This application claims the benefit of Korean Patent Application No. 10-2016-0163892, filed on Dec. 2, 2016, in the Korean Intellectual Property Office, the entire disclosure of which is hereby incorporated by reference.
Incorporated by reference in its entirety herein is a computer-readable nucleotide/amino acid sequence listing submitted concurrently herewith and identified as follows: One 3,650 Byte ASCII (Text) file named “728994_ST25.TXT,” created on Dec. 4, 2017.
The present disclosure relates to an exhaust gas decomposition apparatus and an exhaust gas decomposition system including the same. In addition, the present disclosure relates to a strain KCTC 13107BP of Pseudomonas saitens (hereinafter, also referred to as “SF1 strain”), which is capable of reducing a concentration of hydrofluorocarbon or fluorocarbon in a sample, and a method of reducing a concentration of hydrofluorocarbon or fluorocarbon in a sample by using the strain.
Greenhouse gases, such as fluorinated gases, exhausted from industrial processes including semiconductor processes, cause global warming or other environmental problems, and thus a remedial process, for example, a decomposition treatment, is required. Often, exhaust gas is treated by a high-temperature or catalytic chemical decomposition method. For example, a method of decomposing exhaust gas at a high temperature of at least 1,400° C., or a catalytic thermal oxidation method of decomposing exhaust gas by oxidization of exhaust gas by using a metallic catalyst, e.g., Ce/Al2O3, is often used. Such a chemical decomposition method requires large-capacity facilities and involves mass energy consumption.
Therefore, there is a need for new environmentally friendly and economical decomposition methods for decomposing exhaust gas.
In this regard, there has been a demand for a microorganism capable of reducing a concentration of fluorinated methane in a sample.
Provided is an exhaust gas decomposition apparatus for improving a decomposition rate of a fluorine-containing compound.
Provided is an exhaust gas decomposition system including the exhaust gas decomposition apparatus.
Provided is a microorganism of the genus Pseudomonas, the microorganism being capable of reducing a concentration of fluorinated methane in a sample.
Provided is a method of removing fluorinated methane in a sample by using the microorganism of the genus Pseudomonas that is capable of reducing a concentration of fluorinated methane in a sample.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.
According to an aspect of an embodiment, there is provided an exhaust gas decomposition apparatus and system including:
one or more reactors, each including one or more first inlets and one or more first outlets,
wherein a fluorine-containing compound is decomposed by contact between first fluid and second fluid in each of the one or more reactors,
the first fluid is supplied through the one or more first inlets and is exhausted through the one or more outlets, and flows in a first direction in each of the one or more reactors, and
one of the first fluid and the second fluid includes a biological catalyst, and the other includes a fluorine-containing compound.
According to an aspect of another embodiment, there is provided an exhaust gas decomposition apparatus and system including:
the exhaust gas decomposition apparatus;
a first supplier for supplying the first fluid into the exhaust gas decomposition apparatus;
a second supplier for supplying the second fluid into the exhaust gas decomposition apparatus; and
a collecting device for collecting a decomposition product discharged from the exhaust gas decomposition apparatus.
According to an aspect of another embodiment, there is provided a KCTC 13107BP strain of Pseudomonas saitens, the strain being capable of reducing a concentration of tetrafluoromethane (CF4) in a sample.
According to an aspect of another embodiment, there is provided a method of reducing a concentration of fluorinated methane in a sample, the method including:
reducing a concentration of fluorinated methane in a sample by contact between the KCTC 13107BP strain of Pseudomonas saitens and the sample, the sample including fluorinated methane represented by CHnF4-n (where n is an integer of 0 to 3).
These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which:
Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.
The term “increase in activity” or “increased activity”, as used herein, refers to a detectable increase in an activity of 2-haloacid dehalogenase (HAD) in a cell. For instance, an “increase in activity” or “increased activity” may refer to an activity level of HAD in a modified (for example, genetically engineered) cell that is higher than that of a comparative cell of the same type that does not have a given genetic modification (e.g., original or “wild-type” cell). Activity of HAD in a modified or engineered cell may be increased by any amount, such as by about 5% or more, about 10% or more, about 15% or more, about 20% or more, about 30% or more, about 50% or more, about 60% or more, about 70% or more, or about 100% or more than an activity of a cell of the same type without a given genetic modification, e.g., activity of HAD in a non-engineered or “wild-type” cell. A cell having an increased activity of HAD may be identified by using any method known in the art.
An increase in an activity of HAD in a cell may be achieved by an increase in expression or specific activity. The increase in expression may be caused by introduction of an exogenous polynucleotide encoding the HAD enzyme into a cell, by otherwise increasing of the copy number of a gene encoding a HAD enzyme, or by modification of a regulatory region of the polynucleotide encoding the HAD enzyme so as to increase expression levels. A microorganism into which the polynucleotide encoding the enzyme is introduced may be a microorganism that may or may not already include the polynucleotide (e.g., gene). The polynucleotide encoding the enzyme may be operably linked to a regulatory sequence that enables expression thereof, for example, a promoter, a polyadenylation site, ribosomal binding site, start and stop codons, or a combination thereof. The exogenous polynucleotide may be homologous (i.e., native to the microorganism into which it is introduced) or heterologous (i.e., not natively present in the organism).
The term “increase of the copy number”, as used herein, refers to a case in which the copy number is increased by introduction of another copy of an existing gene, amplification of an endogenous gene, or introduction of a gene that does not normally exist in the non-engineered cell. The introduction of the gene may be mediated by a vehicle, such as a vector. The introduction may be a transient introduction in which the gene is not integrated into a genome (e.g. via an unstable episome), or introduction that results in stable integration of the gene into the genome (e.g. episomal or chromosomal). The introduction may be performed by, for example, introducing a vector into the cell, the vector including a polynucleotide encoding a target polypeptide, and then, replicating the vector in the cell, or by integrating the polynucleotide into the genome.
The introduction of the gene may be performed by a known method, for example, transformation, transfection, or electroporation. The gene may be introduced via a vehicle or as it is. The term “vehicle” (or, alternatively “vector”), as used herein, refers to a nucleic acid molecule that is able to deliver other nucleic acids linked thereto into a cell. As a nucleic acid sequence mediating introduction of a specific gene, the vehicle used herein may be a nucleic acid construct, such as a vector or a cassette, a plasmid vector, a virus-derived vector, such as a replication-defective retrovirus, adenovirus, adeno-associated virus, or a combination thereof.
The term “parent cell” refers to an original cell, for example, a non-genetically engineered cell of the same type as an engineered microorganism. With respect to a particular genetic modification, the “parent cell” may be a cell that lacks the particular genetic modification, but is identical in all other respects. Thus, the parent cell may be a cell that is used as a starting material to produce a genetically engineered microorganism having an increased activity of a given protein (e.g., a protein having an amino acid sequence identity of about 90% or higher with respect to 2-haloacid dehalogenase (HAD)). The same comparison is also applied to other genetic modifications.
The term “gene”, as used herein, refers to a nucleic acid fragment encoding a particular protein, and may or may not include a regulatory sequence, e.g., a-non coding sequence 5′ and/or a 3′ of the coding sequence.
The term “sequence identity” of a polynucleotide or a polypeptide, as used herein, refers to a degree of identity between bases or amino acid residues of sequences obtained after the sequences are aligned so as to best match in certain comparable regions. The sequence identity is a value that is measured by comparing two sequences in certain comparable regions via optimal alignment of the two sequences, in which portions of the sequences in the certain comparable regions may be added or deleted compared to reference sequences. A percentage of sequence identity may be calculated by, for example, comparing two optimally aligned sequences in the entire comparable regions, determining the number of locations in which the same amino acids or nucleic acids appear so that the number of matching locations may be obtained, dividing the number of matching locations by the total number of locations in the comparable regions (that is, the size of a range), and multiplying a result of the division by 100 to obtain the percentage of the sequence identity. The percentage of the sequence identity may be determined using a known sequence alignment or comparison program, for example, BLASTN (NCBI), BLASTP (NCBI), CLC Main Workbench (CLC bio), MegAlign™ (DNASTAR Inc), etc.
Various levels of sequence identity may be used to identify various types of polypeptides or polynucleotides having the same or similar functions or activities. For example, the sequence identity may include a sequence identity of about 50% or more, about 55% or more, about 60% or more, about 65% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 96% or more, about 97% or more, about 98% or more, about 99% or more, or 100%.
The term “genetic modification”, as used herein, refers to an artificial alteration in a constitution or structure of the genetic material of a cell.
Hereinafter, embodiments of an exhaust gas decomposition apparatus, an exhaust gas decomposition system including the same, and methods of using the apparatus or system will be described in detail.
The term “exhaust gas” used herein refers to all kinds of gases including a fluorine-containing compound exhausted from fixed or mobile machinery, equipment, or the like. The exhaust gas may be a mixture containing liquid or solid particles in addition to pure gas.
According to an embodiment, an exhaust gas decomposition system may include: one or more bioreactors, each of which includes one or more first inlets (inlets for introduction of a first fluid) and one or more first outlets (outlets for expelling a first fluid). Each bioreactor can further comprise one or more second inlets (inlets for introduction of a second fluid) and one or more second outlets (outlets for expelling a second fluid) Thus, each bioreactor of the apparatus or system can include a plurality of inlets (e.g., at least 1, 2, 3, 4, or more inlets) and a plurality of outlets (e.g., at least 1, 2, 3, 4, or more outlets. In each of the one or more bioreactors, a fluorine-containing compound may be decomposed by contact between a first fluid and a second fluid, wherein the first fluid may be supplied through the one or more first inlets (e.g. from a supply via a line) and exhausted through the one or more first outlets, and may flow in a first direction, and the second fluid may be supplied through the one or more second inlets (e.g. from a supply via a line) and exhausted through the one or more second outlets, and may flow in a second direction generally opposite the first direction. One of the first fluid and the second fluid may include a biological catalyst that catalyzes decomposition of the fluorine-containing compound, and the other may include a fluorine-containing compound. The bioreactor can provide a bed on which a thin film of the first fluid is formed and it flows in a first direction. For example, the bed can be an inner wall of the reactor.
Since the fluorine-containing compound is decomposed by using a biological catalyst in the exhaust gas decomposition system, the fluorine-containing compound may be decomposed in an environmentally friendly manner without involvement of a high temperature and heat, and without using excessive energy. In addition, due to continuous and repeated flowing of at least one of the first fluid and the second fluid in each of the one or more reactors in the exhaust gas decomposition system by circulation or the like, the contact time between the first fluid and the second fluid may be increased, and accordingly, a decomposition rate of the fluorine-containing compound may be improved.
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Each of the one or more reactors 10 in the exhaust gas decomposition apparatus or system 100 may further include a second circulation line 23 for re-supplying at least a portion of the second fluid 40 discharged from the second outlet 22 back to the second inlet 21. The fluid in the second circulation line 23 may impelled by, for example, a second circulation pump 24, but embodiments are not limited thereto. Any device capable of circulating fluid in the art, such as a fan, may be used. Due to the circulation of the first fluid 30 through each of the one or more reactors 10 and along the first circulation line 13 and the second fluid 40 through each of the one or more reactors 10 and along the second circulation line 23, contact time between the first fluid 30 and the second fluid 40 may be increased, and accordingly, the decomposition rate of the fluorine-containing compound may be improved.
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The volume occupied by the construct 70 within the entire volume of the reactor 10 is not particularly limited, but for example, the construct 70 may account for about 1% to about 99%, about 5% to about 95%, about 10% to about 90%, about 20% to about 80%, or about 30% to about 70% of the entire volume of the reactor 10. When the area of contact between the first fluid 30 and the second fluid 40 increases by disposing the structure 70 within the reactor 10, the decomposition rate of the fluorine-containing compound may be improved.
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In the exhaust gas decomposition apparatus or system 100 of
In the exhaust gas decomposition apparatus or system 100 of
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For example, the biological catalyst may include a microorganism belonging to the genus Pseudomonas. For example, a microorganism included in the biological catalyst may be a strain of P. saitens.
In addition, the biological catalyst may include a genetic modification that increases an activity level of 2-haloacid dehalogenase (HAD). The HAD may be of/classified-as EC 3.8.1.2. For example, the 2-HAD may be derived from strains selected from the group consisting of Bacillus cereus, B. thuringiensis, B. megaterium, and Pseudomonas saitens, but embodiments are not limited thereto. Any suitable strain available in the art may be used as the strain including the 2-HAD. For example, the recombinant microorganism may belong to the genus Escherichia, the genus Bacillus, or the genus Pseudomonas, but embodiments are not limited thereto. Any strain in the art suitable for use as the recombinant microorganism may be used.
Referring to
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C(R1)(R2)(R3)(R4) <Formula 1>
(R5)(R6)(R7)C—[C(R11)(R12)]n—C(R8)(R9)(R10) <Formula 2>
S(R13)(R14)(R15)(R16)(R17)(R18). <Formula 3>
In Formulae 1 to 3, n is an integer of 0 to 10,
R1, R2, R3, and R4 may each independently be fluorine (F), chlorine (CI), bromine (Br), iodine (I), or hydrogen (H), wherein at least one selected from R1, R2, R3, and R4 is F,
R5, R6, R7, R8, R9, R10, R11, and R12 may each independently be F, Cl, Br, I, or H, wherein at least one selected from R5, R6, R7, R8, R9, R10, R11, and R12 is F, and
R13, R14, R15, R16, R17, and R18 may each independently be F, Cl, Br, I, or H, wherein at least one selected from R13, R14, R15, R16, R17, and R18 is F.
Referring to
C(R21)(R22)(R23)(R24) <Formula 4>
(R25)(R26)(R27)C—[C(R31)(R32)]m—C(R28)(R29)(R30) <Formula 5>
S(R33)(R34)(R35)(R36)(R37)(R38). <Formula 6>
In Formulae 4 to 6,
m is an integer of 0 to 5,
R21, R22, R23, and R24 may each independently be F or H, wherein at least one selected from R21, R22, R23, and R24 is F,
R25, R26, R27, R28, R29, R30, R31, and R32 may each independently be F or H, wherein at least one selected from R25, R26, R27, R28, R29, R30, R31, and R32 is F, and
R33, R34, R35, R36, R37, and R38 may each independently be F or H, wherein at least one selected from R33, R34, R35, R36, R37, and R38 is F.
For example, in the exhaust gas decomposition apparatus or system 100, the fluorine-containing compound may include at least one selected from CH3F, CH2F2, CHF3, CF4, and SF6.
According to another aspect of an embodiment, there is provided an exhaust gas decomposition system including the exhaust gas decomposition apparatus or system as hereinbefore described, and further including a first supplier or supply for supplying first fluid into the exhaust gas decomposition apparatus or system, a second supplier or supply for supplying second fluid into the exhaust gas decomposition apparatus or system; and a collector for collecting a decomposition product discharged from the exhaust gas decomposition apparatus or system. The exhaust gas decomposition system may further include other devices, thereby further improving the decomposition rate of exhaust gas. The supplier is a system or unit that supplies the first fluid into the exhaust gas decomposition system. The supplier may be, for instance, a large tank containing the exhaust gas, or a vent line of an industrial plant. The collector is a system or unit that collects some or all of the decomposition product that is discharged from exhaust gas decomposition system. The collector may be, for instance, a condenser or water bath. The exhaust gas decomposition system comprising such other elements is sometimes referred to as an exhaust gas decomposition complex.
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According to another aspect of an embodiment, there is provided strain KCTC 13107BP of Pseudomonas saitens, the strain being capable of reducing a concentration of fluorinated methane in a sample.
The strain may include a genetic modification that increases an activity level of the 2-HAD. The 2-HAD catalyzes a chemical reaction of 2-haloacid+H2O⇔2-hydroxy acid+halide. That is, two substrates of the 2-HAD are 2-haloacid and H2O, and two products of the 2-HAD are 2-hydroxy acid and halide. The 2-HAD may belong to a family of hydrolases that act on a halide bond in a carbon-halide compound. However, reduction of the concentration of fluorinated methane or other fluorinated compound in a sample by the microorganism should not necessarily be interpreted as being limited to such a specific mechanism. The genetic modification may include increasing a number of copies of a gene encoding the 2-HAD. The gene encoding the 2-HAD may be an exogenous gene, and may be derived from the genus Bacillus, the genus Pseudomonas, the genus Azotobacter, the genus Agrobacterium, and the genus Escherichia. The gene encoding the 2-HAD may be derived from strains of B. cereus, B. thuringiensis, B. megaterium, or Pseudomonas saitens KCTC 13107BP. The 2-HAD may be an enzyme classified as EC 3.8.1.2.
The genetic modification may include increasing the number of copies of a gene encoding a polypeptide having a sequence identity of about 95% or higher with an amino acid sequence of SEQ ID NO: 1. The gene may have a sequence identity of about 95% or higher with a nucleotide sequence of SEQ ID NO: 2. The genetic modification may include introducing the gene encoding the 2-HAD, for example, via a vehicle such as a vector. The gene encoding the 2-HAD may exist within or outside the chromosome. A plurality of HAD genes or gene copies may be introduced, for example, 2 or more, 5 or more, 10 or more, 50 or more, 100 or more, or 1,000 or more.
The microorganism may reduce a concentration of fluorinated methane. The reduction may be performed by introducing a hydroxyl group into carbon by using a protein acting on C—F bonds or C—H bonds of fluorinated methane, or may be performed by accumulating fluorinated methane in cells of the microorganism. In addition, the reduction may include cleavage of C—F bonds of fluorinated methane, conversion of fluorinated methane into a different material, or accumulation of fluorinated methane in cells of the microorganism. The sample used herein may be liquid or gaseous. The sample may be factory waste water or waste gas. Any sample including fluorinated methane may be used in the art. Fluorinated methane may include CF4, CHF3, CH2F2, CH3F, or a mixture thereof.
According to another aspect of an embodiment, there is provided a composition for reducing a concentration of fluorinated methane represented by CHnF4-n (wherein n is an integer of 0 to 3), the composition including a strain KCTC 13107BP of Pseudomonas saitens.
Regarding the composition, the recombinant microorganism, the sample, and the fluorinated methane are the same defined in the description above.
Regarding the composition, the term “reducing” refers to reduction of a concentration of fluorinated methane in a sample, including complete removal of fluorinated methane in a sample. Here, the sample may be liquid or gaseous. The sample may or may not include the microorganism. The composition may further include a material that increases solubility of fluorinated methane in a medium or a culture product.
According to another aspect of an embodiment, there is provided a method of reducing a concentration of fluorinated methane in a sample, the method including: contacting a strain KCTC 13107BP of Pseudomonas saitens with a sample including fluorinated methane represented by CHnF4-n (wherein n is an integer of 0 to 3).
Regarding the method, the microorganism and the sample including fluorinated methane represented by CHnF4-n (wherein n is an integer of 0 to 3) are the same as defined in the description above.
Regarding the method, the contacting of the strain with the sample may be performed in a liquid phase environment or a solid phase environment. The contacting of the strain with the sample may be performed by, for example, contacting the sample with a culture product of a microorganism cultured on a medium. The culture may be performed under conditions in which a microorganism may grow. The contacting of the strain with the sample may be performed in a sealed container. The contacting of the strain with the sample may be performed when the growth stage of the microorganism is at an exponential phase or a stationary phase. The culture may be performed under aerobic or anaerobic conditions. The contacting of the strain with the sample may be performed under conditions in which a recombinant microorganism may survive in a sealed container. Such viable conditions may include a condition allowing proliferation of a recombinant microorganism or a condition allowing a recombinant microorganism to exist in a resting state. The contacting of the strain with the sample can be as described in reference to the various embodiments of apparatus and system described above in connection with
Regarding the method, the sample may be liquid or gaseous. The sample may be factory waste water or waste gas. The sample may not only passively contact the culture product of the microorganism, but may also actively contact the culture product of the microorganism. The sample may be, for example, subjected to a sparging process using a culture medium of the microorganism. That is, the sample may be blown through a medium or a culture medium. The sparging process may include blowing gas from the bottom of the medium or the culture medium to the top. The sparging process may include injecting of the sample while preparing droplets of the sample.
Regarding the method, the contacting of the strain with the sample may be performed in a batchwise or continuous manner. The contacting of the strain with the sample may include repeatedly or continuously contacting a sample with new, fresh microorganism. Thus, for instance, a sample having been contacted with the microorganism and having had the fluorine-containing compound in the sample reduced can be again contacted with a second, fresh microorganism and the fluorine-containing compound in the sample further reduced. The second microorganism can be of the same or different type as the first. Thus, for instance, the second microorganism can comprise a genetic modification that increases the activity level of the 2-HAD. Such contacting of the sample with the fresh microorganism may occur twice or more, for example, 2, 3, 5, or 10 times or more. The contacting of the sample with the fresh microorganism may be continuous or repeated for a period of time until a desired reduced concentration of fluorinated methane in the sample is achieved.
Regarding the method, the strain may further include a genetic modification that increases an activity level of the 2-HAD. Regarding the method, the genetic modification may include increasing the number of copies of a gene encoding the 2-HAD. Regarding the method, the gene encoding the 2-HAD may be an exogenous gene, and may be derived from the genus Bacillus, the genus Pseudomonas, the genus Azotobacter, the genus Agrobacterium, and the genus Escherichia. The gene encoding the 2-HAD may be derived from strains of B. cereus, B. thuringiensis, B. megaterium, or Pseudomonas saitens KCTC 13107BP. The 2-HAD may be classified as EC 3.8.1.2.
A method of reducing a concentration of fluorinated methane in a fluid is provided, wherein the method comprises, in the system or apparatus described herein, contacting a first fluid comprising a biological catalyst having 2-haloacid dehalogenase activity with a second fluid comprising fluorinated methane represented by CHnF4-n, wherein n is an integer of 0 to 3, to reduce the concentration of fluorinated methane in the second fluid. In the method, the biological catalyst may be a 2-haloacid dehalogenase enzyme or microorganism comprising a 2-haloacid dehalogenase enzyme. In the method, the microorganism may be Pseudomonas. In the method, the microorganism may be Pseudomonas saitens. In the method, the strain of Pseudomonas may be a strain of KCTC 13107BP strain of Pseudomonas saitens.
Hereinafter, the present inventive concept will be described in more detail with reference to Examples. However, these Examples are provided for illustrative purposes only, and the invention is not intended to be limited by these Examples.
In the present Example, microorganisms capable of reducing a concentration of CF4 in semiconductor factory waste water were selected.
Sludge in the waste water discharged from a Samsung Electronics factory (at Giheung, Korea) was applied to an agar plate containing a medium containing no carbon (supplemented with 0.7 g/L of K2HPO4, 0.7 g/L of MgSO4.7H2O, 0.5 g/L of (NH4)2SO4, 0.5 g/L of NaNO3, 0.005 g/L of NaCl, 0.002 g/L of FeSO4.7H2O, 0.002 g/L of ZnSO4.7H2O, 0.001 g/L of MnSO4, and 15 g/L of agar). The agar plate was placed in a GasPak™ Jar (BD Medical Technology), and the jar was filled with 99.9 v/v % CF4 and sealed. The cells were then cultured at a temperature of 30° C. under anaerobic conditions. Single colonies formed after culture were cultured using a high throughput screening (HTS) system (Thermo Scientific/Liconic/Perkin Elmer), and then, each of the single colonies was inoculated on a 97-well microplate containing 100 μL/well of an LB medium. The colonies were then subjected to stationary culture at a temperature of 30° C. for 72 hours under aerobic conditions. Here, the absorbance of the colonies was measured at 600 nm every 12 hours so that the growth ability of the colonies could be observed. The LB medium used herein contains 10 g/L of tryptone, 5 g/L of yeast extract, and 10 g/L of NaCl.
The top 2% of strains showing excellent growth ability were selected, and each strain was inoculated into a 75 mL glass serum bottle containing 10 mL of an LB medium to have OD600 of 0.5. Then, the glass serum bottle was sealed, and CF4 was injected thereinto with a syringe so that 1,000 ppm of CF4 gas was in the glass serum bottle. The glass serum bottle was incubated in a shaking incubator at a temperature of 30° C. for 4 days while being stirred at a speed of 230 rpm, and then the amount of CF4 in the headspace thereof was analyzed.
For analysis, 0.5 ml of CF4 was collected from the headspace using a syringe, and injected into a gas chromatography (GC) column (Agilent 7890, Palo Alto, Calif., USA). The injected CF4 was separated through a CP-PoraBOND Q column (25 m length, 0.32 mm i.d., 5 um film thickness, Agilent), and changes in the CF4 concentration were analyzed by MSD (Agilent 5973, Palo Alto, Calif., USA). As a carrier gas, helium was used, and applied to the column at a flow rate of 1.5 ml/min. GC conditions were as follows: an inlet temperature was 250° C., and an initial temperature was maintained at 40° C. for 2 minutes and then raised to 290° C. at a rate of 20° C./min. MS conditions were as follows: ionization energy was 70 eV, an interface temperature was 280° C., an ion source temperature was 230° C., and a quadrupole temperature was 150° C. Unless otherwise mentioned, analysis of gas such as CHF3, CHCl3, and CF4 was performed by using the above method. As a control group, 1000 ppm of CF4 was incubated without cells under the same conditions as described above, and then measured.
As a result, it was confirmed that the CF4 concentration was reduced by 10.4% in the selected microorganism relative to the control group having no cells. The selected microorganism had decomposition activity of 0.005 umol/g-cell/min. To identify the selected strain, a 16s rRNA gene (SEQ ID NO: 3) was amplified using the genome of the separated cell as a template. Here, the nucleotide sequences of the 16s rRNA gene were analyzed by BLAST Assembled Genomes.
A final size of assembled genomes was 5.1 Mb, and a GC content thereof was 59.14%. As a result of automated annotation using the Prokaryotic Genome Annotation Pipeline, a total of 328 genes, 25 rRNA operons, 73 tRNAs, and 1 tmRNA were found to be present. As a result of analyzing a phylogenetic tree, it was confirmed that the separated microorganism belongs to genus Pseudomonas.
The selected microorganism was newly designated as a strain of Pseudomonas saitens (hereinafter, referred to as “SF1”), and was deposited with and accepted by the Korea Collection for Type Culture (KCTC) on Sep. 12, 2016, under the Access number of KCTC13107BP.
1. Amplification of an HAD gene derived from Bacillus cereus (hereinafter, referred to as BC HAD), and introduction of the gene to Escherichia coli (E. coli). B. cereus (KCTC 3624) was cultured overnight in an LB medium at a temperature of 30° C. while being stirred at 230 rpm, and then, the genomic DNA was isolated therefrom using a total DNA extraction kit (Invitrogen Biotechnology). Then, PCR was performed using the isolated genomic DNA as a template and a set of primers having nucleotide sequences listed in Table 1, to amplify and obtain a BC3334 gene. A pET-BC HAD vector was prepared by using an InFusion Cloning Kit (Clontech Laboratories, Inc.), wherein the BC HAD gene which was amplified by PCR was ligated with pETDuet-1 (Novagen, Cat. No. 71146-3) which had been digested with restriction enzymes NcoI and HindIII.
Next, pET-BC3334, which is the pET-BC HAD vector, was introduced into an E. coli BL21 strain by a heat shock method, and then the microorganism was cultured on an LB plate containing ampicillin (100 μg/mL). A strain showing ampicillin resistance was selected. The finally selected strain was then designated as a recombinant E. coli BL21/pET-BC3334.
As shown in
Next, the strain of Pseudomonas saitens selected according to Preparation Example 1 was inoculated with a syringe into the LB medium in the straight glass tube cooler. The initial concentration of the inoculated strain in the LB medium was 0.5 at OD of 600 nm. Then, the LB medium to which the strain was inoculated was circulated. The circulation rate of the LB culture medium was 4 mL/min, and the temperature inside the straight glass tube cooler was maintained at 30°. After 66 hours, the amount of CF4 gas in the straight glass tube cooler was confirmed by GC-MS. Here, the decomposition rate of CF4 was calculated according to Equation 1, and results thereof are shown in Table 2.
Decomposition rate of CF4=[(initial amount of CF4−amount of CF4 after 66 hours)/initial amount of CF4]×100 <Equation 1>
In the same manner as in Example 1, except that a vertical glass Dimroth screwed reflux condenser (length of reactor: 350 mm, diameter of outer tube: 35 mm, and volume of inner tube: 200 mL) shown in
After 66 hours, the amount of CF4 gas in the vertical glass Dimroth screwed reflux condenser was confirmed by GC-MS. Here, the decomposition rate of CF4 was calculated according to Equation 1, and results thereof are shown in Table 2.
In the same manner as in Example 1, except that, as shown in
After 66 hours, the amount of CF4 gas in the straight glass tube cooler filled with fillers was confirmed by GC-MS. Here, the decomposition rate of CF4 was calculated according to Equation 1, and results thereof are shown in Table 2.
10 mL of the LB medium to which the strain of Example 1 was inoculated and 1,000 ppm of CF4 gas were added to a 75 ml glass serum bottle. After maintaining the glass serum bottle for 96 hours in a shaking incubator at a speed of 230 rpm and at a temperature of 30° C., the amount of CF4 gas in the glass serum bottle was confirmed by GC-MS. Here, the decomposition rate of CF4 was calculated according to Equation 1, and results thereof are shown in Table 2. The initial concentration of the inoculated strain in the LB medium was 0.5 at OD of 600 nm.
As shown in Table 2, it was confirmed that the decomposition rate of CF4 was significantly improved in the fluorinated gas decomposition devices of Examples 1 to 3 in which the strain-inoculated LB medium was circulated, relative to the fluorinated gas decomposition device of Comparative Example 1 in which the strain-inoculated LB medium was simply stirred. Such improved decomposition rates of CF4 may result from an increased time and/or area of contact of the CF4 gas with the strain-inoculated LB medium, as the strain-inoculated LB medium existed in the form of a thin film on the inner wall of the cooler, on the surface of the screw tube, or on the surface of the porous filler.
As shown in
Next, the strain of E. coli in which 2-HAD BC3334 gene was introduced in Preparation Example 2 was inoculated with a syringe into the LB medium in the straight glass tube cooler. The initial concentration of the inoculated strain in the LB medium was 0.5 OD at 600 nm. Then, the LB medium to which the strain was inoculated was circulated. The circulation rate of the LB culture medium was 4 mL/min, and the temperature inside the straight glass tube cooler was maintained at 30°. After 66 hours, the amount of CF4 gas in the straight glass tube cooler was confirmed by GC-MS. Here, the decomposition rate of CF4 was calculated according to Equation 1, and results thereof are shown in Table 3.
In the same manner as in Example 1, except that a vertical glass Dimroth screwed reflux condenser (length of reactor: 350 mm, diameter of outer tube: 35 mm, and volume of inner tube: 200 mL) shown in
After 66 hours, the amount of CF4 gas in the vertical glass Dimroth screwed reflux condenser was confirmed by GC-MS. Here, the decomposition rate of CF4 was calculated according to Equation 1, and results thereof are shown in Table 3.
In the same manner as in Example 1, except that, as shown in
After 66 hours, the amount of CF4 gas in the straight glass tube cooler filled with fillers was confirmed by GC-MS. Here, the decomposition rate of CF4 was calculated according to Equation 1, and results thereof are shown in Table 3.
10 mL of the LB medium to which the strain of Example 1 was inoculated and 1,000 ppm of CF4 gas were added to a 75 ml glass serum bottle. After maintaining the glass serum bottle for 96 hours in a shaking incubator at a speed of 230 rpm and at a temperature of 30° C., the amount of CF4 gas in the glass serum bottle was confirmed by GC-MS. Here, the decomposition rate of CF4 was calculated according to Equation 1, and results thereof are shown in Table 1. The initial concentration of the inoculated strain in the LB medium was 0.5 at OD of 600 nm.
As shown in Table 3, it was confirmed that the decomposition rate of CF4 was significantly improved in a shorter time in the fluorinated gas decomposition devices of Examples 4 to 6 in which the strain-inoculated LB medium was circulated, relative to the fluorinated gas decomposition device of Comparative Example 2 in which the strain-inoculated LB medium was simply stirred. Such improved decomposition rates of CF4 may result from an increased time and/or area of contact of the CF4 gas with the strain-inoculated LB medium, as the strain-inoculated LB medium existed in the form of a medium thin film on the inner wall of the cooler, on the surface of the screw tube, or on the surface of the porous filler.
As described above, the circulation of at least one of a biological catalyst and a fluorine-containing compound in an exhaust gas decomposition apparatus or system may lead to improvement of a decomposition rate of the fluorine-containing compound.
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
Number | Date | Country | Kind |
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10-2016-0163892 | Dec 2016 | KR | national |