Samantha participates in sports to remain physically fit. She's also a Girl Scout. She aspires to become an FBI agent "to bring justice to the world."
Danielle enjoys dancing and sports. She is in the pre-engineering program at her school and wants to become either an attorney or an engineer.
After an E. coli bacteria outbreak traceable to spinach sickened 187 people in 2006, Samantha and Danielle suspected that cow manure or other organic fertilizers might be to blame. They discussed the idea with a worker at a local plant nursery and developed a strategy to test vegetables for lingering bacteria in a controlled environment. Samantha and Danielle hypothesized that vegetables exposed to soil containing manure-based fertilizers would show more bacterial growth in the days after removal from the soil than vegetables exposed to time-released fertilizers.
Samantha and Danielle prepared four containers of soil. One container was untreated, whereas the others contained cow manure, turkey manure, or time-released fertilizer. They left the soil samples untouched for seven days and then placed nine vegetables into each container. After 24, 48, and 72 hours, they pulled batches of vegetables from each container and swabbed them. Dirt from the swabs was incubated for 24 more hours. They found that vegetables in contact with the manure fertilizers had higher bacterial colony counts 48 hours after exposure to the soil, which is similar to the time it takes some fresh vegetables to go from farm to shelf.
