History of Natto and Its Relatives - Page 1

by William Shurtleff and Akiko Aoyagi

A Chapter from the Unpublished Manuscript, History of Soybeans and
Soyfoods, 1100 B.C. to the 1980s


©Copyright 2004 Soyinfo Center, Lafayette, California

For updated and greatly expanded free information on this subject,
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Natto is made by fermenting cooked whole soybeans with a bacterial starter ( Bacillus natto ) at 40*C (104*F) for 14-18 hours, until the dark-brown beans become covered with a viscous, sticky substance (glutamic acid polymers), which forms long silvery gossamer threads when natto is lifted from a bowl; the longer the threads (they stretch up to 8 feet!), the better the quality of the natto.

Natto, usually sold in its fermentation container, has a slightly musty flavor and a noticeable ammonia odor; some people love it and others can't stand it. Natto is unique to Japan, where it is usually served for breakfast mixed with shoyu (natural soy sauce), mustard, and sometimes minced leeks, generally on top of or mixed in with hot rice. Because natto is made from soybeans that have not been dehulled, it is a whole, lightly processed, natural food. Easily made at home, inexpensive, and nutritious, it can be eaten without additional cooking.

It is interesting to note that all traditional fermented soyfoods except natto (and its close relatives) are cultured with molds; miso, shoyu, and soy nuggets with Aspergillus ; tempeh with Rhizopus , and fermented tofu with Actinomucor . Natto alone is fermented with bacteria. Moreover, it is one of the few foods in the world fermented with aerobic, spore-forming bacteria. In natto, these produce active protease enzymes, which predigest the soybeans.

Relatives of natto, also fermented with Bacillus natto or its close relative Bacillus subtilis (pronounced SUT-il-us, a well-known tempeh contaminant) are found in several East Asian countries. There is tan-shih and kan-shih (salt-free soy nuggets) in China, Joenkuk-jang and Damsue-jang (both salted) in Korea, thua-nao in Thailand, kinema in Nepal, and perhaps sereh in Bali (Indonesia). Yet only in Japan is this type of product widely consumed. The reasons for this, other than taste preferences, are not clear.

Etymology . The term natto (pronounced not-TOE in Japanese) is composed of two characters; the first means "to offer" and the second means "bean" or

"beans," perhaps reflecting the fact that, in early times, natto is thought to have been used as an offering at altars. The term natto first appeared in a Japanese document in 1068, but at that time it referred to soy nuggets (a salty, mold-fermented soyfood). The Honcho Shokkan (1695) mentioned that the term "natto" was derived from the term nassho (literally "offering place"), which referred to the kitchen in Japanese Buddhist temples. Eventually the term "natto" came to be used to refer to two completely different Japanese fermented soyfoods, a salted mold-fermented product (such as Hamanatto, which we call "soy nuggets") and the regular itohiki ("string pulling") natto. It is not known?? when the present term itohiki natto first appeared, but it was probably between the 13th and 16th centuries.

Natto is one of the few soyfoods which has always been called by its native name in every European language, probably because it is so unusual that no equivalent could be found. The term first appeared in a European language (German) document in 1894 and in an English-language document in 1897. Both documents were written by the Japanese researcher Yabe. The term has always been used as a singular noun.


In trying to reconstruct the early history of natto in Japan, we have used a number of Japanese sources, the more important of which are Ohta's Natto Kenkoho (1975, "The Natto Way of Health"), the Japanese National Natto Association's voluminous Natto Enkaku-shi (Zenkoku Natto 1975, "Natto History and Development"), and Ohta's "Natto" (1969). While these works are rich in information, only the last is written in a scholarly manner and none of them contains citations for documents or information prior to about 1700 and only scant documentation prior to 1868. This explains the absence of such citations in the early sections of the present chapter and points to the need for a carefully researched and documented work on the early history of natto in Japan.

Theories of Origin . It is not clear how, when, or where natto originated. At least five theories have been put forth concerning its origin:

Chinese Salt-Free Soy Nuggets Theory. At least 1400 (and perhaps over 2000) years ago the Chinese were producing a fermented soyfood that they called tan-shih ("mild, light-colored soy nuggets") or kan-shih ("sweet soy nuggets"), a salt-free ancestor of the Chinese soyfood sold today as "salted (or fermented) black soybeans." A description of the process for making tan-shih appears in the Ch'i-min yao-shu , the world's first encyclopedia of agriculture, written in AD 535. Here it states that soybeans were cooked, spread in a warm room, inoculated naturally with "yellow robe" (a mold of the genus Aspergillus ), and incubated to make soybean koji. This koji was then washed with water, wrapped tightly in a woven artemisia reed mat, and allowed to ferment for several days, after which it was removed from the mat and dried to make salt-free soy nuggets. If the fermentation reached a high temperature (near 40*C or 104*F) and if the artemisia reed mat that was used carried a (typical) load of Bacillus subtilis , the finished product (which might well have been discarded because of its odor, taste, and appearance) could have resembled today's natto. Records show that Ganjin, a famous blind Buddhist priest, brought 1,428 gallons of salt-free soy nuggets with him to Japan in AD 754. The Japanese could have developed natto from this imported Chinese product, although there are no records indicating that they did.

Japanese Yayoi Period Theory. The period of Yayoi culture in Japan (roughly 300 BC to AD 200) was a time of major agricultural changes. Archaeological discoveries of charred soybeans from the later Yayoi period at various sites throughout Japan (Mt. Komori remains in Senbata village, Akita prefecture, Yasuda-Oka in Yamaguchi prefecture, and Iba-Iseki in Shizuoka prefecture) indicate that soybeans were being consumed in Japan at this early date. Rice cultivation in Japan started in northern Kyushu (Japan's southernmost main island) in the later Jomon period (c. 300 BC); it was slowly adapted to colder climates as cultivation moved northward, reaching the northeast prefectures ( Tohoku Chiho , northeast of Tokyo) by the end of the Yayoi period. (Some sources say rice did not reach there until the Heian period, AD 794-1185). The discovery in 1966 in Swaziland, South Africa, of bacteria of the family used in natto fermentation showed that they existed on the planet over 3 billion years ago. Thus by the end of the Yayoi period, the four crucial elements necessary to produce natto may have existed in northeast Japan: soybeans, rice straw, natto bacteria (probably on the rice straw), and a warm place for incubation. Basically, the production of natto depends on the meeting of warm soybeans and rice straw. The people of early Japan were virtually surrounded by rice straw: they used it to make the roofs of their houses, floor mats ( mushiro , goza , and later tatami ), straw bags or bales ( tawara ), sacred braided ropes ( shimenawa ; rice straw was considered the sacred mother-body of the rice), sandals, and even their horse fodder. It is now known that rice straw in Japan naturally contains a heavy population of natto bacteria. The accidental meeting of rice straw with warm cooked soybeans could have come about in a number of different ways: (1) In a typical Yayoi period tateana -style house, the food was cooked on a stove ( kamado ) over a fire in the center of the main room. On both sides of the stove were hollows in which were stored leftovers (in unglazed earthenware pots that could "breathe") and kitchenwares. A piece of rice straw from the floor matting could easily have fallen into a pot of warm cooked beans before the lid was put on; the next morning the beans could have become natto. Or a single bean could have fallen from the pot onto the straw matting; the next morning it could have developed a sticky coating and a unique, slightly sweet flavor; (2) Leftover warm soybeans, if stored or carried in a rice-straw mat wrapper, could have turned into natto; (3) Leftover warm soybeans, if discarded, could have fallen on a pile of rice straw to be used for horse feed and turned into natto; (4) Freshly-cooked soybeans were probably placed on household Shinto altars ( kamidana ) as a food offering. Across the top of a typical altar hung a thick twisted sacred rope of rice straw ( shimenawa ). A piece of straw from the sacred rope could easily have fallen into the warm beans, inoculating them for natto. One of Japan's foremost natto researchers and historians, Dr. Teruo Ohta, believes that natto probably originated during the Yayoi period in one of these ways, although there are no documents, other evidence, or even legends to prove this . . . except, perhaps, the fact that the first character of the word natto means "to offer," as on the altar.

Split Roasted Soybean Theory. Today in the far northern Japanese prefectures of Akita and Aomori there is a type of natto called hikiwari ("split or cracked") natto, made from split roasted soybeans. In ancient times, people may have dry-roasted then split their soybeans before boiling them to save cooking time and fuel. If they had stored or carried the warm boiled beans in rice straw, they could well have turned into natto. Oyashin-machi in Yokote city, Akita prefecture, has long been said to be the place where hikiwari natto originated. This city is located near Senbata village and Mt. Komori, where the remains of charred soybeans mixed with Yayoi earthenware vessels dating back 2,000 years were excavated in 1930. For these reasons, natto historian Dr. Ohta thinks there is a good chance that hikiwari natto originated there in the early Yayoi period, before the Christian era, and was the most ancient ancestor of today's natto.

Prince Shotoku-Shiga Prefecture Theory. According to a longstanding legend in Shiga prefecture (in central Japan, just east of Kyoto), during the early seventh century, the renowned Prince Shotoku rode through the Omi valley and rested at the village of Warado, an area famous for growing soybeans. He gave some leftover cooked soybeans to his horse, wrapped the remaining soybeans in rice straw, and hung them from a tree. The next day the beans had turned into natto, which the Prince tasted, seasoned with salt, and liked. Thereafter the village made lots of natto, and even changed the village name to Warazuto Mura ("rice straw wrapper village"). It is a fact that village was well known until the late 1920s for the natto they sold in fan-shaped rice straw wrappers ( ogi natto ). Ohta notes that Prince Shotoku may have learned to make fermented soyfoods from a Korean monk, Keiiji, his close friend, from whom he also learned Buddhism. Note that all other theories say that natto originated in Japan's northeast prefectures.

Hachiman Taro Yoshiie Theory. Hachiman Taro Yoshiie is the popular nickname for Minamoto no Yoshiie, son of Minamoto no Yoriyoshi. A famous general from Kyoto during the Heian Period, he was the hero of the Zenkunen War (1051) and the Gosannen War (1083), both of which were fought in Japan's northeast prefectures. Prior to the first war the combination of cold weather, poor crops, and threats of harsh government taxes, led to tax refusals and a threatened peasant revolt. Hearing of this, the central government in Kyoto dispatched Yoshiie, his father, and their soldiers to suppress the revolt. Traveling by horseback from Kyoto to Edo (Tokyo), they then took the Oshu Road ( Oshu Kaido ) north to Shirakawa in Fukushima prefecture, and headed up through Miyagi prefecture toward Akita in the far cold north. According to one version of the legend, one night during the war Yoshiie's soldiers were in camp cooking soybeans as feed for their horses when suddenly they were attacked. They hurriedly packed the beans into a rice-straw sack ( tawara ), tied the sack to a horse's back, and either escaped or fought. A day or two later, when the straw sack was opened, because of the warmth of the horse's body, the soybeans had turned into natto. Yoshiie and his soldiers tasted the soybeans and enjoyed them.

According to another version of the legend, Yoshiie had to go to the town of Iwadeyama in Miyagi prefecture in order to win the Zenkunen war. There, say the local people, they offered him natto, which they had already developed. He enjoyed this natto and it helped him win the war. By the middle of the Edo period, Iwadeyama had become a famous center of natto production. One of the leaders of the revolt (Abe Sonin??, So-To) was banished to Dazaiku, far to the south in the Hida area of Kyushu, Japan's southernmost main island. There, in 1062, he is said to have started propagating the way of making natto used in the northeast prefectures.

In the second war, 32 years later, Yoshiie had captured a fortress in Sankanbu, Yokote city, Akita prefecture. During the protracted battle many had died from cold and starvation. Yoshiie wanted to give cooked soybeans as a gift to the surviving peasants, but since he was in a hurry and had no other container, he put them in a rice-straw sack for the farmers. The peasant were surprised when, after several days, the beans gave off a unique odor and were stringy. They liked the flavor and soon adopted natto as a food, producing it themselves, and starting a tradition that has been passed down to the present day.

After both of his northern victories, Yoshiie and his army returned to Kyoto and, according to legend, taught people all along the way how to make natto. His road, which has now come to be called the "Natto Road," passed through Yokote in Akita prefecture, Yamagata, Iwadeyama, Sendai, Fukushima, Haizu, Otahara, Mito, Urawa, Tokyo, Kofu, Omi, and finally Tanba near Kyoto. In each of those areas natto is widely produced and consumed (especially in the north) and the legend of Hachiman Taro Yoshiie is well known to this day. It is said that Yoshiie, a poet, and a popular, respected, intelligent person, recognized the potential of his discovery and made a special effort to teach others about it.

Natto was not the only war food developed by Hachiman Taro Yoshiie. He also created Japan's first concentrated high-protein, high-energy processed food called hyoryogan or "soldiers' food pellets," consisting of a mixture of ground roasted soybeans, buckwheat groats, and hemp seeds, shaped into lightweight little balls to be carried by soldiers on long marches. Hitler developed a similar food prior to World War II, his famous Nazi Food Pills (see Chapter 45??).

Heian Period (794-1185). The various theories discussed above hold that natto originated in Japan sometime during the period from about the first to the 11th century, a span of roughly a thousand years. Yet the word "natto" first appeared in a a Japanese document in about 1068, the Shinsaru Gakki by the noblewoman Fujiwara no Akihira, who lived from 986-1067. (The date of this document is sometimes given as 1286, as in the Motoyama's Inshoku Jiten and Zenkoku Natto's Natto Enkakushi , apparently?? erroneously.) The fermented soyfood referred to in that work, however, was an entirely different product. Called spring (or crab) salty ( shiokara ) natto, it was what we call "salted soy nuggets," a product fermented with a mold rather than a bacterium. (See Chapter 32 for a discussion of why the two different foods might both have been called types of "natto".) It was probably ?? not until the 13th century that the word natto was first used to refer to the sticky natto that Japanese now call itohiki natto ("thread pulling natto").

One might well ask why, if natto could have been developed as early as the Yayoi period (300 BC to AD 200), there is no record of it in written documents. The main reason is that natto developed in areas far from the centers of culture and power; the people in the northeast prefectures did not learn to read or write until a rather late date. Moreover, natto was not considered a very high class food.

From the Heian period natto was most widely produced and consumed in the regions north of Tokyo and in the six northeast prefectures (Fukushima, Miyagi, Iwate, and Aomori, Akita, and Yamagata). Other enclaves of popularity were the mountains of central Kyushu and of Tanba (north of Kyoto). Most of the areas where natto is most popular have certain characteristics: the areas are far from the sea and often mountainous so that the people have little protein from fish and other seafoods in their diet (in some of these areas, soybeans came to be known as yama-no-maguro or "tuna of the mountains"); there is a long, cold winter with deep snow necessitating food self-sufficiency; rice is a main crop; horses are widely used.

In the old days natto was generally made in individual homes by simply wrapping cooked soybeans in rice straw and putting them in a warm place overnight until they became sticky. The rice straw was either layered above and below a layer of beans on a flat round bamboo tray, wrapped in a small bundle around about one-third cup of cooked soybeans, or made into a mat or bag and wrapped around a larger quantity of soybeans. Warm places included a kotatsu (a table covered with a blanket set over a small charcoal heater, Fig. ??.?), a wooden vat ( taru ) or snow hole with a hot water bottle ( yutampo ) in it, or the warm ashes under a stove; methods differed from province to province. Straw was always used to supply the natto bacteria, regulate the temperature, moisture, and air flow, keep out unwanted bacteria, and absorb some of the ammonia produced during fermentation.

Throughout the areas where it was used, natto developed a strong reputation for being able to prevent and cure contagious digestive diseases such as dysentery, intestinal typhus, and the like. Folk traditions abound with suggestions for its use. It was also said to aid digestion and give people strength and stamina.

Kamakura, Muromachi (Ashikaga), and Momoyama Periods (1185-1600). Tanba, just north of Kyoto, has long been famous for its natto. The tradition may have started with Hachiman Taro Yoshiie or 270 years later with Emperor Kogen, who was emperor from 1331-1333, until he got tired of politics and fighting and decided to become a monk. In 1334 he went to the snowy mountains in the village of Yamaguni in Tanba and practiced meditation alone. The legend goes that when the villagers learned of his presence, they offered him freshly cooked soybeans wrapped in rice straw. It was much more than he could eat at once so he kept it carefully and ate it little by little after his long periods of meditation. A few days later he noticed many shiny threads as he lifted the beans from their wrapper. Cautiously he sprinkled a little salt on the beans then found them sweeter and tastier than plain cooked soybeans. He told the villagers of his discovery and they started to make the new food, which they called "the Emperor-monk's natto" and later hosei natto. Each year until 1868 they made an offering of this natto at the Imperial Palace in Kyoto together with black beans and azuki beans. Today the beautiful Joshokoji temple in Yamaguni is famous for its delicious Tanba Natto or Yamaguni natto, made wrapped in rice straw.

During the Muromachi period (1338-1573) soy sauce extracted from hishio or miso first came to be used fairly widely in Japan. Using soy sauce in place of salt to season natto increased the flavor, and hence the popularity of natto. Natto and tofu came to be very widely used in Zen Temple Cookery ( Shojin Ryori ), and natto became widely used among monks, samurai, and the nobility. In the Shojin Gyoruigun Monogatari (1450) natto appeared as a person named Natto Taro Itogasane (the last name means "many threads"). During this period in the Kyoto area natto came to be nicknamed ito or o-ito ("threads" or "honorable threads"). The Daisoke Ryori-sho (1532), a cookbook, contained a detailed recipe for making Natto Miso Soup ( natto-jiru , a special miso soup containing diced natto), which became popular during this period. During the Warring States Period ( Sengoku Jidai ) samurai and soldiers started to ferment natto underground in much the same way they had learned to cook rice. To make this tsuchi-natto ("earth natto") cooked soybeans were thoroughly covered and wrapped in rice straw, placed in a hole in the ground, then heated by placing hot coals or a fire (like an Hawaiian imu ) over the top. Natto was also used as an emergency food in castles during the various wars. In 1570 the head of Kotani castle in Omi (near Kyoto) made natto mochi (pounded steamed glutinous rice with chunks of natto in it) and gave the castle people new strength and stamina. During the Bunroku War (1592), Kiyomasa Kato, a famous warrior from Kumamoto in Kyushu, went to fight in Korea. According to the legend, one day he put cooked soybeans in a rice-straw sack that had formerly contained dried miso (hoshi miso). The heat from the horses carrying the sack turned the soybeans into natto. He and his retainers liked the flavor and stringiness. They called it ko-no-mame ("beans of fragrance") and found that during the war it helped keep them free from infectious diseases in the foreign country, aided their digestion under the stress of battle, and provided them with protein and vitamin B. On returning to Kumamoto he taught the people about natto, which to this day is known there as ko-no-mame or koru-mame . He also developed a technique for sprinkling finished natto with salt water and sun drying them to make dried natto ( hoshi korumame ), which could be stored.

Edo (Tokugawa) Period (1600-1868). By the beginning of the Edo period people in the town of Mito were already making their now-famous homemade small-bean natto wrapped in rice straw ( warazuto-natto ). Split-bean natto ( hikiwari natto ) was being widely made in private homes in various parts of the northeast prefectures, especially in Aomori and Akita. The soybeans were roasted over an open fire (which filled the huge living room with a wonderful aroma), split into halves using loosely set hand-turned millstones, dehulled by blowing off the hulls, simmered in a caldron, drained in a bamboo colander, packed in rice-straw wrappers, then placed in a snowhole or earthhole and incubated for about 3 days until done. The favorite season for making split-bean natto was the fall, when the rice straw was fresh, and the aromas and flavors were part of the poetry of snowy nights. At about this time goto natto appeared; an ancestor of today's Finger Lickin' Natto ( yukiwari natto ), it was made with 10 parts by volume of cooked soybeans, 5 parts of rice koji, and 5 parts salt. It became a famous product of the Yonezawa area of Yamagata prefecture.

The sankin kotai system, inaugurated in 1635, required that feudal lords spend half of each year in Edo (Tokyo) in attendance on the shogun. This helped the spread of natto, especially from the northeast prefectures southward and into Tokyo, from the countryside into the city. Also at this time in Fukushima prefecture cotton-bag natto ( momen natto ) and princess natto ( hime natto ) were developed. The former was fermented in a cotton bag. The latter was made by wrapping the natto in a long bundle of rice straw, folding together both ends, then inserting a slender doll, made from one strand of rice straw, into the fold. The doll, called a virgin or matchmaker, was thought to provide the key to the mysterious fertilization of the natto in a ritual with clearly erotic overtones: the natto is put to bed in a warm place and, thanks to the doll, becomes sticky and ripe. In the mid-1600s the Tale of Natto (Natto Monogatari) was written containing a recipe for Natto Miso Soup ( natto jiru ).

In the mid-1600s, natto sellers in Tokyo started the famous tradition of walking through the neighborhoods in the early morning and calling out "Natto! Natto!" in a loud voice. Awoken by the sound, the townspeople rolled out of bed and ran, half asleep, into the streets to buy fresh natto for breakfast. The pattern for today's typical Japanese breakfast was established during this period; it consisted of fresh cooked rice with salt-pickled vegetables, miso soup, and natto served with shoyu, mustard, and perhaps some grated daikon and/or minced leeks. The natto sold in Tokyo at that time was made by lining a large deep bamboo colander with rice straw, putting in 3.8 gallons (8 sho ) of cooked soybeans, covering them with rice straw, and incubating in a large warm underground chamber. The colander or basket was carried by the natto seller by hand or suspended from the ends of a shoulder pole. Each person's order would be measured and scooped out with a ladle or small wooden box. The natto seller typically also sold salt pickled greens ( tsukena ) with the natto. This type of natto was called "one-night natto" ( ichiya natto ; it was made in one night) or "scattered natto" ( bara natto ; since individual portions were not yet wrapped in rice straw). Some natto was also sold in front of pickle shops. Natto was prized as an instant food among busy Tokyoites, instant also in the sense that they could eat it in an instant or on the run and still not get indigestion afterwards. During this same period seasoned minced natto ( tataki natto ) became popular. It was made by mincing natto finely, adding chopped fresh tofu, vegetables, and seasonings, then selling the mixture in a small package to be added to a miso broth to make an instant natto miso soup ( natto-jiru ). Both natto and tofu venders sold seasoned minced natto, packing the mixture in fan-shaped rice-straw wrappers, which were carried in baskets suspended from shoulder poles. It also became popular in Kyoto after 1800; until 1925 peddlers from Omi in Shiga prefecture east of Kyoto went to Kyoto and Tokyo to sell this popular product.

In 1689 (Ref??) natto first became the subject of a haiku poem. The haiku master Matsuo Basho (1644-1694) wrote: "In a mountain temple/cutting the coldness/ natto miso soup." The sound of his knife dicing the natto for the warming soup ran out in the cold silent air. In another haiku Basho also wrote of the sound of mincing natto. Over 100 years later the haiku master Issa (1763-1827 Ref??) wrote about sleeping with the same pillow as natto to help keep it warm overnight.

Natto was increasingly described in books of this period. The Gorui Nichiyo Ryorisho , a cookbook of 1690, contained detailed recipes for making and serving natto plus a history of natto. The Honcho Shokkan of 1695 stated that the word natto was derived from nassho meaning "temple kitchen" or literally "place of offering," perhaps because the food was offered to the Buddha before being offered to the monks. It also gave the first written mention of natto's medicinal or healing effects together with recipes for preparing natto miso soup. The Wakan Sansai Zukai , a sort of encyclopedia of 1713??, and the Shokumotsu Waka Honso (1795) both also mentioned natto miso soup. The Kiyu Shoran (1830) told the story of seasoned minced natto and whole-bean ( tsubu ) natto in Tokyo (Edo). At about this same time a type of natto called "Purple Bamboo Natto" wrapped in individual rice-straw packets and sold by the Kawasaki-ya shop was very popular in Kyoto. Also during this period natto, which had formerly been sold only during the winter, started

to be sold in the summer as well. Seasoned minced natto fell in popularity, being replaced by whole-bean natto.

Meiji Period (1868-1911). At the start of the Meiji period, Japan opened its doors after more than 250 years of isolation. Edo was renamed Tokyo. With the increasing awareness of sanitation, natto scooped out of straw-covered bamboo baskets or trays on dusty city streets fell in popularity. In 1870 Mr. Kyozaemon Sasanuma from Otawara in Tochigi prefecture, north of Tokyo, began to sell the first individual packets of straw-wrapped natto (warazuto natto) in downtown Tokyo. He piled the packets high in two baskets suspended from a shoulder pole and sold a little mustard in a bamboo leaf wrapper with each packet. In 1887 Mr. Torakichi Abe, a natto technical expert, teamed up with Mr. Sasanuma and they started Mito Natto in the town of Mito, Ibaragi prefecture. The product was modernized and its distribution greatly expanded in the early 1900s (when??) when the railway (the Joban line) arrived in town. By 1894 production of natto in Iwadeyama, Miyagi prefecture, had grown rapidly because of the excellent straw with its abundance of natto bacteria.

The traditional method of making natto basically remained unchanged from ancient times until the middle of the Meiji period. It was transformed by the modern science of microbiology, which was introduced from Europe during the 1870s and 1880s. The Japanese microbiologist who brought natto into the modern era was Dr. K. Yabe. In 1894, he published the first scientific report on natto fermentation, his landmark "On the Vegetable Cheese, Natto," which was also summarized that year?? in German under the title Pflanzenkaese ("plant cheese"). In 1895 he published "Natto no Kenkyu" ("Investigations on Natto") in the Journal of the Japanese Chemist's Society and, simultaneously, a German version, "Ueber einen Vegetabilischen Kaese aus Sojabohnen." Yabe's repeated use of the term "cheese" (and the use by his colleagues, such as Inouye in 1895 and Sawa in 1902) would subsequently cause much confusion about natto's true nature among generations of Westerners. Prior to Yabe's investigations, no Japanese had understood what caused straw-wrapped soybeans to turn into natto; the process was a mystery, which led to complex superstitions about the best way to make consistently good natto. Basing his research on the new science of microbiology, Yabe showed for the first time that the natto fermentation was caused by microorganisms. He isolated four types of bacteria (three micrococci and one bacillus), which he thought were responsible for the fermentation. (He specifically mentioned Bacillus subtilis as a bacterium on the soybeans which could withstand long boiling, but he did not mention it specifically as one of the bacteria in natto.) He described in detail the four types of bacteria he had isolated without attempting to name or identify them, discussed their nutritional requirements, and described the Japanese commercial natto-making process. Dr. Yabe's article, the first on natto in English, introduced this unique Japanese food to the world and greatly stimulated further research on natto microbiology in Japan.

Production of natto using traditional methods continued to expand. By 1899 the four largest producers of natto in Tokyo were making a total of 15,000 packets of straw-wrapped natto each month. Apparently women performed most of the hand labor in natto production, including the wrapping with straw (see Fig. ??.?). During the Russo-Japanese War (1904-05), the Japanese army ate rice and cooked soybeans three times a day. A Mr. Sakamoto from Fukushima prefecture is said to have made natto for his division using rice straw from horse fodder and the body warmth of his horse. His group reported to be the only one in Manchuria free of diarrhea, dysentery, and other stomach ailments . . . much the same phenomenon experienced in Korea by Kiyomasa Kato over 300 years earlier. Japan won the war and the military showed new interest in natto.

In 1905 Dr. Shin Sawamura, Professor of Agronomy at Tokyo University, successfully isolated two natto bacteria which, when used to inoculate cooked soybeans, would consistently produce good natto with the characteristic sticky filaments and proper flavor. Upon researching the morphological and propagative characteristics as well as the physiological makeup of these two bacteria, he found them to be very similar, yet clearly different. And he believed that both were necessary to produce good natto. The first, which he believed was necessary to produce natto's good flavor and aroma, he named Bacillus natto Sawamura. The second, which he believed provided the necessary stringiness he identified as Bacillus mesentericus vulgatus . Muto subsequently found that only the first bacterium was necessary to make good natto. In 1913 Sawamura reported that, in the years following his initial investigations, he did bacteriological analyses of many samples of natto obtained from various localities and in each case found that the key microorganism was Bacillus natto . He gave a detailed description of this bacterium, its enzymes, and its needs.

Today in Japan B. natto is considered to be the sole bacterium needed to produce good natto and Sawamura is honored as the man who identified and named it. Internationally, however, there has been much confusion concerning the name of this bacterium. In the 8th edition of Bergey's Manual of Determinative Bacteriology (Buchanan and Gibbons 1974), recognized throughout the world as the authoritative source on bacterial classification, B. natto is listed as a synonym for B. subtilis . Yet Japanese researchers have found repeatedly that fermenting cooked soybeans with any of the numerous bacteria closely resembling B. natto (including B. subtilis , B. cereus , B. megaterium , B. mycoides , etc.) fails to produce a product of natto's characteristic sticky filaments and flavor. Moreover, B. natto can neither grow nor propagate without biotin; other strains of B. subtilis can. A bacteriophage that dissolves B. natto has no effect on B. subtilis . Thus Japanese researchers believe that B. natto is clearly a different species from B. subtilis (Watanabe et al. 1971).

Traditionally natto was always widely considered to be a food that promoted long life and good health. Ohta (1975) made the interesting observation that the five Japanese researchers who pioneered the development of natto in the early 1900s, each ate natto daily and had an average lifespan of 80.4 years, far above the average.


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