Colorectal cancer (CRC), with multifactorial influences of genetic, molecular, inflammatory, and environmental factors, is a leading cause of cancer-related deaths. Due to the high diversity and concentration of microbes found in the human colon, the microbiome has become a prime suspect of being a biological contributor. This prompts the need to investigate the relationship between microorganisms and CRC. Recent studies have shown that Fusobacterium nucleatum, Campylobacter showae, Leptrotrichia buccalis, and Selenomonas sputigena are overrepresented in colon tumors. These anaerobes have known associations to the oral microbiome and cause infections. Here, these findings are further expanded in an experimental attempt to investigate a possible etiological relationship between the four microbes and CRC. This was done by examining bacterial biofilm impact on the viability of CRC. Crystal violet biofilm assays showed that each of the four anaerobes are capable of producing biofilms, which is a known contributor to disease and has been proven to alter host tissue microenvironment of the human colon. The images of bacterial biofilms grown in presence and absence of CRC cells were generated through confocal microscopy studies. Co-cultured bacterial and cellular formation was visualized in 2D and 3D perspectives using ImageJ and Icy, respectively. Comstat2 was used to quantitatively analyze 3D biofilm characteristics. The results showed that L. buccalis is a prime suspect of possessing key “driver” genes that not only encouraged the proliferation of CRC cells but also minimized cell deaths. Furthermore, the relationship between bacterial biofilms and CRC is not only statistically significant but suggests that one factor influences the other inasmuch as the opposite holds true.

Library of Congress Subject Headings

Colon (Anatomy)--Cancer--Etiology; Anaerobic bacteria

Publication Date


Document Type


Student Type


Degree Name

Bioinformatics (MS)

Department, Program, or Center

Thomas H. Gosnell School of Life Sciences (COS)


Robert C. Osgood

Advisor/Committee Member

Gary R. Skuse

Advisor/Committee Member

Maureen Ferran


Physical copy available from RIT's Wallace Library at RC280.C6 C65 2016


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