Comparative genomics of the Pseudomonas corrugata subgroup reveals high species diversity and allows the description of Pseudomonas ogarae sp. nov.

Pseudomonas corrugata constitute one of the phylogenomic subgroups within the Pseudomonas fluorescens species complex and include both plant growth-promoting rhizobacteria (PGPR) and plant pathogenic bacteria. Previous studies suggest that the species diversity of this group remains largely unexplored together with frequent misclassification of strains. Using more than 1800 sequenced Pseudomonas genomes we identified 121 genomes belonging to the P. corrugata subgroup. Intergenomic distances obtained using the genome-to-genome blast distance (GBDP) algorithm and the determination of digital DNA–DNA hybridization values were further used for phylogenomic and clustering analyses, which revealed 29 putative species clusters, of which only five correspond to currently named species within the subgroup. Comparative and functional genome-scale analyses also support the species status of these clusters. The search for PGPR and plant pathogenic determinants showed that approximately half of the genomes analysed could have a pathogenic behaviour based on the presence of a pathogenicity genetic island, while all analysed genomes possess PGPR traits. Finally, this information together with the characterization of phenotypic traits, allows the reclassification proposal of Pseudomonas fluorescens F113 as Pseudomonas ogarae sp. nov., nom rev., type strain F113T (=DSM 112162T=CECT 30235T), which is substantiated by genomic, functional genomics and phenotypic differences with their closest type strains.

Production of Polyhydroxyalkanoates and Extracellular Products Using Pseudomonas Corrugata and P. Mediterranea: A Review

Some strains of Pseudomonas corrugata (Pco) and P. mediterranea (Pme) efficiently synthesize medium-chain-length polyhydroxyalkanoates elastomers (mcl-PHA) and extracellular products on related and unrelated carbon sources. Yield and composition are dependent on the strain, carbon source, fermentation process, and any additives. Selected Pco strains produce amorphous and sticky mcl-PHA, whereas strains of Pme produce, on high grade and partially refined biodiesel glycerol, a distinctive filmable PHA, very different from the conventional microbial mcl-PHA, suitable for making blends with polylactide acid. However, the yields still need to be improved and production costs lowered. An integrated process has been developed to recover intracellular mcl-PHA and extracellular bioactive molecules. Transcriptional regulation studies during PHA production contribute to understanding the metabolic potential of Pco and Pme strains. Data available suggest that pha biosynthesis genes and their regulations will be helpful to develop new, integrated strategies for cost-effective production.