Gene expression characteristics of a cystic fibrosis epidemic strain of Pseudomonas aeruginosa during biofilm and planktonic growth

Webb, Jeremy, Manos, Jim, Arthur, Jonathan, Rose, Barbara, Bell, Scott, Tingpej, Pholawat, Hu, Honghua, Kjelleberg, Staffan, Gorrell, Mark D., Bye, Peter and Harbour, Colin (2009) Gene expression characteristics of a cystic fibrosis epidemic strain of Pseudomonas aeruginosa during biofilm and planktonic growth. FEMS Microbiology Letters, 292 (1), 107-114. (doi:10.1111/j.1574-6968.2008.01472.x).

Abstract

Epidemic Pseudomonas aeruginosa have been identified in cystic fibrosis (CF) patients worldwide. The Australian Epidemic Strain-2 (AES-2) infects up to 40% of patients in three eastern Australian CF clinics. To investigate whether AES-2 isolates from chronically infected CF adults differentially express well-conserved genes potentially associated with transmissibility, we compared the transcriptomes of planktonic and biofilm-grown AES-2, infrequent P. aeruginosa clones and the reference P. aeruginosa PAO1 using the Affymetrix PAO1 array. The most interesting findings emerged from comparisons of planktonic and biofilm AES-2. AES-2 biofilms upregulated Type III secretion system genes, but downregulated quorum-sensing (QS)-regulatory genes, except lasR, QS-regulated, oxidative-stress and iron-storage genes. QS-regulated and iron-storage genes were downregulated to a greater extent in AES-2 biofilms compared with infrequent clone and PAO1 biofilms, suggesting enhanced anaerobic respiration in AES-2. Chitinase and chitin-binding protein maintained high expression in AES-2 biofilms compared with infrequent clone and PAO1 biofilms. Planktonic AES-2 upregulated QS regulators and QS-regulated genes, iron acquisition and aerobic respiration genes, and had high expression of Group III Type IV pilA compared with low expression of Group I Type IV pilA in infrequent clones. Together, these properties may enhance long-term survival of AES-2 in CF lung and contribute to its transmissibility.

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Contributors

Author: Jeremy Webb

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