What are you aiming to achieve?

Fig. 1: Plastic made from plants gradually decomposes over time when buried in the ground.

 We hear the words “green innovation” fairly regularly nowadays. This is the slogan of the movement to develop environmentally friendly industry and society. “Green” stands for plants, and “innovation” stands for technological advance. But why plants? If you wander around the vast grounds of Hokkaido University, you will see majestic poplars and gingko trees changing color. That cycle of life goes on forever, unless some sort of man-made or natural disaster occurs. Plants have existed since before human beings appeared on the Earth; in the summer they fill with leaves, which fall beneath our feet in the autumn and then change back into nutrients to produce the next round of life. This is a true “recycling society”. This is a model for science and technology, and an age is coming in which we will be able to create industrial systems where matter and energy are recyclable. In Hokkaido, we are seeing less and less snowfall each year, and we have become able to grow our own brand of rice. We are seeing the effects of global warming in these ways on a day-to-day basis. Every time I hear news of abnormal weather around the globe, I hope that this is not going to be the end of the world. Up until now we have used petroleum like water, making chemical materials and plastics, but now that we have nearly reached the end of our petroleum resources, we will not be able to carry on in the same way. We need to change over to using other materials. For this reason, we are attempting to make a bioplastic from biomass, which consists of renewable resources such as plants, and comprises the three important qualities of high performance, environmental friendliness and being non-hazardous to living organisms. I hope that we will be find a way to recycle carbon, the raw material of plastic, without waste. Achieving this would be our trump card—allowing us to finally create a low-carbon society.

 

What sort of equipment are you using to perform what type of experiments?

We are experimenting with using microorganisms in place of the flasks usually used in chemical experiments. Microorganisms are “microfactories”, which offer excellent chemical reactions. They ferment and produce yogurt and natto, which we need in our diets, and can manufacture antibiotics with complex structures. I got a bit greedy and wondered if they might also make plastic, and lo and behold, they did! Not only that, but we used plants as the raw material. When we started to look at what was behind this magic, we had to look at it from an enzyme and genetic level. This is the “micro” world, so it is possible to watch the microorganisms synthesizing plastic with an electron microscope (Fig. 2), and to take it out and stretch it (Fig. 3). In addition, we used genetic engineering to produce large quantities of optimized plastic-synthesizing microorganisms in a culture device. The plastic samples were measured in a tensile testing machine (Fig. 4) and subjected to other tests, in order to consider what they might be applicable for. Making things and then exploring what they can do is the real thrill of being in the engineering department!

Fig. 2 Plastic is synthesized inside the microorganism cells.	Fig. 3 Plastic removed from the microorganism cells
Fig. 4 Analysis using a tensile testing device	Fig. 5 3D structure of enzymes

There is always another key performer in the shadow of a major player like plastic. In this case, it is enzymes. Enzymes are catalysts that promote reactions within a living body, and they are extremely elaborate molecular machines. If microorganisms are the factory, enzymes are precisely manufactured machinery. It is also possible to improve the function of plastic manufacturing by remodeling these enzymes through engineering. In order to explain the 3D structure of enzymes (Fig. 5) that are vital to remodeling research, we sometimes use a device that can emit vast quantities of synchrotron emitted light. At present, we are in the process of creating a system that can manufacture many and various types of bioplastics extremely efficiently, using many evolved enzymes.

 

What are you aiming for next?

My dream is to be able to create plastic on an allotment! By that I mean I would like to create plastic within plants, from water and CO2, and using only sunlight. It is perhaps the ultimate future technology – a system wherein scientific techniques that began with plants are in the end completed using plants. They share genetic information relating to living things, so the software to synthesize plastic still works even if it is transferred from microorganisms to plants. If we use them wisely, the world can develop such that plants can be used for both food and plastic production. I hope that many students will share this dream, and come and join us. Please see our website for more details.

 

References

Taguchi S. (joint author), Biotechnology – from Molecules to the Environment, pp. 134 – 154, Kyoritsu Shuppan (2000)