Action of the Selenomorpholine Compounds on the Bacterium Growth by Microcalorimetry

The action of β-(N-selenomorpholine) ethyl phenyl ketone hydrochloride and 4-(N-selenomorpholine)-2-butanone hydro-chloride on Escherichia coli and Staphylococcus aureus was studied by microcalorimetry,Differences in their capacities to affect the metabolism of this bacterium were observed.The kinetics shows that the selenomorpholine compounds had action on the metabolism process of Escherichia coli and Staphylococcus aureus.The rate constant (k) of the studied bacterium in the presence of the drugs are concentration-dependant.The growth rate constants decrease with an increase in the mass of the selenomorpholine compounds ,but their relationship is different.As deduced from the rate constant(k) of the studied bacterium(in log phase )and the half inhibitory concentration (IC50),the experimental results reveal that the studied selenomorpholine compounds all have good antibiotic activity and better antibacterial activity on Staphylcoccus aureus than on Escherichia coli.     

微量热法研究硒代吗啉衍生物的抑菌作用

大肠杆菌;生长代谢;微量热法研究硒代吗啉衍生物的抑菌作用     

Study on interaction between antibiotics and Escherichia coli DH5α by microcalorimetric method

A microcalorimetric technique based on the bacterial heat output was applied to evaluate the influence of antibiotics PIP (Piperacillin Sodium) and composite preparation of PIP and SBT (Sulbactam Sodium) on the growth of E. coli DH5α. The power–time curves of the growth metabolism of E. coli DH5α were studied using a TAM Air Isothermal Microcalorimeter at 37°C. By analyzing the power–time curves, the parameters such as growth rate constants (k), inhibitory ratio (I), the maximum heat power (P _m) and the time of the maximum heat power (t _m) were obtained. The results show that different concentrations of antibiotics affect the growth metabolism of E. coli DH5α. The PIP in the concentration range of 0–0.05 μg mL^–1 has a stimulatory effect on the E. coli DH5α growth, while the PIP of higher concentrations (0.05 –0.25 μg mL^–1) can inhibit its growth. It seems that the composite preparation composed of PIP and SBT cannot improve the inhibitory effect on E. coli DH5α as compared with the PIP.     

Influences of levofloxacin salts on the metabolism of Escherichia coli by microcalorimetry

A microcalorimetric technique was used to evaluate the influence of both Levofloxacin lactate in sodium chloride injection (drug A) and Levofloxacin hydrochloride in sodium chloride injection (drug B) on the metabolism of Escherichia coli. By means of an isothermal calorimeter and ampoule method at 37 °C, the power-time curves of E. coli growth were obtained under different conditions. The parameters such as the growth rate constant k, maximum power output P _m, time t _m corresponding to the maximum power output and inhibitory ratio I of these two drugs were obtained. The results reveal that the inhibitory abilities enhance with increasing concentrations of the two drugs. The critical growth concentration and the half-inhibitory concentration IC₅₀ were 0.15 and 0.079 μg mL^?1 (for drug A), 0.13 and 0.061 μg mL^?1 (for drug B), respectively. These results show the drug A has slightly better inhibitory effect on E. coli than that of drug B.     

Investigation of the Effect of Four Organic Acids in Radix Isatidis on E. coli Growth by Microcalorimetry

The inhibitory effects of four organic acids (OAs) in Radix Isatidis, a traditional Chinese medicinal herb, on Escherichia coli (E. coli) growth were investigated by microcalorimetry. The power‐time curves of E. coli growth with and without OAs were acquired, meanwhile the extent and duration of inhibitory effects on the metabolism were evaluated by growth rate constants (k₁, k₂), half inhibitory ratio (IC₅₀), maximum heat output (P_max) and peak time (t_p). The values of k₁ and k₂ of E. coli growth in the presence of the four OAs decreased with the increasing concentrations of OAs. Moreover, P_max was reduced and the value of t_p increased with increasing concentrations of the four drugs. The sequence of anti‐microbial activity of the four OAs was: syringic acid>2‐amino‐benzoic acid>salicylic acid>benzoic acid. IC₅₀ of the four OAs was respectively 56 µg/mL for syringic acid, 75 µg/mL for 2‐amino‐benzoic acid, 86 µg/mL for salicylic acid and 224 µg/mL for benzoic acid. The existence of the functional groups on phenyl ring improves the anti‐microbial activity compared to benzoic acid. The functional groups methoxyl at C(3) and C(5) improve anti‐microbial activity more strongly than the other functional groups, and the functional group amino at C(2) improve anti‐microbial activity more strongly than hydroxyl at C(2) on phenyl ring.     

微量热法研究硒对大肠杆菌生长代谢的作用

硒 是生物必需的微量元素之一．自从１９７３年Ｒｏｔｒｕｃｋ报导了第一个硒酶———红细胞谷胱甘肽过氧化物酶［１］,硒在生命科学中的研究取得了令人瞩目的进展．继红细胞谷胱甘肽过氧化物酶之后 ,从哺乳动物中还发现硒为多种酶所必需 ;此外 ,在不同的动物组织中一系列含硒蛋白被分离和鉴别．随着分子生物学技术的发展和硒在生物化学中的应用 ,人们对硒的生物化学本质有了更加深刻的认识 ,其中 ,遗传基因硒代半胱氨酸密码子ＵＧＡ的发现使硒的生物化学研究进入了一个新的阶段．与此同时 ,小分子有机硒化合物Ｅｂｓｅｌｅｎ生物活性的发现…     

Microcalorimetric investigation of the effect of berberine alkaloids from <Emphasis Type="Italic">Coptis chinensis</Emphasis> Franch on <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> growth

The inhibitory effects of three berberine alkaloids (BAs) from rhizome of Coptis chinensis Franch, a traditional Chinese medicinal (TCM) herb, on Staphylococcus aureus growth were investigated by microcalorimetry. The power-time curves of S. aureus with and without BAs were acquired; meanwhile the extent and duration of inhibitory effects on the metabolism were evaluated by studying the growth rate constant (k), half inhibitory ratio (IC₅₀), maximum heat-output power (P _max), peak time of maximum heat-output power (t _p) and total heat production (Q _t). The value of k of S. aureus in the presence of the three BAs decreased with the increasing concentrations of BAs. Moreover, P _max was reduced and the value of t _p increased with increasing concentrations of the three drugs. The inhibitory activity varied with different drugs. The values of IC₅₀ of the three BAs are respectively, 101.4 μg/mL for berberine, 241.0 μg/mL for palmatine and 792.3 μg/mL for jateorrhizine. The sequence of antimicrobial activity of the three BAs is: berberine > palmatine > jateorrhizine. It is suggested that the functional group methylenedioxy or methoxyl at C2 on the phenyl ring could possibly improve antimicrobial activity more strongly than hydroxyl at C2 on the phenyl ring. Supported by the National Natural Science Foundation of China (Grant No. 30625042)     

Microcalorimetric Study on Effect of Chromium(III) and Chromium(VI) Species on the Growth of Escherichia coli

The effects of Cr(III) and Cr(VI) species (Cr₂O₇^2?, CrO₄^2? and Cr³⁺) on the growth of Escherichia coli (E. coli) have been investigated in detail by microcalorimetry at 37 °C. Parameters including the growth rate constant (k), inhibitory ratio (I), half‐inhibitory concentration (IC₅₀), total heat output (Q_total), time of the maximum heat production (t_log) in the log phase have been obtained. The results showed that Cr(VI) and Cr(III) had the inhibition effect on the growth of E. coli in aquatic environment; however, the inhibitory ratio of Cr(III) to E. coli was smaller than that of Cr(VI). The k values of E. coli in the presence of Cr(VI) and at high concentrations of Cr(III) were decreased with increasing the concentrations of these chromium species. Among the three chromium species investigated, Cr₂O₇^2? was found to be the most poisonous species against E. coli with an IC₅₀ value of 35.52 µg·mL^?1. CrO₄^2? exhibited moderate toxicity on E. coli with an IC₅₀ of 50.24 µg·mL^?1, and Cr³⁺ had the lowest toxicity with an IC₅₀ of 84.30 µg·mL^?1. Microcalorimetry can provide a convenient, sensitive and reliable method to study the effect of various metal species on the growth of bacteria or other microorganisms.     

Studying the toxic effect of cadmium and hexavalent chromium on microbial activity of a soil and pure microbe

Using TAM III multi-channel calorimetry combined with direct microorganism counting (bacteria, actinomycetes and fungi) under laboratory conditions, we determined the microbial population count, resistance and activity toward cadmium (Cd(II)) and hexavalent chromium (Cr(VI)) toxicity in soil. The thermokinetic parameters, which can represent soil microbial activity, were calculated from power-time curves of soil microbial activity obtained by microcalorimetric measurement. Simultaneous application of the two methods showed that growth rate constant (k), peak-heat output power (P _max) and the number of living microorganisms decreased with increasing concentration of Cd and Cr. The accumulation of Cr on E. coli was conducted by HPLC-ICP-MS. Cr⁶⁺ accumulation by Escherichia coli was increased steadily with increasing Cr⁶⁺ concentration. The results revealed that the change in some thermo-kinetic parameters could have good corresponding relationship with metal accumulation. Our work also suggests that microcalorimetry is a fast, simple, more sensitive, on-line and in vitro method that can be easily performed to study the toxicity of different species of heavy metals on microorganism compared to other biological methods, and can combine with other analytic methods to study the interaction mechanism between environmental toxicants and microbes.     

Microcalorimetric studies on the antimicrobial actions of different cephalosporins

Microcalorimetry was applied to study the effect of cephalosporins (cefazolin sodium and cefonicid sodium) on the E. coli growth. The microbial activity was recorded as power-time curves through an ampoule method with a TAM Air Isothermal Microcalorimeter at 37°C. The parameters such as the growth rate constant (k), inhibitory ratio (I), the maximum power output (P _m) and the time corresponding to the maximum power output (t _m) were calculated. The change tendencies of k, with the increasing of concentration (C) of the two cephalosporins, are similar which show that cefazolin sodium and cefonicid sodium have the same inhibitory mechanism. The experimental results reveal that cefonicid sodium has a stronger antibacterial activity towards E. coli than that of cefazolin sodium and this was coincide with the clinical manifestations.     

微量热法比较黄连中四种生物碱的抗菌作用

采用微量热法研究和比较中药黄连中四种生物碱(BAs)的抗菌(大肠杆菌)作用。这四种生物碱分别为小檗碱、黄连碱、巴马汀和药根碱。用LKB-2277生物活性检测系统,以停留法测定了37 ℃时大肠杆菌在BAs作用下的热流功率-时间曲线,并记录生长速率常数k, 指数生长期和稳定期的最大热功率Pm, log、Pm, stat, 生长抑制率I, 传代时间tg,指数生长期的总产热量Qt, log,半数抑菌浓度IC50等热动力学参数。结果显示这四种生物碱具有相异的抗大肠杆菌生长代谢的作用,k, Pm, log和Qt, log值随BAs浓度的增加而相应的减少。综合分析k, Pm, log, Qt, log, I 和IC50值可以看出,BAs抑制大肠杆菌生长代谢强度按小檗碱、黄连碱、巴马汀、药根碱的顺序依次减弱。构效关系研究表明,母环C-2和C-3上连接的亚甲二氧基比甲氧基更能显著增强相应化合物的抗菌作用,而C-9和C-10上连接的亚甲二氧基或甲氧基对这种抗菌作用影响不大。     

Determination of the Inductive Constant of the Succinimide Group from the Reaction Series of Thermolysis of Nitro Esters

The inductive constant σ* of the succinimide group was determined using the previously obtained equation correlating the rate constant k _l ofliquid-phase homolysis of the O-NO₂ bond in nitro esters with the σ* constants of electronegative substituents. The kinetics of thermolysis of N-nitroxymethyl- and N-(2-nitroxyethyl)succinimide in the melt and solutions was studied manometrically. Adequate data for k _l were obtained. The σ* constant of the succinimide group was determined to be 4.5. The σ* constants for the phthalimide group and some other imide substituents were determined by a similar procedure.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 954–957.Original Russian Text Copyright © 2005 by Goncharov, Dubikhin, Nazin, Fedorov, Shastin.     

Study on eruption of heat for Escherichia coli B aroused by lanthanum nitrate and its mechanism

Biological effect of rare-earth lanthanum nitrate on the growth of Escherichia coli B was studied using the calorimetric method. There were exceptional changes on the growth thermogenic curves for high concentrations of lanthanum nitrate. For example, the peak high, the total quantity of heat (Q) of cultures and the growth rate constants (k) are evidently increased when compared with normal E. coli B cultures. When the concentration of lanthanum nitrate was at 300 mg/L and 500 mg/L, and Q of the cultures reached 3.89 and 2.54 times of normal cultures, respectively. The survivability of cells and the biomass of the cultures were measured using biological methods and the results show that the growth and multiplication of cells were inhibited and that the biomass decreased at high concentration of lanthanum nitrate. These revealed that the inhibiting cells discharged more quantity of heat than the normal growing cells. We named this phenomenon as “eruption of heat”. It was suggested that the mechanism for the eruption of heat was that La³⁺ ion damages the outer cell membrane and increases its permeability and the proton-electron potential energy across the cell membrane was reduced or couldn’t even be initiated. Energy could not be translated into ATP effectively in the course of oxidative phosphorylation resulting in heat release. So, the growth of the cells was inhibited due to scarceness of energy ATP. __________ Translated from Acta Chimica Sinica, 2007, 65(10): 917–922 [译自: 化学学报]     

两种希夫碱对大肠杆菌抗菌活性的微量热法研究

The microcalorimetric method was used to study the antibacterial activity of two newly synthesized Schiff base compounds （H2L3＇ and H2L3） on Escherichia coli, trying to obtain the action on both of multiplying bacteria and non-multiplying bacteria at one experiment. The metabolic power-time curves of the bacteria treated with the compounds were obtained, and the thermokinetic parameters were analyzed, from which the antibacterial activities of these compounds were evaluated. The results showed that both of the two compounds have good activity on aerobic multiplying metabolism of E. coli, with the value of ICso 75.8 and 168.8 mg/L respectively, but have not effective action on fermentation metabolism of E. coli. The action of the compounds on the non-multiplying metabolism was investigated by taking the heat output of E. coli in the stationary phase as the guideline of the activity. The value of MSCso （minimum stationary-cidal concentration 50） of them is 118 and 187.5 mg/L, respectively. So, H2L^3 has stronger antibacterial action on E. coli than H2L^3 either for multiplying bacteria or non-multiplying bacteria, and their activity on the aerobic multiplying bacteria of E. coil is mainly shown. It does strongly suggest that the calorimetric method should play an important role in the fight against the drug-resistant bacteria.     

Reaction rate of crosslinkings by using metallated polymer. I. Grafting and intramolecular crosslinkings at the first stage

Lithium-metallated styrene–p-benzylstyrene copolymer was reacted with chlorine-terminated polystyrene as a crosslinker polymer in tetrahydrofuran (THF) at 25°C. The rate constant was estimated from the changes in the concentration of metallated polymer by using photometrical measurements. The various reaction conditions were chosen and it became clear that the rate constants of grafting (k₁) and intramolecular crosslinkings (k_2intra) were gotten separately at the first stage. As a result, k_2intra showed larger values than k₁ and decreased with increasing degree of polymerization of crosslinker polymers.     

Kinetics of Malachite Green Fading in Water‐ethanol‐1‐propanol Ternary Mixtures

The rate constant of malachite green (MG⁺) alkaline fading was measured in water‐ethanol‐1‐propanol ternary mixtures. This reaction was studied under pseudo‐first‐order conditions at 283‐303 K. It was observed that the reaction rate constant increases in the presence of different weight percentages of ethanol and 1‐propanol. The fundamental rate constants of MG⁺ fading in these solutions were obtained by SESMORTAC model. In each series of experiments, concentration of one alcohol was kept constant and the concentration of the second one was changed. It was observed that at constant concentration of one alcohol and variable concentrations of the second one, with increase in temperature, k₁ values increase and this indicates that presence of ethanol (or 1‐propanol) increases dissolution of 1‐propanol (or ethanol) in the activated complex formed in these solutions. Also, in each zone, fundamental rate constants of reaction at each certain temperature change as k₂ » k₁ » k_?1.     

Potentiometric measurement of lipoic acid reduction in microbial cultures: Part II. Evaluation of the bactericidal efficacity of drugs affecting bacterial growth

Multichannel potential-time measurements were carried out in cultures of Escherichia coli growing in the presence of increasing amounts of aminoglycoside antibiotics. The potentiometric lag times were an increasing function of the drug concentration.Theoretical apparent growth rates of organisms in the presence of the drug could be calculated from these potential-time data, and were related to the antibiotic concentration. For each antibiotic tested, it was possible to determine an inhibition rate constant as a function of the drug concentration, which characterized the bactericidal efficacity of the drug.A potentiometric MIC (minimal inhibitory concentration) was defined as the concentration at which the inhibition rate constant would be equal to the specific growth rate of organisms with no drugs added to the culture broth: the potentiometric MIC values were consistent with the conventional MIC's determined by a standard diffusion technique.     

Kinetics of malachite green fading in water–ethanol–2‐propanol ternary mixtures

The rate constant of malachite green (MG⁺) alkaline fading was measured in water–ethanol–2‐propanol ternary mixtures. This reaction was studied under pseudo‐first‐order conditions at 283–303 K. It was observed that the observed reaction rate constants, k_obs, were increased in the presence of different weight percentages of ethanol and 2‐propanol. The fundamental rate constants of MG⁺ fading in these solutions were obtained by using the SESMORTAC model. In each series of experiments, the concentration of one alcohol was kept constant and the concentration of the second one was changed. It was observed that at the constant concentration of one alcohol and variable concentrations of the second one, with an increase in temperature, k₂ values decrease according to the trend of hydroxide ion nucleophilic parameter values and k₁ values increase. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 441–453, 2011     

Detection of volatile metabolites of <Emphasis Type="Italic">Escherichia coli</Emphasis> by multi capillary column coupled ion mobility spectrometry

Detection and immediate quantification of microbial metabolic activities is of high interest in fields as diverse as biotechnology and infection biology. Interestingly, the most direct signals of microbial metabolism, the evolution of volatile metabolites, is largely ignored in the literature, and rather, metabolite concentrations in the microbial surrounding or even disruptive methods for intracellular metabolite measurements (i.e., metabolome analysis) are favored. Here, the development of a multi capillary column coupled ion mobility spectrometer (MCC-IMS) was described for the detection of volatile organic compounds from microbes and the MCC-IMS was used for characterization of metabolic activity of growing Escherichia coli. The MCC-IMS chromatogram of the microbial culture off-gas of the acetone-producing E. coli strain BL21 pLB4 revealed four analytes that positively correlated with growth, which were identified as ethanol, propanone (acetone), heptan-2-one, and nonan-2-one. The occurrence of these analytes was cross-validated by solid-phase micro-extraction coupled with gas chromatography mass spectrometry analysis. With this information in hand, the dynamic relationship between the E. coli biomass concentration and the metabolite concentrations in the headspace was measured. The results suggest that the metabolic pathways of heptan-2-one and nonan-2-one synthesis are regulated independent of each other. It is shown that the MCC-IMS in-line off-gas analysis is a simple method for real-time detection of microbial metabolic activity and discussed its potential for application in metabolic engineering, bioprocess control, and health care.     

OYGEN DEPENDENCE AND REPAIR OF LETHAL EFFECTS OF NEAR ULTRAVIOLET AND VISIBLE LIGHT*

Abstract— –Lethality in a repairable strain (WP2) and an excision repair deficient strain (WP2hcr) of Escherichia coli was studied at wavelengths of 254, 313, 365, and 390–750 nm. Survival curves were empirically fitted to the expression S= 1 - (1-e^-kl)“, where S is the fraction surviving, D is the incident dose in ergs mm^-2, k is the inactivation constant in units of (erg mm^-2)^-1 and n is the ‘shoulder constant’. The repairable sector (k(hcr^-)–k(hcr^-)lk(hcr^-), a conservative estimate of the repair capability of E. coli WP2, was 0.91 at 254 nm, 0.92 at 313 nm, 0.60 at 365 nm, and 0.13 at 390–750 nm. Although there was no oxygen enhancement of inactivation at 254 nm and 313 nm, a strong enhancement was identified at 365 nm and 390–750 nm. These results suggest that oxygen-dependent damage induced by near u.v. (365 nm) can be partially repaired by the excision-repair system in E. coli.