Message from the Group Leader

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Masayuki Inui

Molecular Microbiology and Biotechnology Group
Group Leader
Masayuki Inui

"Biorefining" is defined as the sustainable processing of biomass into a spectrum of bio-based products and bioenergy. Over the past several years, the biorefinery concept attracts rising attention as a key strategy to achieve a low-carbon society. In 2014, the first commercial-scale (over 25 million gallons per year) cellulosic ethanol plants in the United States opened for business thanks to the support from the government. Cellulosic ethanol, which is produced from non-food biomass and more carbon-efficient, is a promising alternative to corn-based ethanol. According to a survey conducted by a private company in the United States, commercial production of bio-based products is expected to double over the next few years and reach over 13 million tons per year by 2017. The expected increase is attributable to growing demand for bioplastics such as bio-polyethylene terephthalate and the bio-polyethylene.

The ongoing shale gas revolution reshapes the energy industry and markets, and the rapid growth of the shale gas-based "New petrochemical industry" is expected. The rise of the shale gas industry greatly influences on the biorefinery industry. For example, price competitions in the methane or ethylene-based product markets will get keen. The advent of shale gas, on the other hand, may provide a new business opportunity to the biorefinery industry. With the current technologies, it is hard to produce compounds that contain more than 4 carbons or aromatic rings from shale gas, and the demand for these compounds, which can be produced through bio-based processes, will increase as the shale gas industry grows.

In 1990s, we started a research project to develop biorefinery technologies and established our core system "Growth-arrested bioprocess". Based on this unique system, we have achieved efficient bio-production of ethanol, organic acids, and amino acids. We are currently working on commercialization of our technologies. Our workforce Corynebacterium glutamicum has a unique property, which is the key for "Growth-arrested bioprocess". Under a certain condition, the bacterium stops growing while its major metabolic pathways remain active. "Growth-arrested bioprocess" takes advantage of this feature, achieving higher yields and rates compared to the conventional fermentation processes, in which formation of products and biomass inevitably occurs in parallel. "Simultaneous utilization of C6 and C5 mixed sugars" and "tolerance to fermentation inhibitors" are the two major challenges for processing of non-food biomass to bio-products and biofuels. To the best of our knowledge, our "Growth-arrested bioprocess" is the only bioprocess that overcome both of these challenges.

In recent years, long-chain alkanes and aromatic compounds draw increasing attention as materials for jet fuels, polymers, pharmaceuticals, cosmetics, dyes and so on. Due to the intrinsic toxicities of these compounds, however, their commercial-scale production by conventional growth-associated fermentation has been hampered. We found that C. glutamicum is much more tolerant to the toxicities of long-chain alkanes and aromatic compounds compared to other industrial microorganisms such as Escherichia coli and a solvent-tolerant bacterium Pseudomonas putida. Indeed, we have achieved higher productivities of toxic compounds like phenol compared to the published data, using our "Growth-arrested bioprocess".

Aiming at commercialization of our technologies, we, RITE, launched collaboration with Sumitomo Bakelite Co., Ltd., and developed a "two step bioprocess for phenol production". The invention opened the door to commercial-scale production of phenol from C5 and C6 mixed sugars derived from non-food cellulosic biomass. In 2014, we established "Green Phenol Development Co., Ltd." in order to speed up the commercialization process.

A current goal of our group is to further improve our "Growth-arrested bioprocess" and enable bio-production of diverse fuels and chemicals regardless of their toxicities. Through our research activities, we would like to contribute to establishing an energy- and carbon-efficient society. I would appreciate your continued support.


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