Effect of Oxygen on the Growth and Biofilm Formation of Xylella fastidiosa in Liquid Media

• Published in: Current microbiology 2014-12, Vol.69 (6), p.866-873
• Main Authors: Shriner, Anthony D, Andersen, Peter C
• Format: Article
• Language: English
• Subjects: anaerobic conditions; Bacteria; biofilm; Biofilms; Biofilms - drug effects; Biofilms - growth & development; Biomedical and Life Sciences; Biotechnology; Culture Media - chemistry; Dissolved oxygen; Erwinia carotovora; gene activation; Growing season; Hypoxia; Life Sciences; metabolism; Microbiology; nitrogen; Oxygen; Oxygen - metabolism; pathogens; Pectobacterium carotovorum; Pectobacterium carotovorum - drug effects; Pectobacterium carotovorum - physiology; Plant diseases; Plant species; Pseudomonas syringae; Pseudomonas syringae - drug effects; Pseudomonas syringae - physiology; scorch; Transpiration; Vitaceae; Vitis; Xanthomonas campestris; Xylella - drug effects; Xylella - physiology; Xylella fastidiosa; xylem
• ISSN: 0343-8651; 1432-0991
• DOI: 10.1007/s00284-014-0660-2

Xylella fastidiosa is a xylem-limited bacterial pathogen, and is the causative agent of Pierce’s disease of grapevines and scorch diseases of many other plant species. The disease symptoms are putatively due to blocking of the transpiration stream by bacterial-induced biofilm formation and/or by the formation of plant-generated tylosis. Xylella fastidiosa has been classified as an obligate aerobe, which appears unusual given that dissolved O₂levels in the xylem during the growing season are often hypoxic (20–60 μmol L⁻¹). We examined the growth and biofilm formation of three strains of X. fastidiosa under variable O₂conditions (21, 2.1, 0.21 and 0 % O₂), in comparison to that of Pseudomonas syringae (obligate aerobe) and Erwinia carotovora (facultative anaerobe) under similar conditions. The growth of X. fastidiosa more closely resembled that of the facultative anaerobe, and not the obligate aerobe. Xanthomonas campestris, the closest genetic relative of X. fastidiosa, exhibited no growth in an N₂environment, whereas X. fastidiosa was capable of growing in an N₂environment in PW⁺, CHARDS, and XDM2-PR media. The magnitude of growth and biofilm formation in the N₂(0 % O₂) treatment was dependent on the specific medium. Additional studies involving the metabolism of X. fastidiosa in response to low O₂are warranted. Whether X. fastidiosa is classified as an obligate aerobe or a facultative anaerobe should be confirmed by gene activation and/or the quantification of the metabolic profiles under hypoxic conditions.