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Applied and Environmental Microbiology, May 2006, p. 3458-3467, Vol. 72, No. 5
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.5.3458-3467.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Effects of Various Growth Conditions in a Chemostat on Expression of Virulence Factors in Porphyromonas gingivalis

Takashi Masuda,1,2 Yukitaka Murakami,2* Toshihide Noguchi,1 and Fuminobu Yoshimura2

Departments of Periodontology,1 Microbiology, School of Dentistry, Aichi-Gakuin University, Nagoya, Aichi, Japan2

Received 2 July 2005/ Accepted 27 February 2006

Porphyromonas gingivalis, one of the gram-negative organisms associated with periodontal disease, possesses potential virulence factors, including fimbriae, proteases, and major outer membrane proteins (OMPs). In this study, P. gingivalis ATCC 33277 was cultured in a chemostat under hemin excess and presumably peptide-limiting conditions to better understand the mechanisms of expression of the virulence factors upon environmental changes. At higher growth rates, the amounts of FimA and the 75-kDa protein, forming long and short fimbriae, respectively, increased significantly, whereas gingipains decreased in amount and activity. In a nutrient-limited medium, lesser amounts of the above two fimbrial proteins were observed, whereas clear differences were not found in the amounts of gingipains. In addition, two-dimensional electrophoresis revealed that proteins in cells were generally fewer in number during nutrient-limited growth. Under aeration, a considerable reduction in gingipain activity was found, whereas several proteins associated with intact cells significantly increased. However, the expression of major OMPs, such as RagA, RagB, and the OmpA-like proteins, was almost constant under all conditions tested. These results suggest that P. gingivalis may actively control expression of several virulence factors to survive in the widely fluctuating oral environment.

* Corresponding author. Mailing address: Department of Microbiology, School of Dentistry, Aichi-Gakuin University, Nagoya, Aichi 464-8650, Japan. Phone: 81-52-751-2561. Fax: 81-52-752-5988. E-mail: yukimu{at}dpc.aichi-gakuin.ac.jp.

Applied and Environmental Microbiology, May 2006, p. 3458-3467, Vol. 72, No. 5
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.5.3458-3467.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.





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