A review of metabolic calorimetric applications in plant stress, waste management, and diagnostics (original) (raw)
1. Introduction
Since heat effects predate all known isothermal, metabolic, and biological events, calorimetry is a useful procedure for quantifiable and analytical inquiries that do not compromise heat mechanisms [1]. The quasicalorimetric signal from a dynamic network is often challenging to understand on a molecular scale in the absence of more precise quantitative information [2]. An important method that has received much attention in the broad field of contemporary research and technology is isothermal microcalorimetry (IMC) measured in microwatts (μW) [2]. Under similar conditions, a delicate calorimeter useful for measurements in the microwatt range is referred to as a microcalorimeter [2].
Various complex physical, chemical, and metabolic interactions occur continuously in the environment, and these reactions are associated with various levels of heat loss and can be simply monitored via microcalorimetry [3]. Plants generate heat during metabolism, and measuring this heat and moisture could lead to a better understanding of plant metabolism [4]. Calorimetric measurements have proven to be effective as indicators of numerous biological processes, including seed germination, seedling growth, and plant cell viability, which, in turn, indicates the extent of the influence of environmental stresses on plants with respect to heat output.
IMC is a sensitive approach that can measure actual and persistent biological system activity and offers descriptive and analytical indicators of soil status and soil deterioration [5]. The available isothermal calorimetric measurements of soil microorganisms are always performed using heat conduction calorimeters, with thermopiles serving as heat flow sensors between the reaction chamber and a bordering absorber plate [6]. Studying the increase in the bacterial cell population is often useful for evaluating the influence of a specific parameter (the efficacy of a new medicine or the effect of a harmful substance) [7].
Differential scanning calorimetry (DSC) is a technique that measures the heat flow associated with thermal transitions in materials, providing insights into the thermodynamic properties of biological molecules. Buffa et al. [8] investigated the distribution and microbial ecology of enterococci in environmental habitats, demonstrating the use of DSC in understanding the impact of environmental stressors on microbial communities. The principle behind DSC involves comparing the heat flow of a sample to that of a reference material as a function of temperature, enabling precise quantification of thermal events in biological systems. Seibert et al. [9] used DSC to estimate the thermal conductivity of graphene quantum dots in epoxy, demonstrating the versatility of DSC for characterizing materials with biological applications. The operational dynamics of DSCs involve subjecting a sample to a controlled temperature program while measuring the heat flow, facilitating the characterization of thermal properties and phase transitions in biological samples. Consequently, this review aims to decipher the advancements and applications of calorimetric techniques in clinical diagnostics, plant metabolism studies, soil microbial characterization and environmental assessments by leveraging on the biophysical metabolic dynamics of ecological bacteria in soil, sludge, wastewater, and plants as displayed in Figure 1.
Figure 1
Illustration of calorimetric experiments for the biophysical metabolic dynamics of ecological bacteria in soil, sludge, wastewater, and plants.
2. Applications of calorimeters in biological dynamics
Since Lavoisier and Laplace invented the ice calorimeter in the 17th century, calorimeters have been used in various applications [10]. Along with IMC, several calorimeter models, including adiabatic calorimeter, isochoric calorimeter, isobaric calorimeter, and temperature scanning calorimeter, emerged around the start of the 19th century. The use of isothermal calorimeters in microbiology has made it easier to understand many microbial processes [2]. These microcalorimeters work through heat conduction or heat compensation. In heat conduction, heat transfers from the reaction vessel to the heat sink. In heat compensation, a hot material is used as the source of heat. The heat is measured as calories in the unit Joules (J) [2]. As a new technology, isothermal microcalorimeters have been used to measure microbial activity by analyzing the microwatts of heat produced by a wide range of sample specimens [2]. These devices have been used to characterize microbial processes and to understand food deterioration and pharmaceutical shelf life [2]. Nykyri et al. [11] stated that although there is a growing demand for additional research, there is still a great deal of untapped potential for this instrument in the field of microbiology. They also highlighted the increasing attractiveness of IMC’s applications in microbiology due to the recent development of highly parallel instruments and decreasing equipment costs. Leyva-Porras et al. [12] investigated the use of DSC and modulated differential scanning calorimetry (MDSC) in the food and drug industries, shedding light on the supercooling phenomena and the chemistry behind DSC. While their focus was on the food and drug sectors, the insights gained from their study can be extrapolated to biological systems.
Microbes are necessary for the breakdown of organic components and for a range of biological processes, many of which are preceded by biochemical reactions that generate heat. This makes them are important for accessing the ecosphere [13]. A microcalorimeter measures the amount of heat produced by these microbial processes. In environmental and agricultural science, the use of microcalorimeters has become extremely important for describing microbial activities in the soil under various conditions [14]. Microcalorimeters have been extensively used for comparing and establishing relationships and correlations between microorganisms and determining the impact of microbial activities on various soil types and compositions as well as on environmental factors such as humidity, temperature, pH, moisture, and oxygen [14]. Awode et al. [15] showed that a microcalorimeter, which measures the heat produced during the treatment of sewage from factories and industries (J), may be used to measure microbial activity. Microcalorimeters are becoming increasingly important because they can be used to measure nitrification and sulfate-reducing reactions in sludge from wastewater treatment plants and to detect mild exothermic reactions [16]. As the calorimetric technology continues to evolve, with the development of highly parallel instruments and decreasing costs, the future of calorimetry in biological research and applications appears promising and ripe for further exploration and innovation.
3. Applications of calorimeters in plant metabolic characterization
According to Larsson et al. [17], the name and definition of IMC include five components: the way heat is measured, how the environment’s temperature is controlled, how heat is generated, how the calorimeter functions, and how the data are analyzed. Basically, all calorimetric research on plant systems has been conducted in the dark. By introducing light, the heat responses associated with photosynthetic activity and the dynamic interplay between light-driven processes and dark metabolism in plant physiology metabolism could be ascertained. This dual approach could allow for the quantification of light’s influence on thermal outputs during photosynthesis, providing insights into plant energy efficiency and growth responses.
The biochemical heat production in plants has been a relatively understudied area until recently, despite its potential significance in plant physiology. The lack of research attention can be attributed to the challenges in accurately measuring the small amounts of heat generated during biochemical processes in plants, which requires sensitive calorimetric techniques capable of detecting heat capacities in the range of J g–1K–1 [18]. Calorimetry monitors an entirely separate attribute (energy) (J), whereas other techniques measure mass (g and kg). Thus, it offers more than just another way to gauge metabolic rate (J/s) [19]. According to Waele et al. [19], all metabolic processes naturally produce heat as a byproduct.
The rate of heat loss (Rq) from catabolism and anabolism was calculated using a calorimeter according to Popa et al. [20]. Equation (1) specifically addresses the recording and calculation of sensible and evaporative heat losses, which is directly related to the use of a calorimeter for heat loss calculations. As a result, calorimetric measurements of metabolic heat generation are frequently insufficient for assessing the metabolic efficiency of plant tissues, as demonstrated by Yusof et al. [21], who reported the impact of vacuum impregnation with various materials on the generation of metabolic heat and glucose metabolism in spinach leaves. The bioenergetic efficiency of cell metabolism considering heat rates and CO2 and O2 fluxes was demonstrated by Papkovsky [22]. The amount of heat produced (Rq), the rate of oxygen consumption (mL/min) (_R_O2), and the rate of carbon dioxide release (mL/min) (Rq) can be used to approximately represent the aeration mechanisms in biological cells (_R_CO2), as described by Manan and Webb [23]. These three respiratory rate data can be used to calculate three ratios: Rq:_R_CO2, Rq:_R_O2, and _R_CO2:_R_O2. As replicated in Manan and Webb [23], each of these ratios provides diverse information on biochemical processes and reliability because Rq:_R_CO2 and Rq:_R_O2 have different informational contents. Monitoring both of these ratios together provides information that cannot be obtained when they are used separately. Equation (2) gives the ratio of the anabolic rate to the CO2 generation rate, where ɛ is the carbon conversion efficiency of the substrate. The anabolic rate is expressed in the equation as the product of an efficiency term [ɛ/(1 – ɛ)] and a rate (_R_CO2), both of which are dependent on the surrounding conditions. Cell suspensions, callus tissues, algae, mosses, seeds, seedlings, cotyledons, leaves, roots, tuber tissue, and fruits have all undergone recent calorimetric research in the field of plant biology, as conducted by Yang et al. [24]. Negrini et al. [25] demonstrated the creation of three-dimensional microstructures from single plant cells in vitro, mimicking the plant tissue environment. This research used biocompatible scaffolds to provide developmental cues and structural stability to isolated callus-derived cells grown in liquid cultures. The findings supported the implications and connections of the demonstrated three-dimensional microstructures to plant responses, highlighting the relevance of this research in advancing our understanding of plant development, responses to external signals, and plant cell micromechanics.
RANAB=(ΔHB/ΔHO2) × (γs × RCO2)
Δ_H_B is the enthalpy change for the anabolic process, γs is the chemical oxidation state of carbon in the substrate, and Δ_H_O2 is the constant from Thornton’s rule, –455 ± 15 kJ/mol O2. Here, RANAB is the anabolic rate in _C-_moles per mass of insect per unit time. The value of γs was determined by using the respiratory quotient, calculated as the ratio of oxygen consumption to carbon dioxide production RO2/RCO2, yielding an approximate value.
The substrate carbon conversion efficiency is denoted by ε. This formula gives the link, accounting for substrate carbon-conversion efficiency, between the anabolic rate and the CO2 generation rate.
Khan and Hemalatha [26] explored the biochemical and molecular changes induced by salinity stress in Oryza sativa L. They investigated the expression of antioxidant proteins and the autophagy mechanism under salinity stress, providing insights into the genetic responses to salinity stress in rice plants. Their finding supports the notion that salinity stress affects plant metabolism and oxygenation. Winter wheat cell suspensions can be cultured for nine weeks without changing the medium as measured by IMC. This process involves cold adaptation and metabolic slowing, which is followed by rapid growth and stabilization. Suspensions can be used to investigate how isolated cells react to cold [27]. Wu et al. [28] determined the precise time- and temperature-dependent declines in the metabolism of tomato (Lycopersicon esculentum L.) cultivar cells after high- and low-temperature exposures. An increase in the glycolytic pathway was observed below approximately 12°C under intense heat according to an examination of metabolic heat rates, O2 utilization rates, and CO2 generation rates via luminous intensity (cd).
Islam et al. [29] focused on using DSC to authenticate edible fats and oils, emphasizing its significance in evaluating the authenticity of different types of fats and oils by characterizing oil from roasted hemp seeds using DSC, highlighting the method’s applicability in determining the oxidative stability of plant-derived oils [30]. Moreover, applications of DSCs and MDSCs in the food and drug industries have been investigated, demonstrating the versatility of DSCs for analyzing the supercooling and heat capacity of various materials [12]. This highlights the broad spectrum of fields where DSCs can be effectively employed for understanding thermal properties.
4. Calorimetry in assessing plant responses to environmental stressors and pathogens
Yu et al. [31] investigated calorimetric heat energy related to seed germination by investigating the impact of exogenous melatonin on promoting rice seed germination under high-temperature conditions by activating antioxidant systems. Furthermore, calorimetric analyses by Zhang et al. [32] revealed that salt treatment increased the rate of metabolic activity in plant leaves infected with Piriformospora indica. Under salt treatment, the accumulation of malondialdehyde, hydrogen peroxide (H2O2), and superoxide anion (O2–) was less than that in noncolonized plants, but the cultivation of P. indica greatly increased the activities of antioxidant enzymes, such as glutathione reductase (GR), peroxidase, catalase, and superoxide dismutase. This increase in metabolic activity (J/s) in _P. indica_-colonized barley may be related to improved salt tolerance. Two varieties of quinoa (Chenopodium quinoa Willd.) was examined by Chaganti and Ganjegunte [33] for saline stress tolerance using isothermal calorimetric studies of seedling growth in various salt solutions comprising NaCl, KCl, Na2SO4, K2SO4, and Na2CO3. The study of saline stress tolerance in quinoa aligns with the broader context of addressing environmental stresses in agriculture, which underscores the significant reduction in crop growth and productivity due to various environmental stresses, including salinity.
Research has explored the use of calorimetric methods to determine the minimum amount of salt added (450 mM NaCl) and its impact on the growth rate of organisms such as Chlorella vulgaris [34]. This study emphasizes that a higher metabolic rate alone may not be sufficient to compensate for energetic losses under salt stress, leading to a decrease in growth. Furthermore, calorimetry has been instrumental in evaluating plant tolerance to drought, as evidenced by studies involving specific Medicago sativa L. cultivars and populations of Sanguisorba minor Scop. [35]. By employing calorimetry, researchers can gain valuable insights into how plants respond to drought stress, thereby assisting in the assessment of plant resilience under challenging environmental conditions. Research on the moss Mnium undulatum investigated the effects of dehydration and rehydration on metabolic heat production. The results indicated a significant decrease in metabolic activity during dehydration, suggesting a reduction in metabolic heat production in this moss [36]. This study underscores the physiological changes occurring in plants such as M. undulatum in response to dehydration stress, emphasizing the importance of understanding metabolic adaptations to environmental challenges. This response is consistent with the plant’s adaptation to water stress, as it conserves energy and resources during periods of limited water availability. Upon rehydration, the moss exhibited a rapid increase in metabolic heat production, suggesting a swift recovery of metabolic activity following the restoration of the water supply. Avila et al. [37] also proposed IMC for identifying herbicide-resistant weeds. In a calorimetry ampoule containing an herbicide solution, three-day-old wild oat plants (Avena fatua L.) were sown on filter paper. They discussed the challenges posed by the evolution of herbicide resistance in weeds, the impact of noninversion tillage practices on weed management strategies, and the importance of accurately identifying herbicide-resistant weeds to inform effective management practices. The authors emphasized the need for innovative approaches to weed control due to the limited herbicide options available.
Rys et al. [38] investigated the effects of different extracts from sunflower and mustard leaves on catabolic activity during mustard germination. The total catabolic activity was calculated using the surface heat input (mW) of growth parameters in an isothermal calorimetric closed scheme. This research aimed to assess the impact of herbal extracts with allelopathic effects on the physiological and biochemical processes of white mustard (Sinapis alba L.) and oilseed rape (Brassica napus L. var.). To further comprehend the allelopathic reactions and elucidate the effects of various herbal extracts on seedling growth, IMC was used as a monitoring agent, during which the authors highlighted the significant endothermic effects induced by allelopathic interactions among mustard, wheat, and clover seedlings. The same study investigated the impact of volatile chemicals emitted from plant tissues on the metabolism of winter wheat and white mustard plants via IMC (Triticum aestivum L. and S. alba L.). In the context of the other studies mentioned, this research contributes to the understanding of how plant-derived compounds can influence the germination and growth of sensitive seeds. The use of IMC as a monitoring tool allows for the detection of subtle changes in metabolic activity during the germination process, which is crucial for elucidating the mechanisms underlying allelopathic interactions.
Assat et al. [39] investigated the thermal effects of voltage hysteresis in anionic redox-based lithium-rich cathodes using IMC. Their research aimed to explore the benefits of IMC in developing energy-efficient electrode materials for next-generation batteries. Using IMC, the authors were able to analyze the thermal effects related to voltage hysteresis, offering valuable insights into the physical stability and performance of lithium-rich cathodes. Microcalorimetry can be used to monitor pathogenic processes, particularly interactions between pathogens and plants. Wang et al. [40] discussed the use of microcalorimetry to monitor pathogenic processes, particularly interactions between pathogens and plants. In their study on protein acetylation and deacetylation in plant‒pathogen interactions, they highlighted the role of acetylation interference in the battle between microbial pathogens and host plants, indicating that both parties use various measures, including acetylation, to strengthen themselves while suppressing the other. This sheds light on the intricate mechanisms involved in plant‒pathogen interactions and the significance of monitoring these processes using advanced techniques such as microcalorimetry.
Calorimetric changes in plant metabolism in response to external pressures, such as viral infections and fungal attacks, are rapid processes that involve intricate cellular reactions. Studies have shown that plant cells react swiftly to viral infections such as tobacco mosaic virus and fungal pathogens such as Bipolaris sorokiniana Sacc. These responses are crucial for plant defense mechanisms against pathogens such as bacteria (e.g., Pseudomonas syringae pv. Syringae) and Mycoplasma (Chlorella vulgaris) [41]. The research by Zhang et al. [42] delves into the molecular mechanisms underlying the colonization of wheat by Bipolaris sorokiniana, a common pathogen causing spot blotch disease. This study highlights the essential role of a novel effector, CsSp1, from B. sorokiniana in wheat colonization and triggering host immunity, shedding light on the intricate interactions between the pathogen and the host plant. Furthermore, the study by Guo et al. [43] reported the involvement of the cysteine-rich repeat protein TaCRR1 in the defense of wheat against pathogens such as Rhizoctonia cerealis and B. sorokiniana. This protein plays a crucial role in disease-resistance mechanisms in wheat, indicating the complex genetic and molecular pathways plants employ to combat pathogenic attacks. Through his findings, Skoczowski [44] showed that ozone considerably decreases the metabolic activity of cabbage leaves. He examined how ozone influences the metabolic activity (heat production pace) of Chinese cabbage leaves (Brassica pekinensis Lour.) and demonstrated that ozone significantly decreases the metabolic activity of cabbage leaves. The rapid calorimetric changes observed in plant metabolism in response to external pressures, such as viral infections and fungal attacks, underscore the intricate and dynamic nature of plant defense mechanisms. The molecular interactions between pathogens and host plants inferred how specific effectors and proteins, such as CsSp1 and TaCRR1, are pivotal in facilitating pathogen colonization and activating host immunity. Moreover, the research by Skoczowski [44] also indicates that environmental stressors like ozone can significantly influence plant metabolic activity, further complicating the plant’s ability to respond to pathogens. Collectively, these studies illustrate that the plant immune response is not only a product of genetic and biochemical pathways but is also influenced by external environmental factors, suggesting that a comprehensive understanding of plant–pathogen interactions requires an integrative approach that considers both intrinsic metabolic processes and extrinsic stressors. This perspective is essential for developing sustainable agricultural practices and enhancing crop resilience against a backdrop of increasing biotic and abiotic stresses.
Ruan et al. [45] investigated the hydration kinetics and microstructure development of normal and CaCl2-accelerated tricalcium silicate pastes using the DSC technology. Their research focused on construction materials but did not directly study plant responses to stressors or pathogenic interactions in soil environments. This interdisciplinary approach, combining DSC with plant biology and soil science, has the potential to advance our understanding of how plants respond to environmental stressors and pathogenic interactions in soil environments. By using DSC to assess the intricate processes involved in plant responses to stressors, researchers aim to enhance our knowledge of plant‒soil interactions and contribute to the development of strategies for sustainable agriculture and environmental management.
5. Calorimetry as a powerful tool for assessing soil microbial activity
IMC is a nondestructive method used to precisely measure the heat flows present in systems to ascertain heat production in soil [2]. All biochemical systems generate/consume heat in direct proportion to the pace at which specific chemical or physical processes occur therein. As a corollary, carbon assimilation in a soil system may be measured using microcalorimetry [14]. In an effort to provide an alternative technique for soil microorganisms, Jing et al. [46] determined the values for the typical heat released from soil to which glucose had been added. Xing et al. [47] explored the caloric ratio as a measure of baseline heat output per unit biomass, similar to the heat output per microbial cell following glucose addition. Their research focused on evaluating soil microbial activity through heat output and CO2 respiration. They established a significant correlation between total heat output per unit microbial biomass and microbial biomass, as determined by total phospholipid fatty acids. This investigation contributes valuable insights into the connection between heat production and microbial activity, offering a deeper understanding of the metabolic processes of soil microorganisms. The study demonstrated that the caloric quotient of different forest soils appeared to vary across different layers, which supports the notion of varying caloric quotients in different forest soils, highlighting the complex interplay of soil composition and plant dynamics.
By creating an index that expresses the total isothermal performance of soil microbial communities, Bölscher et al. [48] demonstrated that one of the best ways to measure and evaluate the thermodynamic efficiency of soil microbial populations is by evaluating the amount of heat flow released following substrate addition per unit input of thermal energy into the soil system. Compared to enzymatic activity, isothermal microcalorimetry is a sensitive technique that continuously and in real time monitors system activity, provides qualitative and quantitative indicators of soil state, and measures soil deterioration [49]. A study by Bararunyeretse et al. [50] showed that heavy metals and flotation agents have acute toxicological effects on soil microbial activity. Visconti-Moreno and Valenzuela-Balcázar [51] also discussed the use of microcalorimetry in investigations of soil microorganisms to determine the relationships between soil properties and microbial activities, particularly focusing on the breakdown of readily biodegradable carbohydrates. In their study on the influence of pore distribution on the response of soil microorganisms to temperature and moisture changes, they observed a significant effect of temperature on soil respiration, aligning with previous findings that highlighted the exponential increase in microbial respiration with increasing soil temperature.
Devine et al. [52] discussed how microcalorimetry has been used as the primary method for determining soil health. Their study focused on investigating the relationships between soil properties such as moisture content, organic matter concentration, biomass production, and microbial activities. This research supplemented microcalorimetric analyses with investigations into the mechanical, biochemical, and microbiological characteristics of soil, providing a comprehensive understanding of soil health dynamics (Figure 2). A study by Faheen and Mansoor [53] focused on assessing the impact of potassium permanganate on soil microbial activity using IMC and DSC with the soil bacteria Arthrobacter oxydans. This research highlighted a biphasic dose-dependent response to stress induced by potassium permanganate.
On the other hand, Leyva‐Porras et al. [12] explored the applications of DSC and MDSC in the food and drug industries, emphasizing the importance of thermodynamic parameters for product development. Both studies underscore the significance of DSC in understanding the effects of environmental stressors on microbial systems and material properties for industrial applications. In addition, microcalorimetric research on the impacts of organic additions on soil microbial activity and biomass content has received little attention. A study by Devine et al. [52] emphasized the impact of animal waste on soil microbial communities and nutrient cycling, underscoring the relevance of understanding the interactions between animal wastewater and soil microbiota. The impact of solid‒liquid effluents from anaerobic treatment on soil microbial activity was investigated using IMC and DSC.
Figure 2
A schematic flow chart illustrating the distinct basic principles of isothermal microcalorimetry and differential scanning calorimetry for investigating the metabolic analysis of plant stress response, plant metabolism, waste management, and clinical diagnostics.
Arcand et al. [54] explored the differences in soil microbial carbon use between organically managed and conventionally managed soils. They combined isothermal microcalorimetry with stable isotope probing to assess the thermodynamic efficiency of microbial communities in these soils. Li et al. [55] highlighted the use of IMC as a method to study thermodynamics and biokinetics, emphasizing its importance in structural biology research. By combining IMC and DSC methods, researchers have been able to gain insights into the thermodynamic efficiency of microbial communities in different soil management systems and under the influence of various substances, highlighting the importance of understanding these interactions for environmental and agricultural purposes. Figure 2 shows the substantial differences between the operating philosophies of the IMC and DSC technologies, complimented with a schematic flowchart that illustrates the distinct basic operational dynamics of the IMC and DSC in investigating the metabolic gauge of plant stress response, plant metabolism, waste management, and clinical diagnostics. Awode et al. [15] demonstrated how poultry droppings can be used as substrates for the production of biogas from the anaerobic decomposition of waste. The addition of certain substances to waste has been proven to increase biogas production. The effect of these additives on the microorganisms responsible for digestive processes has been studied using IMC [56]. These studies demonstrated that the enhancement of biogas production through the addition of specific additives provides insights into strategies for improving the efficiency of anaerobic digestion processes using poultry waste as a substrate.
Nafady et al. [57] investigated the effects of combinations of Ni, sodium butyl xanthate (SBX), and Ni/SBX on soil microbes using microcalorimetry. This research focused on the transfer of nickel from polluted soil to Pisum sativum L. and Raphanus sativus L. under composted green amendment and native soil microbes. The study highlighted that the minimum transfer factors of Ni from polluted soil to pea and radish plants were 0.067 and 0.089, respectively, which were achieved by applying compost (0.6% of the soil weight) inoculated with mycorrhizal fungi. By reducing the growth rate constant compared to that of a control, SBX has been found to suppress biological populations in soil. Microbial activity returned with SBX breakdown and removal because SBX is unstable and soil microbes continue to be sensitive to pollutants. This shows that microbial processes are critical for both removing and breaking down organic molecules. The is also reflected in the work of Marycz et al. [58] who synthesized insights into microbial processes related to soil health and environmental sustainability through the effective removal and breakdown of organic molecules.
The phytoremediation of polluted soil, the recycling of nutrients, and the breakdown of organic materials are examples of how important soil microorganisms are [59]. This study emphasized the ability of soil microbes to degrade pollutants and enhance soil quality, which highlights the significant contribution of soil microorganisms to the degradation of organic pollutants and the restoration of contaminated environments. When assessing microbial activity in soil, IMC approaches are generally used for observations in the microwatt range under nearly isothermal conditions [60].
A study by Bararunyeretse et al. [61] investigated the interactive effect of copper and its mineral collectors on soil microbial activity using microcalorimetric analysis. The research demonstrated that the microbial activity in soil was more influenced by the combination of copper and mineral collectors than by the individual components alone. This study provided valuable insights into the complex interactions between contaminants and soil microbes, highlighting the significance of considering the combined effects on microbial processes. It also observed the impacts of microbial activity resulting from different soil‒water concentrations and different pre-incubation periods using an isothermal calorimeter to measure the heat produced by living organisms in the soil. Braissant et al. [62] provided new insights into terrestrial carbon cycling using IMC. By employing this technique, this research sheds light on the energetics of soil microbial processes, offering valuable information on how soil microbes influence carbon cycling dynamics. This study contributes to a better understanding of the ecological and biogeochemical implications of soil microbial activity, particularly in relation to nutrient cycling and ecosystem functioning.
6. Applications of calorimetry in clinical diagnostics
IMC has been demonstrated to be useful in a number of biological disciplines, including microbiology, enzymology, pharmacology, plant physiology, and ecology [63]. It is mostly employed in the field of biological materials for the diagnosis of diseases or the detection of infections, and it has been effectively applied to identify infectious diseases in a range of samples [64]. Blood or cerebrospinal fluid (CSF) samples provide a simpler method for detecting bacterial growth. The method involves inoculating a portion of blood or CSF samples into a calorimetry ampule prefilled with rich growth media. The ampule is then inserted into an isothermal microcalorimeter for detecting bacterial growth. If the calorimeter detects a metabolic heat production rate that is higher than a set entry, the sample is regarded as positive. The study by Popa et al. [65] revealed that this method was useful for assessing meningitis, bloodstream, and urinary infections. The IMC approach can be used to evaluate important information about microbial pathogenicity in connection to the rate of growth [66]. Additionally, infections with slow growth rates that are difficult to culture can be treated with IMC [67]. The IMC has been used to study the genetic requirements for fast and slow growths in mycobacteria, providing insights into the growth dynamics of Mycobacterium tuberculosis. In addition, IMC has been employed in the management of immune-mediated colitis, where early introduction of selective immunosuppressive therapy has shown favorable clinical outcomes. The integration of IMC and DSC into clinical diagnostics represents a transformative approach to disease detection and monitoring, offering rapid and sensitive insights into microbial activity and metabolic changes. As these techniques continue to evolve, their potential to enhance diagnostic accuracy and inform treatment decisions will likely contribute significantly to personalized medicine and improve patient outcomes.
According to several investigations, IMC can be used to sonicate bacteria from the surface of large solid specimens, similar to diseased prosthetic devices and breast augmentation [65, 68, 69]. According to Liskova et al. [70], urogenital tumorous biopsies generate more heat per unit of time than do healthy tissues. Similarly, Sherman et al. [71] focused on stochastic DSC using nonlinear optical microscopy. This research explores the application of DSC in a stochastic framework, providing valuable insights into the thermodynamic properties of materials with enhanced sensitivity and measurement capabilities. This study introduces a novel approach to studying phase transitions and thermal behavior, aligning with advancements in DSC techniques for characterizing complex materials and biological samples. Braissant et al. [62] juxtaposed the distinction between methicillin-susceptible Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). The purpose of the study was to examine how much heat the cefoxitin-incubated sample produced throughout a control period of four to five hours. Another study was conducted to determine the growth rates of the organisms to calculate their inhibition indices. According to the study findings, the difference in inoculum size between the study on MRSA and that on uropathogens took longer to complete [62]. The European Committee on Antimicrobial Susceptibility Testing [72] also gave guidelines on how to find pathogens using analytical techniques at the cut-off concentration. These values are used to categorize pathogens as susceptible, intermediate, or resistant to antimicrobial agents. The organisms devoid of phenotypically detectable, acquired resistance mechanisms have the highest minimum inhibitory concentration (MIC). In a related study, Michnik et al. [73] explored the application of DSC analysis of blood serum in response to CrossFit training and green tea extract supplementation. By using DSC to detect post-exercise changes in blood serum, this research highlighted the utility of this technique in monitoring physiological responses to training and supplementation, showing its potential in sports medicine and performance evaluation. Furthermore, Garbett et al. [74] discussed the complementary diagnostic role of DSC in evaluating biological samples. Their study emphasized the use of DSC to measure the thermal stability profiles of molecular interactions in biological fluids, providing insights into complex molecular processes relevant to disease states. This research highlighted the clinical utility of DSC analysis in characterizing biological samples and identifying potential biomarkers for various diseases.
7. Advanced calorimetry techniques in clinical diagnostics, soil microbial characterization, and environmental assessment
7.1. Advancements and applications in clinical diagnostics
DSC is a powerful analytical technique that measures the heat flow associated with thermal transitions in materials [30]. In clinical diagnostics, DSC has emerged as a valuable tool for studying the thermal properties of biological samples, providing insights into disease mechanisms and drug interactions. Brys et al. [30] further characterized oil from roasted hemp seeds using DSC and Fourier transform infrared spectroscopy, highlighting the potential of DSC for analyzing the thermal behavior of biological materials. Furthermore, Roberts et al. [75] used isothermal titration calorimetry to study fatty acid effector binding to soybean lipoxygenase, demonstrating the application of DSC in understanding protein‒ligand interactions. These studies underscore the potential of DSC in clinical diagnostics, offering a deeper understanding of biological processes and disease pathways (Figure 2).
7.2. Advancements in calorimetric applications in soil microbial characterization
In soil microbial characterization, DSC has been instrumental in studying the thermal properties of soil components and microbial interactions. Trupiano et al. [76] emphasized the significant impact of biochar application on soil properties and microbial activity. Biochar combined with organic or inorganic fertilizers has shown potential for enhancing physical, chemical, and biological characteristics of soil, ultimately promoting plant growth. This technique has proven valuable for characterizing soil samples from various environmental settings. In the field of soil microbiology characterization, DSC has emerged as a valuable tool. Hardy et al. [77] also demonstrated the potential of DSC in quantifying charcoal in soil samples, offering insights into soil composition and history. Their work highlighted the underexploited nature of dynamic thermal analysis in providing interpretable information on soil organic matter (Figure 2).
7.3. Advancements in calorimetric applications in environmental assessments
In environmental assessments, DSC has been used to study the thermal behavior of environmental samples and assess their interactions with contaminants. Huang et al. [78] investigated the interactions, transformations, and bioavailability of nanocopper exposed to root exudates using DSC, providing insights into the environmental fate of nanoparticles. Yang et al. [79] studied the three-dimensional microstructure of tricalcium silicate (C3S) using electron microscopy, providing insights into the spatial structure of raw C3S materials. This understanding is crucial for comprehending the hydration kinetics of C3S and other cement minerals. Analyzing the 3D structure of C3S contributes to a deeper understanding of the interactions and microstructural evolution of construction materials during the hydration process, aligning with the theme of microstructure development and hydration kinetics in construction materials. These studies highlight the potential of DSC in environmental assessments, offering valuable information on the thermal behavior of environmental samples and their interactions with contaminants. Braissant et al. [62] described how DSC has been instrumental in determining viability, viability, and metabolic rates in microbiology, offering a sensitive culture-based technique for measuring heat generated by microbial activities. Hardy et al. [77] quantified charcoal in soil samples via DSC, providing valuable information on soil composition and history. By integrating DSC technology into soil microbiology studies, researchers have gained a deeper understanding of microbial processes and their interactions with the environment, contributing to environmental sustainability efforts (Figure 2).
8. Conclusions
Inferences from the literature survey in this review showed how IMC calscreeners have the potential to revolutionize the diagnosis and treatment of infectious diseases, offering rapid and accurate detection methods for a wide range of microbial infections and biofilm-related infections. Advances in IMCs have the potential to enhance our understanding of plant responses to environmental stressors and pathogenic interactions, contributing to the development of effective strategies for plant protection and disease management. The increased use of IMC in environmental microbiology has the potential to enhance our understanding of soil microbial activity and environmental impacts, contributing to the development of sustainable agricultural practices and environmental management strategies. The advancements and applications of DSC techniques in clinical diagnostics, soil microbiology characterization, and environmental assessments have significant implications for understanding biological processes, microbial interactions, and environmental dynamics for further integration and standardization of DSC techniques in diverse fields. Future perspectives include the continued integration of DSC techniques with advanced analytical methods, such as mass spectrometry and spectroscopic techniques, to further enhance the understanding of complex biological and environmental systems. Moreover, the development of standardized protocols and reference databases for DSC analysis in clinical, soil microbiology, and environmental studies is crucial for advancing the field and ensuring the reproducibility and comparability of results.
In addition to improving our knowledge of how plants respond to environmental stressors and pathogenic interactions, this review emphasizes the potential of IMC calscreeners to improve the diagnosis and treatment of infectious diseases and support environmentally friendly farming methods. Specifically, IMC can contribute to achieving SDG 3 (Good Health and Well-being) by improving diagnostic tools and enabling better disease management. In addition, IMC can support SDG 9 (Industry, Innovation, and Infrastructure) by advancing scientific research and innovation in the field of microbiology and SDG 17 (Partnerships for the Goals) by fostering collaboration and partnerships in the development and implementation of new diagnostic technologies. This review highlights the significance of developing standardized protocols and reference databases for the DSC analysis in environmental, clinical, and soil microbiology studies, as well as the ongoing integration of DSC techniques with cutting-edge analytical methodologies. Specifically, measurable, achievable, relevant, and time-bound (SMART) goals offer a precise and quantifiable strategy for accomplishing suggested studies, which can assist in guaranteeing their effective implementation.