Ph.D.: 1990, University of California at Davis
Pre-OUHSC: University of California at Los Angeles, University of Alabama at Birmingham
Research Interests: The human microbiome and its associated diseases.
Teaches: Regulation of prokaryotic transcription
My lab is currently involved in three important projects, each is summarized briefly below.
1) Molecular mechanisms of interspecies interactions in the human oral biofilms. We are currently focusing on the interactions of veillonellae, a group of prevalent and numerically dominant bacteria in the human oral biofilm, with the pathogens of both dental caries and periodontal diseases. The goal is to develop a holistic approach to control or prevent these costly oral diseases.
2) Inter-kingdom communications between bacteria and yeast in the oral biofilm. Through understanding the mechanisms by which oral bacteria keep yeast in check, we hope to find a novel way to prevent yeast infections (oral thrush).
3) Determine the causal effect of human gut microbiota on cancer. The association between the human gut microbiota and colorectal cancer has been known for a long time; however, the causal relationship has not been established. In collaboration with Dr. Xia at OMRF, we are using a mice model to determine whether the gut flora plays a causal role in cancer development.
Current Laboratory Personnel:
Peng Zhou, Associate Research Scholar
Xiaoli Li, Research Assistant I
Beibei Liu, Associate Research Scholar
Niu G, Okinaga T, Qi F, Merritt J. 2010. The Streptococcus mutans IrvR repressor is a CI-like regulator that functions through autocleavage and Clp-dependent proteolysis. J Bacteriol 192(6):1586-95
Okinaga T, Niu G, Xie Z, Qi F, Merritt J. 2010. The hdrRM operon of Streptococcus mutans encodes a novel regulatory system for coordinated competence development and bacteriocin production. J Bacteriol. 192: 1844-52 2010 PMID: 20118256
Okinaga T, Xie Z, Niu G, Qi F, Merritt J. 2010. Examination of the hdrRM regulon yields insight into the competence system of Streptococcus mutans. Mol Oral Microbiol. 2010 Jun;25(3):165-77. PMID: 20536745
Chenggang Wu, Robert Cichewicz, Yihong Li, Jinman Liu, Bruce Roe, Joseph Ferretti, Justin Merritt, and Fengxia Qi 2010. The Genomic Island TnSmu2 of Streptococcus mutans Encodes a NRPS-PKS Gene Cluster Responsible for the Biosynthesis of Pigments Involved in Oxygen and H2O2 Tolerance. Appl. Env. Microbiolo. 76: 5815-5826 PMID: 20639370
Chenggang Wu, Eduardo A. Ayala, Jennifer S. Downey, Justin Merritt, Steven D. Goodman, and Fengxia Qi, 2010. Regulation of the ciaXRH Operon Expression and Identification of the CiaR Regulon in Streptococcus mutans. J. Bacteriol. 192: 4669-79PMID: 20639331
Gary Xie, Patrick S. G. Chain, Chienchi Lo, Kuan-Liang Liu, Jason Gans, Justin Merritt, and Fengxia Qi, 2010. Community and Gene Composition of a Human Dental Plaque Microbiota Obtained by Metagenomic Sequencing. Mol. Oral Microbiol. Dec;25(6):391-405. doi: 10.1111/j.2041-1014.2010.00587.x. PMID: 21040513
P. Matthew-Joyner, Jinman Liu, Zhijun Zhang, Justin Merritt, Fengxia Qi, and Robert H. Cichewicz, 2010. Mutanobactin A, produced by the human oral pathogen Streptococcus mutans, contains an unusual 1,4-thiazepan-5-one system and is a cross-kingdom regulator of the yeast-mycelium transition in Candida albicans. Org. Biomol. Chem. Sep 17. [Epub ahead of print] PMID: 2085277
Qi F, Kreth J. Characterization of anti-competitor activities produced by oral bacteria. Methods Mol Biol. 2010;666:151-66. PMID: 20717784
Xie Z, Okinaga T, Niu G, Qi F, and Merritt J. Identification of a novel bacteriocin regulatory system in Streptococcus mutans. Mol Microbiol. 2010 Dec;78(6):1431-47. doi: 10.1111/j.1365-2958.2010.07417.x. Epub 2010 Nov 2. PMID: 21143316 [PubMed - indexed for MEDLINE]
Hung DC, Downey JS, Ayala EA, Kreth J, Mair R, Senadheera DB, Qi F, Cvitkovitch DG, Shi W, Goodman SD. Characterization of DNA Binding sites of ComE Response Regulator from Streptococcus mutans. J Bacteriol. 2011 May 20. [Epub ahead of print] PMID: 21602345 [PubMed - as supplied by publisher]
Liu J, Wu C, Huang IH, Merritt J, Qi F. Differential Response of Streptococcus mutans towards Friend and Foe in Mixed Species Cultures. Microbiology. 2011 May 12. [Epub ahead of print] PMID: 21565931 [PubMed - as supplied by publisher] Selected by F1000 as one of the top 2% articles in biology and medicine.
Qi, F. & Ferretti, J. (2011). The Streptococcus-Veillonella Community: How Genome Sequencing Aids Our Understanding of Interspecies Interaction. In Oral Microbial Communities: Genomic Inquiry and Interspecies Communication, pp. 351-370. Edited by P. E. Kolenbrander. Washington, D.C.: ASM Press.
Liu, J., J. Merritt, and F. Qi. 2011. Genetic transformation of Veillonella parvula. FEMS Microbiol. Lett. 2011 Jun 24. doi: 10.1111/j.1574-6968.2011.02344.x. [Epub ahead of print] PMID: 21707732