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Home 9 2021 Student Research Symposium 9 Shrihari Nagarajan

Shrihari Nagarajan

Junior at Thomas Jefferson Independent Day School
Physical and Biological Sciences Category


Shrihari Nagarajan is a junior at Thomas Jefferson Independent Day School in Joplin,  Missouri. He enjoys various extracurriculars and sports. Since middle school, Shrihari has participated in several math competitions and quiz bowl tournaments, earning local, state, and national recognition. Shrihari is also passionate about the arts, excelling as a speaker, writer, piano and saxophone player. In addition to the arts, he is a dedicated athlete, participating in both swim and tennis. However, in all of his activities, Shrihari is most interested in the sciences. From taking AP science classes during the school year to completing a community health internship and attending science camps during the summer, Shrihari constantly immerses himself in the field. Just this year, he designed his own research project and conducted a study at a local university. After he graduates from high school, Shrihari hopes to continue his scientific studies as he pursues further education in medicine with the goal of becoming a neurologist.


According to the World Health Organization (WHO), nearly 1.7 billion cases of diarrheal disease are reported per annum, making the diarrheal disease a leading cause of malnutrition, morbidity, and death amongst children under five years old. Although antibiotics have been traditionally used to treat diarrheal disease induced by pathogenic gut microbes, increased antibiotic resistance amongst these microbes drives the need for a novel yet effective treatment. Thus, this study sought an efficacious prebiotic-probiotic pairing to inhibit the growth of specific pathogenic gut microbes through competition (growth promotion) and antimicrobial activity by means of cell-free culture supernatants (CFCS). A combination of absorbance analysis to measure growth and observed zones of inhibition from CFCS to measure antimicrobial activity was  used to deduce this “efficacious pairing.” The utilized probiotics, Lactobacillus casei and Bifi dobacterium bifidum, showed good growth with all pairings, particularly with the prebiotics galactooligosaccharides (GOS) and fructooligosaccharides (FOS) respectively. However, the  CFCSs obtained from prebiotic-probiotic pairing cultures did not possess antimicrobial activity against the pathogenic gut microbes Shigella sonnei, Salmonella enterica subsp. enterica, and  Escherichia coli. This suggests that the compounds produced by the observed pairings do not effectively inhibit the growth of the observed pathogenic gut microbes. Nevertheless, with further investigation, the observed prebiotic-probiotic pairings could potentially serve as treatments of diarrheal disease in the future by means of the “prebiotic effect” or different mechanisms entirely, in the gut microbiota.

Poster Presentation