格氏乳酸球菌在懸浮態和生物膜態之蛋白質表現分析及辨識生物膜形成相關的免疫原性蛋白

Abstract

Lactococcus garvieae is an aquatic pathogen that causes disease in a wide range of aquatic species all over the world. It is generally believed that latent bacterial infections and resulting antibiotic resistance are caused by the in vivo formation of biofilms. Moreover, previous studies have revealed that biofilm formation causes a change in protein expression and the antigen profile available for host-recognition. In view of this, proteomic and immunoproteomic analysis were used to compare the proteomes of L. garvieae grown either as a biofilm or in the planktonic state. Proteomic analysis using two-dimensional gel electrophoresis (2-DE) revealed varying amounts of protein in nine protein spots, among which seven were up-regulated and two were down-regulated in the biofilm form when compared to the planktonic controls. Among the up-regulated proteins, four of them (glmU, gtaB, rmlB, and rfbC) participated in extracellular polymeric substances (EPS) synthesis, which is the main component of biofilm. In the immunoproteomic analysis, polyclonal rabbit antibodies raised against biofilm and planktonic bacteria reduced biofilm formation by L. garvieae, while the anti-biofilm serum showed stronger inhibition of biofilm formation. The sera were later used to perform 2-DE Western blot assays on whole cell protein extracted from both biofilm and planktonic forms. Two immunoreactive proteins specifically recognized by anti-biofilm sera were selected, among which a moonlighting protein, arginine deiminase (AD), was considered to be associated with biofilm formation, and thus may be a potential vaccine candidate against biofilm infections.