Azospirillum baldaniorum Sp245 exploits Pseudomonas fluorescens A506 biofilm to overgrow in dual‐species macrocolonies

Abstract

Biofilms are essential for plant‐associated bacteria to colonize their host. In this work, we analysed the interaction of Azospirillum baldaniorum Sp245 and Pseudomonas fluorescens A506 in mixed macrocolony biofilms. We identified certain culture conditions where A. baldaniorum Sp245 exploits P. fluorescens A506 to boost its growth. Azospirillum growth increased proportionally to the initial number of pseudomonads building the biofilm, which in turn were negatively affected in their growth. Physical contact with P. fluorescens A506 was essential for A. baldaniorum Sp245 growth increase. Biofilm ultrastructure analysis revealed that Pseudomonas produces a thick structure that hosts Azospirillum cells in its interior. Additional experimentation demonstrated that Azospirillum growth boost is compromised when interacting with biofilm‐deficient Pseudomonas mutants, and that a low oxygen concentration strongly induce A. baldaniorum Sp245 growth, overriding Pseudomonas stimulation. In this line, we used a microaerophilia reporter strain of A. baldaniorum Sp245 to confirm that dual‐species macrocolonies contain a higher number of cells under microaerophilic conditions. Taking all the results into consideration, we propose that A. baldaniorum Sp245 can benefit from P. fluorescens A506 partnership in mixed biofilms by taking advantage of the low oxygen concentration and scaffold made up of Pseudomonas‐derived matrix, to expand its growth.

Fourier Transform Infrared (FTIR) Spectroscopic Study of Biofilms Formed by the Rhizobacterium Azospirillum baldaniorum Sp245: Aspects of Methodology and Matrix Composition

“…It should be emphasized that studies specially devoted to biofilms formed by Azospirillum spp. have been relatively limited (see, e.g., reports [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ] (and some earlier references cited therein) on various biochemical and physiological properties of biofilms formed by these bacteria, including a report on dual-species biofilms [ 51 ]), so this important field for azospirilla is yet to be investigated in more detail.…”

Correction to “Azospirillum baldaniorum Sp245 exploits Pseudomonas fluorescensA506 biofilm to overgrow in dual‐species macrocolonies”

“…In Díaz et al (2022), the third author's name has been corrected from Luciana Pagnussatt to Luciana Pagnussat.…”