Multitalented researcher tackling challenges in the world of microorganisms

Researcher Mai Shimizu encountered microbiology for the first time when she joined Dai Nippon Printing Co., Ltd. (DNP) six years ago, but her fascination with how Escherichia coli and other bacteria found in food behave has helped her research and development team at the Packaging Operations department complete a rare product emblazoned with the DNP brand name.

“Even though they belong to the same strain of bacteria, say E. coli, each behaves differently from the others, like human beings,” Shimizu explains about the objects of her research that culminated in her team's development of Medi・Ca, a ready-made dry medium for bacteriological tests. “We selected chromogenic enzyme substrates for Medi・Ca that emit a certain color when they react to a chemical substance produced by more than 90 percent of E. coli. Some produce the substance right away, others do so very slowly. For nutrients in the medium, we selected a 'recipe' most likely to be loved by every coliform.”

Shimizu smiles as she discusses bacteria. Her affinity toward microorganisms perhaps stems from her mission to facilitate growth of bacteria in a medium, rather than killing them.

Medi・Ca, which went on the market in September 2014, makes testing for bacteria in food much simpler. Conventionally, the food industry conducted bacteriological tests by preparing an agar medium inside a Petri dish, a process that requires specific skills and takes a few hours. Medi・Ca eliminates this cumbersome preparation and allows testers to conduct tests without acquiring special skills. In this method, a tester puts one milliliter of a liquid sample on a sheet coated with gelling agents, nutrients and color former, covers with the attached plastic cover and leaves it for several minutes on a flat surface. The sample then is ready for incubation for a couple of days.

Medi・Ca has four kinds of media for testing bacteria: aerobic bacteria; coliform bacteria; E. coli and coliform; and staphylococcus aureus, which was added to the lineup in June 2016. These four media are able to deal with 70 percent of food microbiology testing conducted by food makers and other companies.

Challenges of a latecomer

DNP is a latecomer in developing the sheet-type medium for bacteriological tests, so the company must differentiate its products from those of its rivals. To overcome this challenge, the team put priority on making the product considerably easier to use: A plastic cover was attached over the medium so the sample can be spread evenly, while a hydrophobic resin ring surrounds the medium to prevent the sample from spilling off the sheet.

Harnessing its top-level image processing technology, DNP also introduced an automatic colony counting system in June 2015. A special scanner and sophisticated software enable testers to count colonies of bacteria within five seconds per sheet, much faster than manual counting.

But why is DNP, one of Japan's largest printing firms, making such a product in the first place? The move is in line with DNP's strategy to tap markets for products related to medical or health care as well as life science at a time when Japan faces a declining population and a shrinking domestic market.

DNP decided to produce Medi・Ca partly because it already possessed technologies needed to make it. DNP acquired expertise in controlling bacteria growth and microorganisms as it strived to extend the shelf life of food items that use its packaging products. The company's state-of-the-art technologies in coating materials on films or making functional sheets by bonding films together also were applied. Fortunately, the products' target customers are food makers and food processing firms, with which DNP has long-established business relationships.

Shimizu was able to rely on a DNP team of sterilization experts to teach her about the basics, including how to handle and test bacteria. “At first, I didn't even know which equipment I need to conduct research or how to handle bacteria, as my major was materials science and engineering at graduate school,” she said. “The team has specialized knowledge about sterilization.”

Working as a team

Nonetheless, DNP remains a minor player in the field of bacteriological testing. To improve its standing, the team of researchers – mostly in their late 20s and early 30s – with versatile talents handles a wide range of work from research and development to designing machines for mass-producing the product and sales promotions, including making pamphlets and videos. Every member plays an important part in this endeavor.

One of Shimizu's many talents is her linguistic ability. She began honing her English speaking and writing abilities one year after joining DNP, taking two hours of lessons per week. She wrote a scientific paper required for obtaining certification for one Medi・Ca variety as a reliable analysis method from the AOAC Research Institute, a nonprofit, third-party organization based in the United States. She is currently writing a paper for the fourth variety, for testing for S. aureus. Receiving approval from AOAC is regarded as vital for promoting a product to potential clients at home and abroad. Shimizu also plays a central role when the team receives visitors from abroad, explaining – as one of the developers­– the merits of the products in English, while listening to their needs.

Furthermore, Shimizu designed the packaging and decided how many test sheets should be inside each of several aluminum pouches in a box. To cap it off, Shimizu coined the name Medi・Ca from the English words “medium” and “card.”

Meticulous attention to detail an asset

Being a woman is sometimes advantageous for Shimizu. She often accompanies DNP sales representatives when they visit potential customers to explain about the company's products. “Since most people who carry out bacterial tests are women, I am able to see eye-to-eye with them,” Shimizu says. “If testers feel it cumbersome to count many colonies grown on a medium, I introduce them to the colony counting system. I sometimes conduct a test of the client's mainstay product to demonstrate the merits of using our products.”

Given Shimizu's vast knowledge of bacteriological testing and in addition to her meticulous attention to detail, testers often consult with her about problems in conducting tests on certain food items. She offers to conduct tests at DNP to find a solution, which can potentially lead to sales of Medi・Ca.

Hitoshi Kyotani, manager of Shimizu's team, heaps praise on her abilities. “Shimizu is a positive thinker who infuses insights men sometimes lack into her work,” he said. “We have two women in our team and their presence is a tremendous asset.” One-third of researchers at DNP's Basic Technology Development Department in Packaging Operations are women.

One more hat

In addition to being responsible for multiple tasks at work, Shimizu wears yet another hat during the weekends: she is a member of three amateur orchestras, including the DNP one. She plays the trumpet, while her husband – whom she met when she was a university student at the Tokyo Institute of Technology – plays the French horn.

“DNP is a huge organization, so I would never meet many of the employees just throw my own work,” Shimizu says. “Being part of the DNP orchestra gives me an opportunity to associate with people beyond the sphere of my work.

“In an orchestra, several dozen men and women, young and old, work together to create music by a deadline, which is the day a concert is held. It resembles a project team like our one at DNP.”

Many challenges lie ahead

Shimizu is determined to research microorganisms and media further and improve Medi・Ca. “This field has so much potential,” Shimizu says. “As far as technologies are concerned, there are ways to grow bacteria other than incubation. There are different media we can use to test for bacteria. We can make improvements, such as by shortening the time required for incubation, making bacteria colonies appear more clearly or detecting microorganisms even when there is a small amount of bacteria in the sample.”

Bacteriological tests at food makers are expected to gain greater importance around the world as they work to ensure food safety. DNP plans to market Medi・Ca in foreign countries including Thailand, where it already has some clients. Shimizu hopes to visit abroad to gather information about how bacterial tests are carried out and what potential clients' priorities are. “Medi・Ca is a rare product for DNP as it carries the DNP brand name for a company that makes mostly nonfinished products. We would like to make it an even more extraordinary product by, for example, selling it online – a small-lot sales method DNP has seldomly tried.”

DNP aims for ¥300 million in sales for Medi・Ca, including the colony count system, during the three years starting from 2016.

Medi・Ca is a trademark or registered trademark of Dai Nippon Printing Co., Ltd.

  • * Publication date:  Nov. 30, 2017
  • * DNP department names, product specifications and other details are correct only at the time of writing. They are subject to change without prior notice.