Human Microbiome Project Case Study

Rob Knight’s TED talk, “How our microbes make us who we are,” addresses the role of microbes in our development and health along with our genetic makeup. He discusses many important microbial roles in the human body, including those discovered by the Human Microbiome Project. Knight has incorporated the basis of the Human Microbiome Project to essentially map out the microbes of the human body on a worldwide spectrum into the oral, skin, vaginal, and fecal communities. In his project, Knight indicates that the microbes that colonize the human gut have a role in identifying obesity with more precision than genetic studies. He presents findings in studies with microbial associations with obesity in mice, which will be discussed next. (Knight)
Further inspection of the specific microbes involved caused researchers to speculate that Bacteroides species of the Bacteriodetes phylum prevented further weight gain in obese mice upon transfer from the lean mice. Unfortunately, this idea was proven false upon placing obese mice and lean mice in the same habitat, which resulted in a lack of reduced weight gain in the obese mice. In fact, Bacteroides was found to be more prevalent in obese mice than lean mice, possibly indicating that they thrive on high-fat diets. Thus, the researchers began to question the role of diet in microbial influence on obesity. Upon a healthy diet (i.e., low-fat, high-fiber) change and a microbial transfer from lean mice, obese mice experienced significant weight loss. The fiber can be used by microbes in the gut to produce short-chain fatty acids (SFCAs). Then, the microbial host can use the SFCAs as energy, which explains the ability of the lean mice to remain lean. If obese mice begin eating a low-fat, high-fiber diet, then they will produce more SFCAs and expend more energy to
Kefir contains live and active probiotic cultures. In lab, we isolated Lactobacilli colonies from dilutions of kefir on LBS plates. Both the TED talk and Walker & Parkhill’s article emphasize the importance of identifying microbes that carry out certain functions that the human body cannot due on its own, such as gut microbes that covert fiber into short-chain fatty acids. Lactobacilli are capable of fermenting sugars to lactic acid. Since they are acidic, they can live in the harsh environment of the gut. These bacteria can prevent the colonization of harmful bacteria, thus diverting unnecessary symptoms such as diarrhea that would otherwise occur. Thus, similar to the bacteria discussed in the article and the TED talk, Lactobacilli is