Effects on Bacteria

In 2006, the space shuttle Atlantis carried salmonella bacteria into space as part of an experiment designed by Arizona State University biologist Cheryl Nickerson. Salmonellosis is the second most common foodborne illness, with 30,000 confirmed cases every year in the U.S., and the most common cause of enteric disease (Salmonella, 2011). The salmonella was returned to Earth and immediately used to infect mice before it could become accustomed to Earth's gravity again. The mice got sicker faster and were affected more severely than when infected with normal salmonella, showing that the bacteria became more dangerous after being in microgravity (National Public Radio, 2007).

Previous studies have indicated that some bacteria grow faster and become more resistant to antibiotics in space. The salmonella cells were studied and changes were found in 167 genes and 73 proteins. Some salmonella even formed biofilms, a slime layer that could account for causing worse diseases and a higher resistance to antibiotics. (Stemp-Morlock, 2007). Microgravity affects how fluid reacts with cell membranes, or fluid shear. Low shear environments, such as in space and in the intestinal tract, allow bacteria to thrive. In space, astronauts' immune systems weaken, because osteopontin is affected, which is important in bone remodeling and is also found in the spleen and thymus (MSNBC, 2007). These organs create white blood cells, which battle infections. Osterpontin is an important factor in cell attachment and wound healing. Therefore, astronauts are at an increased risk of falling sick because bacteria can be altered and the body is less capable of countering illnesses.