Saccharomyces cerevisiae

Abstract

The objective of this invention is to provide a yeast that can be used for the fermentation of various foods. [Solution] The above problem can be solved by Saccharomyces cerevisiae, which is the deposit number NITE P-04172 of the present invention.

Description

Technical Field

[0001] The present invention relates to Saccharomyces cerevisiae. According to the present invention, foods with excellent flavor can be produced.

Background Art

[0002] Saccharomyces cerevisiae is used as beer and bread yeast (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, yeasts that can be used for the fermentation of various foods have been desired. Therefore, an object of the present invention is to provide a yeast that can be used for the fermentation of various foods.

Means for Solving the Problems

[0005] As a result of intensive research on yeasts that can be used for the fermentation of various foods, the present inventor surprisingly found that yeasts isolated from the leaves of Armillaria mellea can be used for the fermentation of various foods. The present invention is based on such findings. Therefore, the present invention relates to [1] Saccharomyces cerevisiae with deposit number NITE P-04172, [2] Foods fermented by the Saccharomyces cerevisiae described in [1], and [3] The foods described in [2], which are bread, cake, confectionery, wine, beer, or sake.

Effects of the Invention

[0006] According to the Saccharomyces cerevisiae of the present invention, it can be used as baker's yeast, beer yeast, wine yeast, or brewing yeast. [Brief explanation of the drawing]

[0007] [Figure 1] (A) is a photograph of a colony on a plate used to isolate Saccharomyces cerevisiae according to the present invention, and (B) is a micrograph showing the morphology of Saccharomyces cerevisiae according to the present invention. [Figure 2] This is a photograph of a plate used to measure the killer activity of Saccharomyces cerevisiae against other yeasts, as described in the present invention. [Figure 3] These are photographs of bread dough (A) and baked bread (B) produced using Saccharomyces cerevisiae of the present invention. [Modes for carrying out the invention]

[0008] [1] Saccharomyces cerevisiae The Saccharomyces cerevisiae of the present invention has a ribosome gene ITS region having the nucleic acid sequence described in Sequence ID No. 1. The Saccharomyces cerevisiae of the present invention is preferably the Saccharomyces cerevisiae with deposit number NITE P-04172.

[0009] Saccharomyces cerevisiae is also commonly known as budding yeast. Baker's yeast is also Saccharomyces cerevisiae, but it is sometimes simply called yeast. Furthermore, Saccharomyces cerevisiae can metabolize sugar and carry out alcoholic fermentation. That is, it can be used as wine yeast, beer yeast, and brewing yeast (sake yeast). Haploid and diploid organisms reproduce by budding. Daughter cells budding from the mother cell gradually grow larger, and when the bud reaches the same size as the original cell, it divides into two cells. Budding is asexual reproduction. When the nitrogen source is depleted, diploid cells undergo meiosis and form spores. Haploid cells are oval-shaped (yeast-type) with a long diameter of about 5 μm, while diploid cells are slightly larger and lemon-shaped with slightly pointed ends.

[0010] The Saccharomyces cerevisiae of the present invention does not possess killer activity that inhibits the growth of other yeasts, although this is not limited to the present invention. The Saccharomyces cerevisiae of the present invention exhibits alcohol tolerance, preferably at 12% or less, more preferably at 10% or less, even more preferably at 9% or less, and even more preferably at 8% or less. The Saccharomyces cerevisiae of the present invention can be used as baker's yeast, wine yeast, beer yeast, or brewing yeast (sake yeast).

[0011] [2] Food The food of the present invention is fermented with Saccharomyces cerevisiae of the present invention. The food of the present invention is not particularly limited as long as it is a fermented food, but examples include bread, wine, beer, or sake.

[0012] "bread" The bread of the present invention can be made using conventional bread-making methods, except that the Saccharomyces cerevisiae of the present invention is used as the bread yeast. Specific bread-making methods include direct kneading, sponge and dough method, accelerated method, liquid starter method, sourdough method, sake starter method, hop starter method, medium dough method, Chollywood method, continuous bread-making method, or refrigerated dough method. The fermentation conditions are not particularly limited, for example, 5 to 24 hours in an atmosphere of 25 to 37°C and 50 to 90% humidity. The baking temperature is also not particularly limited, for example, 5 minutes to 1 hour in an atmosphere of 180 to 300°C. Bread produced using the Saccharomyces cerevisiae of the present invention had a slower fermentation rate than commercially available dry yeast bread, but it had a superior flavor.

[0013] "wine" The wine of the present invention can be produced using conventional wine production methods, except that the Saccharomyces cerevisiae of the present invention is used as the wine yeast. For example, a white wine production method is the skin contact method, in which aromatic components are extracted from the skins by briefly contacting the skins and juice of white wine grapes, and then fermenting with only the juice. Another method for producing red wine is to destemize and crush red wine grapes, and then ferment the skins, seeds, and juice together to extract red pigments and astringent components from the skins, after which the skins and seeds are removed and post-fermentation takes place. The fermentation temperature is, for example, in the range of 10 to 30°C, more preferably in the range of 15 to 25°C. The fermentation time is, for example, in the range of 3 to 14 days, more preferably in the range of 5 to 10 days. In addition, as a fermentation accelerator, for example, diammonium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, or magnesium sulfate can be used. The wine produced using Saccharomyces cerevisiae of the present invention is a low-alcohol wine with a pleasant aroma and a clean taste.

[0014] "Beer" The beer of the present invention can be produced using conventional beer manufacturing methods, except that the Saccharomyces cerevisiae of the present invention is used as the brewer's yeast. For example, the beer manufacturing method includes a step of fermenting a liquid containing malt, etc., and a step of filtering the liquid in which the yeast has been dispersed after fermentation. The beer of the present invention also includes so-called beer-flavored beverages (carbonated beverages). Examples of raw materials include malt, soybeans, yeast extract, peas, and unsprouted grains. Examples of unsprouted grains include unsprouted barley, wheat, rye, oats, oats, pearl oats, oats, soybeans, and peas. The fermentation temperature is, for example, 20-35°C. The fermentation time is about 1-10 days, preferably 3-9 days.

[0015] "Sake" The sake of the present invention can be produced by using the usual sake production method, except that Saccharomyces cerevisiae of the present invention is used as the brewing yeast. Examples of the sake production method include a method comprising a step of preparing a mash by blending yeast, rice (which can also be referred to as polished rice), koji, and water, a step of fermenting the mash, and a step of separating sake from the fermented mash. The step of preparing the mash and the step of fermenting the mash may both be repeated two or more times. The fermentation temperature is, for example, 10 to 40°C, more preferably 20 to 40°C, and even more preferably 25 to 32°C. The lower limit of the fermentation time is preferably 2 days or more, more preferably 3 days or more, and even more preferably 4 days or more. The upper limit is 21 days or less, more preferably 14 days or less, and even more preferably 12 days or less.

Example

[0016] Hereinafter, the present invention will be specifically described by way of examples, which do not limit the scope of the present invention.

[0017] 《Example 1》 In this example, yeast was isolated from the leaves of Nezumimochi, and the nucleotide sequence of the ITS region of the ribosomal gene was determined. Leaves of Nezumimochi growing on the mound of practical learning on the Hachioji campus of Teikyo University were inoculated into about 40 mL of the following culture medium and statically cultured at 32°C for 4 days. Fermentation was observed due to the production of a large amount of bubbles including white turbidity of the medium and an aromatic odor. Culture medium: Ethanol-added liquid Sabouraud glucose medium (1% peptone, 2% glucose, 5% ethanol, 0.2% chloramphenicol) The turbid culture solution was streaked with a loop, spread on the surface of a chromo agar Candida plate medium (Kanto Chemical Co., Inc.), cultured at 32°C for 2 days, and the purple colonies that grew isolated from other colonies were streaked with a loop. As the isolated yeast, it was inoculated into a Sabouraud glucose agar slant medium (1% peptone, 2% glucose, 2% agar), cultured at 32°C, and the morphology was observed under a microscope. Oval to ovoid budding yeast with a major axis of 3 to 7 μm was confirmed.

[0018] Gene extraction was performed on the isolate according to standard procedures, the ITS region of the ribosome gene was amplified by PCR, and the amplified gene was sequenced. The gene sequence was then subjected to homology search in NCBI. It showed 100% agreement with the gene sequence of Saccharomyces cerevisiae registered in GenBank.

[0019] The isolated strains underwent glucose metabolism testing using the API® microbial identification test kit (bioMerieux Japan Ltd.). Their glucose metabolic characteristics were 100% identical to those of Saccharomyces cerevisiae. Based on these results, the isolate was identified as Saccharomyces cerevisiae and named Practical Science No. 8. The nucleotide sequence of the ITS region of the ribosome gene in this strain has been registered in GenBank (GenBank registration number: LC834914).

[0020] The obtained Saccharomyces cerevisiae did not possess killer activity to inhibit other yeasts. Killer activity was confirmed as follows: Commercially available dry yeast was inoculated into 3 mL of liquid Sabouraud glucose culture medium (1% peptone, 2% glucose) and incubated at 32°C for 14 hours. After centrifugation, the culture medium was removed, and the dry yeast was suspended in sterile physiological saline and adjusted to a McFaland 0.5 turbidity. The yeast solution was spread onto the surface of Sabouraud glucose agar plates. Practical Disease No. 8 was inoculated into 3 mL of liquid Sabouraud glucose culture medium and incubated at 32°C for 14 hours. After centrifugation, the culture supernatant was collected. A circular filter paper with a diameter of 8 mm was placed on the surface of the culture medium coated with yeast, and 10 μL of culture supernatant was dropped onto it. The mixture was then left to stand at 32°C for 24 hours. When we observed whether a zone of inhibition, which inhibits yeast growth, was formed around the filter paper soaked in the culture supernatant, we determined that there was no zone of inhibition, and therefore no killer activity against other yeasts (Figure 2).

[0021] The alcohol tolerance of the obtained Saccharomyces cerevisiae was less than 10%. Alcohol tolerance was confirmed as follows: A dome-shaped glass tube called a Durham tube was placed at the bottom of the test tube to detect carbon dioxide gas production due to fermentation, and then liquid Sabouraud culture medium was added and the test tube was autoclaved. After confirming that there was no gas in each Durham tube after sterilization, ethanol was added to each test tube to achieve concentrations of 5%, 10%, 15%, 20%, and 25%. Practical Science No. 8 was inoculated into each test tube and incubated at 32°C in a static environment. After 3 days, fermentation was determined by the accumulation of gas in the Durham tube. With 5% and 10% ethanol added, the Durham tube was filled with gas, confirming fermentation. At 15%, only about half of the tube was filled with gas, indicating insufficient fermentation. Furthermore, no gas production was observed at ethanol concentrations of 20% or higher. Based on these results, the alcohol tolerance of Jitsugaku No. 8 was determined to be 10% or less.

[0022] Example 2 In this example, bread was produced using Saccharomyces cerevisiae obtained in Example 1. Practical Yeast No. 8 was inoculated into 100 mL of liquid Sabouraud medium and incubated at 32°C for 2 days. After incubation, the culture supernatant was removed by centrifugation and the yeast was suspended in 30 mL of tap water. This was used as the yeast solution to be added to the bread dough. The bread dough (180g strong flour, 70g weak flour, 20g sugar, 5g salt, 150mL tap water) was prepared, yeast solution was added, and the dough was kneaded well in a bowl according to the standard method. It was then left to stand at room temperature overnight to ferment. After confirming that the dough had more than doubled in size (Figure 3A), the dough was kneaded again, shaped, and left to rest for 15 minutes as a bench rest. The dough was placed in an oven preheated to 200°C and baked for about 25 minutes. Bread produced using Saccharomyces cerevisiae of the present invention exhibited excellent flavor.

[0023] Example 3 In this example, wine was produced using Saccharomyces cerevisiae obtained in Example 1. Sugar was added to commercially available 100% grape juice to a concentration of 4%, then Jitsugaku No. 8 was inoculated and left to stand at 28°C. From the second day of culture, we checked for the production of bubbles due to fermentation and for the presence of an aromatic odor. On the tenth day, the production of bubbles ceased, so we determined that fermentation had ended. After centrifugation, we collected the fermentation liquid and measured the alcohol concentration with an alcohol refractometer, which showed a concentration of approximately 12%. Wine produced using Saccharomyces cerevisiae of the present invention exhibited a pleasant aroma and a clean, crisp taste.

[0024] Example 4 In this example, beer was prepared using Saccharomyces cerevisiae obtained in Example 1. A commercially available beer-making kit (a paste containing malt, hops, sugar, etc.) was prepared by adding sugar according to the instructions and then diluting it with sterilized tap water to create the beer concentrate. The stock solution was inoculated with Jitsugaku No. 8 and allowed to ferment statically at room temperature for 10 days until bubble production ceased. 360 mL of the fermentation supernatant was added to a glass beer bottle containing 3 grams of sugar, capped with a crown cap using a capping machine, mixed by inverting several times, and then left at room temperature for 4-5 days to allow the produced carbon dioxide to dissolve into the beer. The beer was then stored in a refrigerator and aged for at least 7 days before being opened. Foam formation was confirmed, and the alcohol concentration was measured. Beer produced using Saccharomyces cerevisiae of the present invention exhibited a pleasant aroma and a clean, refreshing taste. [Industrial applicability]

[0025] The Saccharomyces cerevisiae of the present invention can be used in the production of bread, wine, beer, or sake. [Accession Number]

[0026] Saccharomyces cerevisiae strain No. 8 was deposited domestically on October 4, 2024, at the Patent Microorganism Depository Center (NPMD) of the National Institute of Technology and Evaluation (NITE) (Room 122, 2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture 292-0818, Japan) under accession number NITE P-04172.

Claims

1. Saccharomyces cerevisiae, deposit number NITE P-04172.

2. A food product fermented with Saccharomyces cerevisiae as described in claim 1.

3. The food according to claim 2, which is bread, wine, beer, or sake.

Images