Proteome analysis of the hyaluronic acid-producing bacterium, Streptococcus zooepidemicus

BACKGROUND: Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a commensal of horses and an opportunistic pathogen in many animals and humans. Some strains produce copious amounts of hyaluronic acid, making S. zooepidemicus an important industrial microorganism for the production of this valuable biopolymer used in the pharmaceutical and cosmetic industry. Encapsulation by hyaluronic acid is considered an important virulence factor in other streptococci, though the importance in S. zooepidemicus remains poorly understood. Proteomics may provide a better understanding of virulence factors in S. zooepidemicus, facilitate the design of better diagnostics and treatments, and guide engineering of superior production strains. RESULTS: Using hyaluronidase to remove the capsule and by optimising cellular lysis, a reference map for S. zooepidemicus was completed. This protocol significantly increased protein recovery, allowing for visualisation of 682 spots and the identification of 86 proteins using mass spectrometry (LC-ESI-MS/MS and MALDI-TOF/TOF); of which 16 were membrane proteins. CONCLUSION: The data presented constitute the first reference map for S. zooepidemicus and provide new information on the identity and characteristics of the more abundantly expressed proteins.