Yutaka Mitani talks to a Brazilian researcher via his home computer. It is past 8 a.m. for the researcher, who has just started work for the day. (Atsuo Hirata)
By ETSUSHI TSURU and ATSUO HIRATA/ The Asahi Shimbun GLOBE
Although the beer-making process is known for creating refreshing beverages served the world over, it is now on the verge of helping Japanese researchers create cleaner fuel cells, reduce greenhouse gases and eliminate waste.
Japan, Europe and the United States are making advances into the production of hydrogen by using micro-organisms to decompose food and agricultural waste.
Sapporo Breweries of Japan’s Frontier Laboratories of Value Creation in Yaizu, Shizuoka Prefecture, has been carrying out studies on hydrogen production since 2002. The team is led by chief of research Yutaka Mitani, 56.
The studies are important for the environment because the burning of hydrogen does not produce any gas that contributes to global warming or air pollution.
Furthermore, demand for and production of hydrogen is expected to soar if fuel cells that create electricity by inducing a chemical reaction between hydrogen and oxygen become widely used.
Currently, hydrogen is largely manufactured from oil and other fossil fuels, emitting carbon dioxide in the process. If hydrogen can be produced from food and agricultural waste, carbon dioxide emissions will be kept in check while reducing the amount of garbage.
In beer-making, yeast breaks down the sugar content in malt to create alcohol and carbonated gas. It has long been known that certain bacteria produce hydrogen during fermentation, in the same way as brewing.
These bacteria are classified into two major groups.
One variety, which photosynthesize in bright places, is better at producing hydrogen. But its need for sunlight requires greater costs because a large pool-like area must be constructed.
The other variety, which prefers dark and oxygen-free environments, is more suitable because it can decompose food and agricultural waste within the darkness of a tank.
The Sapporo Breweries researchers searched for a type of bacteria that fulfilled several criteria, such as the ability to produce sufficient amounts of hydrogen, being able to remain active within the acidic environment of a reactor tank, and not growing under a temperature of 50 degrees Celsius to ensure it has no ill-effect on humans.
Mitani and his team gathered mud from different parts of the country, believing that airless mud would give them the best chance of finding the bacteria they were looking. They gave up their vacation days and carried out their studies for four straight months.
Sludge at a sewage treatment plant in Hiroshima Prefecture finally gave them a variety of bacteria that fulfilled all of the criteria. Mitani’s team named it PEH8.
However, other obstacles remained.
Waste contains various kinds of bacteria, some of which would surely invade the sewage treatment plant from the outside.
If PEH8 lost this turf war with other bacteria and ceased to function adequately, it would be unable to produce a stable supply of hydrogen. The researchers learned that its most formidable “enemies” were methane-producing bacteria and lactic acid bacteria.
A chemical was found that efficiently eradicated the methane-producing bacteria, but lactic acid bacteria were more resilient. As the team tried various ways to eliminate the stubborn bacteria, Mitani had a revelation: “What about hops?”
Lactic acid bacteria also hinder the beer-brewing process, turning it sour when mixed in. But plant-derived hops, which are essential in forming a beer’s flavor and aroma, also play the important function of suppressing the growth of lactic acid bacteria.
The hops had an immediate effect when mixed with PEH8. They killed only lactic acid bacteria, leaving the PEH8 unscathed.
“Being a beer company certainly helped us to come up with this idea,” Mitani says.
Mitani and his team subsequently created a variant strain called PEH9 that grows even in strong acidic conditions. A factory owned by Hiroshima City-based Takaki Bakery is carrying out trials to produce hydrogen from baking waste. The production tank being used is 5 cubic meters, the largest in the world.
Trials have also been progressing in Brazil since 2009. Sapporo Breweries is working with local biofuel company Ergostech and oil company Petrobras to extract hydrogen from sugar cane leftovers and other byproducts from the manufacture of bioethanol.
“A bioethanol giant like Brazil has a massive amount of waste,” says Osaka University professor Jun Miyake, who chaired the International Energy Agency Hydrogen Implementing Agreement (IEA HIA). “This plant is the closest in the world to putting this technology into practical use.”
JAPAN, ONCE A BACTERIAL POWERHOUSE, LOSING ITS ‘WEALTH’
On a clear day, South Korea is visible from Tsushima, a Nagasaki Prefecture island in the Genkai Sea.
In the garden of a farm facing the island’s fishing port, a line of baseball-sized dumplings dries in the sun.
“These are called ’sendango.’ They’re not done yet,” says Sanae Okada, a professor of microbiology at Tokyo University of Agriculture.
The dumplings are a local delicacy made from fermented sweet potato starch.
“Sen” means sweet potato while “dango” is the Japanese word for dumpling.
On Tsushima where rice could not be grown, sweet potatoes have been farmed for generations as a traditional nonperishable food.
I visited the island in mid-December 2012, when the sweet potato harvest was over and the sendango-making season was in full swing.
The potatoes are ground with a mortar and formed into large dumplings, then left in the sun to dry and ferment before being softened in water and strained. Micro-organisms grow within as this process is repeated, resulting in a pure-white dumpling after around four months. The finished product is slightly larger than the tip of a thumb.
Before visiting the farm, I sampled the folk dish “rokube-jiru” at a nearby eatery. It is made from sendango boiled in water and stretched into long, thin noodles. They look like udon noodles, but the firm texture is clearly different.
“Sweet potato starch and fiber aren’t enough to make them this way,” Okada says. “Their chewiness comes from mold.”
Tsushima is not the only place where this mold is found, but it is the only place where sendango are made.
Okada began visiting Tsushima frequently seven or eight years ago. To understand how sendango ferment, he had to analyze not only the dumplings, but also the mold and other micro-organisms at the various stages in their production.
“As sweet potato ferments, the mold goes through several generations. I study its relationship with yeast, bacteria, and other things in great detail,” he says.
Okada began a survey 13 years ago of fermented foods made with the aid of micro-organisms.
He phoned local government offices around the country and searched for unusual regional foodstuffs passed down through generations.
“Fermented foods are part of Japan’s traditional culture. We have to look into the types of micro-organisms at work in regional foods, and protect the rare ones,” he says.
In fact, Okada has made some intriguing discoveries, including “sunki,” which has been made from the pickled leaves of red beets in the Kiso region of Nagano Prefecture for centuries.
Japanese pickles are typically fermented by sprinkling salt on leaves to bring out their nutrient content, which is used to grow lactic acid bacteria. However, sunki is fermented without the use of salt.
“There are several kinds of lactic acid bacteria at work that are completely different from those found in pickles that need salt in order to ferment,” Okada says. “They have great potential for use in making pickles with a reduced sodium content.”
Lactic acid bacteria were originally one of Okada’s research specialties. He has collected around 5,500 Japanese and Southeast Asian varieties, and says that those found in Japan are diverse in type and qualities.
“Even lactic acid bacteria of the same variety can produce different smells depending on where the sample was collected. Just like people, each has its own individual personality,” Okada says.
The diversity of micro-organisms is deeply linked to the flora of a particular area. Japan, which spans 2,700 kilometers from north to south and has a wildly varying climate that includes subarctic, tropical and subtropical zones, possesses a rich array of plant life.
Based on these conditions, it is estimated that about 13 percent of the world’s eumycetes, or true fungi, exist in Japan, one of the world’s foremost “bacterial powerhouses.”
Recently though, with the population aging and the hollowing out of its rural areas, the country’s bounteous culture of fermentation, represented by miso, soy sauce and pickles, is slowly dying. This includes Tsushima, where the number of farms making sendango continues to dwindle. If one fermented food disappears, it will become even more difficult to study the micro-organisms involved in making it.
To begin with, there is very little in the way of comprehensive data on micro-organisms in Japan. Concerns are also rising that eumycetes and bacteria that have been steadily collected by universities and research institutions will be discarded due to financial pressure.
“We’re only aware of about 5 percent of the yeasts used in beer, sake and bread,” says Moriya Ohkuma, head of RIKEN’s microbe division, which holds around 21,000 specimens of micro-organisms. “For the sake of Japanese industry as well, we must grasp the distribution and characteristics of these resources.”