A Study of the Relationship Between Acidity and Bacteria Common in the Human Intestine

Abstract

In today's age, companies are producing more and more carbonated and sweetened beverages. The pancreas and stomach are responsible for breaking down the compounds in these drinks using acid, and drinking too much soda may cause pain or indigestion. But is it possible that acidic compounds could be a breeding ground for more serious issues, even including cancer? About 60-70 million people in the U.S. suffer from intestine-related diseases, including colon and intestinal cancer. A common cause of these cancers is Escherichia coli, a rod-shaped, coliform bacterium that lives in the intestine when introduced to a host. This study aims to find a relationship between the acidity of an E.coli culture and the number of E.coli cells present in that culture, incubated under similar temperatures sustained in the human body, in three days. To successfully carry out this study, 10 Petri dishes were marked in pairs of two, marked down with their corresponding level of acidity. The dishes were marked in halves such that 4 trials could be made, and the pH of the dishes ranged from 2 (very acidic) to 11 (very basic). A serial dilution was used to achieve these levels, and a streaking technique was used to achieve accurate data with the cultures. The agar plates were incubated at 37 degrees Celsius, and after 4 days were taken out and examined. The zone of inhibition was measured for each culture. There was a larger zone of inhibition for more basic pHs, while there was little to no zone of inhibition for the acidic cultures. This is significant to demonstrate a relationship between the acidity of an E.coli culture and the number of E.coli cells present in that culture, as the more acidic the culture is, the less inhibited the growth of the cells became.