挥发性有机废气生物净化过程中生物膜的作用研究

依据对生物膜填料塔净化低浓度甲苯废气过程的动力学机理问题的分析探讨,从“吸附—生化降解”的新角度,对生物膜的作用进行了研究。结果表明:随着生物膜的生长,甲苯的生物净化过程有一个从液膜传质控制向气膜传质控制的转变。因此,可以定义其为一个以生物膜为有效吸附表面、以活菌体为生物反应活化中心的吸附—生物化学反应过程。

辽东半岛复州湾剖面寒武系第二统光合作用生物膜建造的核形石

作为一种经常大于鲕粒的包覆颗粒类型,核形石以其不平滑的圈层被解释为微生物成因,区别于成因存在较大争议的鲕粒,而且常与鲕粒和其他类型的碳酸盐颗粒相互共生;作为一种在围绕着生物碎屑和非生物碎屑核心的序列式纹层化作用过程中形成的球形或假球型生物沉积构造,核形石还常常单独产出和分布,所以又被解释为微生物碳酸盐岩,或者被归为球状叠层石。在辽东半岛寒武系第二统碱厂组和馒头组之中,厘米级别大小的核形石密集发育在三级层序的顶部,成为一种时间特化的相。另外,以下重要特征将辽东半岛寒武系第二统的核形石特征化,包括:(1)与凝块和微凝块共生;(2)多为球状和椭球状;(3)由不均一的非纹层状致密泥晶和微亮晶构成;(4)核形石皮层以及核形石间凝块中发育特别的蓝细菌鞘钙化化石等。尽管穿越成岩作用过滤器去解释古代核形石复杂的形成机理存在着巨大的挑战,也尽管形成这些核形石的复杂生物膜钙化作用细节需要更加深入地研究才能得到更好地了解,但是,辽东半岛第二统碱厂组和馒头组核形石中直接的微生物化石证据,尤其是核形石内较为丰富的钙化蓝细菌鞘化石,使其成为一个了解光合作用生物膜建造核形石的典型实例。

光合作用生物膜建造的凝块:来自于辽东半岛芙蓉统长山组凝块石生物丘中的一些证据

作为一种以非纹层状组构而区别于叠层石的微生物碳酸盐岩类型,中凝块(mesoclots)是产生凝块石凝块组构关键的微结构。构成这种中凝块的离散性凝块状泥晶,似乎代表了细胞外聚合物质(EPS)复杂的钙化作用,但是,由于常常缺乏直接的微生物证据,造成其所涉及的准确成因和特殊过程还不太清楚。在辽东半岛大连金州湾和本溪田师傅剖面芙蓉统下部的长山组顶部,发育较为典型的凝块石生物丘,组成三级层序的强迫型海退体系域沉积,代表着较为壮观的沉积学现象;在这些凝块石生物丘中,毫米级别大小的暗色离散性凝块状泥晶是其最为基本的沉积组构,而且在这些凝块之中以较高密度保存的丝状蓝细菌鞘化石反映的微生物构成,意味着它们具有明显的光合作用生物膜成因。尽管穿越成岩作用过滤器去解释古代凝块石复杂的形成机理将存在着巨大的挑战,也尽管形成这些凝块石复杂的生物膜钙化作用细节需要更加深入的研究才能得到更好的了解,但是,辽东半岛芙蓉统长山组的凝块石,尤其是在凝块内较为丰富的钙化蓝细菌鞘化石所表征的直接的微生物活动证据,使其成为一个了解光合作用生物膜建造凝块的典型实例;再者,与凝块共生的三叶虫化石、底栖鲕粒和皮壳粒,以及围绕着这些多样化颗粒特别的放射纤维状方解石结壳,说明这些凝块石可能属于较厚的微生物席内多重状生物膜以及构成这些微生物席和微生物膜的细胞外聚合物质复杂的钙化作用建造物。

光合作用生物膜诱发的放射鲕粒:以江苏徐州贾旺剖面寒武系苗岭统张夏组为例

几年来针对巴哈马现代文石鲕粒的持续性研究表明,微生物和细胞外聚合物质(EPS)在鲕粒的形成和发育中起着关键而重要的作用,从而产生了一个重要的认识,即:鲕粒可以看作是"纹层状的有机沉积构造"并遵循着微生物岩体系的一些形成特征。但是,鲕粒30亿年的发育历史、多样化的产出环境、特征性的矿物构成和各种各样的沉积组构,确实赋予了鲕粒生长和形成机理的复杂性和神秘性,因为鲕粒在何处而且如何形成、以及鲕粒究竟记录着何种生物与非生物过程的许多问题还存在剧烈争论。来自于江苏徐州贾旺剖面苗岭统张夏组上部鲕粒滩相灰岩,由较为典型的方解石放射鲕粒所组成,表现出放射状、放射—同心状和泥晶质的沉积组构,而且在鲕粒核心、鲕粒皮层以及在鲕粒间的不规则团块或凝块的暗色泥晶质构成中高密度地保存着精美的葛万菌(Girvanella)化石,进一步表明了这些暗色泥晶构成代表着较为特征的光合作用生物膜,从而提供了一个苗岭世方解石海中放射鲕粒形成较为直接的微生物证据,以及与光合作用生物膜之间复杂的成因联系,因为葛万菌是相对较为肯定地类比于近代钙化织线菌(Plectonema)的丝状蓝细菌化石,尽管还可类比于现代的伪枝菌(Scytonema)。虽然形成放射状鲕粒皮层的放射纤维状方解石的沉淀作用确实不能解释为直接的微生物沉淀作用的结果,但是,这些放射鲕粒确实表现出光合作用生物膜诱发、滋养并促进了放射纤维状方解石皮层增生作用的重要证据,为拓宽"鲕粒谜"的阐释提供了一个较为重要的典型实例,而且还成为寒武纪苗岭世方解石海与后生动物辐射相耦合的蓝细菌繁荣的重要证据。

氨基丁酸联合卡泊芬净抗白色假丝酵母菌生物被膜协同作用研究

目的探讨氨基丁酸联合卡泊芬净抗白色假丝酵母菌生物被膜的协同作用。方法利用白色假丝酵母菌标准菌株SC5314,采用生物被膜形成实验,分为空白对照组、氨基丁酸单用组、卡泊芬净单用组、氨基丁酸联合卡泊芬净组,对比各组生物被膜形成情况。采用XTT还原法测定氨基丁酸、卡泊芬净单用以及氨基丁酸联合卡泊芬净对成熟生物被膜细胞代谢活性的抑制作用。采用YNB培养基菌丝形成实验,考察氨基丁酸与卡泊芬净合用是否具有协同抑制菌丝形成的作用。结果卡泊芬净0.1μg·mL-1联合氨基丁酸0.1μmol·L-1对白色假丝酵母菌SC5314生物被膜的形成具有显著的抑制作用。此外,XTT还原法测定氨基丁酸6.25μmol·L-1联合卡泊芬净0.1μg·mL-1时降低被膜细胞代谢活性的效率能够达到约15%。采用YNB培养基形成菌丝,氨基丁酸6.25μmol·L-1联合卡泊芬净0.1μg·mL-1对白色假丝酵母菌SC5314菌丝形成能力有显著的抑制作用。结论氨基丁酸联合卡泊芬净表现出显著的体外协同抗白色假丝酵母菌标准菌株SC5314生物被膜作用。

寒武纪丝状蓝细菌生物膜主导和诱发的巨型鲕粒:以河南新安县石井剖面苗岭统徐庄组为例

多样化的产出环境和30×108年的分布历史表明,鲕粒成因一直是一个谜一样的沉积学难题,争论的关键问题是其究竟是有机(微生物)成因还是无机成因。来自于华北地台寒武系苗岭统徐庄组鲕粒滩相灰岩顶部的方解石巨鲕表现出同心状、放射-同心状和泥晶质的沉积组构,在鲕粒核心和鲕粒皮层中保存着精美的葛万菌(Girvanella)化石所主导的光合作用生物膜的钙化作用残余物,这为研究鲕粒形成与光合作用生物膜之间复杂的成因联系提供了一个较为直接的微生物证据,因为葛万菌可相对较为肯定地类比于近代的钙化织线菌(Plectonema)丝状蓝细菌化石。所以说,在伴随着后生动物辐射的寒武纪蓝细菌繁盛的方解石海中,尽管形成放射状鲕粒皮层的放射纤维状方解石的沉淀作用机理还没有得到完全彻底的了解,但是这些巨鲕确实表现出光合作用生物膜诱发、滋养并促进了鲕粒形成的直接证据,进一步支持了"鲕粒沉积可以作为一种不同的微生物岩体系新类型"的重要科学理念。

生物絮凝泥沙的干容重研究

生物絮凝泥沙是指微生物通过生物膜作用在泥沙颗粒上形成的类絮凝结构,是泥沙与环境科学交叉研究中的一类新问题,在泥沙传统理论中涉及较少。本文以官厅水库细颗粒底泥为载体培养生物膜,采用Logistic生长曲线方程描述生物膜随时间生长变化的规律,通过环境扫描电子显微镜和激光扫描共聚焦显微镜观察生物絮凝泥沙的生长过程,并采用图像处理的方法对其结构特性进行分析,最终给出生物絮凝泥沙的干容重计算公式,为泥沙输移计算打下基础。

Methanol Perturbing Modeling Cell Membranes Investigated using Linear and Nonlinear Vibrational Spectroscopy

Cell membranes play a crucial role in many biological functions of cells. A small change in the composition of cell membranes can strongly influence the functions of membrane-associated proteins, such as ion and water channels, and thus mediate the chemical and physical balance in cells. Such composition change could originate from the introduction of short-chain alcohols, or other anesthetics into membranes. In this work, we have applied sum frequency generation vibrational spectroscopy （SFG-VS）, supplemented by attenuated total reflectance Fourier transform infrared spectroscopy （ATR-FTIR）, to investigate interaction between methanol and 1,2-dimyristoyl-d54-sn-glycero-3-phosphocholine （d54-DMPC） lipid bilayers. Lipid＇s hydrocarbon interior is deuterated while its head group is hydrogenated. At the same time, CH3 symmetric stretch from methanol and lipid head amine group has different frequency, thus we can distinguish the behaviors of methanol, lipid head amine group, and lipid hydrocarbon interior. Based on the spectral feature of the bending mode of the water molecules replaced by methanol, we determined that the methanol molecules are intercalated into the region between amine and phosphate groups at the lipid hydrophilic head. The dipole of CH3 groups of methanol and lipid head, and the water O-H M1 adopt the same orientation directions. The introduction of methanol into the lipid hydrophilic head group can strongly perturb the entire length of the alkyl chains, resulting that the signals of CD2 and CD3 groups from both leaflets can not cancel each other.

Preliminary Study on Airlift Membran-Bioreactor

A new type of membrane bioreactor named 'airliftmembrane-bioreactor' is discussed. For municipal wastewaterreclamation, the preliminary study on airlift membrane-bioreactorshows its good performance such as higher flux and lower energyconsumption. The airlift membrane-bioreactor is potentiallyapplicable in bioengineer- ing and environmental protection fields.

Effects of Substrate Permeation on Kinetics of Phenol Biodegradation

Based on the theory of substrate permeation through the cytoplasmic membrane,and considering the effect of initial concentration of substrate,a new kinetic model of phenol degradation process was proposed,Comparing with the widely used Haldane model,which is greatly dependent on the initial phenol concentration,our model can be used to simulate the phenol degradation process in a wide range of initial phenol concentration by using only one set of model parameters ,Therefore,this new kinetic model has much more potential applications to industrial design and operation.

The interaction of laminin and its membrane receptor on mouse macrophage membrane studied by STM and FRAP

The variation of membrane surface and lateral diffusion of membrane protein was studied after the interaction of laminin with its membrane receptor in mouse macrophages. A pattern of membrane surface which showed smaller and bigger peaks was obtained by scanning tunneling microscope(STM), looking like the domains of lipid groups and proteins in the model of fluid mosaic biomembrane. Some even more higher and wider peaks projected out from the membrane surface in STM image after the interacting of laminin with membrane receptor were, probably, the complexes of laminin and membrane receptor. Furthermore, the decreased lateral diffusion coefficient value (D) was obtained by fluorescence recovery after photobleaching (FRAP) after the laminin was reacted with membrane receptor. This phenomenon provides an evidence that the complexes of laminin and its membrane receptor were located on the membrane of macrophages. So we could consider that the laminin is combined with membrane receptor leading to the variation in the properties of membrane surface.

Analysis of the Secondary Structure of the Transmembrane Domain of SARS CoV E Protein Using FTIR Spectroscopy

One of the major obstacles facing the field of structural biology in the post genomic era is the inherent difficulty of analyzing the structure of membrane proteins under native conditions. The method of choice for studying such proteins is FTIR spectroscopy. Following the outbreaking of the severe acute respiratory syndrome （SARS） virus, in 2003, extensive work has been directed at elucidating the structure of the E transmembrane proteins of the SARS coronavirus. In this study, the secondary structure of the transmembrane a-helical bundles was analysised using the biophysical method site specific infrared dichroism （SSID）. Sixteen amino acids were isotopically labeled with （~3C=180） at different positions of the primary structure of the synthesized E protein CoV. The secondary structure was studied using Attenuated Total Internal Reflection （ATR） FTIR spectroscopy. Based on our findings, the presence of two possible H-bonding interactions between the carbonyl oxygen of two residues 26 and 31 （Phe and Leu） respectively with water molecules which may be trapped within the helix structure were postulatesed. These interactions may cause a change in this structure.

A mechanism study on the tamoxifen-mediated cellular internalization of liposomes

It was reported previously that tamoxifen （TAM） could increase the intracellular accumulation of drug-loaded liposomes, but the exact mechanism is unknown although it was supposed that TAM might enhance the cell uptake by inhibiting the drug efflux caused by P-glycoprotein （P-gp）. To identify the mechanism of increased cellular uptake of liposomes induced by tamoxifen, PEGgylated liposomes （SSL） ofP-gp-substrate doxorubicin （DOX） or non-P-gp-substrate coumarin （Cou） were prepared with or without TAM. The cell uptake of these liposome systems was investigated in cell lines with different P-gp-expressing levels and the interaction of TAM with lipid membrane was also studied. As the results, the co-encapsulation of TAM with DOX-SSL increased the intracellular uptake in all three tumor cell lines. In P-gp-highly-expressing MCF-7/Adr cells, the effect of TAM was the strongest and in negative control Hela cells, the impact weakened but still significant. The improvement was also observed in the cellular uptake of Cou-SSL. Surface plasmon resonance （SPR） studies demonstrated that TAM-SSL exhibited a much stronger atYmity with model biomembrane compared with empty SSL, and ft^her test with isothermal titration calorimetry （ITC） showed that free TAM had an obvious interaction with lipid membrane. In conclusion, TAM could increase the affinity of liposomes with biomembrane and enhance the intracellular accumulation of liposomes via both TAM-mediated P-gp inhibition and the increased interaction between hydrophobic TAM molecules and lipid membrane.

Antibacterial mechanism of high-mobility group nucleosomalbinding domain 2 on the Gram-negative bacteria Escherichia coli

Objective： To investigate the antibacterial mechanism of high-mobility group nucleosomal-binding domain 2 （HMGN2） on Escherichia coil K12, focusing on the antibacterial and antibiofilm formation effects. Its chemotactic activity on human neutrophils was also investigated. Methods： Human tissue-derived HMGN2 （tHMGN2） was extracted from fresh uterus fiber cystadenoma and purified by HPl100 reversed-phase high-performance liquid chromatography （RP-HPLC）. Recombinant human HMGN2 （rHMGN2） was generated in E. coil DE3 carrying PET-32a- c（＋）-HMGN2. Antibacterial activity of HMGN2 was determined using an agarose diffusion assay and minimum inhibitory concentration （MIC） of HMGN2 was determined by the microdilution broth method. Bacterial membrane permeability assay and DNA binding assay were performed. The antibiofilm effect of HMGN2 was investigated using a crystal violet assay and electron microscopy scanning. The activating effect and chemotactic activity of HMGN2 on neutrophils were determined using a nitroblue tetrazolium （NBT） reduction assay and Transwell chamber cell migra- tion assay, respectively. Results： HMGN2 showed a relatively high potency against Gram-negative bacteria E. coli and the MIC of HMGN2 was 16.25 μg/ml. Elevated bacterial membrane permeability was observed in HMGN2-treated E. coil K12. HMGN2 could also bind the bacterial plasmid and genomic DNA in a dose-dependent manner. The antibiofilm effect of HMGN2 on E. coil K12 was confirmed by crystal violet staining and scanning electron microscopy. However, the activating effects and chemotactic effects of HMGN2 on human neutrophils were not observed. Con- clusions： As an antimicrobial peptide （AMP）, HMGN2 possessed a good capacity for antibacterial and antibiofilm activities on E. coil K12. This capacity might be associated with disruption of the bacterial membrane and combination of DNA, which might affect the growth and viability of E. coil.

Interactions between natural biofilm,substratum surface wettability,and mussel plantigrade settlement

Mytilus galloprovincialis is a major fouling organism in the inter-tidal zone.However,the interactions between M.galloprovincialis plantigrade settlement,biofilm characteristics,and surface wettability remains unknown.Here,we examined M.galloprovincialis plantigrade settlement responses to marine biofilms(BFs)on surfaces of varying wettability.No significant difference in mussel settlement was observed on young BFs(7 d)on surfaces of differing wettability;while settlement decreased on older BFs(14,21,and 28 d)formed on low compared to high wettability surfaces.Surface wettability affected BF characteristics.The standardized harmonic mean and water contact angles values were not correlated with diatom density and chlorophyll a concentration,but were correlated with bacterial density,dry weight,and thickness.Denaturing gradient gel electrophoresis revealed that bacterial community structure differed on BFs on surfaces of varying wettability.Thus,surface wettability affects biofilm characteristics,and the subsequent changes in BF characteristics may be responsible for the variation in biofilm-inducing activity of M.galloprovincialis plantigrade settlement.

Interaction between curcumin and mimetic biomembrane

Curcumin, a major bioactive compound in turmeric, has a broad spectrum of antioxidant, anticarcinogenic, antimutagenic and anti-inflammatory properties. At the molecular level, curcumin modulates many structurally unrelated membrane proteins through several signaling pathways. Curcumin has been suggested to change the properties of cell membranes and affect the membrane-bound proteins indirectly; however, the detailed mechanism has yet to be investigated. In this paper, self-assembled bilayer lipid membranes are artificially constructed on the surface of a gold electrode to miinic biomembranes, and interaction between the supported membranes and curcumin is studied electrochemically. Results show that curcumin interacts with the membranes strongly, in a concentration-dependent manner. At low concentrations, curcumin tends to insert into the outer monolayer only, while at high concentrations, it may also begin to penetrate the inner monolayer. The results obtained in this work may enhance our understanding of the effect of curcumin, and possibly flavonoids, on ceU membranes and membrane proteins.