Patent Application
20220340864
The present invention relates to a production method for a composition for cell culturing, to a composition for cell culturing obtained by it and to a cell culturing method using it.
Mammalian cells are used in a diverse range of research and industrial fields including medicine, pharmacy, science and technology, agriculture and veterinary medicine. Such research has helped to elucidate the causes of diseases and has led to methods for their treatment. Biomedicines and vaccines produced from cells are used for treatment and prevention of a large host of diseases. Cultured cells have also contributed in a major way to development in basic academic fields such as cell biology, biochemistry, genetics, physiology and molecular biology. More recently, cultured muscle cells have been used as cell sources for “cultured meat”. The protein production efficiency for “cultured meat” is much higher than by production via conventional livestock breeding, and based on data from published reports, since meat production has traditionally depended on livestock breeding, switching to cultured meat production systems can result in reduction of up to 99% for utilization of land, 96% for water consumption, 96% for greenhouse gas emissions and 45% for energy consumption. It is believed, therefore, that food production systems allowing continuous meat production using cultured cells will become more widely popular in the future. Using cultured mammalian cells as a food source will require very large amounts of cells.
Since culture media are essential for culturing of mammalian cells, mass quantities of culture media are used for cell research. Such culture media contain various types of nutrients which consist mainly of glucose and amino acids. The nutrients are generally derived from cereals or heterotrophic microorganisms, the latter also requiring nutrients derived from cereals. Chemical fertilizers and agricultural chemicals are necessary in large amounts for cereal cultivation, which in turn requires massive amounts of energy and can lead to generation of more greenhouse gases (GHG) and cause environmental pollution. Cereal production is in turn significantly influenced by environmental effects such as global warming and environmental pollution.
At the current time, over 150,000 species of algae have been registered in AlgaeBase (http://www.algaebase.org/), with the number continuing to be updated on a daily basis. Numerous different algae traits exist because of the huge variety of their species, ranging from species that are able to grow in environments of either purified water or seawater, or both, to basophilic and alkaliphilic species. A wide variety of uses are currently under development to take advantage of those traits. Such development includes drainage treatment utilizing the nitrogen assimilation properties of microalgae, and fixation of carbon dioxide gas generated by combustion of fossil fuels (NPLs 1 to 3).
Microalgae synthesize nutrients such as carbohydrates (saccharides) and lipids from carbon dioxide by photosynthesis, and produce amino acids using nitrogen gas/ammonia/nitrates. Microalgae also produce various nutrients by utilizing solar energy and inorganic materials. The nutrients produced by microalgae are currently being actively utilized in the fields of energy and food industry. For example, lipids extracted from microalgae are considered promising as an alternative energy source to petroleum (NPL 4). Glucose extracted from microalgae is also utilized as a nutrient for bioethanol-producing yeast (NPLs 5 to 6). Nutrients containing amino acids produced by microalgae are also used in nutritional supplements, pet foods and soil fertilizers (NPLs 7 to 10). It is generally thought that microalgae are the photosynthetic organisms that synthesize nutrients most efficiently without residue (NPL 11).
Culturing of cells in vitro often requires fetal calf, cow neonatal, horse, chicken or rabbit serum in addition to synthetic medium containing amino acids, vitamins and minerals. Serum contains factors necessary for cell growth, such as growth factors, which are often essential for growth of the cells. However, because serum is unstable and may differ in quality depending on the lot, while also being problematically expensive, there is a need to find alternative substances. In light of these problems, PTLs 1 and 2 describe microalgal extract that can partially substitute for the function of serum in cell culturing. However, these publications nowhere mention that cells can be cultured by mixing of an microalgal extract with synthetic media (such as inorganic salt medium) that lack components such as amino acids (especially glutamine) and vitamins that are essential for cell culturing.
[NPL 1] L. Wang, M. Min, Y. Li, P. Chen, Y. Chen, et al., Cultivation of green algae Chlorella sp. in different wastewaters from municipal wastewater treatment plant. Appl. Biochem. Biotechnol. 162 (2010) 1174-1186.
It is an object of the present invention to establish a novel cell culturing system that lowers the risk of environmental load or environmental change.
The present inventors have conducted research and development based on examination of the aforementioned problem from many angles, in order to solve the problems described above. As a result it was found, surprisingly, that cells can be cultured in medium (for example, medium free of amino acids and/or vitamins) comprising added nutrients extracted from microalgae. Specifically, the invention encompasses the following.
[1] A composition for cell culturing comprising algae-derived components, wherein the components are obtained by the following steps:
(1) subjecting algae to treatment by acid hydrolysis and/or alkali hydrolysis; and
(2) neutralizing the hydrolysate obtained by step (1).
[2] The composition according to [1] above, wherein the cells are animal cells.
[3] The composition according to [1] or [2], wherein the algae are unicellular algae.
[4] The composition according to any one of [1] to [3] above, wherein the algae are at least one type selected from the group consisting of unicellular green algae, unicellular blue-green algae, unicellular red algae, unicellular charales and unicellular ulvophytes.
[5] The composition according to any one of [1] to [4] above, wherein the algae are at least one type selected from the group consisting of Chlorococcum littorale, Stichococcus sp., Chlorella vulgaris Beijerinck, Euglena gracilis, Spirulina subsalsa and Arthrospira platensis.
[6] The composition according to any one of [1] to [5] above, wherein step (1) is carried out under pressure.
[7] The composition according to any one of [1] to [6] above, wherein step (1) is carried out at 60° C. to 200° C.
[8] A method of culturing cells in medium containing an added composition for cell culturing comprising algae-derived components, wherein the components are obtained by the following steps:
(1) subjecting algae to treatment by acid hydrolysis and/or alkali hydrolysis, and
(2) neutralizing the hydrolysate obtained by step (1).
[9] The method according to [8] above, wherein the cells are animal cells.
[10] The method according to [8] or [9] above, wherein the algae are unicellular algae.
[11] The method according to any one of [8] to [10] above, wherein the algae are at least one type selected from the group consisting of unicellular green algae, unicellular blue-green algae, unicellular red algae, unicellular charales and unicellular ulvophytes.
[12] The composition according to any one of [8] to [11] above, wherein the algae are at least one type selected from the group consisting of Chlorococcum littorale, Stichococcus sp., Chlorella vulgaris Beijerinck, Euglena gracilis, Spirulina subsalsa and Arthrospira platensis.
[13] The method according to any one of [8] to [12] above, wherein step (1) is carried out under pressure.
[14] The method according to any one of [8] to [13] above, wherein step (1) is carried out at 60° C. to 200° C.
[15] A production method for a composition for cell culturing, wherein the method comprises the following steps:
(1) subjecting algae to acid hydrolysis and/or alkali hydrolysis;
(2) neutralizing the hydrolysate obtained from step (1) to obtain an algal extract; and
(3) mixing the algal extract with cell culturing medium, wherein the cell culturing medium contains substantially no L-glutamine.
[16] The method according to [15] above, wherein the cell culturing medium is also substantially free of one or more amino acids selected from the group consisting of L-arginine, L-cysteine, glycine, L-histidine, L-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-serine, L-threonine, L-tryptophan, L-tyrosine and L-valine.
[17] The method according to [15] or [16] above wherein the cell culturing medium contains substantially no vitamins.
[18] The method according to any one of [15] to [17] above, wherein the cell culturing medium contains substantially no glucose.
[19] The method according to any one of [15] to [18] above, wherein the cell culturing medium is an inorganic salt medium.
[20] The method according to any one of [15] to [19] above, wherein the cultured cells are animal cells.
[21] The method according to any one of [15] to [20] above, wherein the algae are unicellular algae.
[22] The method according to any one of [15] to [21] above, wherein the algae are at least one type selected from the group consisting of unicellular green algae, unicellular blue-green algae, unicellular red algae, unicellular charales and unicellular ulvophytes.
[23] The composition according to any one of [15] to [22] above, wherein the algae are at least one type selected from the group consisting of Chlorococcum littorale, Stichococcus sp., Chlorella vulgaris Beijerinck, Euglena gracilis, Spirulina subsalsa and Arthrospira platensis.
[24]
The method according to any one of [15] to [23] above, wherein step (1) is carried out under pressure.
[25] The method according to any one of [15] to [24] above, wherein step (1) is carried out at 60° C. to 200° C.
[26] A composition for cell culturing which is obtained by the method according to any one of [15] to [25] above.
[27] A cell culturing method using a composition for cell culturing which is obtained by the method according to any one of [15] to [25] above.
According to the method of the invention, nutrients necessary for cell culturing can be easily and economically extracted from microalgae, and it is thereby possible to provide a novel cell culturing system that reduces environmental load.
Embodiments of the invention will now be explained with reference to the accompanying drawings as necessary. The embodiments serve merely for example and the construction of the invention is not limited by the concrete constructions of the embodiments.
According to one embodiment, the invention provides a composition for cell culturing comprising an alga-derived component. The alga-derived component in the composition of the invention is obtained by the following steps:
(1) subjecting algae to treatment by acid hydrolysis and/or alkali hydrolysis, and
(2) neutralizing the hydrolysate obtained by step (1).
According to another embodiment, the invention provides a production method for a composition for cell culturing, wherein the method comprises the following steps:
(1) subjecting algae to acid hydrolysis and/or alkali hydrolysis;
(2) neutralizing the hydrolysate obtained from step (1) to obtain an algal extract; and
(3) mixing the algal extract with cell culturing medium, wherein the cell culturing medium contains substantially no L-glutamine.
According to yet another embodiment, the cell culturing medium to be used for the invention may be cell culturing medium that is also substantially free of one or more amino acids selected from the group consisting of L-arginine, L-cysteine, glycine, L-histidine, L-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-serine, L-threonine, L-tryptophan, L-tyrosine and L-valine.
According to yet another embodiment, the cell culturing medium to be used for the invention may be cell culturing medium that contains substantially no vitamins. Cell culturing medium that contains substantially no vitamins to be used for the invention may be medium that is substantially free of one or more vitamins selected from the group consisting of pantothenic acid, choline chloride, folic acid, i-inositol, niacinamide, pyridoxine, riboflavin, thiamine, and pharmaceutically acceptable salts of the same.
According to yet another embodiment, the cell culturing medium to be used for the invention may be cell culturing medium that contains substantially no glucose, or it may be cell culturing medium that also contains substantially no pyruvic acid.
As used herein, “contain(s) substantially no (or substantially free of)” means containing substantially none of the substance in question, but it does not mean containing absolutely none of the substance, and for example, glucose may be present at less than 10 mg/L as the minimum limit of determination, amino acids (such as L-glutamine) may be present at less than 0.1 mg/L as the minimum limit of determination, or vitamins may be present at less than 1 μg/L as the minimum limit of determination.
Also as used herein, “algae” is a general term referring to organisms that produce oxygen by photosynthesis, with the exclusion of primarily land-inhabiting bryophytes, pteridophytes and spermatophytes. If given an environment necessary for photosynthesis, algae can produce oxygen and nutrients (such as glucose and amino acids) by themselves and proliferate. The present invention has been completed based on the finding that cells can be cultured in medium containing an added composition that comprises components extracted from algae.
The algae used for one embodiment of the invention may be “unicellular algae” (also known as “microalgae”). As used herein, “unicellular algae” refers to algae with individuals consisting of single cells, and it includes unicellular algae in which multiple unicellular algae cluster together to form groups. Examples are unicellular green algae in which chlorophyll a and b are the major pigments of the chloroplasts, unicellular blue-green algae (cyanobacteria) in which chlorophyll d is the major pigment, and unicellular red algae in which chlorophyll a and phycobilin proteins are the major pigments. More specific examples include the green algae Chlamydomonas reinhardtii of the class Chlorophyceae, order Chlamydomonadales, Dunaliella salina of the order Dunaliellales, Volvox carteri of the order Volvocales, Chlorococcum littorale of the order Chlorococcales, Hydrodictyon reticulatum, Pediastrum duplex and Scenedesmus dimorphus of the order Sphaeropleales, Chlorella vulgaris Beijerinck (chlorella) of the class Trebouxiophyceae, order Chlorellales, Euglena gracilis and Euglena proxima of the phylum Euglenozoa, class Euglenophyceae, order Euglena. Unicellular blue-green algae include Acaryochloris marina, Spirulina subsalsa and Arthrospira platensis of the phylum Cyanobacteria. Unicellular red algae include Cyanidium caldarium of the phylum Rhodophyta, class Cyanidiophyceae, order Cyanidiales, and Galdieria partita of the phylum Rhodophyta, class Cyanidiophyceae, order Cyanidiales. Unicellular charales include Stichococcus sp. of the phylum Chlorophyta, class Chlorophyceae, order Klebsormidiales. Unicellular ulvophyte algae include filamentous ulvophytes. The algae used for the invention may also be gene recombinant forms produced by genetic engineering of the aforementioned algae, and are not limited to the algae mentioned above.
The algae used for the invention may be natural algae or algae grown by publicly known culturing methods.
The algae-derived components in the composition used for the invention can be extracted by subjecting algae to acid hydrolysis and/or alkali hydrolysis treatment.
Biopolymers such as proteins and polysaccharides usually hydrolyze by mixing with strong organic or inorganic acids (such as hydrochloric acid, sulfuric acid, trifluoroacetic acid, p-toluenesulfonic acid or methanesulfonic acid), or strong alkalis (such as sodium hydroxide or potassium hydroxide) with addition of water, while heating (at 60° C. to 200° C., preferably 80° C. to 180° C. and more preferably 90° C. to 150° C., for example), producing oligomers or monomers (peptides and amino acids in the case of proteins, or oligosaccharides and monosaccharides in the case of polysaccharides). Therefore, the term “acid hydrolysis” as used herein refers to hydrolysis using a strong acid, and the term “alkali hydrolysis” refers to hydrolysis with a strong alkali. Publicly known “acid hydrolysis” and/or “alkali hydrolysis” may be used to obtain the composition of the invention. The reaction time for “acid hydrolysis” or “alkali hydrolysis” may be adjusted depending on the conditions such as the type, amount and concentration of algae or the pH and temperature of the reaction mixture, and it may be 1 to 1440 minutes, 3 to 720 minutes, 5 to 360 minutes, 5 to 120 minutes or 5 to 30 minutes, for example.
According to one embodiment, acid hydrolysis alone or alkali hydrolysis alone may be carried out to obtain a composition comprising algae-derived components, or both acid hydrolysis and alkali hydrolysis may be carried out. When both acid hydrolysis and alkali hydrolysis are carried out, the alkali hydrolysis may be carried out after acid hydrolysis or the acid hydrolysis may be carried out after alkali hydrolysis. Neutralizing treatment may also be carried out between the acid hydrolysis and alkali hydrolysis.
According to one embodiment, the algae used in step (1) may be subjected for drying treatment before acid hydrolysis and/or alkali hydrolysis.
According to another embodiment, step (1) may be carried out under pressure. The term “under pressure” as used herein may be air pressure conditions higher than atmospheric pressure, i.e., 1 atmosphere, such as 1.1 atmosphere or higher, 1.5 atmosphere or higher, 1.8 atmosphere or higher or 2 atmosphere or higher. For example, it may be 1.1 to 300 atmospheres, 1.5 to 200 atmospheres, 1.8 to 100 atmospheres, 2 to 50 atmospheres or 2 to 20 atmospheres. The pressure conditions may be conditions created using any apparatus or method, such as pressurized conditions produced with an autoclave.
The composition of the invention can be obtained by neutralizing the hydrolysate obtained from step (1) (neutralization step (2)). This allows the hydrolysate to be neutralized and used for culturing of cells. When acid hydrolysis has been carried out at the end of step (1), for example, a basic substance or its aqueous solution (sodium hydroxide, potassium hydroxide or an aqueous solution of the same) may be added for neutralization. When alkali hydrolysis has been carried out at the end of step (1), an acidic substance (such as sodium hydroxide or potassium hydroxide) or its aqueous solution (such as hydrochloric acid, sulfuric acid, trifluoroacetic acid, p-toluenesulfonic acid or methanesulfonic acid) may be added for neutralization.
The composition of the invention can be used for culturing of cells, such as prokaryotic cells (such as E. coli, lactic acid bacteria, Bacillus subtilis or cyanobacteria) or eukaryotic cells (such as yeast cells, plant cells, insect cells or animal cells), and especially animal cells. According to one embodiment, the source of animal cells to be cultured according to the invention may be a mammal, bird, amphibian, reptile or fish, and the source of mammalian animal cells may be a mouse, rat, rabbit, human, horse, cow, monkey, pig, dog, sheep, cat or goat, though with no limitation to these. The cells may be primary cells harvested from biological tissue, or from an established cell line, or pluripotent stem cells (such as ES cells, ntES cells, Muse cells or iPS cells), or tissue stem cells (such as mesenchymal stem cells), or cells obtained by inducing differentiation from such cells.
The composition used for the invention may comprise one or more algae-derived components, such as two or more algae-derived components, for example. For example, the composition may comprise a combination of a glucose-rich algae-derived component and an proteinogenic amino acid-rich algae-derived component.
The invention provides a method of culturing cells in medium containing an added composition for cell culturing comprising algae-derived components, wherein the components are obtained by the following steps:
(1) subjecting algae to treatment by acid hydrolysis and/or alkali hydrolysis, and
(2) neutralizing the hydrolysate obtained by step (1).
According to another embodiment, the method of culturing cells of the invention may also include (3) mixing the algal extract with cell culturing medium, wherein the cell culturing medium contains substantially no L-glutamine.
In the method of culturing cells of the invention, the medium to which the composition comprising the algae-derived component is added may be selected as appropriate for the type of cells to be cultured, but preferably the medium has buffering action, and it may be phosphate buffer solution, Eagle medium, Dulbecco's Modified Eagle Medium (DMEM), DMEM:F12 medium, Glasgow Minimum Essential Medium, Grace's Insect Medium, Ham's Medium, Iscove's Modified Eagle Medium, RPMI-1640 medium, L-15 medium or McCoy's 5A Medium, for example, which may also contains substantially no glucose and/or proteinogenic amino acids (one or more amino acids selected from the group consisting of such as L-glutamine, L-arginine, L-cysteine, glycine, L-histidine, L-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-serine, L-threonine, L-tryptophan, L-tyrosine and L-valine). The culture medium may be liquid medium or solid medium. Addition of a composition comprising algae-derived components according to the invention to medium allows nutrients necessary for cell survival (such as glucose, proteinogenic amino acids and vitamins) to be supplied for cell culturing. The proportion in which the composition comprising algae-derived components is added to the medium may be adjusted as appropriate for the type of cells to be cultured, and the composition comprising the algae-derived components may be present at 0.1 to 99% (v/v), 1 to 80% (v/v), 2 to 50% (v/v), 3 to 20% (v/v), or 3 to 15% or 3 to 12% (v/v), for example, with respect to the total volume of the medium to which the composition comprising the algae-derived components is added.
The present invention will now be explained in greater detail by examples, with the understanding that the invention is not limited in any way by the examples.
For this experiment there were used four eukaryotic microalgae, the green algae Chlorococcum littorale (C. littorale) (NBRC 102761), Stichococcus sp. (NBRC 102709), (National Institute of Technology and Evaluation (NITE), independent chemical corporation, Chiba Prefecture, Japan), Chlorella vulgaris Beijerinck (C. vulgaris) (NIES-2170) and Euglena gracilis (E. gracilis) (NIES-49), and two prokaryotic microalgae, Spirulina subsalsa (S. subsalsa) (NIES-3373) and Arthrospira platensis (A. platensis) (NIES-39) (National Institute for Environmental Studies, Ibaraki Prefecture, Japan) (
1-2. Nutrient Extraction from Microalgae
Hydrolysis was used to extract the nutrients from the microalgae. The microalgae cultured in the flask were collected in a screw bottle (As One Corp., Osaka Prefecture, Japan) regardless of the culturing period, and dried in an oven (Tietech Co., Ltd., Saitama Prefecture, Japan). After drying, the dry weight was measured and purified water was added for adjustment to the optimal concentration (10 g/L or 50 g/L). Acid/alkali hydrolysis reaction was then conducted. Heating was carried out using an autoclave (Tomy Seiko Co., Ltd., Tokyo, Japan), a heat block (Labnet International Inc., New Jersey, U.S.) or a dry air sterilizer (Advantech, Inc., Tokyo, Japan). The heating conditions were as follows: Temperature: 20 to 180° C.; heating time: 10 to 1440 min; sulfuric acid concentration: 0.0036 to 1.8 N; hydrochloric acid and sodium hydroxide concentration: 0.36 to 1 N. The experiment was conducted with different combinations of temperature, time and reagent concentration. After heat treatment, the mixture was neutralized with hydrochloric acid or sodium hydroxide. The glucose and amino acid concentrations were measured by quantitative analysis using the hexokinase method [Reference 2] and the liquid chromatography-mass spectrometry method.
C2C12 mouse myoblasts (Sumitomo-Dainippon Pharmaceutical Co., Ltd., Tokyo, Japan) were cultured with Dulbecco's Modified Eagle Medium (DMEM) (Sigma-Aldrich, Missouri, U.S.) supplemented with 10% fetal bovine serum (FBS, Thermo-Fischer Scientific, Massachusetts, U.S.) and 1% penicillin-streptomycin (P/S, Invitrogen, Carlsbad, Calif., U.S.), at 37° C. under a moist atmosphere containing 5% CO2 [Reference 3]. The cell proliferation and survival rates were evaluated by XTT assay (Biological Industries, Connecticut, U.S.). The C2C12 cells were inoculated into a 96-well plate (AGC Techno Glass Co., Ltd., Shizuoka Prefecture, Japan) at a density of 10,000 cells/well, and cultured overnight in DMEM supplemented with 10% FBS and 1% P/S. After overnight culturing, the medium was discarded and washing was performed twice with phosphate buffered saline (PBS, Sigma-Aldrich). Nutrient-deficient medium containing or not containing algal extract or glucose/glutamic acid was then used for culturing of the cells. The solution-added cells were then incubated for 2 days. In order to eliminate the difference in absorbance by the pigment in each solution, each solution was used with addition of 100 μL of 10% FBS and 1% P/S and 50 μL of XTT reagent, just before starting the XTT assay. The subsequent cell viability assay was carried out according to protocol. Glucose-free DMEM (Invitrogen), glucose/glutamine-free DMEM (Invitrogen) and glucose/amino acid-free DMEM (United States Biological, Massachusetts, U.S.) were used as nutrient-deficient media. Glucose (Kanto Kagaku Co., Ltd., Tokyo, Japan) or glutamic acid (FujiFilm-Wako Pure Chemical Industries) were added to each medium as necessary.
The media used in Examples 1 and 2 had the following compositions unless otherwise specified.
Algal extract was used to demonstrate its suitability as a substitute for sugars (glucose pyruvic acid).
Algal extract was used to demonstrate its suitability as a substitute for sugars (glucose pyruvic acid) and amino acids (L-arginine, L-cysteine, L-glutamine, glycine, L-histidine, L-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-serine, L-threonine, L-tryptophan, L-tyrosine, L-valine).
Algal extract was used to demonstrate its suitability as a substitute for sugars (glucose pyruvic acid), amino acids (L-arginine, L-cysteine, L-glutamine, glycine, L-histidine, L-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-serine, L-threonine, L-tryptophan, L-tyrosine, L-valine) and vitamins (pantothenic acid, choline chloride, folic acid, i-inositol, niacinamide, pyridoxine, riboflavin and thiamine).
All of the data in the drawings are represented as mean±SD. Unpaired Student t-test was carried out for comparison of two groups, while one-way ANOVA with post-hoc Tukey's HSD test was used for comparison of multiple groups.
2-1. Glucose Extraction from Microalgae.
Initially, it was attempted to extract glucose, as an important nutrient for mammalian cell medium. In a preliminary experiment, glucose extraction efficiency by acid hydrolysis using sulfuric acid was highest with Chlorococcum (C. littorale) among the six microalgae shown in
It was then examined which microalgae from among the six microalgae C. littorale, Stichococcus sp., S. subsalsa, C. vulgaris, E. gracilis and A. platensis had the highest glucose yield (
In order to obtain a microalgal extract with a high glucose concentration, the initial algae concentration was increased from 10 g/L to 50 g/L. The concentration of glucose extracted from C. littorale was 2.4±0.3 g/L with 10 g/L, and 13.1±1.5 g/L with 50 g/L. The concentration of glucose extracted from A. platensis was 1.9±0.3 g/L with 10 g/L, and 10.8±0.6 g/L with 50 g/L (
2-2. Amino Acid Extraction from Microalgae.
DMEM contains 15 of the 20 different proteinogenic amino acids. The 15 amino acids are the amino acids arginine to valine, shown at left in
It was then examined which among the 6 microalgae had the maximum amino acid yield (
In order to obtain a microalgal extract with a higher amino acid concentration, the initial algae concentration was increased from 10 g/L to 50 g/L. Similar to extraction of glucose, the concentration of each amino acid was likewise further increased by increasing the algae concentration (
No glutamine was extracted by acid hydrolysis, but glutamine was abundantly present in the DMEM (
Most of the C2C12 mouse myoblasts had died after 2 days of culturing with glucose- and glutamine-free medium (
2-3. Cell Culturing with Microalgal Extract
It was next examined whether or not algal extract can be utilized as a nutrient in mammalian cell culturing. Most of the C2C12 mouse myoblasts had died after 2 days of culturing with glucose-free medium (
Finally, it was examined whether or not algal extract can be utilized as a surrogate for amino acids. Glucose- and amino acid-free medium was used for this experiment. Most of the cells died after culturing for 2 days using this medium (
Cells were cultured using combinations of glucose-rich C. littorale and amino acid-rich C. vulgaris and glucose-rich A. platensis and amino acid-rich C. vulgaris extracts (
The results verified that nutrients extracted from microalgae can be utilized as surrogates for glucose and amino acids for mammalian cells.
The results described above are only for analysis of glucose and amino acids. Lipids are not included in DMEM. Eight different vitamin B molecules are present in DMEM, but at much lower concentrations than glucose and amino acids. Experimentation by the present inventors has shown that the 8 different vitamin B molecules can also be extracted from microalgae. Therefore, it is believed that all of the nutrients and vitamins necessary for mammalian cell culturing can be provided from microalgae.
Algal extracts were shown to function as a surrogates for nutrients during mammalian cell culturing. Since the use of cereals for production of biofuels is in competition with food, it is a promising alternative to use microalgae which are not in competition with food [Reference 7]. The present research has demonstrated the possibility not only of novel cell culturing systems which can reduce effects on the environment and protect against environmental change, but also of the alternative of using microalgae instead of cereal-dependent culture systems.
Liquid extract was prepared from Chlorella vulgaris Beijerinck by the method of Example 1, 1-2. The medium used was DMEM or inorganic salt medium, and the effect of Chlorella algal extract on culturing of cow muscle tissue cells was investigated. The experiment was carried out by the method described in Example 1, 1-3. The cow muscle tissue cells were cow cheek muscle cells purchased from Tokyo Meat Market Co., Ltd. and treated with protease, and the cells were isolated for use.
The results demonstrated that addition of algal extract to inorganic salt medium allowed maintenance culturing of cow muscle tissue cells similar to DMEM (
Liquid extract was prepared from Chlorella vulgaris Beijerinck by the method of Example 1, 1-2. The medium used was DMEM or inorganic salt medium, and the effect of the presence or absence of Chlorella algal extract and the presence or absence of fetal bovine serum (FBS) on culturing of cow muscle tissue cells was investigated. The experiment was carried out by the method described in Example 1, 1-3.
As a result, a tendency toward increased relative viable cell count of cow muscle tissue cells was found with addition of algal extract to inorganic salt medium, and with further addition of serum (
Liquid extract was prepared from Chlorella vulgaris Beijerinck by the method of Example 1, 1-2. The medium used was DMEM or inorganic salt medium, and the effect of the presence or absence of Chlorella algal extract and the presence or absence of fetal bovine serum (FBS) on culturing of cow muscle tissue cells, especially during the cell growth stage, was investigated. The experiment was carried out by the method described in Example 1, 1-3.
As a result, growth of cow muscle tissue cells was found with addition of algal extract to inorganic salt medium, and with further addition of serum, on the same level as with 10% FBS DMEM (
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-181336 | Oct 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/037471 | 10/1/2020 | WO |
