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Topic

Genetic Determinants of Mucin-Driven Growth and Competitive Interactions in Akkermansia massiliensis

Department of Biochemistry and Microbiology

Date & location

• Thursday, April 2, 2026
• 8:30 A.M.
• Clearihue Building, Room B017

Examining Committee

Supervisory Committee

• Dr. Lauren Davey, Department of Biochemistry and Microbiology, ̽��ϵ�� (Supervisor)
• Dr. Julian Lum, Department of Biochemistry and Microbiology, UVic (Member)
• Dr. Peter Constabel, Department of Biology, UVic (Outside Member)

External Examiner

• Dr. Caroline Cameron, Department of Biochemistry and Microbiology, UVic

Chair of Oral Examination

• Dr. Brenda Mishak, School of Nursing, UVic

Abstract

Akkermansia species are mucus-degrading gut bacteria that engage in dynamic interactions with the host. While Akkermansia muciniphila is well characterized for its role in metabolic health, the recently identified Akkermansia massiliensis exhibits distinct physiological features, including vitamin B12 biosynthesis, oxygen tolerance and strong TLR2 and TLR4 activation. Notably, A. massiliensis outcompetes A. muciniphila in murine colonization models, suggesting unique genetic determinants of fitness; however, these factors remain undefined. We hypothesized that A. massiliensis possesses specific genes that enhance colonization and competitive capacity. To further understand A. massiliensis gene functions, a pooled transposon mutant library of approximately 32,000 mutants was developed for functional genomic studies. Our approach included: (1) evaluating the extent of wildtype A. massiliensis competitiveness in vitro and in vivo; and (2) introducing the transposon mutant library to similar conditions in (1) to identify genes critical for growth, mucus degradation and competition. We found that A. massiliensis consistently outcompeted A. muciniphila under gut-like conditions in vitro, as well as across dietary conditions and inoculation ratios in vivo. Furthermore, transposon sequencing identified mutants with reduced fitness in mucin, implicating key genes involved in mucin degradation. When the mutant pool was challenged against wildtype A. muciniphila, 23 competition-specific genes were identified, seven of which were unique to A. massiliensis. These data indicate that A. massiliensis competitiveness arises from multiple genetic pathways supporting nutrient acquisition, biosynthesis and transcriptional regulation rather than a single dominant mechanism. Overall, this work establishes a functional genomic framework for A. massiliensis, providing genetic insight into niche adaptation and interspecies competition.