Investigation of pectinolytic bacteria in surface waters, update of the outline of the Pectobacteriaceae family

Speaker:  Dr Nicole-Hugouvieux-Cotte-Pattat, University of Lyon, Laboratory MAP CNRS UMR5240

Talk:  Investigation of pectinolytic bacteria in surface waters, update of the outline of the Pectobacteriaceae family

Time: 06.10.2023, 9:00 am

Venue:  Intercollegiate Faculty of Biotechnology, Abrahama 58, hall 042B

Nicole Hugouvieux-Cotte-Pattat got a PhD in microbiology in 1981, delivered by INSA-Lyon and Lyon 1 University, on the Escherichia coli metabolic pathways used for hexuronate degradation. In 1982, she obtained a permanent researcher position at CNRS (Centre National de la Recherche Scientifique, France). She studied the different pectinases involved in the degradation of pectin by the plant pathogenic bacterium Dickeya dadantii (called at the time Erwinia chrysanthemi). Pectinolytic enzymes are essential factors of the bacterial virulence against plants. She obtained the research habilitation in 1987 and she had a post-doctoral position at the University of Geneva in 1988-1989, to study the expression of genes of the TOL catabolic plasmid of Pseudomonas putida. From 1994, she supervised her team studying the virulence functions of the plant pathogenic bacterium Dickeya dadantii. She explored the D. dadantii genes involved in virulence, the regulation of their expression and the metabolic pathways necessary for the assimilation of plant compounds. From 1995 to 2005, she was the deputy director of the laboratory Microbiology and Genetics. In 2005, she created the laboratory Microbiology, Adaptation and Pathogenesis (MAP, UMR5240) supported by CNRS, INSA and Lyon 1 University. She directed this laboratory until 2015. From 2016 to 2020, she headed a molecular biology platform of the Lyon University. She developed genomic approaches to investigate the diversity of the genus Dickeya by analysing poorly characterized strains from old collections and carrying out surveys of Dickeya strains present in the environment, particularly in lake water. These recent works enable her to describe three new Dickeya species, D. lacustris, D. parazeae and D. poaceiphila and a new genus Musicola inside the Pectobacteriaceae family.

The Pectobacteriaceae family includes plant pathogenic bacteria able to provoke various diseases, in particular plant maceration due to the production of pectinases attacking the plant cell wall. To better understand their natural diversity, a survey of pectinolytic bacteria was carried out in lakes of the French region La Camargue near the Mediterranean Sea. Numerous isolates of two Dickeya species were found in this type of surface water. In addition, some atypical pectinolytic isolates were recovered from some lakes containing brackish water. In phylogenetic trees, the novel strains forms a new clade of Pectobacteriaceae, distinct from the previously known genera of this family. Based on phenotypic, genomic and phylogenetic characteristics, we propose the creation of a new genus for these pectinolytic isolates. Our phylogenomic studies confirm that Symbiopectobacterium also belongs to the Pectobacteriaceae family but indicate that the genus Acerihabitans should be reclassified in the Bruguierivoracaceae family.