Li, Yung-Hua

Phone: (902) 494-3063


Associate Professor, Department of Applied Oral Sciences

Academic Credentials:
PhD (UM), MSc (UM), DMD (WU)
Professional Appointments:
Cross Appointment, Department of Microbiology and Immunology, Faculty of Medicine
Personal Website:

Research Interests:

Bacteria in nature or in the human body are predominately associated with a surface and form biofilms. Formation of biofilms enables bacteria to resist inhibition or removal by the host defense mechanisms or by the highest deliverable level of antibiotics or antimicrobial agents. This will increase potential risk for antibiotic resistance. There are many examples of biofilm infections threatening human health, including infections of the bone, the gastrointestinal tract, the urogenital tract, the eye, the middle ear, the airway and lung tissues, cardiac tissues, prosthetic devices, indwelling catheters, surgical implants as well as dental diseases and dental device infections. The Center for Disease Control and Prevention (CDC) has recently reported that over 65% of hospital infections involve microbial biofilms. Because of the insensitivity to antibiotics or antimicrobial agents, biofilm infections can be life threatening to immuno-compromised patients. Therefore, development of new strategies to control biofilm infections is highly desirable.

Studies of biofilms have led to us to realize that bacteria present in biofilms behave differently from their free-living counterparts in liquid phase. Living in biofilms allow bacteria to have several advantages in that they can intimately interact with each other and function as a group for coordinated activities. These activities in biofilms (biofilm phenotypes) are now known to result largely from interactions with surfaces and bacterial group behaviors. Importantly, these phenotypes are usually associated with bacterial virulence and pathogenicity. In modern clinical microbiology, the establishment of bacterial biofilms has been considered as an important pathogenic trait in chronic infections. The armament of therapeutic agents available to treat bacterial infections today does not take into account the unique biology of bacterial group behaviors in biofilms. This becomes a problem because biofilms resulting in persistent infections cannot be resolved with standard antibiotic treatment. Since we have not considered the problem of bacterial group behaviors until recently, good therapeutic strategies to treat biofilm infections are not available.

- molecular mechanisms of biofilm formation and the pathogenecity of oral bacteria
- identifying genes important for bacterial virulence by functional genomic approaches
- identifying natural and synthetic compounds that potentially interfere with oral biofilm formation

Research Projects:

Molecular Analysis of the Competence Regulatory Network in Steptococcus mutans
Funding Agency:NSERC Discovery Grant
Start Date:2014End Date:2019
Investigator Status:Principal Investigator
Functional genomic analysis of a peptide antibiotic-sensing and response regulon in Streptococcus mutans
Funding Agency:CIHR Operating Grant
Start Date:01/09/2011End Date:31/03/2016
Investigator Status:Principal Investigator
The killing mechanisms of pheromone-guided antimicrobial peptides against Steptococcus mutans
Funding Agency:Faculty of Dentistry Research Fund
Start Date:2013End Date:2014
Investigator Status:Principal Investigator
Molecular analysis of a peptide-mediated two-component signal transduction system.
Funding Agency:NSERC Discovery Grant
Start Date:01/04/2007End Date:31/03/2012
Investigator Status:Principal Investigator
Functional genomic approaches to identifying virulence-associated gene in Streptococcus mutans.
Funding Agency:CIHR-Nova Scotia Regional Partnership Program New Investigator Award
Start Date:01/04/2007End Date:31/03/2012
Investigator Status:Principal Investigator
CFI New Opportunity project, Research laboratory for biofilm control.
Funding Agency:CFI Infrastructure Operating Fund
Start Date:01/04/2006End Date:31/03/2012
Investigator Status:Principal Investigator
Identification of virulence-associated genes in Streptococcus mutans by a genome-scale functional analysis.
Funding Agency:CIHR Operating Grant
Start Date:01/04/2005End Date:31/03/2010
Investigator Status:Principal Investigator