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Infection and Immunity, November 2008, p. 4944-4951, Vol. 76, No. 11
0019-9567/08/$08.00+0     doi:10.1128/IAI.00692-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Type IV Pili and the CcpA Protein Are Needed for Maximal Biofilm Formation by the Gram-Positive Anaerobic Pathogen Clostridium perfringens{triangledown}

John J. Varga,{dagger} Blair Therit,{ddagger} and Stephen B. Melville*

Department of Biological Sciences, 2119 Derring Hall, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

Received 2 June 2008/ Returned for modification 10 July 2008/ Accepted 23 August 2008

The predominant organizational state of bacteria in nature is biofilms. Biofilms have been shown to increase bacterial resistance to a variety of stresses. We demonstrate for the first time that the anaerobic gram-positive pathogen Clostridium perfringens forms biofilms. At the same concentration of glucose in the medium, optimal biofilm formation depended on a functional CcpA protein. While the ratio of biofilm to planktonic growth was higher in the wild type than in a ccpA mutant strain in middle to late stages of biofilm development, the bacteria shifted from a predominantly biofilm state to planktonic growth as the concentration of glucose in the medium increased in a CcpA-independent manner. As is the case in some gram-negative bacteria, type IV pilus (TFP)-dependent gliding motility was necessary for efficient biofilm formation, as demonstrated by laser confocal and electron microscopy. However, TFP were not associated with the bacteria in the biofilm but with the extracellular matrix. Biofilms afforded C. perfringens protection from environmental stress, including exposure to atmospheric oxygen for 6 h and 24 h and to 10 mM H2O2 for 5 min. Biofilm cells also showed 5- to 15-fold-increased survival over planktonic cells after exposure to 20 µg/ml (27 times the MIC) of penicillin G for 6 h and 24 h, respectively. These results indicate C. perfringens biofilms play an important role in the persistence of the bacteria in response to environmental stress and that they may be a factor in diseases, such as antibiotic-associated diarrhea and gas gangrene, that are caused by C. perfringens.

* Corresponding author. Mailing address: Department of Biological Sciences, 2119 Derring Hall, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061. Phone: (540) 231-1441. Fax: (540) 231-9307. E-mail: melville{at}vt.edu

{triangledown} Published ahead of print on 2 September 2008.

Editor: A. Camilli

{dagger} Present address: Infectious Disease Group, J. Craig Venter Institute, 9704 Medical Center Drive, Rockville, MD 20850.

{ddagger} Present address: Department of Molecular and Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough St., Raleigh, NC 27606.

Infection and Immunity, November 2008, p. 4944-4951, Vol. 76, No. 11
0019-9567/08/$08.00+0     doi:10.1128/IAI.00692-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.





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