What is E. coli? E. coli bacteria live in the digestive systems of humans and other warm-blooded animals, as well as in soils and water. Most strains of the E. coli bacteria are not dangerous, but certain strains can cause illness in humans. The presence of E. coli in water is a strong indication of recent sewage or animal waste contamination. Water is monitored for E. coli because it can indicate the presence of other disease-causing bacteria. Source: NOAA Center of Excellence for Great Lakes and Human Health |
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Elizabeth AlmResearchers Test Shoreline Sand for Genetic Pollution A brisk June breeze cooled the pubic beach in East Tawas as Central Michigan University (CMU) student David Sadler twisted a sterile plastic tube into the wet Lake Huron sand. After removing the core, Sadler held it steady as fellow student Erica Clark divided five sections of sand into sterile plastic bags. The students, led by CMU microbiologist Elizabeth Alm, are analyzing sand at four other Great Lakes recreational beaches in 2006 as part of Michigan Sea Grant funded research investigating the bacterial environment of shoreline sand. Alm has studied microorganisms contained in shoreline sand since 2001. “When we first started, we had the idea that some beaches would be better than others,” says Alm. “But we’re finding that they’re all the same. Fecal bacteria is present everywhere.” In most cases, she adds, bacteria contained in shoreline sand persists in higher quantities than bacteria measured in the water. While bacteria are part of the natural environment, Alm is investigating the potential for this rich bacterial environment to promote the exchange of genetic material, creating what amounts to “genetic pollution.” At issue are three specific genes that could be transferred among bacteria that inhabit the sand. The genes, if present, would indicate the presence of bacteria with the potential to cause disease. In tests conducted in 2005, Alm reports that while two of the genes are rare, one of the genes was detected in 80 percent of beach sand samples analyzed (69 percent of sand samples from the Michigan beaches of Lake Huron, and 92 percent of sand samples from the metro Detroit beaches of Lake St. Clair). Sand was collected from public beaches in Iosco County, St. Clair County and Macomb County. James Herrick, Alm’s colleague at James Madison University, also confirmed the presence of genetic material called plasmids from bacterial populations in a sample of sand collected from Metro Beach on Lake St. Clair in July 2005. The plasmids are capable of conferring resistance to the antibiotic tetracycline. Herrick will test resistance to additional antibiotics on new samples being collected this summer. |