Method for measuring microbial activity in cement-containing molded articles

Abstract

To provide a method for measuring the activity of microorganisms in a cement-containing molded body by which a measurement result can be immediately obtained and analysis can be conducted in an environment where microorganisms are generally present.SOLUTION: A method for measuring the activity of microorganisms in a cement-containing molded body is to measure the degree of activity of microorganisms in a cement-containing molded body obtained by molding a concrete composition including a cement-containing composition, microorganisms, and nutrient sources, wherein at least some of the nutrient sources are isotopically labeled nutrient sources, and the method includes the steps of: exposing a part of the cement-containing molded body in an environment where acidic substances or basic substances are present, thereby extracting a metabolite generated when the microorganisms included in the cement-containing molded body decompose the isotopically labeled nutrient sources into the environment where the acidic substances or the basic substances are present; and measuring an amount of isotopes included in the metabolite, thereby estimating an amount of the isotopically labeled nutrient sources decomposed by the microorganisms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for measuring microbial activity in cement-containing molded articles. [Background technology]

[0002] By incorporating microorganisms along with nutrients into concrete, it may be possible to obtain useful effects such as repairing cracks in concrete. Research on such concrete crack repair is actively being conducted. For example, self-healing concrete is known in which bacteria and polylactic acid are mixed into the concrete material, and when the concrete cracks, the activated bacteria metabolize calcium carbonate to repair the cracks. On the other hand, since the reaction by microorganisms varies greatly depending on temperature, moisture, and nutrient source, there are challenges in knowing how much of the desired reaction actually occurs and how much effect can be obtained from that reaction.

[0003] One known method for estimating the activity level of microorganisms in the environment is to measure the amount of mRNA using quantitative PCR. This method is used in bioremediation and other applications to estimate microbial activity in the soil and to confirm the activity of microorganisms that decompose target substances. Furthermore, measuring ATP activity is a known method for rapidly estimating the activity level of microorganisms in the environment. Among the methods for measuring ATP activity, ATP swab testing, for example, is useful as a means of rapidly measuring the microbial activity level on the surface of an object being tested. Furthermore, a method for quantitatively determining intracellular metabolic fluxes by performing trace experiments of isotopic compounds is known, which involves stoichiometrically analyzing the quantitative ratio (carbon balance) of each metabolite in the metabolic reaction pathway of the target cell (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent No. 4742528 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] The method of estimating the activity amount of microorganisms in the environment by quantitative PCR requires many processes such as mRNA extraction from soil, treatment with deoxyribonuclease (DNase), reverse transcription PCR, etc. for analysis, and it is difficult to obtain measurement results immediately. The ATP swab test is usually used for the cleanliness test after cleaning, etc., and is not suitable for analysis in environments where microorganisms are generally present, such as concrete surfaces and soil. The method described in Patent Document 1 is a method for determining intracellular metabolic flux from the analysis value of cells cultured in a medium containing a substrate labeled with an isotope as a carbon source, so it is difficult to obtain measurement results immediately.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for measuring the activity of microorganisms in a cement-containing molded body that can obtain measurement results immediately and can analyze in an environment where microorganisms are generally present. [Means for Solving the Problems]

[0007] The present invention has the following aspects. [1] A method for measuring the activity of microorganisms in a cement-containing molded body formed by molding a concrete composition containing a cement composition, microorganisms, and a nutrient source, where at least a part of the nutrient source is a nutrient source labeled with an isotope, a step of extracting metabolites generated when the microorganisms contained in the cement-containing molded body decompose the isotope-labeled nutrient source into an environment where an acidic substance or a basic substance is present by exposing a part of the cement-containing molded body to an environment where an acidic substance or a basic substance is present, A method for measuring microbial activity in a cement-containing molded body, comprising the step of estimating the amount of isotope-labeled nutrient source decomposed by the microorganism by measuring the amount of isotopes contained in the metabolites. [2] The isotope-labeled nutrient source is 13 C-labeled nutrients, 15 N-labeled nutrients and 17 A method for measuring microbial activity in a cement-containing molded body according to [1], comprising at least one selected from the group consisting of O-labeled nutrient sources. [3] A method for measuring microbial activity in a cement-containing molded body according to [1] or [2], wherein the amount of isotopes contained in the metabolites is determined by mass spectrometry of the metabolites. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for measuring microbial activity in cement-containing molded articles that allows for immediate measurement results and enables analysis in environments where microorganisms are universally present. [Modes for carrying out the invention]

[0009] The following describes a method for measuring microbial activity in cement-containing molded articles according to embodiments of the present invention. This embodiment is provided to give a better understanding of the spirit of the invention and does not limit the present invention unless otherwise specified.

[0010] [Method for measuring microbial activity in cement-containing molded articles] The method for measuring microbial activity in a cement-containing molded body according to this embodiment is a method for measuring the activity of microorganisms in a cement-containing molded body obtained by molding a concrete composition containing a cement-containing composition, microorganisms, and a nutrient source, wherein at least a portion of the nutrient source is an isotope-labeled nutrient source, and the method comprises the steps of: (hereinafter referred to as "the first step"), which involves exposing a portion of the cement-containing molded body to an environment where an acidic or basic substance is present, thereby extracting metabolites generated when microorganisms contained in the cement-containing molded body decompose the isotope-labeled nutrient source into an environment where an acidic or basic substance is present; and (hereinafter referred to as "the second step"), which involves measuring the amount of isotopes contained in the metabolites to estimate the amount of the isotope-labeled nutrient source decomposed by the microorganisms.

[0011] "Cement-containing molded body" The cement-containing molded body in this embodiment is formed by molding a concrete composition containing a cement-containing composition, microorganisms, and a nutrient source.

[0012] (Contains cement composition) The cement-containing composition contains cement and water. Examples of cement-containing compositions include concrete, mortar, cement milk, and the like. Concrete is a mixture of cement, fine aggregate (sand), and coarse aggregate (gravel (crushed stone)), which is then mixed with water. Mortar is a mixture of cement and fine aggregate (sand), which is then mixed with water. Cement milk is a mixture of cement and water.

[0013] Cement is a powder made primarily from limestone, clay, silica, iron oxide, and other raw materials, which hardens through a chemical reaction with water. Fine aggregate refers to sand with a diameter of 5 mm or less. Coarse aggregate refers to gravel (crushed stone) with a diameter of more than 5 mm. Preferably, the diameter of the coarse aggregate is 25 mm or less.

[0014] The mixing ratio of cement, fine aggregate, and coarse aggregate in concrete can be appropriately determined according to the required strength of the concrete. Preferably, the mixing ratio of cement, fine aggregate, and coarse aggregate is, for example, 1 part cement to 2-3 parts fine aggregate and 4-6 parts coarse aggregate by mass.

[0015] The mixing ratio of cement to fine aggregate in mortar can be appropriately determined according to the required strength of the mortar. Preferably, the mixing ratio of cement to fine aggregate is, for example, 1 part cement to 2 to 4 parts fine aggregate by mass.

[0016] The water content in concrete is preferably 6% by mass or more and 15% by mass or less of the total amount of concrete. The water content in the mortar is preferably 10% by mass or more and 15% by mass or less, relative to the total amount of mortar. The water content in the cement milk is preferably 30% by mass or more and 40% by mass or less, relative to the total amount of cement milk.

[0017] The content of cement-containing composition in the concrete composition is preferably 10% by mass or more and 60% by mass or less, relative to the total amount of the concrete composition.

[0018] (microorganisms) Examples of microorganisms include bacteria, fungi, and archaea.

[0019] The microbial content in the concrete composition is preferably 0.001% by mass or more and 10% by mass or less, and more preferably 0.005% by mass or more and 5% by mass or less, relative to the total amount of the concrete composition. If the microbial content is above the lower limit, useful effects for the concrete, such as sufficient crack repair, can be achieved. If the microbial content is below the upper limit, the concrete can be used without impairing its strength or other properties.

[0020] (Source of nutrients) Examples of nutrient sources include polylactic acid, urea, ethanol, acetic acid, glucose, polypeptide, yeast extract, etc. At least a part of the nutrient source is an isotope-labeled nutrient source. For example, when using polylactic acid as the nutrient source, at least a part of the polylactic acid is 13 polylactic acid labeled with 13C.

[0021] The content of the nutrient source in the concrete composition is preferably 0.001% by mass or more and 10% by mass or less, more preferably 0.005% by mass or more and 5% by mass or less, based on the total amount of the concrete composition. If the content of the nutrient source is at least the above lower limit value, useful effects for concrete, such as sufficient repair of cracks, can be achieved. If the content of the nutrient source is at most the above upper limit value, it can be used without impairing the strength of the concrete.

[0022] The mixing ratio of the microorganism and the nutrient source in the concrete composition is preferably 0.5 or more and 50 or more, more preferably 1 or more and 30 or more, by mass ratio, for example, with respect to microorganism 1. If the ratio of the nutrient source is at least the above lower limit value, the microorganism can grow under sufficient nutrition, so useful effects for concrete, such as sufficient repair of cracks, can be achieved. If the ratio of the nutrient source is at most the above upper limit value, the amount of the nutrient source remaining in the concrete composition after the metabolism by the microorganism can be reduced, and an excessive reaction can be suppressed.

[0023] (Isotope-labeled nutrient source) The isotope-labeled nutrient source is a compound containing an isotope and serves as a nutrient source for the above microorganism. Examples of the isotope-labeled nutrient source include nutrient sources labeled with 13C, which is an isotope of 12C, 15N, which is an isotope of 14N, 17O, which is an isotope of 16O, etc. 12 13C), nutrient sources labeled with 15N, which is an isotope of 14N 13 13C), nutrient sources labeled with 15N, which is an isotope of 14N 14 14N), 15N, which is an isotope of 14N 15 15N), nutrient sources labeled with 17O, which is an isotope of 16O 16 16O), 17O, which is an isotope of 16O 17 17O), etc. 13 Examples of C-labeled nutrients include, 13 C-labeled polylactic acid, 13 C-labeled urea, 13 C-labeled ethanol, 13 C-labeled acetic acid, 13 Examples include 14C-labeled glucose. 15 Examples of N-labeled nutrients include, 15 N-labeled urea, 15 Examples include nitrogen-labeled polypeptides. 17 Examples of O-labeled nutrients include, 17 O-labeled polylactic acid, 17 O-labeled ethanol, 17 Examples include oxygen-labeled acetic acid, etc. Isotope-labeled nutrients may be used individually or in combination of two or more.

[0024] 13 Since 14C-labeled glucose is commercially available, this glucose can be used as a carbon source for various purposes. 13 C-labeled compounds can be produced. 13 Examples of 1C-labeled compounds include: 13 C-labeled polylactic acid, 13 C-labeled urea, 13 C-labeled ethanol, 13 Examples include 14C-labeled acetic acid, etc.

[0025] The content of isotope-labeled nutrients is preferably 0.01% by mass or more and 10% by mass or less, and more preferably 0.1% by mass or more and 1% by mass or less, relative to the total amount of nutrients. If the content of isotope-labeled nutrients is above the lower limit, the isotope label can be detected with high sensitivity during analysis. If the content of isotope-labeled nutrients is below the upper limit, the concrete composition can be manufactured at low cost.

[0026] The nutrients contained in the cement-containing molded body may all be isotope-labeled nutrients, or not all of them may be isotope-labeled nutrients. For example, if 0.01% by mass of the nutrients are isotope-labeled nutrients, the amount of nutrients decomposed by microorganisms can be estimated by multiplying the amount of isotope-labeled metabolites by 10,000.

[0027] The concrete composition may contain chemical admixtures such as water-reducing agents and thickening agents.

[0028] "The first step" In the first step, a portion of the cement-containing molded body formed from the above-mentioned concrete composition is first taken. Methods for taking the cement-containing molded body include, for example, scraping off a portion of the cement-containing molded body or cutting a portion of the cement-containing molded body. The amount of cement-containing molded material to be sampled is not particularly limited, but is preferably between 1g and 1000g, and more preferably between 10g and 500g. If the amount of cement-containing molded material sampled is above the lower limit, a sufficient amount can be secured for analysis. If the amount of cement-containing molded material sampled is below the upper limit, the area and amount of concrete composition removed can be reduced.

[0029] Next, a portion of the collected cement-containing molded body is exposed to an environment containing acidic or basic substances. In other words, a portion of the collected cement-containing molded body is immersed in an acidic substance. Alternatively, a portion of the collected cement-containing molded body is immersed in a solution containing a basic substance. Furthermore, a portion of the collected cement-containing molded body is exposed to an atmosphere containing acidic or basic substances.

[0030] The acidic substance is not particularly limited as long as it can dissolve the metabolites generated when microorganisms contained in the cement-containing molded body decompose nutrients, but examples include hydrochloric acid, sulfuric acid, and nitric acid.

[0031] The concentration of the acidic substance is not particularly limited as long as it can dissolve the metabolites generated when microorganisms contained in the cement-containing molded body decompose the nutrient source. However, it is preferably 1% by mass or more, and more preferably 10% by mass or more. If the concentration of the acidic substance is above the above lower limit, the cement-containing molded body can be sufficiently dissolved with ample margin.

[0032] The amount of cement-containing molded material immersed in the acidic substance is not particularly limited as long as it is sufficient to dissolve the metabolites generated when microorganisms contained in the cement-containing molded material decompose the nutrient source. However, it is preferably expressed as the mass per unit volume of the acidic substance, and is more preferably 0.01 g / L to 100 g / L, and more preferably 0.05 g / L to 10 g / L. If the amount of cement-containing molded material is above the lower limit, the concentration of metabolites can be maintained at a high level, allowing for sensitive analysis. If the amount of cement-containing molded material is below the upper limit, the amount of cement-containing molded material used in the test can be reduced.

[0033] The concentration of the acidic substance in the atmosphere containing the acidic substance is not particularly limited as long as it can dissolve the metabolites generated when microorganisms in the cement-containing molded body decompose the nutrient source. For example, it is expressed as the mass per unit volume of the atmosphere containing the acidic substance, and is preferably 1 g / L or more, and more preferably 10 g / L or more. If the amount of cement-containing molded body is above the above lower limit, the cement-containing molded body can be sufficiently dissolved with ample margin.

[0034] The amount of cement-containing molded material exposed to an atmosphere containing acidic substances is not particularly limited as long as it can dissolve the metabolites generated when microorganisms contained in the cement-containing molded material decompose nutrients. For example, it is expressed as the mass per unit volume of the atmosphere containing acidic substances, and is preferably 0.01 g / L to 100 g / L, and more preferably 0.05 g / L to 10 g / L. If the amount of cement-containing molded material is above the lower limit, the concentration of metabolites can be maintained at a high level, allowing for sensitive analysis. If the amount of cement-containing molded material is below the upper limit, the amount of cement-containing molded material used in the test can be reduced.

[0035] The basic substance is not particularly limited as long as it can dissolve the metabolites generated when microorganisms contained in the cement-containing molded body decompose nutrients, but examples include sodium hydroxide, calcium hydroxide, and potassium hydroxide. Examples of solvents for the solution containing the basic substance include water and alcohol.

[0036] The concentration of the basic substance in a solution containing the basic substance is not particularly limited as long as it can dissolve the metabolites generated when microorganisms contained in the cement-containing molded body decompose the nutrient source. However, it is preferably 1% by mass or more, and more preferably 10% by mass or more. If the concentration of the basic substance is above the above lower limit, the cement-containing molded body can be sufficiently dissolved with ample margin.

[0037] The amount of cement-containing molded body immersed in a solution containing a basic substance is not particularly limited as long as it can dissolve the metabolites generated when microorganisms contained in the cement-containing molded body decompose the nutrient source. For example, it is expressed as the mass per unit volume of the solution containing the basic substance, and is preferably 0.01 g / L to 100 g / L, and more preferably 0.05 g / L to 10 g / L. If the amount of cement-containing molded body is above the lower limit, the concentration of metabolites can be maintained at a high level, allowing for sensitive analysis. If the amount of cement-containing molded body is below the upper limit, the amount of cement-containing molded body used in the test can be reduced.

[0038] The concentration of the basic substance in the atmosphere containing the basic substance is not particularly limited as long as it can dissolve the metabolites generated when microorganisms contained in the cement-containing molded body decompose the nutrient source. For example, it is expressed as the mass per unit volume of the atmosphere containing the basic substance, and is preferably 1 g / L or more, and more preferably 10 g / L or more. If the amount of cement-containing molded body is above the above lower limit, the cement-containing molded body can be sufficiently dissolved with ample margin.

[0039] The amount of cement-containing molded material exposed to an atmosphere containing a basic substance is not particularly limited as long as it can dissolve the metabolites generated when microorganisms contained in the cement-containing molded material decompose nutrients. For example, it is expressed as the mass per unit volume of the atmosphere containing the basic substance, and is preferably 0.01 g / L to 100 g / L, and more preferably 0.05 g / L to 10 g / L. If the amount of cement-containing molded material is above the lower limit, the concentration of metabolites can be maintained at a high level, allowing for sensitive analysis. If the amount of cement-containing molded material is below the upper limit, the amount of cement-containing molded material used in the test can be reduced.

[0040] In this way, by exposing a portion of the collected cement-containing molded body to an environment containing acidic or basic substances, metabolites generated when microorganisms contained in the cement-containing molded body decompose nutrients are extracted into the environment containing the acidic or basic substances. Examples of metabolites include carbon dioxide (CO2) and ammonia (NH3).

[0041] for example, 13 When a 14C-labeled nutrient source is used, the following is generated by microbial metabolism (microorganisms consuming nutrients and oxygen). 13 Most of the 1C-labeled CO2 precipitates as calcium carbonate (CaCO3) in the cement-containing molded body. Therefore, the cement-containing molded body is exposed to an acidic substance (e.g., hydrochloric acid) or a solution containing an acidic substance to dissolve the CaCO3 in the acidic substance or solution containing an acidic substance, and the CO2 is extracted. The CO2 contains 13 The amount of C is measured in the second step. Also, for example, 15 When N-labeled nutrients are used, the following are generated by microbial metabolism. 15 Some of the N-labeled NH3 remains inside the cement-containing molded body. Therefore, the cement-containing molded body is exposed to an aqueous solution containing a basic substance (e.g., sodium hydroxide) to dissolve the NH3 in the aqueous solution containing the basic substance, and the NH3 is extracted. 15 The amount of nitrogen (N) is measured in the second step.

[0042] "The second step" In the second step, the amount of nutrients broken down by microorganisms is estimated by measuring the isotope content of the metabolites extracted in the first step. One method for measuring the isotope content of metabolites is to extract the metabolites as a gas and then measure the isotope content in the gas by mass spectrometry. The metabolites extracted as gas are analyzed using a gas chromatograph-mass spectrometer (GC-MS). Alternatively, the extracted metabolites are recovered in a basic solution and analyzed as a liquid using a liquid chromatography-mass spectrometer (LC-MS). By measuring the isotope content of metabolites in this way, the amount of nutrients decomposed by microorganisms can be estimated. As mentioned above, at least a portion of the nutrients contained in cement-containing molded products are isotope-labeled nutrients. Therefore, the amount of nutrients actually decomposed by microorganisms can be estimated from the amount of isotope-labeled nutrients decomposed by microorganisms.

[0043] For example, carbonates are universally present in cement-containing molded products because they are included in the material of the cement-containing molded product, or because carbonates are incorporated into the cement-containing molded product and react with the calcium and CO2 in the cement-containing molded product. 13 When C-labeled nutrients are not used, carbonates that are commonly present in cement-containing molded bodies and microorganisms 13 It is impossible to distinguish between CO2 produced by the decomposition of 1C-labeled nutrients and CO2 produced by microorganisms. 13 When 14C-labeled nutrients are broken down, CO2 with a mass number of 45 is produced. By analyzing the difference in mass numbers using a mass spectrometer, it is possible to determine even in environments where various microorganisms exist. 13 This method allows for the specific detection of only the degradation of 14C-labeled nutrients.

[0044] The method for measuring microbial activity in a cement-containing molded body according to this embodiment includes the steps of: exposing a portion of the cement-containing molded body to an environment containing an acidic or basic substance, thereby extracting metabolites generated when microorganisms contained in the cement-containing molded body decompose isotope-labeled nutrients into an environment containing an acidic or basic substance; and estimating the amount of isotope-labeled nutrients decomposed by microorganisms by measuring the amount of isotopes contained in the metabolites. Therefore, the method for measuring microbial activity in a cement-containing molded body according to this embodiment can specifically and accurately estimate the activity level of microorganisms contained in the cement-containing molded body. Furthermore, by estimating the activity level of microorganisms contained in the cement-containing molded body, the repair state of the self-healing concrete can be estimated as described below. The repair of concrete by microorganisms is thought to occur through the following mechanism: When cracks appear in a cement-containing molded body, oxygen and water penetrate into the molded body, activating the microorganisms contained within. The carbon dioxide generated by the metabolism of these microorganisms reacts with calcium in the molded body to precipitate calcium carbonate, which fills the cracks in the molded body. Therefore, if we can estimate the activity level of microorganisms, we can estimate how much calcium carbonate has been generated, that is, how much concrete repair has occurred. [Examples]

[0045] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0046] [Example 1] A concrete composition containing polylactic acid was prepared as a nutrient source for microorganisms (bacteria). This concrete composition is shown in Table 1. As shown in Table 1, the concrete composition is 20 kg / m³ 3 It contains polylactic acid. Since the carbon content of polylactic acid is 40%, this concrete composition contains 8 kg / m³ 3 It contains carbon. Of the polylactic acid contained in this concrete composition, 0.1%13 It was substituted with 14C-labeled polylactic acid. The total concentration in the concrete composition was 80 g / m². 3 of 13 Includes C. The above concrete composition was molded to obtain a cement-containing molded body. A portion of the above cement-containing molded body is removed, and the cement-containing molded body is cut to 1000 cm 3 It was collected. The above-mentioned cement-containing molded body was placed in 30% hydrochloric acid by mass to dissolve the calcium carbonate contained in the cement-containing molded body and release carbon dioxide. The released carbon dioxide was subjected to mass analysis using a gas chromatograph-mass spectrometer (product name: GCMS-QP2020NX, manufactured by Shimadzu Corporation), and the results were as follows: 13 40 mg of 14C-labeled carbon dioxide was detected. As a result, it was found that 50% of the added nutrient source (polylactic acid) was decomposed by bacteria into carbon dioxide, which then exists in the concrete as calcium carbonate. This method allows us to determine how much polylactic acid contained in the cement-containing molded body has been consumed, and to estimate the level of microbial activity. For example, in the 1000 cm² area that was excavated in this case... 3 Since 40g of carbon dioxide was generated by microbial metabolism within the material, it means that 90g of calcium carbonate was generated in the cement-containing molded body by microbial metabolism. This means that within the area removed in this study, 1000cm³ of carbon dioxide was generated. 3 It can be estimated that self-repair equivalent to 90g of calcium carbonate occurred per unit.

[0047] [Table 1]

[0048] [Example 2] A concrete composition containing urea as a nutrient source for microorganisms (bacteria) was prepared. This concrete composition is shown in Table 2. As shown in Table 2, the concrete composition is 20 kg / m³ 3It contains urea. Since the carbon content of urea is 20%, this concrete composition contains 4 kg / m³ 3 It contains carbon. Of the polylactic acid contained in this concrete composition, 0.1% 13 It was replaced with 14C-labeled urea. The total concentration in the concrete composition was 4 g / m². 3 of 13 Includes C. The above concrete composition was molded to obtain a cement-containing molded body. A portion of the above cement-containing molded body is removed, and the cement-containing molded body is cut to 1000 cm 3 It was collected. The above-mentioned cement-containing molded body was placed in 30% hydrochloric acid by mass to dissolve the calcium carbonate contained in the cement-containing molded body and release carbon dioxide. The released carbon dioxide was subjected to mass analysis using the gas chromatograph-mass spectrometer described above, and the results showed that 13 One milligram of carbon dioxide labeled with 14C was detected. As a result, it was found that 25% of the added nutrient (urea) was broken down by bacteria into carbon dioxide, which then exists in the concrete as calcium carbonate. This method allows us to determine how much urea contained in the cement-containing molded body has been consumed and to estimate the activity level of microorganisms. For example, in the 1000 cm² area that was excavated in this case... 3 Since 1g of carbon dioxide was produced by microbial metabolism within the material, it means that 2.3g of calcium carbonate was produced in the cement-containing molded body by microbial metabolism. This means that within the area removed in this study, 1000cm³ of material was produced. 3 It can be estimated that self-repair equivalent to 2.3g of calcium carbonate occurred per unit.

[0049] [Table 2]

Claims

1. A method for measuring the activity of microorganisms in a cement-containing molded body obtained by molding a concrete composition containing a cement-containing composition, microorganisms, and a nutrient source, At least a portion of the aforementioned nutrient source is an isotope-labeled nutrient source, The process involves exposing a portion of a cement-containing molded body to an environment containing an acidic or basic substance, thereby extracting metabolites generated when microorganisms contained in the cement-containing molded body decompose the isotope-labeled nutrient source into an environment containing an acidic or basic substance, The steps include: measuring the amount of isotopes contained in the metabolites to estimate the activity level based on the amount of isotope-labeled nutrients decomposed by the microorganisms; A method for measuring microbial activity in a cement-containing molded body.

2. The isotope-labeled nutrient source is １３ C-labeled nutrients, １５ N-labeled nutrients and １７ A method for measuring microbial activity in a cement-containing molded body according to claim 1, wherein the microbial activity is at least one selected from the group consisting of O-labeled nutrients.

3. A method for measuring microbial activity in a cement-containing molded body according to claim 1 or 2, comprising measuring the amount of isotopes contained in the metabolites by mass spectrometry of the metabolites.

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