JP2020202813A - Culture medium for yeast culture - Google Patents

Abstract

To provide a culture medium that can increase viable cell counts per unit capacity.SOLUTION: A culture medium for yeast culture contains carbon source, nitrogen source and magnesium source, the nitrogen source containing glutamic acid and glycine.SELECTED DRAWING: None

Description

The present invention relates to a medium for yeast culture.

Yeast is used in the production of fermented foods, alcohols, organic acids and the like. Further, yeast having a fat and oil resolution is used for decomposing fats and oils in wastewater in a grease trap or the like.

Wastewater from food factories contains a large amount of fats and oils, and abatement facilities are set up to treat these fats and oils. Wastewater standards are set for treated water discharged from abatement facilities by the Sewerage Law or the Water Pollution Control Law.

If the concentration of oil and fat in the wastewater is high, the treated water does not meet the wastewater standards, the chemicals used for treatment such as pressure flotation, the cost of disposing of the generated oil balls and scum, etc. Various problems such as blockage of water and generation of foul odor occur.

Therefore, in order to efficiently reduce fats and oils in abatement facilities, a method of utilizing microorganisms having high fats and oils resolution is being studied. For example, Patent Document 1 discloses yeast having an excellent effect of reducing fats and oils in a grease trap.

JP 2015-192611

In yeast culture, a nutrient-rich medium such as YM medium or LB medium is usually used. According to the study of the present inventor, it has been found that when yeast is cultured in YM medium, LB medium or the like, there is a problem that the amount of collected bacteria per unit volume of the medium is not sufficient. Therefore, a technique for further improving the culture efficiency, that is, increasing the number of viable cells per unit volume of the medium is desired.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a medium capable of increasing the number of viable cells per unit volume.

The present inventor has conducted diligent research in order to solve the above problems. As a result, they have found that a yeast culture medium containing a carbon source, a nitrogen source and a magnesium source, wherein the nitrogen source contains glutamic acid and glycine, solves the above-mentioned problems. It was completed.

According to the present invention, there is provided a medium capable of increasing the viable cell count per unit volume.

Hereinafter, embodiments according to one embodiment of the present invention will be described. The present invention is not limited to the following embodiments.

In the present specification, "X to Y" indicating a range means "X or more and Y or less". Unless otherwise specified, the operation and physical properties are measured under the conditions of room temperature (20 to 25 ° C.) / relative humidity of 40 to 50% RH.

<Medium for yeast culture>
According to one embodiment of the present invention, there is provided a yeast culture medium containing a carbon source, a nitrogen source and a magnesium source, wherein the nitrogen source contains glutamic acid and glycine. With such a configuration, the yeast culture efficiency can be improved and the viable cell count per unit volume of the medium can be increased (that is, the maximum viable cell count per unit volume of the medium can be increased).

(Carbon source)
The yeast culture medium according to the present invention contains a carbon source.

The carbon source is not particularly limited, and is, for example, glucose, fructose, cellobiose, raffinose, xylose, maltose, galactose, sorbose, glucosamine, ribose, arabinose, ramnorth, sucrose, trehalose, α-methyl-D-glucoside, salicin, melibiose. , Lactose, meregitose, inulin, erythritol, glucitol, mannitol, galactitol, N-acetyl-D-glucosamine, starch, starch hydrolysate, sugar such as sugar, waste sugar, natural products such as wheat and rice, glycerol, methanol , Alcohols such as ethanol, hydrocarbons such as hexadecane and the like. These carbon sources are appropriately selected in consideration of the assimilation property of the yeast to be cultured. Moreover, one kind or two or more kinds of the said carbon sources can be selected and used.

When the genus Asteltremera is used as the yeast, the carbon source contains glucose from the viewpoint that the culture efficiency can be further improved.

(Nitrogen source)
The yeast culture medium according to the present invention contains a nitrogen source. The nitrogen source contains glutamic acid and glycine as essential components.

Since the yeast culture medium according to the present invention contains glutamic acid and glycine, glutamic acid and glycine are preferentially incorporated into yeast, and glutamic acid and glycine are not suppressed by the nitrogen source catabolite unlike branched amino acids. Therefore, it is considered that the yeast culture efficiency can be further improved.

The total amount of glutamic acid and glycine blended is preferably 0.01 to 5.0 parts by mass, and more preferably 0, with respect to 1 part by mass of the carbon source, from the viewpoint that the yeast culture efficiency can be further improved. .1 to 2.5 parts by mass.

Further, the blending amount of glutamic acid is preferably 0.01 to 5.0 parts by mass, more preferably when the blending amount of glycine is 1 part by mass, from the viewpoint that the culture efficiency of yeast can be further improved. Is 0.1 to 2.5 parts by mass.

The yeast culture medium according to the present invention can further contain substances other than glutamic acid and glycine as a nitrogen source.

The nitrogen source other than glutamic acid and glycine may be an inorganic nitrogen source or an organic nitrogen source.

Examples of the inorganic nitrogen source include nitrates such as sodium nitrate and calcium nitrate; ammonium salts such as ammonium nitrate, ammonium sulfate and ammonium chloride; nitrites such as sodium nitrite; ammonia; urea and the like.

Organic nitrogen sources include yeast extract, wheat extract, meat extract, fish meat extract, peptone, polypeptone, malt extract, soybean hydrolyzate, soybean powder, casein, milk casein, casamino acid, aspartic acid and other amino acids, and corn steep. Examples include liquor and other animal, plant and microbial hydrolysates. These organic nitrogen sources are appropriately selected in consideration of the assimilation property of the yeast to be cultured.

One or more nitrogen sources other than the above-mentioned glutamic acid and glycine can be selected and used.

When the genus Asterotremera is used as the yeast, nitrogen sources other than glutamic acid and glycine are preferably organic nitrogen sources, and more preferably at least one of yeast extract and malt extract, from the viewpoint of improving culture efficiency. Included, more preferably yeast extract and malt extract.

When a nitrogen source other than glutamic acid and glycine is used, the blending amount of the nitrogen source (the total amount when two or more kinds are used) is, for example, 0.1 to 3.0 parts by mass with respect to 1 part by mass of the carbon source. It is preferably 0.3 to 1.0 parts by mass.

(Magnesium source)
The yeast culture medium according to the present invention contains a magnesium source.

It is considered that the yeast culture medium according to the present invention can further improve the yeast culture efficiency because it promotes the uptake of amino acids, that is, the uptake of glutamic acid and glycine by containing a magnesium source. Further, when yeast extract, malt extract or the like is used as the nitrogen source, it is considered that the yeast culture efficiency can be further improved by promoting the uptake of amino acids contained in these nitrogen sources.

The magnesium source is not particularly limited, but is preferably a magnesium salt. Magnesium salts include, for example, magnesium sulfate, magnesium nitrate, magnesium chloride, magnesium sulfite, magnesium thiosulfate, magnesium carbonate, magnesium primary phosphate, magnesium secondary phosphate, magnesium tertiary phosphate, magnesium pyrophosphate, magnesium nitrite, Examples thereof include magnesium acetate, magnesium citrate, magnesium oxalate and hydrates thereof. The magnesium salt is preferably magnesium sulfate or a hydrate thereof (for example, magnesium sulfate heptahydrate), and more preferably magnesium sulfate. One or two or more of the above magnesium sources can be selected and used.

The blending amount of the magnesium source (the total amount when two or more kinds are used) is, for example, 0.01 to 0.5 parts by mass, preferably 0.01 to 0.5 parts by mass, in terms of mass of the magnesium source compound with respect to 1 part by mass of the carbon source. 0.1 to 0.3 parts by mass.

(Form of yeast culture medium)
The form of the yeast culture medium according to the present invention is not particularly limited, and may be liquid, solid, or solid. In the present specification, the solid medium means a solidified liquid medium. Further, the solid medium means a granular medium, a powder medium, a granular medium, a pellet medium, or the like containing the components of the yeast culture medium according to the present invention. The yeast culture medium according to the present invention is preferably a liquid medium or a solid medium.

(Other ingredients)
The yeast culture medium according to the present invention may contain, if necessary, other components in addition to the carbon source, nitrogen source, magnesium source and solvent.

Examples of other components include solvents, minerals other than magnesium, pH adjusters, and the like.

Water is usually used as the solvent. Examples of water include pure water, distilled water, deionized water, RO water, and the like, but there is no particular limitation.

Examples of minerals other than magnesium include phosphorus, sulfur, potassium, calcium, iron, sodium, cobalt, copper, zinc, nickel and boron. These minerals are appropriately selected in consideration of the assimilation property of the yeast to be cultured. In addition, one or more of the above minerals can be selected and used.

Examples of the pH adjuster include acids such as sulfuric acid, hydrochloric acid, nitric acid, acetic acid and citric acid; and bases such as sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.

(PH)
The pH of the yeast culture medium according to the present invention is not particularly limited, but in general, yeast culture is preferably carried out under weakly acidic conditions, and is preferably 3.0 to 7.0, more preferably. Is 3.5 to 6.5. In particular, it is suitable for culturing the genus Asterotremera such as Asterotremella humicola, which is a yeast used in Examples described later. Here, the pH of the yeast culture medium can be measured using a pH meter.

(yeast)
The yeast cultivated in the yeast culture medium according to the present invention is not particularly limited, but is limited to the genus Asterotremella (current name: Vanrija), the genus Cryptococcus, the genus Trichosporon, and the genus Yarrowia (current name: Vanrija). Yeast, Candida, Pichia, Hansenura, Saccharomyces, Kluyveromyces, Lipomyces, Lipomyces, Lipomyces, Lipomyces, Lipomyces Yeasts such as the genus Schizosaccharomyces, the genus Lactobacillus, and the genus Enterococcus are preferably used. Of these, the genus Asterotremera, the genus Cryptococcus, the genus Trichosporon, the genus Saccharomyces, the genus Candida, the genus Pikia, the genus Hansenula, the genus Kruiberomyces, the genus Lipomyces, the genus Rhodtorula, the genus Sizosaccalomyces, the genus Lactobacillus Yeast such as is more preferably used.

In the yeast culture medium according to the present invention, among these yeasts, the culture efficiency of the genus Asterotremera, which has high oil decomposition activity, can be further improved. Yeasts of the genus Asterotremella include Asterotremella humicola, Asterotremella pseudolonga, Asterotremella longa, Asterotremella avitala, Asterotremella, and Asterotremella. Examples include Asterotremella muscii. The yeast of the genus Astero Tremera is preferably Astero Tremera Humicola, more preferably Astero Tremera Humicola 2-141-1 (accession number NITE BP-02641) (hereinafter, simply "2-1141-1 strain". Also called).

The yeasts mentioned above are available from cultural collections such as ATCC, NBRC, DSMZ and the like.

(Method of preparing medium for yeast culture)
The method for preparing the yeast culture medium according to the present invention is not particularly limited, and conventionally known methods can be used.

When the yeast culture medium according to the present invention is a solid medium, for example, a carbon source, a nitrogen source (essentially containing glutamic acid and glycine) and a magnesium source, and if necessary, a nitrogen source other than glutamic acid and glycine and It can be prepared by mixing minerals other than magnesium. After mixing, it may be crushed, dried or the like, if necessary.

When the yeast culture medium according to the present invention is a liquid medium, for example, a carbon source, a nitrogen source (essentially containing glutamic acid and glycine) and a magnesium source, and, if necessary, nitrogen other than glutamic acid and glycine. It can be prepared by dissolving the source and minerals other than magnesium in a solvent (eg, water). It can also be prepared by dissolving the solid medium in a solvent. When it is necessary to adjust the pH of the yeast culture medium, the above acid or alkali may be used as the pH adjusting agent. In addition, an antifoaming agent may be added if necessary.

When the yeast culture medium according to the present invention is a liquid medium, the blending amount of each component is as follows.

The blending amount of the carbon source (the total amount when two or more kinds are used) is, for example, 0.01 to 20.0 w / v%, preferably 0.1 to 10.0 w, based on the total amount of the yeast culture medium. / V%, more preferably 0.5 to 3.0 w / v%.

The total amount of glutamic acid and glycine to be blended is, for example, 0.01 to 5.0 w / v%, preferably 0.1 to 2.5 w / v%, based on the total amount of the yeast culture medium.

When a nitrogen source other than glutamic acid and glycine is used, the blending amount of the nitrogen source (the total amount when two or more kinds are used) is, for example, 0.1 to 3.0 w / v with respect to the total amount of the yeast culture medium. %, Preferably 0.3 to 1.0 w / v%.

The blending amount of the magnesium source (the total amount when two or more kinds are used) is, for example, 0.01 to 0.5 w / v% in terms of mass of the magnesium source compound with respect to the total amount of the yeast culture medium, which is preferable. Is 0.1 to 0.3 w / v%.

<Yeast culture method and growth method>
In one embodiment of the present invention, there is provided a method for culturing yeast, which comprises culturing yeast in the above-mentioned yeast culture medium. In this embodiment, the yeast culture medium is a liquid medium.

The yeast according to the present invention can be cultured by a usual method. Depending on the type of yeast, it is cultured under aerobic or anaerobic conditions. In the former case, yeast is cultured by shaking or aeration and stirring. Yeast may also be cultured continuously or in batches. The culturing conditions are appropriately selected, and are not particularly limited as long as the yeast according to the present invention can grow, and can be appropriately selected depending on the type of yeast to be cultivated. Further, the amount of bacterial cells added to the yeast culture medium is not particularly limited and can be appropriately adjusted.

The culture temperature is usually 15 to 50 ° C, preferably 25 to 40 ° C. For example, when a strain 2-141-1 is used as yeast, the culture temperature is usually 15 to 35 ° C, preferably 20 to 30 ° C.

When culturing yeast in the yeast culture medium of the present invention, various forms of yeast can be used. For example, yeast can be suspended in a culture medium, recovered as solids from the culture medium, dried, or immobilized on a carrier.

When yeast recovered as solid content from the culture solution is used, any means known to those skilled in the art can be adopted as the recovery method. For example, the yeast culture solution cultured by the above method can be obtained by solid-liquid separation by centrifugation, filtration, or the like, and the solid content can be recovered. If this solid content is dried (for example, freeze-dried), yeast in a dried state can be obtained.

When yeast in a state of being immobilized on a carrier is used, the carrier for immobilizing yeast is not particularly limited as long as it can immobilize yeast, and generally for immobilizing microorganisms. The carrier used is used in the same manner or modified as appropriate. For example, a method of comprehensively fixing to a gel-like substance such as alginic acid, polyvinyl alcohol, gellan gum, agarose, cellulose, dextran, or a method of adsorbing and fixing to the surface of glass, activated carbon, polystyrene, polyethylene, polypropylene, wood, silica gel, etc. is used. it can.

Further, the method for immobilizing yeast on the carrier is also not particularly limited, and a general method for immobilizing microorganisms is used in the same manner or appropriately modified. For example, the immobilization method by pouring the yeast culture solution into the carrier, the immobilization method by placing the carrier under reduced pressure using an aspirator and pouring the yeast culture solution into the carrier, and the medium in which the yeast culture solution is sterilized. Examples thereof include a method of pouring into a mixture of yeast and a carrier, culturing with shaking, and air-drying the carrier taken out from the mixture.

In the preferred form of the present invention, the yeast is used in the form of a live bacterial preparation from the viewpoint of the viability of the yeast during storage. As the yeast, the above-mentioned yeast can be used. When the above yeast is used, the viable bacterial preparation contains a yeast-containing layer formed on a porous carrier, and the yeast-containing layer is 0.8 parts by mass with respect to 1 part by mass of the yeast as a dry bacterial cell. It contains less than 1.5 parts by mass of trehalose, 0.01 to 5 parts by mass of milk protein, 0.03 to 10 parts by mass of amino acids, and 0.02 to 10 parts by mass of metal salt. When trehalose is contained in the yeast-containing layer in an amount of 0.8 parts by mass or more with respect to 1 part by mass of the yeast as a dried bacterial cell, the survival rate of the yeast at the time of formulation can be improved. Further, when it is contained in an amount of less than 1.5 parts by mass, it is possible to prevent a decrease in the survival rate of yeast during the storage period of the viable bacterial preparation. From the viewpoint of a more preferable balance between the survival rate during yeast formulation and the survival rate during the storage period, the trehalose content of the yeast-containing layer is preferable with respect to 1 part by mass of yeast in terms of dried cells. Is more than 0.9 parts by mass and less than 1.5 parts by mass, and more preferably 1 part by mass or more and 1.4 parts by mass or less.

Disaccharides other than trehalose, for example, disaccharides other than trehalose such as sucrose, lactose, and maltose may be used alone or in combination of two or more in combination with trehalose. In this case, the content of the disaccharide other than trehalose is, for example, 0.01 part by mass or more and less than 0.8 part by mass, preferably 0.1 part by mass, with respect to 1 part by mass of the non-spore-forming bacterium as a dried bacterial cell. Parts or more and 0.5 parts by mass or less.

The milk protein in the yeast-containing layer is not particularly limited, and conventionally known materials containing various milk proteins can be used. It is possible to use a raw material having a high milk fat content such as skim milk powder, but when producing a viable bacterial preparation for fat decomposition such as used in a grease trap, it is preferable that the oil content in the preparation is low, so for example. , Preferred specific examples include casein, casein sodium, whey, concentrated whey, whey protein concentrate (WPC), whey protein isolate (WPI), whey powder, skim milk, milk protein concentrate (MPC), skim milk powder, α. -Lactalbumin, β-lactoglobulin and the like can be exemplified, and these can be used alone or in combination of two or more. The milk protein is contained in the yeast-containing layer in an amount of 0.01 to 5 parts by mass, preferably 0.02 to 1 part by mass, more preferably 0.05 to 0, based on 1 part by mass of the yeast as dried cells. By containing 5.5 parts by mass, the survival rate of yeast at the time of formulation can be improved.

Amino acids in the yeast-containing layer include, for example, glycine, alanine, valine, leucine, isoleucine, phenylalanine, glutamine, glutamic acid, asparagine, aspartic acid, cysteine, lysine, serine, threonine, methionine, tryptophan, histidine, argin, proline, tyrosine, And these derivatives can be exemplified. Examples of the amino acid derivative include amino acid salts (for example, potassium salt and sodium salt), esters, hydrates, solvates and the like. The above amino acids may be used alone or in admixture of two or more. Amino acids are contained in the yeast-containing layer in an amount of 0.03 to 10 parts by mass, preferably 0.1 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, based on 1 part by mass of the yeast as dried cells. By including the part, the survival rate of yeast at the time of formulation can be improved. When two or more kinds of amino acids are contained in the oil decomposition layer, the above numerical values indicate the total amount of two or more kinds.

The metal salts in the yeast-containing layer include, for example, sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), nickel (Ni), zinc (Zn), Sulfates, sulfites, hyposulfates, persulfates, thiosulfates, carbonates, phosphates, pyrophosphates, hydrochlorides, nitrates, nitrites, acetates, propions of metal elements such as copper (Cu) Examples include, but are not limited to, acid salts, butyrates, citrates, oxalates, halides (eg, fluorides, chlorides, bromides, iodides). More specifically, the metal salt is, for example, sodium sulfate, sodium sulfite, sodium hyposulfate, sodium thiosulfate, sodium carbonate, sodium persulfate, monosodium phosphate, disodium phosphate, trisodium phosphate, sodium acetate. , Sodium nitrate, sodium nitrite, sodium acetate, sodium citrate, sodium oxalate, sodium chloride, potassium sulfate, potassium sulfite, potassium hyposulfate, potassium thiosulfate, potassium carbonate, potassium persulfate, monopotassium phosphate, phosphoric acid Dipotassium, tripotassium phosphate, potassium acetate, potassium nitrate, potassium nitrite, potassium acetate, potassium citrate, potassium oxalate, potassium chloride, magnesium sulfate, magnesium sulfite, magnesium thiosulfate, magnesium carbonate, primary magnesium phosphate, first Magnesium diphosphate, magnesium tertiary phosphate, magnesium pyrophosphate, magnesium nitrate, magnesium nitrite, magnesium acetate, magnesium citrate, magnesium oxalate, magnesium chloride, calcium sulfate, calcium sulfite, calcium thiosulfate, calcium carbonate, nitrate Examples thereof include calcium, calcium nitrite, potassium acetate, calcium citrate, calcium oxalate, and calcium chloride. The above metal salts may be used alone or in admixture of two or more. The metal salt is 0.02 to 10 parts by mass, preferably 0.05 to 1.5 parts by mass, more preferably 0.1 parts by mass, relative to 1 part by mass of the yeast as dried cells in the yeast-containing layer. By containing ~ 1 part by mass, it is possible to prevent a decrease in the survival rate of yeast during the storage period of the viable bacterial preparation. When the yeast-containing layer contains two or more kinds of metal salts, the above numerical values indicate the total amount of two or more kinds.

Sulfates, carbonates, phosphates, or combinations thereof, in which the metal salt is an element selected from the group consisting of Na, K, Mg and Ca, from the viewpoint of particularly excellent yeast viability during the storage period. Is preferable, and it is more preferable that it is a sulfate of Mg and / or Ca. The above-mentioned "metal salt" also includes hydrates and solvates of metal salts.

In addition to the above components, the yeast-containing layer may optionally contain monosaccharides such as glucose and fructose; disaccharides other than trehalose such as sucrose, lactose and maltose; cyclodextrin, hydroxypropyl cellulose, hydroxypropyl methyl cellulose and carboxy. Polysaccharides such as methyl cellulose, crystalline cellulose and corn starch; proteins such as soy protein; protein hydrolysates and peptides such as soy peptide, gelatin, peptone and tripton; fats and oils such as soybean oil, rapeseed oil, palm oil, sesame oil and olive oil; ascorbin Vitamins such as acids, salts thereof and tocopherols; surfactants such as polyglycerin fatty acid ester, sucrose fatty acid ester and sorbitan fatty acid ester; polyethylene glycol, glycerin and the like may be contained.

The material of the porous carrier that can be used in the viable bacterial preparation is not particularly limited, but is, for example, diatomaceous earth, pearlite, vermiculite, talc, clay, zeolite, bentonite, kaolin, calcium carbonate, activated clay, titanium dioxide. , Diatomaceous earth, pumice stone, activated carbon, carbon black, graphite, polylactic acid, polystyrene, polyvinyl chloride and the like, but are not limited thereto. The material of the porous carrier is preferably diatomaceous earth from the viewpoint of yeast survival rate at the time of formulation.

The term "porous" in the porous carrier that can be used in the viable bacterial preparation means a state in which a large number of small bubble-like voids are present on the surface of the carrier. Preferably, the bulk density (tapping bulk density) of the porous carrier is 0.01 to 2 g / ml. By using the bulky porous carrier as described above, the survival rate of yeast after the formulation step can be further improved. The bulk density of the porous carrier is more preferably 0.05 to 1.5 g / ml, still more preferably 0.2 to 1 g / ml. The above bulk density is a value measured by the tapping bulk density measuring method.

From the viewpoint of the viability of yeast during formulation, the carrier is preferably in the form of particles having an average particle size (diameter, volume standard) of 1 to 300 μm, and an average particle size (diameter, volume standard) of 10. It is more preferably in the form of particles of about 200 μm, and even more preferably 30 to 150 μm. The particle size of the carrier is a value measured by a laser diffraction method.

The viable bacterial preparation can be formulated by spraying a spray solution onto the porous carrier that can be used for the viable bacterial preparation. The spray solution can be prepared by adding the above-mentioned yeast and trehalose, milk protein, amino acids, metal salts and, if necessary, other components to water, and stirring as necessary. As the water used for preparing the spray liquid, for example, tap water, distilled water, ion-exchanged water, pure water, ultrapure water, etc. may be used, but distilled water with less impurities, ion-exchanged water, pure water, etc. may be used. , Or ultrapure water is preferably used. A mixed solution in which a lower alcohol such as methanol, ethanol or propanol or a polar solvent such as acetone is appropriately added to water may be used.

The spray solution can be sprayed onto the porous carrier that can be used in the viable cell preparation, for example, by using a fluidized bed granulator. By formulating by the fluidized bed granulation method, the yeast-containing layer can be formed on the porous carrier at a relatively low temperature. Therefore, it is advantageous from the viewpoint of improving the survival rate at the time of formulation. It is also advantageous in that the yeast-containing layer can be uniformly formed on the porous carrier by formulating by the fluidized bed granulation method.

The amount of the spray liquid sprayed on the porous carrier can be arbitrarily set and is not particularly limited, but the solid content of the spray liquid is, for example, 0.1 to 10 mass with respect to 1 part by mass of the porous carrier. It is a ratio of parts, preferably 0.5 to 2 parts by mass.

The spray liquid is usually sprayed onto the porous carrier at a rate of about 50 to 300 g / min.

When formulating by the fluidized bed granulation method, the temperature of the warm air may be appropriately set in consideration of the heat resistance of yeast and the like. For example, the inlet temperature is 30 to 60 ° C, preferably 35 to 50 ° C. Is. The temperature of the fluidized bed may be appropriately set in consideration of the heat resistance of yeast and the like. For example, the temperature is 30 to 60 ° C, preferably 35 to 50 ° C. After spraying, the porous carrier sprayed with the spray liquid may be dried as it is in the fluidized bed granulator, or may be dried separately in the dryer.

The powdered viable bacterial preparation may be partially or wholly coated with a known coating agent, depending on the intended use. Further, powders such as a lubricant (for example, talc, mica, silica, magnesium stearate), a desiccant (calcium oxide, silica gel), and a filler may be mixed with a viable bacterial preparation in an arbitrary ratio to prepare a mixed preparation. .. Further, the preparation may be pulverized or classified so as to have a desired particle size.

From the viewpoint of the survival rate of yeast during the storage period, the water content of the viable bacterial preparation after formulation is preferably 3 to 8% by mass, more preferably 4.5 to 7.5% by mass. ..

By using the yeast culture medium of the present invention, the yeast culture efficiency is improved and the viable cell count per unit volume of the medium is increased (that is, the maximum viable cell count per unit volume of the medium is increased). be able to. For example, when culturing by the method described in Examples described later, in the conventionally used YM medium, even if Asterotremella humicola is cultured for 24 to 72 hours, the viable cell count is 4. .3 × 10 ^{8 to} 4.8 × 10 ⁸ CFU / mL. On the other hand, by using a medium for yeast cultures of the present invention, when cultured for about 24 hours, it can be grown Asuterotoremera & Humicola the (Asterotremella humicola) to 1.1 × ¹⁰ 9 CFU / mL.

As described above, the yeast culture medium of the present invention improves the yeast culture efficiency and increases the number of viable cells per unit volume of the medium (that is, per unit volume of the medium) as compared with the conventional medium. (Maximum viable cell count can be increased). Therefore, in one embodiment of the present invention, there is provided a method for promoting the growth of yeast, which comprises culturing yeast in the above-mentioned yeast culture medium.

The effects of the present invention will be described with reference to the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples.

(Preparation of yeast culture medium)
Each component was dissolved in distilled water so as to have the composition shown in Table 1 below, and the yeast culture medium of the example was prepared. The pH of the yeast culture medium of the examples was not adjusted.

Each component was dissolved in distilled water to prepare a YM medium (comparative example) so as to have the composition shown in Table 2 below. The pH of the YM medium has not been adjusted.

(Preparation of live bacterial preparation)
Asterotremella humicola 2-141-1 strain (February 21, 2018, National Institute of Technology and Evaluation Patent Microorganisms Depositary Center (2-5-8 Kazusakamatari, Kisarazu City, Chiba Prefecture) (The receipt number is NITE BP-02641) is inoculated into the following liquid medium and cultured in a jar fermenter at 30 ° C. for 48 hours (stirring rate: 300 rpm) to prepare the culture solution. Obtained.

Method for preparing liquid medium: final concentration 0.18% (w / v) polypeptone, 0.12% (w / v) meat extract, 0.07% (w / v) NaCl ₃ , 0.005% (w) /v)NaCl,0.002%(w/v)KCl,0.002%(w/v)CaCl ₂ · _{2H 2} O, a 0.003% (w / v)) MgSO 4 · 7H 2 O Soaked in pure water. After adjusting to pH 5 with hydrochloric acid, autoclave sterilized medium was used as a liquid medium.

The obtained culture solution was centrifuged (× 10,000 g) for 10 minutes, and the cells were collected. The resulting 11 wt% of yeast with respect to cells, trehalose 14 weight%, the skim milk 3% (1% by weight as a milk protein), glycine 3 wt%, 1 weight MgSO ₄ · 7H ₂ O %, was added to distilled water to 1 mass% of CaSO ₄ · 2H ₂ O, was prepared by mixing the spray solution. As the milk protein, skim milk containing 35% by weight of protein and 52% by weight of lactose in the solid content was used.

300 g of diatomaceous earth (average particle size 75 μm, bulk density 0.32 g / ml, radiolite (registered trademark) # 3000, Showa Chemical Industry Co., Ltd.) in a fluidized bed granulator (FA-LAB-1, Paulec Co., Ltd.) Was set. 1077 g of the above spray liquid was sprayed on the diatomaceous earth at a rate of 143 g / min, and warm air at 40 ° C. was blown to dry the contents in a flowing state. After spraying, warm air at 40 ° C. was subsequently blown in the fluidized bed granulator for 40 minutes to dry the granulated product. As a result, a viable bacterial preparation was obtained. The water content of the viable bacterial preparation was 5.5% by weight.

(Yeast culture)
Yeast was cultivated by the following method.
(1) 200 mL of the above yeast culture medium or YM medium was dispensed into a 500 mL tall beaker.
(2) the viable cell preparations prepared above tall beaker (1) 6 mg ^{(Yeast: 5.1 × 10 7 CFU / L} ) was added.
(3) After adding the viable cell preparation, the tall beaker of (2) was aerobically cultured at 30 ° C. for 24 hours to obtain a culture solution.

(Calculation of viable yeast count)
In Examples and Comparative Examples, the culture broth was sampled every 24 hours from the start of the culture, serially diluted with a 5% Tween 80 solution, and applied to the surface of the NB medium solidified with agar. After application, the colonies of the 2-141-1 strain formed on the medium were measured by culturing at 30 ° C. for 48 hours. The results are shown in Table 3.

As shown in Table 3, it can be seen that in the examples, the culture efficiency of the 2-141-1 strain can be significantly improved as compared with the comparative examples.

Claims (10)

A yeast culture medium containing a carbon source, a nitrogen source and a magnesium source.
A medium for yeast culture in which the nitrogen source contains glutamic acid and glycine. The yeast culture medium according to claim 1, wherein the total amount of the glutamic acid and the glycine is 0.01 to 5.0 parts by mass with respect to 1 part by mass of the carbon source. The yeast culture medium according to claim 1 or 2, wherein the amount of the glutamic acid compounded is 0.01 to 5.0 parts by mass, where 1 part by mass of the glycine is compounded. The yeast culture medium according to any one of claims 1 to 3, wherein the magnesium source contains magnesium sulfate. The yeast culture medium according to any one of claims 1 to 4, wherein the amount of the magnesium source blended is 0.01 to 0.5 parts by mass with respect to 1 part by mass of the carbon source. The yeasts are asterotremera, cryptococcus, trichosporon, saccharomyces, candida, pichia, hansenula, kluyberomyces, lipomyces, lordtorula, schizosaccharomyces, lactobacillus and enterococcus. The yeast culture medium according to any one of claims 1 to 5, which is a yeast selected from the group consisting of. The yeast culture medium according to any one of claims 1 to 6, wherein the yeast is Asterotremella humicola. The yeast culture medium according to any one of claims 1 to 7, which is a liquid medium. The yeast culture medium according to any one of claims 1 to 7, which is a solid medium. A method for culturing yeast, which comprises culturing yeast in the yeast culture medium according to claim 8.