Proteomic Analysis of Acinetobacter baumannii in Biofilm and Planktonic Growth Mode
Ji-Hyun Shin1, Hee-Woo Lee1,2, Sung-Min Kim1, and Jungmin Kim1*
1Department of Microbiology, Kyungpook National University, School of Medicine, Daegu 700-422, Republic of Korea, 2Research Institute for Veterinary Science College of Veterinary Medicine, Seoul National University, Seoul 151-742, Republic of Korea
Journal of Microbiology, 47(6),728-735, 2009,
proteomics, biofilm, planktonic cells, 2-dimensional gel electrophoresis, A. baumannii
Recently, multidrug-resistant clinical isolates of Acinetobacter baumannii have been found to have a high capacity to form biofilm. It is well known that bacterial cells within biofilms are highly resistant to antibiotics, UV light, acid exposure, dehydration, and phagocytosis in comparison to their planktonic counterparts, which suggests that the cells in a biofilm have altered metabolic activity. To determine which proteins are up-regulated in A. baumannii biofilm cells, we performed a proteomic analysis. A clinical isolate of A. baumannii 1656-2, which was characterized to have a high biofilm forming ability, was cultivated under biofilm and planktonic conditions. Outer membrane enriched A. baumannii 1656-2 proteins were separated by two-dimensional (2-D) gel electrophoresis and the differentially expressed proteins were identified by MALDI-TOF mass spectrometry. The proteins up-regulated or expressed only in biofilm cells of A. baumannii are categorized as follows: (i) proteins processing environmental information such as the outer membrane receptor protein involved in mostly Fe transport, a sensor histidine kinase/response regulator, and diguanylate cyclase (PAS-GGEDF-EAL domain); (ii) proteins involved in metabolism such as NAD- linked malate dehydrogenase, nucleoside-diphosphate sugar epimerase, putative GalE, ProFAR isomerase, and N-acetylmuramoyl-L-alanine amidase; (iii) bacterial antibiotic resistance related proteins; and (iv) proteins related to gene repair such as exodeoxyribonuclease III and GidA. This proteomic analysis provides a fundamental platform for further studies to reveal the role of biofilm in the persistence and tolerance of A. baumannii.