Micro Lab Project
Quantitative & Semi-quantitative Viable Plate Counts
Molly Wright, Jenny Cano, Rosa Ramirez
BIOL 2420 Lab M/W
4/20/15
Professor Rotibi
ABSTRACT: Accurate evaluation of bacterial colonization as a predictive index for alfalfa sprouts has relied on a quantitative culture technique that provides exact colony counts per gram of tissue by culture of five serial dilutions of the alfalfa water. In this study 1 package of alfalfa sprouts were cultured by a semi-quantitative technique that enumerated the number of gram-negative enteric organism in 1 ml of alfalfa water. Exact colony counts from the experiment were available only from cultures 10-2 and 10-3 CFUs. Other colony counts were reported as less than 10-3 or greater than 10-1 CFUs. Therefore, this quantitative and semi-quantitative culture technique provides us with accurate information, shows us how to calculate the number of colony forming units, and helps us gain a better understanding of the importance of viable plate counts.
Introduction to Literature: It is very important to know not only what types of bacteria are in a sample but also how many of them are present. After a 2010 outbreak, founder Jimmy John Liautaud switched the sandwich chain to clover sprouts after Salmonella illnesses were associated with alfalfa sprouts. According to the Centers for Disease Control and the Food and Drug Administration, unwashed or lightly rinsed vegetables can harbor pathogenic bacteria and have been implicated in numerous food borne infections. Food manufacturers are required by the FDA to monitor the number and type of bacteria in their products. Very few of the things we eat or drink are bacteria free. They merely have greatly reduced numbers of “harmless” bacteria. It is often necessary to determine how many live bacteria are actually in a sample, especially when measuring growth rates or determining disinfectant effectiveness. This involves MacConkey agar which is a selective and differential
Molly Wright, Jenny Cano, Rosa Ramirez
BIOL 2420 Lab M/W
4/20/15
Professor Rotibi
ABSTRACT: Accurate evaluation of bacterial colonization as a predictive index for alfalfa sprouts has relied on a quantitative culture technique that provides exact colony counts per gram of tissue by culture of five serial dilutions of the alfalfa water. In this study 1 package of alfalfa sprouts were cultured by a semi-quantitative technique that enumerated the number of gram-negative enteric organism in 1 ml of alfalfa water. Exact colony counts from the experiment were available only from cultures 10-2 and 10-3 CFUs. Other colony counts were reported as less than 10-3 or greater than 10-1 CFUs. Therefore, this quantitative and semi-quantitative culture technique provides us with accurate information, shows us how to calculate the number of colony forming units, and helps us gain a better understanding of the importance of viable plate counts.
Introduction to Literature: It is very important to know not only what types of bacteria are in a sample but also how many of them are present. After a 2010 outbreak, founder Jimmy John Liautaud switched the sandwich chain to clover sprouts after Salmonella illnesses were associated with alfalfa sprouts. According to the Centers for Disease Control and the Food and Drug Administration, unwashed or lightly rinsed vegetables can harbor pathogenic bacteria and have been implicated in numerous food borne infections. Food manufacturers are required by the FDA to monitor the number and type of bacteria in their products. Very few of the things we eat or drink are bacteria free. They merely have greatly reduced numbers of “harmless” bacteria. It is often necessary to determine how many live bacteria are actually in a sample, especially when measuring growth rates or determining disinfectant effectiveness. This involves MacConkey agar which is a selective and differential