Studies on the nongrowth metabolism of the different strains of Tetrahymena cells by isothermal microcalorimetry

The nongrowth metabolic processes of Tetrahymena strains with the different cell densities were monitored by isothermal microcalorimetry, including Tetrahymena thermophila BF₁, Tetrahymena thermophila SB210, Tetrahymena pyriformis GL, the mixed cells of T. thermophila BF₁ and T. thermophila SB210, and the mixed cells of T. thermophila BF₁ and T. pyriformis GL. All the typical power–time curves showed a decreasing trend on the whole. It was found that total heat production (Q _t) and maximum heat output (P _m) decreased significantly with the decrease of cell density. Cell density did not influence significantly the maximum heat output per cell (P _cell) of Tetrahymena cells, which was probably due to enough oxygen. The P _cell and metabolic decrease rate constant (K) values for the mixture of T. thermophila BF₁ and T. pyriformis GL, and that of T. thermophila BF₁ and T. thermophila SB210 were similar to the mean values of P _cell and K for the corresponding single Tetrahymena strain, respectively. It was speculated that the cell mixing did not possibly influence significantly their P _cell and K values because of no competition for nutrition, oxygen, and room, and the low conjunction percentages.     

Microcalorimetry as a possible tool for phylogenetic studies of Tetrahymena

Using isothermal microcalorimetry, the growth power-time curves of three strains of Tetrahymena were determined at 28°C. Their Euclidean distances and cluster analysis diagram were obtained by using two thermokinetic parameters (r and Q_log), which showed that T. thermophila BF₁ and T. thermophila BF₅ had a closer relationship. Compared with the single molecular biomarker (ITS1) method, microcalorimetry wasmaybe a simpler, more sensitive andmore economic technique in the phylogenetic studies of Tetrahymena species.     

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。     

Microcalorimetry study on the microbial activity of permafrost on the Tibetan plateau of China

Microcalorimetric techniques had been used to study the influence of different physicochemical parameters on microbial growth in different permafrosts on the Tibetan plateau. The total heat evolution of the permafrost samples amended with glucose, Q _T , the values of microbial growth rate constant, k, and the heat output power, P _t , were calculated from the power–time (P–t) curves. It is observed that the same coverage vegetation show similar P–t curves, which strongly suggest that the permafrost microorganisms of the homology vegetation coverage have similar structures of community. Furthermore, the vegetation degradation turns out to have significant influence, that is, the better the status of vegetation is, the higher the values of k, CFU and Q _T are.     

Microcalorimetric Studies on Influence of Sm^3＋, Dy^3＋ on Growth and Sporulation of Bacillus thuringiensis

By using an LKB-2277 Bioactivity Monitor and cycle-flow method, the thermogenic curves of aerobic growth for Bacillus thuringiensis cry Ⅱ strain at 28 ℃ have been obtained. The metabolic thermogenic curves of Bt cry Ⅱ contain two distinct parts: the first part reflects the changes of bacterial growth phase and the second part corresponds to sporulation phase. From these thermogenic curves in the absence or presence of Sm^3 , Dy^3 ions, the thermokinetic parameters such as the growth rate constants k. the interval time τ1, the maximum power PMAX1 and heat-output QLOG for log phase, the maximum power PMAX2 and heat-output QSTAT for stationary phase, the heat-output QSPOR for sporulation phase and total heat effects QT were calculated. Sm^3 and Dy^3 ions have promoting action on the growth of Bt cryⅡ in their lower concentration range, on the other hand, they have inhibitory action on the sporulation of Bt in their higher concentration range, It has also been found that the effects of Sm^3 and Dy^3 ions on Bt during the sporulation phase were far greater than those during the bacterial growth phase. It was concluded that the application of Bt for controlling insecticide could not be affected by the presence of the rare-earth elements in the environmental ecosystem.     

Microcalorimetric Study of the Biological Effects of Zn^＋ on Bacillus thuringiensis Growth

A microcalorimetric technique was used to investigate the influence of Zn^2 on the growth metabolism of Bacillus thuringiensis .LKB-2277 Bioactivity Monitor was employed to obtain the power-time curves,from which the maximum peak-heat output power(Pmax) in the log phase,the growth rate constants(k), the inhibitory ratios(I) ,the generational time(tG) and the total heat effect (Qtotal) in 23 h for the growth metabolism of Bacillus thuringiensis at 28℃ can be evaluated,The results indicate that the concentration of Zn^2 affects its growth obviously,Low concentration (0-50μg/mL) of Zn^2 promotes the growth of Bacillus thuringiensis while high concentration (50-500μg/mL) of Zn^2 inhibits its growth .When the concentration reached up to 600μg/mL,it can not grow at all.     

A microcalorimetric study of the biologic effect of Mn(II) on Bacillus thuringiensis growth

A microcalorimetric technique based on the bacterial heat-output was explored to evaluate the effect of Mn(II) on Bacillus thuringiensis. The power-time curves of the growth metabolism of B. thuringiensis and the effect of Mn(II) on it were studied using an LKB-2277 BioActivity Monitor, ampoules method, at 28°C. For evaluation of the results, the maximum peak-heat output power (P _max) in the growth phase, the growth rate constants (k), the log phase heat effects (Q _log ), and the total heat effect in 23 h (Q _T) for B. thuringiensis were determined. Manganese has been regarded as the essential biological trace element. Mn(II) of different concentration have different effects on B. thuringiensis growth metabolism. High concentration (800-1600 μg mL^-1) of Mn(II) can promote the growth of B. thuringiensis; low concentration (500-800 μg mL^-1) can inhabit its growth. This revised version was published online in August 2006 with corrections to the Cover Date.     

A microcalorimetric method to determine antimicrobial effects of two bile acid derivatives on Staphylococcus aureus

Using microcalorimetry, the characteristic metabolic heat flow power-time curves of S. aureus growth affected by Ursodesoxycholic acid and Hyodeoxycholic acid were measured at 37?°C. The thermal-kinetic parameters such as, growth rate constant k, the maximum power output (P _m), the time corresponding to the maximum power output (t _p), total heat-production Q _t , half inhibitory concentration of the drugs (IC ₅₀) were calculated from the growth curves. For both HDCA and UDCA, with the increasing of concentration, k, P _m, and Q _t decreased, meanwhile, k?Cc fit a linear equation, t _p was prolonged correspondingly. Principle component analysis, the results indicated t _p might be the main parameter in evaluating the antibacterial activity of HDCA and UDCA in microcalorimetric method. Combining with t _p and IC ₅₀, the results revealed that the differences and trends of antibacterial activity of these bile acid derivatives were: HDCA?>?UDCA. Structure-activity relationship (SAR) analysis showed that the ??-OH at C-3 and C-6 position at equal pace on the steroid nucleus enhanced the hydrophilicity of HDCA, which led to a stronger antibacterial effect than UDCA. In this study, a useful tool was provided to accurately evaluate the antibacterial effects of bile acid derivatives. The thermolysis curve recorded by microcalorimetry could provide a lot of kinetic and thermodynamic information for the study of growth process of living microbial, which could be helpful in the screening of high efficacy antibacterial agents.     

A microcalorimetric study of the action of mercuric chloride on the metabolism of mitochondria isolated from Cyprinus carpio liver tissue

After the occurrence of 'Minamata disease' in 1950, mercury aroused much more attention, and lots of studies concerned have been made. The purpose of the present paper is to study the effect of mercuric chloride on the mitochondria suspension isolated from the liver tissue of Cyprinus carpio from the direct viewpoint of energy by using the microcalorimetric method. The metabolic thermogenic curves of the mitochondria suspension at 25°C were obtained, and the mitochondria metabolic thermokinetic equations were established, from which we obtained the thermodynamic and thermokinetic parameters: thermogenic rate constant (k), heat output (Q), average heat power (P_av), etc. Experimental results indicated that low concentration of mercuric chloride (5 nmol Hg²⁺/(mg protein)) stimulates the thermogenesis of mitochondria, suggesting a strong effect of uncoupling action, while high concentration of mercuric chloride (20 nmol Hg²⁺/(mg protein)) inhibits the metabolism of mitochondria completely, suggesting a fatal effect on the phosphorylation system. The effect of Hg²⁺ on mitochondria is concentration-depended, from which the probable reaction mechanism of Hg²⁺ to the mitochondria was proposed. So the microcalorimetric method can be used in the toxicology research.     

Microcalorimetric investigation on antibacterial activity of the peptide from Plutella xylostella

The antibacterial activities of a kind of novel peptide from Plutella xylostella (pxCECA1) on methicillin-resistant staphylococcus aureus (MRSA) and Escherichia coli (E. coli) growth were investigated by microcalorimetry. The heat flow power–time curves of MRSA and E. coli growth in the presence of pxCECA1 were recorded using the 3114/3115 Thermal Activity Monitor Air Isothermal Calorimeter based on ampoule mode at 37 °C. Some parameters including growth rate constant k, maximum power output P _max, total heat output Q_t, generation time t _g, growth inhibitory ratio I, and half-inhibitory concentration of the drugs IC₅₀ were obtained to elucidate the antibacterial activity of pxCECA1. The results showed that k, P _max, and Q _t decreased, but I and t _g increased or delayed with the increase in pxCECA1 concentration. The IC₅₀ of pxCECA1 on E. coli was 6.122 μg mL^?1 and MRSA was 7.809 μg mL^?1. It could be concluded that pxCECA1 had stronger inhibitory effect on E. coli than MRSA. In vivo test was simultaneously performed using an E. coli and MRSA infection model to validate the antibacterial activity of pxCECA1. The results revealed that pxCECA1 with broad spectrum antimicrobial activities hopefully represented a class of promising substitute of antimicrobial agents.     

Calorimetric study of the metabolic activity of Escherichia coli B infected by T4 phage in restricted medium

The effects of T4 phage on the metabolic rate of resting cells of Escherichia coli B in a restricted medium during the early phase of phage infection were measured calorimetrically. Heat output rate (P) and total quantity of heat (Q) of culture, heat output rate (P₀) and quantity of heat (Q₀) of single cell were determined. P and Q of E. coli-T4 phage system, or P₀ and Q₀ of infected cell, are all higher than that of control. The metabolic activity of infected cell is enhanced by 45-62%. P has a linear correlation with cell concentration (C), P (μW) = 1.68 × 10⁻⁶C (cfu/mL) + 1.86, for E. coli B cells, and for E. coli B-T4 phage system, P (μW) = 2.24 × 10⁻⁶C (cfu/mL) + 3.60. Q does not change significantly with the change of cell concentration. But Q₀ decreases with C increasing, indicating that Q₀ is restrained by cell density.     

Anti-bacterial effect of four extracts from leaves of Dracontomelon dao on Escherichia coli growth using microcalorimetry coupled with principal component analysis

The anti-Escherichia coli activities of four extracts in leaves of Dracontomelon dao, a traditional folk herb in China were investigated and compared by microcalorimetry. The four extracts are PE fraction, CHCl₃ fraction, EtOAc fraction, and n-BuOH fraction. The heat flow power–time (HFP–time) curves of E. coli growth in the presence of the four extracts were measured using an ampoule method. Then the nine thermal kinetic parameters were obtained from the curves. From the result of principal component analysis, it can be seen that parameters k ₁, k ₂, P ₁, and Q _p2 might be the main parameters in evaluating the anti-E. coli effects. In the presence of CHCl₃ fraction, EtOAc fraction, and n-BuOH fraction, k ₂, Q _p2 of E. coli decreased with increasing concentrations of the extracts. The EtOAc fraction was observed to have the strongest anti-bacterial activity with half-inhibitory concentration IC50 of 98.5 μg mL^?1. So, it can be concluded that EtOAc fraction can be further developed as anti-bacterial bioactive fraction of leaves of Dracontomelon dao.     

The action of norfloxacin complexes on Tetrahymena investigated by microcalorimetry

Cu(nor)₂·H₂O (1), Zn(nor)₂·4H₂O (2), Ni(nor)₂·2H₂O (3), [Cu(nor)(phen)]NO₃·4H₂O (4), [Zn(nor)(phen)]NO₃·2H₂O (5), and [Ni(nor)(phen)]NO₃·3H₂O (6) were synthesized and their action on Tetrahymena growth was studied by microcalorimetry. The growth constant (k), inhibitory ratio (I), and half-inhibiting concentration (IC₅₀) were calculated, which showed that the complexes had a strong inhibitory effect on Tetrahymena. All these complexes can inhibit the growth of Tetrahymena more strongly than norfloxacin. The norfloxacin?Cmetal complexes exhibited better inhibitory activity than nor?Cphen?Cmetal complexes. The power?Ctime curves of Tetrahymena growth in the presence of norfloxacin were also measured. It was found that all complexes showed higher inhibitory activity than norfloxacin. And the inhibitory mechanism was discussed preliminarily. The diverse inhibition may be due to the ability of the complexes to penetrate into cells and the effect of these complexes on the nucleic acid. Microcalorimetry has been used extensively in many biological and chemical investigations as a universal, non-destructive, continuously running, and highly sensitive tool.     

Isothermal microcalorimetric investigation of the toxic action of the effective constituents of Podophyllum emodi Wall on Tetrahymena thermophila BF5

The effects of podophyllotoxin (PPT), etoposide (VP16), and teniposide (VM26) on the growth of Tetrahymena thermophila BF₅ (T.t.BF₅) was investigated by the TAM AIR isothermal microcalorimetric system. The extent and duration of toxic effects on T.t.BF₅ metabolism were evaluated by studying the growth rate constant (k), inhibitory ratio (I), maximum heat-output power (P _max), peak time of maximum heat-output power (t _p), and total heat production (Q _t). Experimental results showed that the value of t _p increased and the value of k and P _max decreased with the increasing compound concentrations. Furthermore, the growth rate constant k was linear with compound concentration. The corresponding I was obtained from different k values. According to the IC₁₀ (the concentration of inhibitor when the inhibitory ratio is 10 %), the relative toxicity of the three compounds was PPT (IC₁₀ = 49.6 μg mL^?1) > VP16 (IC₁₀ = 117.5 μg mL^?1) > VM26 (IC₁₀ = 359.1 μg mL^?1). The preliminary investigation of structure–activity relationships showed that the thienyl group was likely responsible for reducing the toxicity of the compounds.     

Microcalorimetric Investigation of Toxic Effects of Three Injectable Solubilizing Excipients on Tetrahymena thermophila BF5 Growth

Using microcalorimetry, thermal metabolic curves of Tetrahymena thermophila BF₅ (T. thermophila BF₅) growth at 28°C affected by three injectable solubilizing excipients (ISE) including tween 80, hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) and poloxamer 188 were measured. Meanwhile, the toxicities of three ISE were evaluated by dynamic parameters of thermal metabolic curves. In addition, the irritative effects of the ISE on myoblast L₆ cells were investigated to show their cytotoxicities by biochemical method. The results indicated that the effects of the ISE on T. thermophila BF₅ varied for different ISE. 5% inhibition concentration values (IC₅) of the ISE were 1.33, 1.83 and 1.64 mg/mL for tween 80, HP‐β‐CD and poloxamer 188, respectively. By the principal component analysis (PCA), the total quantity of heat (Q), growth rate constant (k) and second maximum power (P₂) were selected as the main characteristic parameters to present their toxicities, there were good linear relationships between Q, k, P₂ and concentrations c, suggesting that the toxicities of the ISE on T. thermophila BF₅ were closely linked to their concentrations. The results of creatine kinase (CK) bioassay of myoblast L₆ cells indicated that the sequence of irritative effects of the ISE was HP‐β‐CD相似文献   

Microcalorimetric performance of the growth in culture of Escherichia coli,Proteus mirabilis and their mixtures in different proportions

Microcalorimetry is a technique that determines the heat flow produced as a result of microbial activities. The heat variations resulting from chemical reactions, which take place during metabolism, can be used to monitor bacterial growth in a culture medium. However, there are very few studies using calorimetry to investigate the relationships between two bacteria. In this work, we studied the interaction between E. coli and P. mirabilis, two bacteria belonging to the family Enterobacteriaceae. We have prepared three samples, mixing both enterobacteria at a concentration of 10³ CFU mL^?1 but in different proportions. Experimental equipment used was a Calvet microcalorimeter, where a constant temperature of 309.65 K was maintained. Then, we compared the shape of the heat flow–time curves of single microorganisms and their mixtures. Also, we calculated the thermokinetic parameters such as growth constant (k), generation time (G), detection time (t _d) and the amount of heat released (Q). The results obtained showed that when E. coli and P. mirabilis were put together in the culture medium, the growth profile of P. mirabilis seemed to dominate, even at low proportions in the sample.     

Study of Thermokinetic Properties of Sodium Selenite on Bacillus thuringiensis Cry B by Microcalorimetry

By using an LKB2277 Bioactivity Monitor, the power‐time curves of Bacillus thuringiensis Cry B at 28°C effected by Na₂SeO₃ were determined. Some parameters, such as growth rate constants k, inhibitory ratio I, the maximum beat production rate P_max, heat output Q, were obtained. Considering both the growth rate constant k and heat output Q, we found that a low concentration of Na₂SeO₃ had a promoting action on the growth of Bacillus thuringiensis Cry B, but a high concentration of Na₂SeO₃ had an inhibitory action. The toxicity of a toxicant can also be expressed as half inhibitory concentration IC₅₀ of toxicant, i. e., 50% effective in this inhibition. The value of IC₅₀ of Na₂SeO₃on Bacillus thuringiensis Cry B is 117 μg/mL. This microcalorimetric bioassay for cellular toxicity is based on metabolic heat evolution from cultured cells. The assay is quantitative, inexpensive, and versatile.     

Microcalorimetric Investigation of Influence of Fungicide SYP-L190 on Growth Metabolism of Tetrahyrnena therrnophila and Bacillus thuringiensis

Flumorph (SYP‐L190) is a new systemic fungicide with good protective, curative and antisporulant activities but no phytotoxicity to certain plants. Its performance on the environmental ecosystem is unknown. Tetrahymena thermophila and Bacillus thuringiensis are two of biological indicators for the aquatic and soil environmental ecosystem respectively. Microcalorimetric technique based on the heat output was applied to evaluate the influence of fungicide flumorph (SYP‐L190) on the two microorganisms. The thermogenic curves and corresponding thermodynamic and thermokinetic parameters were obtained. SYP‐L190 at a concentration of 50–100 µg·mL^?1 had 5% –10% inhibitory ratios aganist Tetrahymena thermophila and was used as a protection reagent, while at a concentration of 100–200 µg·mL^?1 SYP‐L190 had 10% –20% inhibitory ratios and was used as a therapy reagent. The metabolic thermogenic curves of Bacillus thuringiensis contained bacterial growth phase and sporulation phase. The SYP‐L190 at a concentration of 0–200 µg·mL^?1 had no influence on bacterial growth phase, but led to a little lag of the sporulation phase with a constant heat output. Hormesis was obviously observed in present study.     

Microcalorimetric Study of the Action of Yb^3＋ ion on the Growth of Staphylococcus aureus

A microcalorimetric method was used to evaluate the action of Yb^3 ions onthe growth metabolism of Staphylococcus aureus.The power-time curves of the growth metabolism of Staphylo.coccus aureus and the action of Yb^3 ions were obtained by us-ing stopped-flow method at 37 ℃. For evaluation of the action,the growth rate constants ( k1 and k2) for the log phase 1, log phase 2, and the total heat effect (Qtotal) for Staphylococcus aureus were determined. The results show that Yb^3 ions at low concentrations have the stimnlatory effect on Staphylococcus au-reus and that Yb^3 ions at higher concentration could inhibit its growth.