Changes in Gene Expression of Actinobacillus pleuropneumoniae in Response to Anaerobic Stress Reveal Induction of Central Metabolism and Biofilm Formation
Lu Li1,2, Jiawen Zhu1,3, Kui Yang4, Zhuofei Xu1,3, Ziduo Liu1,2, and Rui Zhou1,3*
1State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, P. R. China, 2College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China, 3College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, P. R. China, 4Modern Education Technology Center, Huazhong Agricultural University, Wuhan 430070, P. R. China
Journal of Microbiology, 52(6),473-481, 2014,
Actinobacillus pleuropneumoniae, anaerobic, gene
expression, central metabolism, biofilm
Actinobacillus pleuropneumoniae is an important porcine respiratory pathogen causing great economic losses in the pig industry worldwide. Oxygen deprivation is a stress that A. pleuropneumoniae will encounter during both early infection and the later, persistent stage. To understand modulation of A. pleuropneumoniae gene expression in response to the stress caused by anaerobic conditions, gene expression profiles under anaerobic and aerobic conditions were compared in this study. The microarray results showed that 631 genes (27.7% of the total ORFs) were differentially expressed in anaerobic conditions. Many genes encoding proteins
involved in glycolysis, carbon source uptake systems, pyruvate metabolism, fermentation and the electron respiration transport chain were up-regulated. These changes led to an increased amount of pyruvate, lactate, ethanol and acetate
in the bacterial cells as confirmed by metabolite detection. Genes encoding proteins involved in cell surface structures, especially biofilm formation, peptidoglycan biosynthesis and lipopolysaccharide biosynthesis were up-regulated
as well. Biofilm formation was significantly enhanced under anaerobic conditions. These results indicate that induction of central metabolism is important for basic survival of A. pleuropneumoniae after a shift to an anaerobic environment.
Enhanced biofilm formation may contribute to the persistence of this pathogen in the damaged anaerobic host tissue and also in the early colonization stage. These
discoveries give new insights into adaptation mechanisms of A. pleuropneumoniae in response to environmental stress.