactic acid production

The production of L(+)-lactic acid (LA) by Rhizopus oryzae immobilized in polyvinyl alcohol (PVA) was investigated. To decrease diffusional resistance, we modified the PVA gel through the addition of sodium alginate and phosphate esterification. The production of L(+)-LA improved notably in the immobilized Rhizopus oryzae. Maximum L(+)-LA production (106.27 g/L), with a yield of 73.1 % and rate of 2.95 g/L·h, was obtained at a temperature of 38 °C, 6 % PVA, and 0.8 % sodium alginate. The immobilized R. oryzae was stable in 14 serial-batch cultures using non-growth medium. The immobilized beads also displayed good tolerance to low temperature and long-term storage at 4 °C with the preservation of biochemical properties.     

高分子量多环芳烃降解菌筛选及在土壤电动-生物修复中应用

采用富集培养和多环芳烃双加氧酶基因检测方法,从焦化场地多环芳烃污染土壤分离筛选出9株PAHs降解菌。以高分子量多环芳烃芘为唯一碳源进行摇瓶降解实验,结果表明,J6、S5、S4、S2和B4对芘具有较好的降解能力,21 d时芘降解率均达55%以上,其中B4处理芘的降解率最高,达到70.2%。进一步研究了该5株菌及其混合菌对土壤中芘的降解效果,发现混合菌的降解效果高于单菌的降解效果,其中混合菌H4和单菌B4的降解效果较好,49 d时混合菌H4和单菌B4处理土壤中芘的降解率达29.3%和18.3%。经过16S rRNA基因序列比对,鉴定J6菌株为赤红球菌(Rhodococcus ruber),S5为芽孢杆菌属(Bacillus sp.),S4和S2是鞘脂单胞菌属(Sphingopyxis sp.),B4为假单胞菌属(Pseudomonas sp.)。在电场条件下,混合菌H4和单菌B4处理微生物数量及活性均显著提高,芘的降解率较单独H4和B4处理提高33.0%和20.1%,说明筛选出的5株高分子量多环芳烃降解菌具有较强的电场适应能力,可在高分子量多环芳烃污染土壤电动-微生物修复中应用。     

Parametric Studies on Batch Degradation of a Plasticizer Di-n-Butylphthalate by Immobilized Bacillus sp

Summary Di-n-butylphthalate (DBP) is one of the phthalate esters (PAEs) used in the manufacture of plasticizers, insect repellents and synthetic fibres and contributes to environmental pollution. We report a novel bacterium belonging to the genus, Bacillus (NCIM 5220), which has the ability to utilize DBP as the sole source of carbon and energy. This bacterium was immobilized in alginate. The degradation of DBP by immobilized cells was compared with free cells. The effects on the degradation of DBP of different factors like gel (alginate) concentration, gel bead size, temperature, and pH were investigated. Oxygen uptake in the presence of DBP by free and immobilized cells was also studied. The results showed that the degradation of DBP by immobilized cells was more efficient than by free cells. Further, the effect of various factors tested on the degradation of DBP by alginate-immobilized cells showed that the degradation of DBP was remarkably affected by alginate concentration between 2 and 5% and drastically decreased between bead size 2 and 5 mm. A change of 10 °C of reaction temperature from 30 to 40 °C did not alter the degradation of DBP, and maximum degradation was appeared to be favoured over a broad pH range of 6.5–7.5 for immobilized cells as compared to free cells, which showed an optimum temperature of about 35 °C and pH of 7.0. The immobilized cells showed higher oxidation of DBP than free cells. Thus more efficient degradation of DBP could be achieved by immobilizing Bacillus sp. in alginate beads.