Total Heat Production Research Articles

Pulso de oxigênio: predição da produção de calor em bovinos e relações com consumo alimentar residual

O interesse quanto ao uso de índices de eficiência alimentar na seleção de bovinos de corte é crescente, tanto pela redução no custo de produção quanto no impacto ambiental, questão esta de grande importância, visto que o foco atualmente prioriza a sustentabilidade dos recursos naturais. O consumo alimentar residual (CAR) obtido pela diferença entre o consumo observado e predito, vem sendo estudado como um índice de eficiência alimentar que além de evitar o aumento do tamanho adulto dos animais selecionado, por ser ajustado para peso metabólico, possibilita a identificação de indivíduos com menor consumo de matéria seca ao mesmo peso e taxa de ganho. Características de desempenho e suas correlações com a eficiência alimentar são bem documentadas na literatura, entretanto as bases biológicas para variação no CAR são parcialmente desconhecidas. Estima-se que 9 % das diferenças em CAR são explicadas pelo incremento calórico, 14 % por processo de digestão, 5 % pela composição corporal e 5 % por diferenças em atividade, Desta forma, 67 % da variação do CAR permanece ainda desconhecida, e pode estar relacionada com a energia requerida pelos processos biológicos, como bombeamento de prótons na mitocôndria, turnover proteico e bombeamento de íons. Portanto, o uso da energia via processos biológicos parece ter um potencial de contribuição com substancial proporção na variação individual da eficiência alimentar. Embora a produção de calor de um animal possa ser medida de forma acurada por meio de câmara calorimétrica ou uso de água duplamente marcada, estes métodos, além de serem praticados em condições artificiais, são extremamente caros e requerem considerável experiência e in-fraestrutura, o que pode tornar impraticável a seleção de animais com menor exigência. Neste contexto, muitos pesquisadores exploram a possibilidade de predizer a produção de calor a partir da frequência cardíaca, uma vez que a maior parte do O2 utilizado por animais homeotermos é transportada aos tecidos pela ação do coração, órgão este cuja atividade representa cerca de 10 % da produção total de calor. O uso da frequência cardíaca, sem a calibração para o volume de O2 consumido por batimento cardíaco, pode apresentar estimativas de baixa acurácia, no entanto, a produção de calor estimada por esta calibração em humanos e animais é altamente correlacionada com a mensuração direta na câmara calorimétrica. Diante disto, o objetivo na presente revisão é apresentar a metodologia de estimativa da produção de calor por meio da frequência cardíaca calibrada para consumo de oxigênio, e sua relação com o CAR em bovinos de corte.

Lunar heat flow: Regional prospective of the Apollo landing sites

AbstractWe reexamine the Apollo Heat Flow Experiment in light of new orbital data. Using three‐dimensional thermal conduction models, we examine effects of crustal thickness, density, and radiogenic abundance on measured heat flow values at the Apollo 15 and 17 sites. These models show the importance of regional context on heat flux measurements. We find that measured heat flux can be greatly altered by deep subsurface radiogenic content and crustal density. However, total crustal thickness and the presence of a near‐surface radiogenic‐rich ejecta provide less leverage, representing only minor (<1.5 mW m−2) perturbations on surface heat flux. Using models of the crust implied by Gravity Recovery and Interior Laboratory results, we found that a roughly 9–13 mW m−2 mantle heat flux best approximate the observed heat flux. This equates to a total mantle heat production of 2.8–4.1 × 1011 W. These heat flow values could imply that the lunar interior is slightly less radiogenic than the Earth's mantle, perhaps implying that a considerable fraction of terrestrial mantle material was incorporated at the time of formation. These results may also imply that heat flux at the crust‐mantle boundary beneath the Procellarum potassium, rare earth element, and phosphorus (KREEP) Terrane (PKT) is anomalously elevated compared to the rest of the Moon. These results also suggest that a limited KREEP‐rich layer exists beneath the PKT crust. If a subcrustal KREEP‐rich layer extends below the Apollo 17 landing site, required mantle heat flux can drop to roughly 7 mW m−2, underlining the need for future heat flux measurements outside of the radiogenic‐rich PKT region.

Comparisons among six strains of Tetrahymena by microcalorimetry

The typical power-time curves of six strains of Tetrahymena were determined by microcalorimetry at 28 A degrees C. Metabolic characteristics were obtained including metabolic rate constant (r), heat output in the log phase (Q (log)), total heat production (Q (T)), peak time, and measured and potential maximum power output (P (m) and P (max)). The power-time curves and metabolic characteristics show the differences among Tetrahymena strains. Euclidean distances and a clustering analysis diagram were obtained by metabolic properties. The smaller distances are between the four strains of Tetrahymena thermophila and the largest distance exists between Tetrahymena pyriformis GL and Tetrahymena pigmentosa HG2. These results are consistent with those obtained by first internal transcriptional spacer sequences. Therefore, the power-time curves and metabolic properties can be noticeable characteristics in distinguishing the different strains of Tetrahymena. And, the heat output in the log phase (Q (log)) is probably the most specific characteristic in distinguishing the different Tetrahymena strains and studying their relationships.

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.

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 (Pmax), peak time of maximum heat-output power (tp), and total heat production (Qt). Experimental results showed that the value of tp increased and the value of k and Pmax 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.

Quantifying the Responses of Mixed Rumen Microbes to Excess Carbohydrate

The aim of this study was to determine if a mixed microbial community from the bovine rumen would respond to excess carbohydrate by accumulating reserve carbohydrate, energy spilling (dissipating excess ATP energy as heat), or both. Mixed microbes from the rumen were washed with N-free buffer and dosed with glucose. Total heat production was measured by calorimetry. Energy spilling was calculated as heat production not accounted by (i) endogenous metabolism (heat production before dosing glucose) and (ii) synthesis of reserve carbohydrate (heat from synthesis itself and reactions yielding ATP for it). For cells dosed with 5 mM glucose, synthesis of reserve carbohydrate and endogenous metabolism accounted for nearly all heat production (93.7%); no spilling was detected (P = 0.226). For cells dosed with 20 mM glucose, energy spilling was not detected immediately after dosing, but it became significant (P < 0.05) by approximately 30 min after dosing with glucose. Energy spilling accounted for as much as 38.7% of heat production in one incubation. Nearly all energy (97.9%) and carbon (99.9%) in glucose were recovered in reserve carbohydrate, fermentation acids, CO2, CH4, and heat. This full recovery indicates that products were measured completely and that spilling was not a methodological artifact. These results should aid future research aiming to mechanistically account for variation in energetic efficiency of mixed microbial communities.

Paleo-heat flows, radioactive heat generation, and the cooling and deformation history of Mercury

Estimates of lithospheric strength for Mercury, based on the depth of thrust faults associated with large lobate scarps (which were most probably formed previously to ∼3Ga) or on the effective elastic thickness of the lithosphere supporting a broad rise in the northern smooth plains (whose formation is poorly constrained, but posterior to 3.8Ga), serve as a basis for the calculation of paleo-heat flows, referred to the time when these structures were formed. The so-obtained paleo-heat flows can give information on the Urey ratio (Ur), the ratio between the total radioactive heat production and the total surface heat loss. By imposing the condition Ur<1 (corresponding to a cooling Mercury, consistent with the observed widespread contraction), we obtain an upper limit of 0.4 times the average surface value for the abundance of heat-producing elements in the outer solid shell of Mercury. We also find that if the formation of the northern rise occurred in a time posterior to ∼3Ga, then in that time the Urey ratio was lower, and the cooling more intense, than when most of large lobate scarps were formed. Thus, because largest lobate scarps deform older terrains (suggesting more intense contraction early in the mercurian history), we conclude that the northern rise was formed previously to 3Ga. If the age of other smooth plains large wavelength deformations is similar, then tectonic activity in Mercury would have been limited in the last 3billion of years.

Heat and Moisture Production of Hy-Line Brown Hens in Aviary Houses in the Midwestern U.S.

Abstract. In considering hen housing systems, up-to-date heat and moisture production data are essential to producing properly designed and managed ventilation and supplemental heating systems. The aviary system is one housing type under consideration by egg producers. The aviary system has a much lower bird stocking density and thus more freedom of movement for the birds compared to conventional cage housing. This study was conducted to obtain baseline heat and moisture production values for Hy-Line Brown hens in such houses in the Midwestern U.S. House-level thermal environment, gaseous concentrations, and bird production performance of two commercially operated 50,000-hen aviary houses were continually monitored over a 19-month period. The two houses used similar management practices and Hy-Line Brown hens with a 20-week difference in age. Data were collected for a complete flock (17 to 83 weeks, no molt) in each house. Total heat production (THP) of the hens, house-level latent heat production (LHP) or moisture production (MP), house-level sensible heat production (SHP), and respiratory quotient (RQ) were determined from the monitored variables using indirect calorimetry and mass/energy balance, respectively. Variations in THP, LHP/MP, SHP, and RQ within the day were delineated. Results of the study showed mean (±SE) THP, house-level LHP, house-level SHP, and RQ values of 5.94(±0.09) W kg -1 , 1.83(±0.03) W kg -1 , 4.11(±0.08) W kg -1 , and 0.94(±0.01), respectively, for the aviary housing system. The new data will improve the design and operation of building ventilation, supplemental heating, and ultimately production efficiency of aviary housing systems. The THP and RQ data will also be useful to indirect determination of building ventilation rate using the carbon dioxide (CO 2 ) balance method.

Anthropogenic Heat Release Into the Environment

This work is intended to systematically study an inventory of the anthropogenic heat produced. This research strives to present a better estimate of the energy generated by humans and human activities, and compare this estimate to the significant energy quantity with respect to climate change. Because the top of atmosphere (TOA) net energy flux was found to be 0.85 ± 0.15 W/m2 the planet is out of energy balance, as studied by the group from NASA in 2005. The Earth is estimated to gain 431 terawatts (TW) from this energy imbalance. This number is the significant heat quantity to consider when studying global climate change, and not the 78,300 TW, the absorbed part of the primary solar radiation reaching the Earth's surface, as commonly cited and used at present in the literature. Based on energy supplied to the boilers (in the Rankine cycle) of at least 13 TW, body energy dissipated by 7 × 109 people and their domestic animals, the value of the total world anthropogenic heat production rate is 15.26 TW or 3.5% of the energy gain by the Earth. Based on world energy consumption and the energy dissipated by 7 × 109 people and their domestic animals, the value of the total world anthropogenic heat production rate is 19.7 TW or about 5% of the energy gain by the Earth. These numbers are significantly different from 13 TW. More importantly, the figures are 3.5–5% of the net energy gained by the Earth, and hence significant. The quantity is not 0.017% of the absorbed part of the main solar radiation reaching the Earth's surface and negligible.

Geo-neutrino review

The principal source of energy for dynamic processes of the earth, such as plate tectonics is thought to come from the radioactive decays of 238U, 232Th, and 40K within the earth. These decays produce electron-antineutrinos, so-called geo-neutrinos, the measurement of which near the earthʼs surface allows for a direct measure of the total radiogenic heat production in the earth. The KamLAND and Borexino experiments have both measured a geo-neutrino flux significantly greater than zero. As shown in these proceedings, more precise future measurements will significantly constrain earth composition models.

Constraints on energy intake in fish: the link between diet composition, energy metabolism, and energy intake in rainbow trout.

The hypothesis was tested that fish fed to satiation with iso-energetic diets differing in macronutrient composition will have different digestible energy intakes (DEI) but similar total heat production. Four iso-energetic diets (2×2 factorial design) were formulated having a contrast in i) the ratio of protein to energy (P/E): high (HP/E) vs. low (LP/E) and ii) the type of non-protein energy (NPE) source: fat vs. carbohydrate which were iso-energetically exchanged. Triplicate groups (35 fish/tank) of rainbow trout were hand-fed each diet twice daily to satiation for 6 weeks under non-limiting water oxygen conditions. Feed intake (FI), DEI (kJ kg−0.8 d−1) and growth (g kg−0.8 d−1) of trout were affected by the interaction between P/E ratio and NPE source of the diet (P<0.05). Regardless of dietary P/E ratio, the inclusion of carbohydrate compared to fat as main NPE source reduced DEI and growth of trout by ∼20%. The diet-induced differences in FI and DEI show that trout did not compensate for the dietary differences in digestible energy or digestible protein contents. Further, changes in body fat store and plasma glucose did not seem to exert a homeostatic feedback control on DEI. Independent of the diet composition, heat production of trout did not differ (P>0.05). Our data suggest that the control of DEI in trout might be a function of heat production, which in turn might reflect a physiological limit related with oxidative metabolism.

Influence of magmatism on mantle cooling, surface heat flow and Urey ratio

Two-dimensional thermo-chemical mantle convection simulations are used to investigate the influence of melting-inducted differentiation on the thermal evolution of Earth's mantle, focussing in particular on matching the present-day surface heat flow and the ‘Urey ratio’. The influence of internal heating rate, initial mantle temperature and partitioning of heat-producing elements into basaltic crust are studied. High initial mantle temperatures, which are expected following Earth's accretion, cause major differences in early mantle thermo-chemical structures, but by the present-day surface heat flux and internal structures are indistinguishable from cases with a low initial temperature. Assuming three different values of mantle heat production that vary by more than a factor of two results in small differences in present-day heat flow, as does assuming different partitioning ratios of heat-producing elements into crust. Indeed, all of the cases presented here, regardless of exact parameters, have approximately Earth's present-day heat flow, with substantial fractions coming from the core and from mantle cooling. As a consequence of the model present-day surface heat flow varying only slightly with parameters, the Urey ratio (the ratio of total heat production to the total surface heat flow) is highly dependent on the amount of internal heat production, and due to the large uncertainty in this, the Urey ratio is considered to be a much poorer constraint on thermal evolution than the heat flow. The range of present-day Urey ratio observed in simulations here is about 0.3 to 0.5, which is consistent with observational and geochemical constraints (Jaupart et al., 2007). Magmatic heat transport contributes an upper bound of 9% to Earth's present-day heat loss but a much higher fraction at earlier times—often more than convective heat loss—so neglecting this causes an overestimation of the Urey ratio. Magmatic heat transport also plays an important role in mantle cooling. Considering these points, it is important to include magmatic effects when attempting to understand the thermal evolution of the Earth.

Oral administration of γ-aminobutyric acid affects heat production in a hot environment in resting humans

BackgroundCentral administration of γ-amino butyric acid (GABA) induces lower body temperature in animals in hot ambient air. However, it is still unknown whether oral GABA administration affects temperature regulation at rest in a hot environment in humans. Therefore, in the present study, we specifically hypothesized that systemic administration of GABA in humans would induce hypothermia in a hot environment and that this response would be observed in association with decreased heat production.MethodsEight male participants drank a 200-ml sports drink with 1 g of GABA (trial G) or without GABA (trial C), then rested for 30 minutes in a sitting position in a hot environment (ambient air temperature 33°C, relative humidity 50%).ResultsWe found that changes in esophageal temperature from before drinking the sports drink were lower in trial G than in trial C (-0.046 ± 0.079°C vs 0.001 ± 0.063°C; P < 0.05), with lower heat production calculated by oxygen consumption (41 ± 5 W/m2 vs 47 ± 8 W/m2; P < 0.05).ConclusionsIn this study, we have demonstrated that a single oral administration of GABA induced a larger decrease in body core temperature compared to a control condition during rest in a hot environment and that this response was concomitant with a decrease in total heat production.

Heat output by marine microbial and viral communities

The Marine Microbial Food Web (MMFW) includes heterotrophicmicrobes and their protist and viral predators. These microbes consume dissolved organic matter thereby making the MMFW a major component of global biogeochemical and energy cycles. However, quantification of the MMFW contribution to these cycles is dependent on a handful of techniques, all of which require laboratory-derived conversion factors. Here we describe a differential calorimeter capable of measuring the small amounts of heat produced by marine microbes and viruses at natural populations. Using this ultra-sensitive calorimeter, we show that heat production in the presence of viruses is significantly larger than in their absence. This increased heat output occurs despite a net decrease in the number of microbes. This provides direct evidence for top-down control of microbial populations by viruses and shows that there is increased re-mineralization. A comparative statics model was developed to interpret the calorimeter measurements. The spirit of the model is thermodynamic – it restricts its view to net changes in the populations and net heat produced. The model predicts that approximately 25% of the total heat production during the growth phase of a pelagic microbial community is due directly to viral activities. This result has implications for the energy budget of our planet and for climate prediction.

Microcalorimetry coupled with principal component analysis for comparing the effects of two Panax species on mice splenic lymphocytes

A powerful microcalorimetric method based on the cell heat production was applied to evaluate the effects of two Panax species on mice splenic lymphocytes growth. Some qualitative and quantitative information, such as the metabolic power-time curves, growth rate constant k, maximum heat-output power Pmax, appearance time for the highest peak tmax, total heat production Qt for all the metabolic progress of mice splenic lymphocytes were obtained to present the effects of Panax ginseng and American Ginseng on these cells. Coupled with principal component analysis (PCA) on these quantitative thermokinetic parameters, the effects of the two Panax species on mice splenic lymphocytes could be quickly evaluated by analyzing the change of the main parameter k. From the values of k, it could be concluded quickly and accurately that Panax ginseng and American Ginseng both showed strong inhibitory effects on mice splenic lymphocytes, and the inhibitory effects was strengthened with increasing concentration of the two Panax species in the concentration range of 0–3.2 mg mL−1. Panax ginseng with IC50 of 1.38 mg mL−1 showed stronger inhibitory effect on mice splenic lymphocytes growth than American Ginseng with IC50 of 2.08 mg mL−1. This study indicates that microcalorimetry is a powerful tool for evaluating the drugs’ efficiency on living system, providing some useful references for the application of Panax ginseng and American Ginseng in practice.

Thermal properties of sediments in southern Israel: a comprehensive data set for heat flow and geothermal energy studies

AbstractTo decipher the thermal structure of the sedimentary veneer in southern Israel, new values of thermal conductivity and porosity as well as of the radiogenic heat budget are provided. Thermal conductivity is measured for lithotypes and scaled up for geological formations. The new data are higher than most of the previously measured values, in particular for sandstones and siltstones, whose mean values are 5.0 and 2.9 W m−1 K−1. Mean values of the most abundant lithotypes, which are dolomites and limestones, are on the order of 4.1 and 2.7 W m−1 K−1, respectively. The total radiogenic heat production of the sedimentary cover varies slightly over southern Israel, due to variable lithology and total sediment thickness, yielding a maximum heat flow on the order of 4 mW m−2 where the sedimentary section is thickest (ca. 7 km). A temperature prognosis was made by calculating temperature profiles to the top of the crystalline basement at five well locations applying the new thermal‐conductivity data set and three scenarios of surface heat flow (50, 55 and 60 mW m−2). The calculated temperatures best match with measured drillstem‐test temperatures by using heat‐flow values close to the upper bound of range. Surface heat flow on the order of 55–60 mW m−2 is supported by a reevaluation of an existing temperature log and the application of thermal conductivity from this study. The temperature prediction for southern Israel shows values of 100–120°C at 3500–4500 m depth, indicating a geothermal potential that can be used for heating as well as electricity production.

Effects of the menstrual cycle on muscle recruitment and oxidative fuel selection during cold exposure

Differences in core temperature and body heat content, generally observed between the luteal and follicular phase of the menstrual cycle, have been reported to modulate the thermogenic activity of cold-exposed women. However, it is unclear how this change in whole body shivering activity will influence fuel selection. The goal of this study was to quantify the effects of the menstrual cycle on muscle recruitment and oxidative fuel selection during low-intensity shivering. Electromyographic activity of eight large muscles was monitored while carbohydrate, lipid, and protein utilization was simultaneously quantified in the follicular and luteal phases of the menstrual cycle in nonacclimatized women shivering at a low intensity. The onset (∼25 min), intensity (∼15% of maximal voluntary contraction), and pattern (∼6 shivering bursts/min) of the shivering response did not differ between menstrual cycle phases, regardless of differences in core temperature and hormone levels. This resulted in lipids remaining the predominant substrate, contributing 75% of total heat production, independent of menstrual phase. We conclude that hormone fluctuations inherent in the menstrual cycle do not affect mechanisms of substrate utilization in the cold. Whether the large contribution of lipids to total heat production in fuel selection confers a survival advantage remains to be established.

Lectin‐like oxidized low‐density lipoprotein receptor‐1 (LOX‐1) activity decreases estrogenesis in ovarian granulosa cells

Lectin‐like oxidized low‐density lipoprotein receptor‐1 (LOX‐1) activity decreases estrogenesis in ovarian granulosa cells

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–c 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 α-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.

Microcalorimetric study of the effect of Benzoinum and Styrax on the growth of Escherichia coli

In this study, the effects of Benzoinum and Styrax on Escherichia coli (E. coli) growth were investigated by microcalorimetry. Using a TAM Air Isothermal Calorimeter, ampoule method, the power–time curves of E. coli growth at 37°C affected by Benzoinum and Styrax were measured. By analysing some quantitative thermokinetic parameters, such as growth rate constants k, the maximum heat-out power P m, the time of the maximum heat-out power t m, the total heat production Q t and inhibitory ratio I, one could find that low concentrations (0–3.9 mg mL−1) of Benzoinum and Styrax had stimulation effects on E. coli growth, and high concentrations (7.8–125.0 mg mL−1) of these two drugs would inhibit the growth of the bacteria. The antibacterial effects of Benzoinum and Styrax can also be expressed as half inhibitory concentration IC50. The IC50 values for Benzoinum and Styrax are 78.5 and 88.0 mg mL−1, respectively, which suggests that the antibacterial effect of Benzoinum on E. coli was much stronger than that of Styrax. This study provides a useful method to investigate the effects of herbal medicines on microbes. It also supplies some references for the application of Benzoinum and Styrax in clinical treatment.