细菌生长的热动力学性质的研究

前文报导了大肠杆菌在不同培养基中生长的速率及热力学函数.本文在此基础上又测定了不同细菌在相同培养基中生长的规律.细菌生长是一系列非常复杂的过程,为便于研究,使复杂问题简单化,我们采取与过渡状态理论类似的模式进行处理,得出了一些热动力学函数,这些数据为进一步探讨这一复杂过程提供了有用的信息.     

微量热法测定细菌的临界生长温度

应用微量热学的方法,我们已能成功地测得细菌生长过程的热谱,这种热谱包含着有关细菌生长代谢过程的丰富信息,例如对热谱曲线的指数生长段进行解析,可得出细菌生长的速率常数、激活能和有关的热力学参数。故采用微量热法测定细菌在不同培养温度下的生长速率常数,利用计算机拟合出相应k(速率常数)和T(培养温度)的线性关系式后,若把生长速率为零的温度定义为临界生长温度时,就可以根据由上述实验所得的k～T线性关系式求得细菌的临界生长温度。本工作仍采用微量热法对福氏志贺氏菌(S. flexneri)和大肠埃希氏菌(E. coli)进行实验测定。按文献的方法求出它们在不同温度下的生长速率常数;对于大肠埃希氏菌还用几种不同的培养基分别进行实验测定。     

细胞不同代谢类型的热化学研究Ⅰ.生长、非生长及内源代谢水平的量热测定

细胞是生命的基本单位．对其代谢过程能量输出水平的直接测定，对细胞生理学来说是重要的实验基础数据，对于生物生理和研究能量代谢方面也有一定的理论意义．当然细胞的多样性及其代谢过程的复杂性使这一研究工作相当困难·作为开展研究的第一步我们选择便于培养处理的单细胞生物大肠杆菌作为研究对象，并对其所进行时三种基本代谢类型29Llxi：L谢；非生长依队和内派代谢分别进行研究，本文分别测定了＊烟三种不同类型代谢的热功率输出水平，得到了单个细胞在上述代谢过程热功率输出的定量数据．实验结果表明，不同类型代谢的能量输出水平…     

微量热法测定细菌的最低生长温度

微量热法测定细菌的最低生长温度南照东，刘永军，孙海涛，张洪林（曲阜师范大学化学系曲阜２７３１６５）关键词微量热法，细菌的生长热谱，最低生长温度，生长速率常数我们应用微量热法测定了大肠杆菌（Ｅ．ｃｏｌｉ），白色葡萄球菌（Ｓ．ａｌｂｕｓ），金黄色葡萄球菌...     

人参对金黄色葡萄球菌的代谢过程促进作用的研究

前文[1]已报导了合成药物对细菌抑制作用的研究．药物抑菌生长的热化学研究是当今热化学法研究的一个活跃领域，Boling[2]、Nordmark[3]等人已做了很有意义的工作．在此基础上，作者对畜养药物促进细菌代谢过程进行了研究，用微量量热仪测定了人参对金黄色葡萄球菌代谢过程起促     

细菌生长的热动力学研究进展

本文简单介绍了绝热式和热导式量热计及理论模型,细菌生长的动力学模型,着重介绍了近五年中热动力学在研究细菌生长代谢过程中的应用;通过测定不同条件下细菌生长代谢过程的产热曲线,求得细菌生长代谢的热力学和动力学参数,研究细菌的生长条件和药物的抑制作用。     

Schiff碱药物与细菌作用的半抑制量比较研究

用微量热法测定了金黄色葡萄球菌和产气杆菌分别与十一种Ｓｃｈｉｆｆ碱药物作用的热谱曲线根据热谱曲线计算了细菌生长的速率常数Ｋ，建立了Ｋ～Ｃ关系式，进行在获得的Ｓｃｈｉｆｆ碱药物对细菌作用的半抑制量Ｃ１／２的基础上，通过对半抑制量大小的比较，分别对配体相同金属离不同，金属离子相同配体不同的Ｓｃｈｉｆｆ碱药物与细菌的作用以及对同一药物与不同细菌作用的情况做了较深入的讨论，发现，同一药物对不同的菌种其药效     

生物质在流化床中的热解和气化研究

在水蒸气及氮气流态化条件下 ,对不同生物质原料进行了热解气化实验 ,研究气体产物产率、成分随反应温度的变化规律。在一个常压鼓泡流化床实验台上 ,对五种生物质原料热解气化综合过程的气体产物产率及成分进行了测定。文中重点分析了原料SD2 0 1 (EucalyptusGlobulus锯末 )与SD2 0 2 (PinusRadiata锯末 )在水蒸气及氮气流化和不同温度条件下的热解气化特性 ,同时还分析了两种流化介质条件下生物质热解气化实验结果的差别。     

热解法制备纳米sno2及气敏性能

在不同温度下热解SnC2O4制备出纳米SnO2。利用XRD、红外光谱测试技术研究了SnO2的形貌、结构及晶粒生长过程,对它们的气敏性能进行了研究。结果表明,随着热解温度的不同,获得的颗粒尺寸不同。机理研究显示:650℃以上或650℃以下SnO2颗粒生长的方式不同。当热处理温度<650℃时,晶核生长以表面扩散为主,晶粒生长缓慢;在650℃以上热解时,晶粒以晶界迁移进行粒子生长,生长比较迅速。热解温度对气敏灵敏度影响很大,对响应恢复时间影响不大。热解法合成的SnO2纳米材料具有较好的酒敏性能,650℃热处理所得样品的气敏性能最佳,在灵敏度、响应恢复时间上表现优良。     

药物对福氏志贺氏菌代谢抑制的微量热法研究

药物抑制细菌生长的热化学研究是当今热化学法研究的一个活跃领域．在这项研究中，Boling[1]、Nordmark[2]、屈松生[3]等人已做了不少有意义的工作．在前人工作的基础上，我们用热活性检测系统测定了福氏志贺氏菌属中五株细菌在药物抑制下生长的完整的热谱曲线．按指数生长模型计算出细菌代谢抑制下的生长速车常数，并用计算机拟会出生长速率常数与不同浓度药物之间的关系式，进一步得到生长速率常数为零（临界生长参数[4]）时的用药物浓度．此项研究工作的开展对于深入研究药物对细菌的抑制作用，筛选对某细菌抑制的特效药提供了一种新的…     

微生物最适生长酸度的微量热法研究

The bacterial growth thermogram curves under different acidities were determined. From these thermogram curves, the growth rate constants(k) at different acidities were calculated and the equation correlating of k with PH could be established. From these k-pH equations,the optimum acidity of bacteria growth could be obtained. These models provide a good method for the study of the metabolism of bacteria.     

Synthesis of star-shaped CuO nanoparticles supported on magnetic functionalized graphene: Catalytic and antibacterial activity

In this study, graphene oxide was modified during consecutive functionalization steps with 1,4-diphenylamine, cyanuric chloride, and ethylenediamine. Then, star-shaped CuO nanoparticles were synthesized on modified graphene oxide using the seed-mediated growth method in which nucleation, growth stages, and reduction of graphene oxide to graphene occurred simultaneously. After ensuring successful synthesis of CuO nanoparticles and to facilitate recycling, a magnetization process was utilized by adding iron oxide nanoparticles. This nanocomposite was characterized by transmission electron microscopy, X-ray powder diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The prepared heterogeneous catalyst was investigated for the reduction of organic dyes in the presence of NaBH₄ as a reducing reagent. The kinetic data obtained for the reduction of methyl orange (MO), methylene blue (MB), 4-nitrophenol (4-NP), and rhodamine 6G (Rh6G) were fitted to first-order rate equations, and the calculated rate constants for the reduction of MO, MB, 4-NP and Rh6G were as follows: −0.091, −0.071, −0.045, and 0.040, respectively. As star-shaped CuO nanoparticles showed a higher antibacterial effect compared to spherical-shaped CuO nanoparticles, the antibacterial activity of star-shaped CuO nanoparticles immobilized on magnetic functionalized graphene was evaluated against Gram-positive and Gram-negative bacteria through an agar well diffusion assay and demonstrated more antibacterial activity against gram-positive bacteria.     

Raman spectroscopic identification of single bacterial cells at different stages of their lifecycle

Early, rapid, and reliable bacterial identification is of great importance in natural environments and in medical situations. Numerous studies have shown that Raman spectroscopy can be used to differentiate between different bacteria under controlled laboratory conditions. However, individual bacteria within a population exhibit macromolecular and metabolic heterogeneity over their lifetime. Therefore it is important to be able to identify and classify specific bacteria at different time points of the growth cycle. In this study, four species of bacteria were used to explore the capability of confocal Raman spectroscopy as a tool for the identification of (and discrimination between) diverse bacterial species at various growth time points. The results show that bacterial cells from different growth time points (as well as from a random growth phase) can be discriminated among the four species using principal component analysis (PCA). The results also show that bacteria selected from different growth phases can be classified with the help of a prediction model based on principal component and linear discriminant analysis (PC-LDA). These findings demonstrate that Raman spectroscopy with the application of a PC-LDA model rooted in chemotaxonomic analysis has potential for rapid sensing of microbial cells in environmental and clinical studies.     

Low‐Voltage Pulsed Electric Field Sterilization on a Microfluidic Chip

A polyimide substrate based microfluidic chip with thousands of comb‐shaped microelectrodes has been designed, fabricated, and tested for sterilization of bacteria by using pulsed electric field. The performance of bacteria sterilization as functions of the electric field strength, pulse number and width, treatment buffer, bacteria growth status, and bacteria enrichment by positive dielectrophoresis has been experimentally investigated on the microfluidic chip. Experimental results show that only 100 V are sufficient to obtain good sterilization of Escherichia coli. Higher electric field strength, bacteria enrichment by positive dielectrophoresis, longer pulse time, buffer with fewer components and nutritions, and suitable bacteria growth status also improve the sterilization of bacteria. In addition, configuration of the microelectrode array affects bacteria sterilization. This microfluidic device allows one to preconcentrate bacteria to a region with high electric field strength by using positive dielectrophoresis, and subsequently kill the enriched bacteria by applying a pulsed electric field through the same microelectrode array.     

nSrDNA Appraisal of High Yield Flocculant Compound Bacteria and Their Application Effect

IntroductionMicrobe flocculant is focused on environmental ar-ea because of its safety and non-toxicity and non-sec-ondary pollution. It is hoped to get preponderantmatching and overfulfilling object by compounding dif-ferent bacteria based on the theory …     

Thermo-kinetic Investigation of Optimum Growth Temperature of Petroleum Bacteria

The power-time curves of the growth of three strains of petroleum bacteria at different temperatures have been determined. A novel equation of a power-time curve has been proposed in this paper. The general formula to calculate the rate constant of the bacterial growth has been derived. The rate constants of the bacterial growth at different temperatures, the heat production per newly formed bacterium, the bacterial number at the end of the bacterial growth and the deceleration rate constant of the bacterial growth at 50.00°C, have been calculated. The optimum growth temperatures of the three strains have been obtained.This revised version was published online in November 2005 with corrections to the Cover Date.     

Remediation of metalliferous soils through the heavy metal resistant plant growth promoting bacteria: Paradigms and prospects

Various industrial, agricultural and military operations have released huge amounts of toxic heavy metals into the environment with deleterious effects on soils, water and air. Under metal stress, soil microorganisms including plant growth promoting bacteria (PGPB) have developed many strategies to evade the toxicity generated by the various heavy metals. Such metal resistant PGPB, when used as bioinoculant or biofertilizers, significantly improved the growth of plants in heavy metal contaminated/stressed soils. Application of bacteria possessing metal detoxifying traits along with plant-beneficial properties is a cost effective and environmental friendly metal bioremediation approach. This review highlights the different mechanisms of metal resistance and plant growth promotion of metal resistant PGPB as well as the recent development in exploitation of these bacteria in bioremediation of heavy metals in different agroecosystems.     

Kinetic growth models at different biological development levels

The quasi-chemical biological growth model suggested earlier was used to derive kinetic equations for population growth of various biological species. A cycle of sequential stages of population development can be represented in the form of quasi-chemical equations; the kinetic equations describing the development cycle allow the population size changes to be predicted quantitatively depending on the conditions. As distinct from the extrapolation-simulation model, the kinetic parameters in kinetic biological growth models are the experimental population growth characteristics. The models developed were verified and parametrically identified on the basis of the experimental data to show that they were in agreement with experiment to within measurement errors.     

Analysis of changes in attenuated total reflection FTIR fingerprints of Pseudomonas fluorescens from planktonic state to nascent biofilm state

Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy is a useful method for monitoring biofilm in situ, non-destructively, in real time, and under fully hydrated conditions. In this work we focused on changes in Pseudomonas fluorescens ATR-FTIR fingerprint accompanying the very early stages of biofilm formation: initial bacterial adhesion and the very beginning of biofilm development in the presence of nutrients. To help interpreting variations in the ATR-FTIR fingerprint of sessile bacteria, ATR-FTIR spectra of planktonic bacteria in different growth phases were also examined, and the average surface coverage and spatial arrangement of bacteria on the ATR crystal were determined by epifluorescence microscopy. The proteins, nucleic acids and polysaccharides ATR-FTIR spectral data recorded during growth of sessile bacteria were shown to be linked to changes in the physiological state of the bacteria, possibly accompanied by extracellular polymeric substances production. This work clearly showed by spectroscopic method how bacteria change drastically their metabolism during the first hours of biofilm formation.     

Characterization of the volatile profile of Antarctic bacteria by using solid-phase microextraction-gas chromatography-mass spectrometry

Bacteria belonging to the Burkholderia cepacia complex (Bcc) are significant pathogens in Cystic Fibrosis (CF) patients and are resistant to a plethora of antibiotics. In this context, microorganisms from Antarctica are interesting because they produce antimicrobial compounds inhibiting the growth of other bacteria. This is particularly true for bacteria isolated from Antarctic sponges. The aim of this work was to characterize a set of Antarctic bacteria for their ability to produce new natural drugs that could be exploited in the control of infections in CF patients by Bcc bacteria. Hence, 11 bacterial strains allocated to different genera (e.g., Pseudoalteromonas, Arthrobacter and Psychrobacter) were tested for their ability to inhibit the growth of 21 Bcc strains and some other human pathogens. All these bacteria completely inhibited the growth of most, if not all, Bcc strains, suggesting a highly specific activity toward Bcc strains. Experimental evidences showed that the antimicrobial compounds are small volatile organic compounds, and are constitutively produced via an unknown pathway. The microbial volatile profile was obtained by SPME-GC-MS within the m/z interval of 40-450. Solid phase micro extraction technique affords the possibility to extract the volatile compounds in head space with a minimal sample perturbation. Principal component analysis and successive cluster discriminant analysis was applied to evaluate the relationships among the volatile organic compounds with the aim of classifying the microorganisms by their volatile profile. These data highlight the potentiality of Antarctic bacteria as novel sources of antibacterial substances to face Bcc infections in CF patients.