A new weapon against vitamin A deficiency: Yogurt
Grad student Christopher Johnson hopes to save lives with a little help from some microscopic partners.
Fri, Oct 11, 2013 at 02:45 PM
What do bacteria, yogurt and vitamin A have in common? For most of us, not so much. For Christopher Johnson, though, the not-so-obvious connections could well be the key to preventing 300,000 child deaths in India each year.
Inspiration struck last year as Johnson was finishing up his undergraduate degree in microbiology at the University of Wisconsin-Madison. While inserting genes into E. coli bacteria to make them produce a type of jet fuel — part of a student competition in synthetic biology (aka genetic engineering) — his mind began flooding with other intriguing possibilities. “I started thinking about the amazing power that we as scientists have … we can program some organisms like computers to produce almost anything,” Johnson says.
A few serendipitous breaks later and Johnson, now a first-year graduate student in bacteriology at UW-Madison, is well on his way to making a dent in the intractable problem of vitamin A deficiency in developing countries. (Johnson is shown at right with Dr. James Steele.)
Not bad for a 23-year-old with ADHD and a less-than-stellar academic record. “I’m not very good at a structured classroom setting,” he says. “I always wanted to go out and do cool things because there are lots of cool things to be done.”
Johnson’s wandering curiosity quickly landed on the idea of coaxing microbes to produce vitamins that could be consumed in foods and help prevent diseases. Fermented foods were an obvious choice because they already contain beneficial bacteria, and vitamin A became a top pick because many bacterial species readily produce it with a few easy genetic tweaks.
Johnson, an avid home beer brewer, briefly flirted with enriching beer (which uses yeast for fermentation instead of bacteria), but finally settled on something with wider age and cultural appeal: yogurt. Another bonus: Yogurt contains Lactobacillus casei, a well-known probiotic bacteria that’s easier to engineer than yeast. Plus, it can be readily modified to produce beta-carotene, which the body converts to usable vitamin A in the amounts needed so there’s no risk of overdose.
Next, Johnson chose India, where yogurt is a staple food and children and pregnant women are disproportionately affected by vitamin A deficiency due to the lack of affordable fruits and vegetables. Vitamin A is critical for eye health, as well as for proper fetal development and for boosting the immune system to fight infections.
In a stroke of serendipity, Johnson also lined up three professors on campus with just the right expertise: Dr. Sherry Tanumihardjo, an expert in Vitamin A metabolism who has worked extensively in India; Dr. Brian Pfleger, a professor of chemical and biological engineering with experience in bacterial biosynthesis of carotenoids (colorful plant compounds that include beta-carotene); and Dr. James Steele, a food scientist specializing in dairy fermentations containing Lactobacillus casei. Steele is also now the project’s principle investigator.
With everything in place, Johnson applied for a grant from a group called Saving Lives at Birth, an international program launched in partnership with the U.S. Agency for International Development (USAID), the Bill & Melinda Gates Foundation, the government of Norway, Grand Challenges Canada, and the UK's Department for International Development (DFID). To Johnson’s surprise he was awarded $175,000, and Project Drsti was born (drsti means sight in Hindi).
“I’m still a bit in shock,” says Johnson. “Not having the best undergraduate record, I think the fact that I took the initiative to make this happen probably also got me into grad school.”
Not your run-of-the-mill Frankenfoods
Over the next two years, Johnson will develop a freeze-dried strain of beta-carotene-producing bacteria that looks like a powder and comes in packets for distribution to women in India who make yogurt for their households and other small-scale yogurt producers. “The idea,” says Johnson, “is to introduce our bacteria to local starter cultures.” Yogurt is created by adding a small portion of the previous batch containing local bacteria strains — a starter culture — to a new vat of milk. “After that our bacteria will remain in all starter cultures, continuously producing bio-fortified yogurt with no change in production methods,” he says.
If this sounds like GMO yogurt, well, technically it is. But as Johnson notes, humans have consumed yogurt, Lactobacillus casei, and plants containing the same beta-carotene genes for millennia. Even if the genes jump to other species (which inevitably happens in nature), those species will simply begin producing beta-carotene or nothing at all. “I’m not worried,” Johnson says. “We’ve made mistakes with genetic engineering, but our power to modify bacteria to do chemistry for us can also yield great things, including better food.”
Johnson ultimately hopes to scale things up. The same process could be used to fortify other fermented foods around the world, such as cheese, kefir and fermented yams (a staple in Africa where vitamin A deficiency is also rampant). “I’d like to start an NGO or partner with one to enable people in developing countries to turn this technology into a business,” Johnson says. “There are lots of intelligent people out there, and sometimes all they need are the tools.”
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Christopher Johnson and James Steele: Busra Aktas