微生物降解菲的机理研究进展*

针对微生物降解菲的机理研究进展,论述了细菌、真菌在好氧、厌氧条件下代谢菲的产物以及推测的降解途径;在此基础上概括了催化反应的酶系以及编码酶系的基因簇。简要介绍了基因探针的应用,并结合本实验室的初步研究,指出了该领域有待深入探讨的问题。     

甲基叔丁基醚微生物降解研究进展*

汽油添加剂甲基叔丁基醚(Methyl tert-Butyl Ether,MTBE)的水体污染问题近年引起广泛关注,因而微生物降解MTBE的研究也渐成热点。对MTBE的微生物降解研究现状进行简要综述,总结好氧条件下降解菌对MTBE的降解情况,以关键中间代谢物-叔丁基醇(tert-butyl alcohol,TBA)为分界点探讨微生物降解MTBE的两步可能途径,浅论MTBE微生物降解的影响因素。     

芳香烃分解代谢的龙胆酸途径*

龙胆酸代谢途径是微生物降解芳香烃的3条典型的代谢途径之一,是一条重要但需要深入研究的代谢途经。综述了龙胆酸代谢途径的研究进展,特别是分子生物学方面的成果。     

黄原胶降解菌的筛选及其降解酶性质的研究*

从野外采集并筛选到一株能降解黄原胶的菌株,并对菌种进行了对照鉴定。此外,对菌株的发酵参数、黄原胶降解酶的性质(最适反应温度、pH值,金属离子的影响、底物专一性、动力学研究等)作了初步的研究。结果显示,该酶的最适催化反应温度和pH分别为30℃～40℃和5.0～7.0;能够专一性降解黄原胶;测试大多数金属离子对酶活力没有明显影响,但Ca²⁺能很大程度地缓解EDTA对酶活的抑制作用。     

微生物降解农药的研究新进展*

农药中,尤其化学农药中高毒、高残留、难降解的农药是重要的环境污染物,而微生物治理农药污染是一项有效手段,几十年来,在这方面已进行了大量研究。从农药降解菌的种类、工程菌的构建、微生物降解农药的机理、降解特性、影响因素及应用效果等几方面综述了近年这些方面的研究进展,并提出农药微生物降解研究领域的发展趋势和有待进一步解决的问题。     

高效复合菌对氯代苯酚类化合物的微生物修复研究

从江苏省扬子石化公司污水处理厂曝气池出口处取活性污泥样品,驯化、培养、分离得到降解氯代酚类芳烃化合物的复合菌作为微生物源,采用细菌生长抑制法分别进行了2-氯苯酚、3-氯苯酚和4-氯笨酚的24h急性毒性试验,求得了相应的24h半数抑制浓度值及24h毒性效应-关系曲线.结果表明:所获得的复合菌群较自然水体中混合细菌对氯代苯酚有更强的耐受性.采用实验室摇瓶法得到了这三种受试化合物的生物降解曲线,对应的降解速率常数K分别为:2.氯酚K=0.0112(h.1)、3.氯酚K=0.0556(h-1)、4-氯酚K=0.0038(h-1);降解半衰期t1/2分别为61.9(h)、12.5(h)和182.4(h).三种化合物在100 h内均达到了降解平衡,且降解平衡时的降解率分别达到:2-氯酚56.3%,3-氯酚81.7%,4-氯酚36.4%,属于高效复合菌,发挥了微生物对外源性化合物的巨大降解和修复潜能.     

香豆素类化合物功能及生物合成研究进展*

香豆素类化合物是自然界中一类重要的化合物,具有抗肿瘤、抗凝血、抗菌、杀虫等多种生物活性,应用领域广泛。目前大多数香豆素类化合物从植物中提取,受环境因素影响较大,得率低、成本高,不利于大规模生产,从而限制了其应用和推广。利用合成生物学的思路合成香豆素类化合物具有无污染、原料易得、成本低、过程可控等优势。对香豆素类化合物生物合成途径的研究,尤其是靶标天然产物生物合成表达元件、宿主和发酵条件的优化,以及合成途径中关键酶的挖掘,已经成为研究热点。综述香豆素类化合物及其衍生物的结构、功能和生物合成研究进展,为其生物合成路径中的基因挖掘及异源表达提供参考。     

微生物染料脱色研究进展*

近年来,利用微生物对各种染料及染料废水脱色的研究报道很多,包括细菌、真菌等,脱色机制包括吸附脱色和降解脱色。综述了国内外有关这两大类微生物脱色研究的最新进展,对各种脱色机制在实际染料废水处理中的应用现状和研究方向进行了讨论。     

未培养的微生物研究进展*

未培养的微生物是指那些到目前为止人们还无法纯培养的微生物。这些微生物可能是以前被描述过的,更多的则是从未被了解过的。近年来,对未培养的微生物的研究方兴未艾,主要是有关环境微生物的遗传多样性分析,从特定环境中鉴定某些未知的微生物,从环境微生物中直接克隆基因以及提高环境微生物的培养率等问题。就有关这几个方面的一些研究进展作一个简要的介绍。     

对-氯代苯胺(PCA)在填充床生物反应器中的降解作用

以氯代苯胺(PCA)为选择基质,用驯化技术从降解对二氯苯(p-DCB)的富集培养物中得到了以同化PCA为唯一碳源和氮源的混合微生物。将这种固定在填充床反应器中的微生物用于PCA的降解作用研究中。在该反应器里,PCA的生物降解遵循Logistic方程q=q_max/(1+e^α-βU_v).由方程求出了主要的动力学常数,K_s(半速率常数)和q_max(最大比基质降解速率).于PCA降解的同时,释放氯离子到培养基中。在水力停留时间3h, 进水PCA浓度为360mg·L^-1情况下,基质的体积降解率达到125mg·L^-1·h^-1;基质的百分去除率为91%.     

Biodegradation of N-Methylpyrrolidone by Paracoccus sp. NMD-4 and its degradation pathway

N-Methylpyrrolidone (NMP), a kind of nitrogen-containing heterocyclic pollutant, is widely used in chemical industry. Microbial degradation is an important environmental fate process in soil and water, however, the microbial metabolic mechanism is still unknown. Strain NMD-4, capable of utilizing NMP as the sole source of carbon and nitrogen, was isolated from the activated sludge of a pesticide plant in Jiangsu, China, and identified as Paracoccus sp. based on its physiological–biochemical properties, as well as 16S rRNA gene sequence analysis. The degradation characteristic of NMP by strain NMD-4 was studied in a liquid culture, and the metabolic pathway of NMP by the strain was investigated. Two metabolites, 1-methyl-2,5-pyrrolidinedione and succinic acid, were detected and identified by liquid chromatography-mass spectrometry analysis, and a plausible microbial degradation pathway of NMP was proposed by the first time.     

Biodegradation of phenanthrene by Pseudomonas sp. BZ-3, isolated from crude oil contaminated soil

A phenanthrene (PHE) degrading bacterium strain BZ-3 was isolated from the crude oil contaminated soil in Binzhou, China. The isolate was identified as Pseudomonas sp. BZ-3 on the basis of 16S rRNA gene sequence. Various experiments were conducted to investigate the effect of pH, salinity and PHE concentration on the degradation efficiency of PHE. The degradation efficiency and degradation metabolites of PHE were detected by using GC–MS and HPLC-MS analyses. The strain BZ-3 could degrade 75% of PHE at an initial concentration of 50 mg/L under 20 g/L salinity in 7 days. PHE degradation kinetics was estimated in a first-order degradation rate model and the rate coefficient was calculated as 0.108 d⁻¹. On the basis of the identified degradation metabolites, the strain BZ-3 could degrade PHE in the salicylate metabolic pathway. In a mixture system consisting of PHE and other PAHs including naphthalene (NA), anthracene (ANTH), and pyrene (PYR), the strain BZ-3 showed an efficiently degradation capability. Further study showed that the strain BZ-3 could also use NA, ANTH, PYR, xylene, 1-hydroxy-2-naphthoic acid, and hexane as the sole carbon and energy source, but did not grow on nitrobenzene-containing medium.     

染料的生物降解研究

生物降解法是染料污染治理的重要方法。针对目前使用量较大的偶氮染料、二苯基甲烷染料和蒽醌染料这3大类染料,重点介绍了厌氧和好氧条件下的偶氮还原及其机理、三苯基甲烷染料降解菌和蒽醌染料降解菌的研究进展。     

Purification and gene cloning of the oxygenase component of the terephthalate 1,2-dioxygenase system from Delftia tsuruhatensis strain T7

The terephthalate 1,2-dioxygenase system (TERDOS) was found in cell extracts of Delftia tsuruhatensis strain T7 (=IFO16741) grown in terephthalate-salt medium. The cell extract was separated by anion exchange chromatography to yield two fractions (R and Z) that were necessary for oxygenation of terephthalate with NADH and Fe(2+). The oxygenase component of TERDOS (TerZ) was purified from fraction Z by gel filtration chromatography to near homogeneity. An alpha(3)beta(3) subunit structure was deduced from the molecular masses of 235, 46 and 17 kDa of the native complex and the alpha- and beta-subunits, respectively. The N-terminal amino acid sequences of the two subunits of TerZ allowed polymerase chain reaction primers to be deduced and the DNA sequence of the alpha-subunit was determined. The amino acid sequence of the alpha-subunit (TerZalpha) showed significant similarities to the large subunits of multicomponent ring-hydroxylating oxygenases. Two motifs in the deduced amino acid sequence, a Rieske [2Fe-2S] center and a mononuclear Fe(II) binding site, were observed. Phylogenetic analyses indicated that TerZalpha and the large oxygenase component subunits ortho-halobenzoate 1,2-dioxygenase and salicylate-5-hydroxylase form a cluster that is distant from the rest of the large oxygenase subunits of multicomponent ring-hydroxylating oxygenases.     

硝基苯污染物的生物降解途径

硝基苯是一种有毒化合物,目前,关于硝基苯污染物的生物降解已进行了大量的研究。综述了生物降解硝基苯的两种主要途径氧化途径和部分还原途径,介绍了两种途径降解硝基苯的具体机制及相关酶和编码基因的特点,并对两种降解途径进行了简要的对比分析,为硝基苯及其它有机污染物生物降解技术的开发应用提供依据。     

聚乙烯醇的生物降解

聚乙烯醇(PVA)是较少的可溶于水并被生物降解的乙烯聚合物之一。研究表明,在受PVA污染的自然环境中存在着能降解PVA的微生物,并从中提取出了PVA降解酶。介绍了国内外研究聚乙烯醇生物降解的情况。分别讨论了聚乙烯醇被单一菌种、共生细菌和真菌降解过程中的生物化学和生理学特性,以及结构因素对聚乙烯醇生物降解的影响。这些研究促进了可有效生物降解的PVA类材料产品项目的发展。     

芳香族化合物生物降解的研究进展

本文综述了以苯、取代苯、联苯和多环芳烃为代表的芳香族化合物的生物降解途径,其共同之处在于经过两步双加氧酶作用,生成二醇和开环。两步双加氧酶分别为芳环羟基化双加氧酶和芳环断裂双加氧酶。以甲苯途径为代表讨论了芳香族化合物的分子生物学研究情况。代谢工程研究是九十年代兴起的芳香族化合物生物降解的研究内容,通过对甲苯途径的代谢工程研究明确了途径中的关键酶,并通过对关键酶的活性提高使整个途径的代谢流增加。     

Biodegradation of bisphenol A by bacterial consortia

The effect of light on BPA degradation by an adapted bacterial consortium was investigated. BPA was completely degraded up to 50 mg l⁻¹, and the degradation followed first-order reaction kinetics both in the light and in the dark. The degradation half-life of BPA when the consortium was grown in presence of light was 21.9, 17.2, and 12.6 h for concentrations of 10, 20, and 50 mg l⁻¹, respectively; the degradation half-life of BPA in the dark was 13.1, 10.8, and 10.2 h for concentrations of 10, 20, and 50 mg l⁻¹, respectively. Therefore, light inhibited BPA biodegradation. However, under both conditions, BPA was completely depleted. The bacterial consortium effectively utilised BPA as a growth substrate to sustain a cell yield of 0.95 g g⁻¹ and 0.97 g g⁻¹ in the light and dark, respectively. A total of ten and nine biodegradation intermediates were detected in the light and dark, respectively. Three bacterial metabolic pathways and one photodegradation pathway were proposed to explain their occurrence. This study demonstrated that bacterial consortia may assemble a wide range of catabolic pathways to allow for efficient degradation of BPA, converting BPA to principally bacterial biomass and metabolites exhibiting low or no oestrogenic activity.     

Isolation and characterization of a benzoylformate decarboxylase and a NAD/NADP-dependent benzaldehyde dehydrogenase involved in d-phenylglycine metabolism in Pseudomonas stutzeri ST-201

Following induction with d-phenylglycine both d-phenylglycine aminotransferase activity and benzoylformate decarboxylase activity were observed in cultures of Pseudomonas stutzeri ST-201. Induction with benzoylformate, on the other hand, induced only benzoylformate decarboxylase activity. Purification of the benzoylformate decarboxylase, followed by N-terminal sequencing, enabled the design of probes for hybridization with P. stutzeri ST-201 genomic DNA libraries. Sequencing of two overlapping genomic DNA restriction fragments revealed two open reading frames which were denoted dpgB and dpgC. Sequence alignments suggested that the genes encoded a thiamin-diphosphate-dependent decarboxylase and an aldehyde dehydrogenase, respectively. Both genes were isolated and expressed in Escherichia coli. The dpgB gene product was confirmed as a benzoylformate decarboxylase while the dpgC gene product was characterized as a NAD⁺/NADP⁺-dependent benzaldehyde dehydrogenase. In keeping with their high sequence identities (both greater than 85%) the kinetic properties of the two enzymes were similar to those of the homologous enzymes in the mandelate pathway of Pseudomonas putida ATCC 12633. However, Pseudomonas stutzeri ST-201 was unable to grow on either isomer of mandelate, and sequencing indicated that the dpgB gene did not form part of an operon. Thus it appears that the two enzymes form part of a d-phenylglycine, rather than mandelate, degrading pathway.     

Biodegradation of polyhydroxyalkanoates

Abstract Degradation of poly(3-hydroxybutyrate) and copolymers with 3-hydroxyvaleric acid was investigated in natural environments, and the microorganisms involved were isolated and identified. The influence of abiotic and biotic factors on the degradation is discussed.