The Rhizobacterium <i>Pseudomonas alcaligenes</i> AVO110 Induces the Expression of Biofilm-Related Genes in Response to <i>Rosellinia necatrix</i> Exudates

• Main Authors: Adrián Pintado, Isabel Pérez-Martínez, Isabel M. Aragón, José Antonio Gutiérrez-Barranquero, Antonio de Vicente, Francisco M. Cazorla, Cayo Ramos
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Microorganisms
• Subjects: <i>Pseudomonas alcaligenes</i>; mycophagy; <i>Rosellinia necatrix</i>; fungal exudates; c-di-GMP; biofilm formation
• Online Access: https://www.mdpi.com/2076-2607/9/7/1388

The rhizobacterium <i>Pseudomonas alcaligenes</i> AVO110 exhibits antagonism toward the phytopathogenic fungus <i>Rosellinia necatrix</i>. This strain efficiently colonizes <i>R. necatrix</i> hyphae and is able to feed on their exudates. Here, we report the complete genome sequence of <i>P. alcaligenes</i> AVO110. The phylogeny of all available <i>P. alcaligenes</i> genomes separates environmental isolates, including AVO110, from those obtained from infected human blood and oyster tissues, which cluster together with <i>Pseudomonas otitidis</i>. Core and pan-genome analyses showed that <i>P. alcaligenes</i> strains encode highly heterogenic gene pools, with the AVO110 genome encoding the largest and most exclusive variable region (~1.6 Mb, 1795 genes). The AVO110 singletons include a wide repertoire of genes related to biofilm formation, several of which are transcriptionally modulated by <i>R. necatrix</i> exudates. One of these genes (<i>cmpA</i>) encodes a GGDEF/EAL domain protein specific to <i>Pseudomonas</i> spp. strains isolated primarily from the rhizosphere of diverse plants, but also from soil and water samples. We also show that CmpA has a role in biofilm formation and that the integrity of its EAL domain is involved in this function. This study contributes to a better understanding of the niche-specific adaptations and lifestyles of <i>P. alcaligenes</i>, including the mycophagous behavior of strain AVO110.