酵母生物转化生产2-苯乙醇的研究进展

主要论述了利用酵母菌生物转化合成天然2苯乙醇的研究进展,从应用微生物学的角度介绍了2苯乙醇生产菌株的筛选,分析了2苯乙醇合成过程中几方面因素的影响和培养条件的选择,并对产物原位转移技术作了简要说明.并从分子生物学的角度出发,对生物转化的重点途径———艾利希途径在基因水平上作了诠释,且例举了利用从头合成途径进行的基因工程育种,旨在为利用微生物生产2苯乙醇的研究开发提供参考.图1参40     

金属元素与环境微生物的互作关系研究进展

在自然环境、人工生态系统等不同的环境介质中,微生物能与各种金属及其化合物共存并产生相互作用,最终影响其在环境中的迁移速率、循环过程及分布状态.本文综述了金属元素的生物地球化学循环、微生物与金属元素的互作机理以及在生产生活中的应用.主要结论为:微生物通过生物矿化、生物浸出等方式使金属发生迁移和生物转化,进而影响其在不同环境介质中的迁移速率、毒性等理化性质,参与了金属地球化学循环的每一步.微生物与金属相互作用的机理探索目前尚处于研究阶段,但较为认可的作用机制包括生物膜作用、电子传递和毒性效应等.而在工业上,微生物与金属元素间的相互作用在微生物燃料电池、金属的回收利用、土壤中重金属污染的治理等诸多方面得到了广泛的应用.未来可在群落水平上利用组学手段解析金属元素生物溶解与析出的调控网络及信号分子等作用机制,并利用基因工程或酶工程等技术开发可有效降低环境中重金属离子毒性的相关菌剂.(图2表1参61)     

利用实际市政污水培养小球藻及优化外加碳源

为探究不同工段市政污水培养小球藻过程中生物量与氮、磷、化学需氧量(COD)的去除效率,利用灭菌前后的进水、初沉池出水、污泥脱水液培养小球藻,经过7 d培养,在未灭菌污泥脱水液中获得最大藻生物量1.17 g/L;总氮、总磷、氨氮、COD的去除率分别为85.3%、99.0%、90.4%、62.0%.为进一步提高污泥脱水液培养小球藻的生物量,对比两种低成本外加碳源CO_2和粗甘油不同浓度(CO_2:5、10、15、20%;粗甘油:1、2、4、6 g/L)下的藻生物量与污水处理效果.结果在5%CO_2和2 g/L粗甘油条件下得到最大藻生物量,分别为1.57 g/L和1.45 g/L,氨氮的去除率分别为95.1%和99.3%,总氮的去除率分别为95.5%和97.5%.本研究表明未灭菌污泥脱水液更适合小球藻的培养,外加碳源于该工段污水中可提高藻生物量和氮的去除,结果可为能源微藻培养耦合实际市政污水处理和生物柴油副产物粗甘油的再利用提供基础参考.     

微生物还原Se(Ⅵ)和Se(Ⅳ)合成SeNPs机理研究新进展

硒(Se)是自然界中重要的元素之一,微生物在硒的生物地球化学循环中发挥着至关重要的作用.细菌、真菌及放线菌等多种微生物能够通过同化还原、异化还原等途径将Se(VI)和Se(IV)还原为硒纳米粒子(Se NPs).本文综述了目前已知的能够还原Se(VI)和Se(IV)的微生物资源及其还原机理,并总结了在硒化合物转运、Se NPs尺寸控制和稳定等过程中发挥重要作用的蛋白质和酶.微生物对Se(VI)的还原主要通过硒酸盐还原酶实现,而对Se(IV)的还原则通过包括亚硫酸盐还原酶、亚硝酸盐还原酶、谷胱甘肽和谷胱甘肽还原酶、硫氧还蛋白和硫氧还蛋白还原酶等多种酶促还原途径、非酶促还原途径以及作为电子受体参与的细胞呼吸过程来实现.多种不同的蛋白质和酶在Se(VI)和Se(IV)的跨膜转运、Se NPs的尺寸控制、稳定及外排等过程中发挥着重要的作用,它们不仅控制着硒化合物的还原过程,也会对Se NPs进行修饰从而改变Se NPs的物理化学性质,影响硒在环境中的归趋.今后仍需要不断开发新的能够代谢硒化合物的微生物资源,并结合基因组学、转录组学、蛋白组学等多种组学手段对微生物转化硒化合物的关键基因和调控系统等进行深入解析.     

环境中汞微生物转化研究进展

汞(Hg)污染是全球最为关注的环境问题之一.Hg的不同形态之间毒性差异大,其以有机形态存在的甲基汞(MeHg)具有强神经毒性,且能在生物体内富集,具有很强的健康与生态风险.环境中不同形态的Hg可以在生物与非生物作用下进行转化,特别是微生物在一定条件下驱动着Hg的甲基化、去甲基化、还原与氧化,从而影响Hg的移动性和生物有效性.因此,理解微生物参与Hg转化的特征与机制对人体健康和生态环境都有着重要的意义.已有不少研究报道了Hg的微生物转化过程,但缺乏一个系统的总结与归纳.本文综述了关于Hg微生物甲基化、去甲基化、还原和氧化的最新研究进展,重点讨论Hg甲基化微生物类群,分析了微生物对Hg的甲基化和还原机制,以及影响Hg甲基化过程的主要环境因子,并提出未来关于Hg微生物转化的研究方向与重点.     

微塑料与污染物相互作用的研究进展

微塑料广泛存在于环境中,其比表面积大、吸附性强,可吸附环境中的重金属、有机物、微生物等污染物,并改变它们在环境中的归趋;同时,这些污染物也会影响微塑料的性质及其在环境中的吸附、迁移、降解等行为,进而对生态环境产生潜在风险.开展微塑料与污染物的相互作用研究是进行微塑料环境风险评价的基础.当前相关研究多集中于微塑料的分布及其对不同污染物的吸附作用等方面,而污染物对微塑料性质的影响研究及吸附后它们性质变化的研究相对较少.据此本文总结了微塑料在环境中的分布情况;以吸附为例,梳理了相互作用过程的影响因素和机理;综述了微塑料与污染物相互作用的研究现状;最后基于此展望日后的研究方向,以期对未来微塑料的相关研究提供参考和帮助.     

氧化微杆菌C3催化3,5-双三氟甲基苯乙酮的不对称反-Prelog还原(英文)

(R)-3,5-双三氟甲基-1-苯乙醇是合成神经激肽1受体拮抗剂阿瑞匹坦的关键手性醇中间体.通过筛选得到一株氧化微杆菌C3(Microbacterium oxydans C3),其能不对称还原底物3,5-双三氟甲基苯乙酮为(R)-3,5-双三氟甲基-1-苯乙醇.在底物浓度为5 g/L时,生物转化反应40 h,能达到>99%的ee值和95%的底物转化率.底物浓度提高到50 g/L时,生物转化的ee值依然保持99%,并能达到56%的底物转化率.利用该氧化微杆菌C3对其他含氟苯乙酮衍生物进行生物转化反应,同样得到了较高的立体选择性和底物转化率.     

用于水产养殖的微生态制剂的研究和应用进展

随着人们对水产养殖可持续发展的需求不断提高,微生态制剂在其中的应用也越来越广泛.本文综述了近年来国内外应用于水产养殖中的各种微生态制剂的研究及应用情况.从提高水产动物生长性能、改善免疫特性和改善养殖环境等方面总结了微生态制剂中主要益生菌、益生元及合生素等在水产养殖中的应用.同时概述了微生态制剂的安全性问题.对微生态制剂的生产与应用中存在的问题进行了讨论,提出选育优良生产菌株、优化改良生产工艺并加强对水产动物自身肠道菌群、添加剂和环境之间的关系研究有利于促进微生态制剂的生产和应用.     

人工微宇宙环境下油气指示微生物的异常特征

为了解烃类对微生物的作用机制,通过人工微宇宙装置进行实验室水平模拟,结合培养法和分子生物学检测技术,以典型含油气区块土壤样品中的油气指示微生物为研究对象,探讨在模拟微渗漏条件下,一定驯化周期内不同轻烃组分驯化下油气指示微生物的数量变化和群落结构演替特征.结果显示,在微量轻烃(1×10~(-8))持续驯化下,土壤中油气指示微生物数量发生了不同程度的增长,甲烷驯化组中甲烷氧化菌的菌落数量增长了76.5%,pmo A基因丰度增幅达180.0%;丁烷驯化组中丁烷氧化菌的菌落数量增长了212.0%,bmo X基因丰度增幅达285.0%.16S rRNA高通量测序进一步显示,在模拟微渗漏(1×10~(-8))的条件下,油气指示微生物属于低丰度种群,其中Methylococcaceae(甲基球菌)、Methylophilaceae(嗜甲基菌)、Methylocystis(甲基孢囊菌)等微生物与甲烷正相关,Rhodosprillaceae(红螺菌)、Pseudonocardia(伪诺卡式菌)等微生物与丁烷正相关,其他的一些硝化微生物Nitrospira(硝化螺旋菌)、Xanthomonas(黄单胞菌)等则与烃类负相关.本研究深化了关于气态烃对油气微生物作用机制的认识,可为油气微生物勘探技术提供新思路.(图6表2参33)     

水环境中微塑料表面细菌群落特征研究进展

微塑料因其比表面积大、难降解等特点,在水环境中长期存在,可作为水环境中微生物的独特栖息地。以细菌群落为主的微生物可定殖在微塑料表面,对生态系统和人类健康产生潜在风险。本文综述了国内外海水、淡水环境中微塑料表面细菌群落特征的研究进展,阐述了微塑料表面细菌群落的研究方法和结构多样性,分析了暴露时间、地点及塑料理化性质对微塑料表面细菌群落多样性的影响,探讨了水环境中微塑料表面细菌群落的生态效应和健康风险。后续研究应采用宏基因组学全面地探究水环境中的“微塑料圈”,并关注远洋、入海口和内陆地表水微塑料表面微生物群落,从全球尺度上探索水环境中微塑料表面微生物群落的定殖规律及其生态效应。此外,鉴于微塑料表面存在降解菌,需进一步明确定殖在微塑料表面的微生物参与微塑料降解的效率及其机制,可为了解微塑料在水环境中的归宿问题提供科学依据。     

海洋微生物来源的天然产物开发研究进展

综述了近年来海洋微生物来源天然产物研究的新进展,总结了该类天然产物的开发策略.通过对样品采用不同的预处理方式、不同的分离培养基以及新的培养方法,讨论如何获得海洋来源的特有微生物和增加海洋来源微生物类群的多样性.阐述了在海洋微生物天然产物的开发过程中,采用宏基因组技术及基因组测序等手段,来发现难培养或不可培养微生物中的天然产物以及处于"沉默"状态的天然产物.最后介绍了异源生物合成、组合生物合成以及核糖体工程等技术在海洋微生物天然产物开发和改造中的应用,并举例论述了海洋微生物天然产物的开发.     

Glycerol as a green solvent for high product yields and selectivities

Organic synthesis is usually performed in solution to dissolve both reactants and catalysts and to deliver heat. Here, we show that glycerol, which is a non-toxic, biodegradable, and recyclable liquid manufactured from renewable sources, has a high potential to serve as alternative green solvent for organic reactions. Several catalytic and non-catalytic reactions were successfully performed in glycerol. High products yields and selectivities were achieved. Besides solubility of the reactants and the catalysts and easy separation of the product, glycerol offers several other benefits such as catalyst recycling, microwave assisting reaction, and biphasic and emulsion modes.     

A facile eco-friendly approach for the one-pot synthesis of 3,4-dihydro-2<Emphasis Type="Italic">H</Emphasis>-naphtho[2,3-<Emphasis Type="Italic">e</Emphasis>][1,3]oxazine-5,10-diones using glycerol as a green media

1,3-Oxazines have a wide variety of biological activities. Naphthoquinone scaffolds also exhibit several biological responses such as antithrombotic, apoptosis and lipoxygenase inhibitors. There is, therefore, a need to develop efficient green methodologies for hybridizing the two scaffolds in a single entity. Herein, we report a novel protocol for the synthesis of 3-aryl-3,4-dihydro-2H-naphtho[2,3-e][1,3]oxazine-5,10-diones by one-pot three-component condensation of 2-hydroxy-1,4-naphthoquinone, aromatic amines and formaldehyde in glycerol at 50 °C. After separation of products, the glycerol–water layer was extracted using ethyl acetate and the dried glycerol layer was successfully reused several times. The products were obtained in 85–95 % yields in 5–10 min. This environmentally benign protocol holds advantages of high yields, operational simplicity and easy workup over our earlier report.     

Movements of tiger sharks (Galeocerdo cuvier) in coastal Hawaiian waters

The giant clam Tridacna crocea harbors in the mantle tissue symbiotic microalgae commonly called zooxanthellae. Isolated zooxanthellae release glycerol into the medium in the presence of mantle tissue homogenate (MH), but it is not clear whether the cells do so in situ. In order to determine the photosynthetic products released by zooxanthellae in the mantle of the giant clam we traced photosynthetic fixation products from ¹³C- and ¹⁴C-bicarbonate both in the clam and in isolated zooxanthellae (IZ) in the presence or absence of MH. After 15 min incubation in the absence of MH the IZ released less than 0.6% of the fixed labeled carbon, mainly as glucose. The major intracellular photosynthates were neutral lipids, which constituted 20 to 40% of the total extractable ¹⁴C. In the presence of MH, the IZ released up to 5.6% of the total fixed ¹⁴C, mostly as glycerol, and the major intracellular photosynthate was glucose. In an intact clam incubated in sea water containing ¹⁴C-bicarbonate, 46 to 80% of the fixed ¹⁴C was translocated from the zooxanthellae to the host tissues. Most of the ¹⁴C in the hemolymph, in the isolated zooxanthellae and in intact mantle tissue (containing zooxanthellae) was recovered as glucose. No ¹⁴C-glycerol was detected in the mantle after 1 to 30 min incubation, and, even after 60 min, far less ¹⁴C-glycerol was synthesized than by IZ in the presence of MH. The possibility that in clam tissue glycerol is converted to glucose was examined by tracing the labeled carbon from ¹⁴C-glycerol injected into the adductor muscle. After 5 min incubation, no labeled glucose was found in the hemolymph, but after 60 min, some 20% was found as glucose. Thin slices containing zooxanthellae, cut from the surface of the mantle, fixed inorganic carbon supplied as NaH¹⁴CO₃ in the medium and mainly released ¹⁴C-glucose. The addition of MH to the surrounding medium did not affect the release rate or form of release product. When the slices were cut into smaller pieces, however, the ratio of glycerol to glucose in the release product increased. These results indicate that in the presence of MH the metabolism of isolated zooxan- thellae was different from that of zooxanthellae in the mantle. In the presence of MH, isolated zooxanthellae release mostly glycerol, whereas in the mantle they release glucose. Received: 18 February 1998 / Accepted: 4 December 1998     

Effects of host-tissue homogenate of the scleractinian coral Plesiastrea versipora on glycerol metabolism in isolated symbiotic dinoflagellates

Symbiotic dinoflagellate algae (Symbiodinium sp.) isolated from the scleractinian coral Plesiastrea versipora and incubated in homogenized host tissue released 4 to 7 times as much glycerol (14 to 46 nmol glycerol/10⁶ algae) as those incubated in seawater (3 to 6 nmol glycerol/10⁶ algae) after 4 h incubation in the light. During this period, no release of triglycerides was detected. Intracellular glycerol increased 2- to 3-fold in algae incubated in host homogenate, but remained unchanged in algae incubated in seawater at a concentration of 0.82 ± 0.47 nmol glycerol/10⁶ algae. In each incubation condition, intracellular triglyceride levels increased. However, in algae incubated in host homogenate, the intracellular levels of triglycerides reached only about 75% of the amount reached in algae incubated in seawater (max. 18.55 ± 2.40 nmol glycerol/10⁶ cells). Host homogenate did not stimulate the release of glycerol from algae during dark incubation. These data show that the glycerol released by algae incubated in host-tissue homogenate was derived from increased synthesis of glycerol or from diversion of some glycerol or other photosynthetic intermediates from incorporation into algal triglyceride stores, and did not come from existing stores. Received: 20 December 1996 / Accepted: 9 January 1997     

氯化消毒过程对抗生素的降解行为及其毒性效应的影响研究进展

抗生素的大量使用导致其通过各种途径进入到污水处理厂、地表水甚至饮用水源水中.在污水处理厂二级出水排放之前以及自来水的生产和供应过程中,都必须进行氯化消毒处理以杀灭病原微生物.在此过程中,抗生素一方面可能被氯化降解,另一方面也可能转化成毒性更高的降解产物.因此,了解抗生素在氯化消毒过程中的降解行为对于明确其生态和健康风险至关重要.本文在大量文献资料调研的基础上,综述了不同种类抗生素的氯化降解行为及其影响因素,分析了抗生素氯化降解前后的毒性效应,提出了今后研究的方向.     

Evolution of plant volatile production in insect-plant relationships

Summary The production of volatile secondary plant substances during the evolution of terrestrial plants is reviewed in regard to the defensive systems of plants to microorganisms and herbivores. Plant volatiles can be produced by both anabolic and catabolic processes. Although attraction of pollinators is a well-studied phenomenon, functions of volatiles range from excretion of waste products to the production of compounds attracting natural enemies of herbivores. During the evolution of the angiosperms a diversity of volatiles were selected to defend generative parts against microorganisms. Many of these allomones were related to or even identical with sex pheromones of insects. As a result flowers of angiosperms became utilized as a mating site. Consequently insects visiting flowers became involved in pollination, facilitating the steps from anemophily to entomophily. The efficiency of entomophily was increased because of nutritional rewards.An evolutionary scenario for the impact of plant volatiles on insects is presented and the role of volatile allomones in the establishment of plant-insect relationships is emphasized by (1) their strong antimicrobial properties, (2) strategies to protect symbiotic microorganisms, (3) their function as repellents and deterrents, (4) the use of volatile allomones as kairomones. These facts speak for an adaptation of insects to plant physiology and a limited importance of phytophagous insects in selection pressure upon plants. Herbivorous insects have realized specific adaptations to be able to discriminate between complex odour blends, but the utilization of chemical groups among insect taxa is different.The main theories on plant chemical defence do not discuss the impact of volatiles on host plant selection and may be apt to revision when pheromones, allomones, kairomones and synomones are not taken into account.     

产1,3-丙二醇新型基因工程菌的构建

以甘油为底物转化生产1,3-丙二醇的生物合成途径中,往往由于还原力NADH的不足,限制了1,3-丙二醇的合成,引起中间代谢产物3-羟基丙醛累积,进而抑制甘油脱水酶的活性,阻碍菌体的生长,严重影响1,3-丙二醇的合成途径.为了解决合成途径中还原力不足这一主要矛盾,本文以大肠杆菌和克雷伯氏菌染色体DNA为模板克隆得到yqhD和dhaB、dhaT基因,构建双启动子表达载体pEtac-dhaB-tac-yqhD及表达载体pUC-tac-dhaT,成功共转入E.coli JM109,得到可利用两种辅酶(NADH、NADPH)将片油转化为1,3-丙二醇且传代稳定的重组大肠杆菌双质粒系统,发酵结果表明,1,3-丙二醇产量提高了28.6%.图6表1参17     

Mikrobiologisch-ökotoxikologische Bodenuntersuchungen von zwei zur Unkrautbekämpfung mit hohen Dosierungen eingesetzten Fettsäure-Herbiziden

Goal and Scope

Products based on fatty acids (including acetic acid) are known in plant protection since more than 100 years to control several harmful organisms. In the following decades, however, they lost their importance due to the rapid development of ‘modern’ chemical pesticides. In the meantime some trials were run to control weeds with relatively high doses. The knowledge on its ecotoxic effects on soil microorganisms as a part of the soil fertility, however, is still incomplete.

Methods

Under laboratory conditions two agricultural soils were treated with different dosages of two products based on acetic acid and pelargonic acid (=nonanoic acid) as well as with a biocidal reference compound (e.g. dinitrophenol herbicide). The applied dosages were related to the concentrations in soil reached after simulated penetration of practical field amounts into upper soil layers. In some cases green manuring was simulated by adding lucerne meal to the soil. During the incubation for several weeks biomass-related microbial activities (dehydrogenase activity, substrate-induced shortterm respiration) as well as the mineralization of carbon and nitrogen (including nitrification) were measured.

Results and Conclusion

As compared to ‘normal’ pesticides (e.g. the reference compound) the effects of both test substances on soil microorganisms showed different behaviour. Nearly none of the effects typical for strongly biocidal compounds, namely a dose-related inhibition of microbial biomass combined with a stimulated mineralization (especially of nitrogen), occurred with the fatty acid products. Depending on the marked input of organic carbon by the higher dosages of fatty acid products and their rapid decomposition, especially of acetic acid, an increase of biomass-related parameters and of carbon mineralization combined with a reduction of the available nitrate content (e.g biological nitrogen immobilization) occurred for several weeks. By combining the results of the soil with that of lucerne meal-amended soil ‘real effects’ can be distinguished from those depending on the decomposition of the introduced carbon. In comparison with the strongly biocidal reference compound the two fatty acid products not only caused little microbiological-ecotoxicological impacts on the soil, but often stimulated important microbiological parameters for some time.

Recommendation and Perspective

As result of the trials we recommend an extended microbiological-ecotoxicological test spectrum especially for those plant protection products (pesticides) which should be applied at high dosages or if they contain higher amounts of well decomposable organic substances. This is necessary to distinguish dose-related enhanced biocidal activities induced by biocidal effects (including the subsequent mineralization of the killed microorganisms) from ‘real’ stimulations directly produced by the substrate.     

Discovery of novel halogenase genes using sequence-driven metagenomics approach北大核心CSCD

It is of great significance to ability to obtain new natural products with diverse activities through the study of soil microorganisms. However, less than 1% of the total soil microorganisms can be cultured under laboratory conditions, thus limiting the discovery of new compounds. Metagenomics, by which the genomic DNA of soil microorganisms can be extracted and expressed in heterologous hosts, provides a new approach for the functional study of soil microorganisms. Natural halides have good bioactivities, including antibacterial and antitumor activities. Halogenases play an important role in biosynthesis, and introducing bioactivities of halogenated compounds. To investigate the potential of halogenated compounds production from soil microorganisms, a soil metagenomic library was screened by PCR for clones harboring reduced flavin adenine dinucleotide (FADH2) - dependent halogenase genes. Sixty-five positive clones were identified from the library, and the amino acid sequences of halogenase genes within the positive clones were analyzed. Phylogenetic analyses revealed that more than 85% of these genes were separated from known halogenases to form new clades in the phylogenetic tree; moreover the soilderived halogenases showed high diversity. By further biosynthetic gene analysis of the positive clones, a new type I polyketide biosynthetic gene sequence was identified, which is probably related to the biosynthesis of the halogenated type I polyketide. In conclusion, novel and diverse halogenase genes were identified on sixty-five metagenomic clones using a sequence-driven metagenomic approach, laying a foundation for the further discovery of novel natural halides biosynthetic gene clusters and halides. © 2018 Science Press. All rights reserved.