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In Monica Ponder’s lab, Jessie Waitt isolates Salmonella spp. colonies extracted from lettuce, using selective media agar plates.
Hydroponic farm to fork; what are the risks?
According to the Centers for Disease Control (CDC) 46 percent of all food outbreaks originate from produce, which includes plants, vegetables, herbs, and fruits. Unlike meats, vegetables are not always cooked to kill food borne pathogens and the risk associated with the contamination of produce from hydroponic farming environments is widely unknown.
Hydroponic farming is different from traditional farming methods where the growth of plants occurs in soil; hydroponic farms replace soil with water to cultivate crops. Hydroponic farming methods are beginning to grow in popularity worldwide, because of their ability to produce a large amount of crops in a limited amount of space. Virginia Tech has its own facility in Saltville, Virginia.
Jessie Waitt of Powhatan Va., a master’s student in food science and technology works with Monica Ponder, assistant professor of food science and technology in the College of Agriculture and Life Sciences to examine the contamination risks associated with harvesting, packaging, transporting and storing hydroponically grown lettuce. The ultimate goal of her research is to inform good agricultural practices.
“There are several instances where lettuce has the opportunity to become contaminated,” said Waitt. Water—the characteristic that makes hydroponic farms unique—can also introduce risk for contamination.
Waitt’s experiment proposed the question: if the water supply becomes contaminated with the pathogen Salmonella enterica, can the pathogen reach the head of the lettuce and survive under recommended storage temperatures?
She found that yes, it can. Waitt modeled the entire process from farm to table in both ideal and ‘reality’ based conditions. The standard for realistic conditions involved warmer storage temperatures of 12 degrees C, which studies have found is the norm in most household refrigerators.
In both conditions Salmonella survived and was found on the head of the lettuce.
“Previous research has stated that removing the outer leaves of lettuce was enough to remove the pathogen, and that is not what I found,” said Waitt. In the photos below, Waitt uses glow germ to demonstrate how easily contamination can spread. Glow germ is only visible to the human eye with a black light, and is often used to train children about the importance of washing hands.
Waitt’s mentor, Monica Ponder, places a large emphasis on the importance of this research informing better agricultural practices.
“Several local hydroponic farmers have demonstrated an interest in these practices and the hope is this research can help us better guide them,” said Ponder. Ponder, along with other Virginia Tech researchers, works with the Virginia Cooperative Extension to train extension agents who in turn train local farmers. One of the program’s aims is to help make food safer.
Waitt is just under three months from achieving her master’s degree and and received her undergraduate degree in biology and chemistry from Sweet Briar College in 2009, after which she spent 18months working as a microbiologist with Pfizer/Wyeth Pharmaceuticals. Ponder and Waitt are working towards publication of these findings.
Waitt’s favorite pastime is riding Tarzana, her horse. “If I don't find a job right away in microbiology, I will just spend more time with Tarzana,” she said.
Another characteristic that makes Waitt unique is that she is deaf. She lost her ability to hear at 2 years old from a bacterial meningitis infection. However, her loss of hearing has not slowed her ability to communicate effective agricultural practices or to help influence farmers.
CDC Citation: Painter JA, H. R., Ayers T, Tauxe RV, Braden CR, Angulo FJ, et al. 2013. Attribution of Foodborne Illnesses, Hospitalizations, and Deaths to Food Commodities by using Outbreak Data, United States, 1998–2008. Emerging Infectious Diseases. 19.
What attracted you to your particular field of science?
It all started in 3rd grade at a science fair/poster competition. I have to admit I was disqualified because I refused to stand by my poster. I was too busy reading everyone posters and asking what may seem like a million and one questions. Later that day, I went home and told my grandparents that when I grow up I wanted to be a scientist. They encouraged me every step of the way.
What are your ultimate career goals?
I would love to go back to my previous job; ensuring over-the-counter consumer drugs are not contaminated with harmful pathogens and are within compliance of the FDA (US Food and Drug Administration) standards.
Which quality of the following do you feel is the most important for a scientist to possess—open-mindedness, precision, time management skills, optimism, cynicism, integrity, a good sense of humor? Why?
I strongly believe all of those characteristics are important to be a successful scientist. A harmonization of all those characteristics will gain respect. When fellow colleagues respect you, you have the power and the responsibility to contribute significant findings in your field of study. This motivates others to fulfill that path by advancing key approaches leading to new discoveries.
Be a geek: what’s your favorite piece of equipment to use in the lab? Why?
Believe it or not, I really enjoy making selective agar plates for isolation of bacterial colonies. I know it may appear time consuming to others, but it relaxes my mind allowing me to be a forward thinking scientist.
Which type of science, other than what you study, interests you most?
I always had a passion for understanding animal behavior. The way animals communicate and interact with one another through body language is extraordinary. In fact, as a deaf person, I heavily depend on body language to communicate with one another. I have gained a greater understanding and appreciation by adopting their techniques and it has opened many opportunities in life for me.
Have any pets?
Aye yes! I have a hamster (Daffy) who has no shame stealing raspberries or carrots in a heartbeat. I recently adopted an 18 pound cat (Jasmine) from a local shelter and she is not too thrilled with her new diet but a total snuggle bug. I also have a thoroughbred horse (Miss Tarzana) whose devotion and sweet love has made every ride therapeutic.