Bacteria Belonging to <i>Pseudomonas typographi</i> sp. nov. from the Bark Beetle <i>Ips typographus</i> Have Genomic Potential to Aid in the Host Ecology

• Main Authors: Ezequiel Peral-Aranega, Zaki Saati-Santamaría, Miroslav Kolařik, Raúl Rivas, Paula García-Fraile
• Format: Article
• Language: English
• Published: MDPI AG 2020-09-01
• Series: Insects
• Subjects: <i>Ips typographus</i>; bark beetle; bacteriome; <i>Pseudomonas</i>; beneficial
• Online Access: https://www.mdpi.com/2075-4450/11/9/593

European Bark Beetle <i>Ips typographus</i> is a secondary pest that affects dead and weakened spruce trees (<i>Picea</i> genus). Under certain environmental conditions, it has massive outbreaks, resulting in the attacks of healthy trees, becoming a forest pest. It has been proposed that the bark beetle’s microbiome plays a key role in the insect’s ecology, providing nutrients, inhibiting pathogens, and degrading tree defense compounds, among other probable traits yet to be discovered. During a study of bacterial associates from <i>I. typographus</i>, we isolated three strains identified as <i>Pseudomonas</i> from different beetle life stages. A polyphasic taxonomical approach showed that they belong to a new species for which the name <i>Pseudomonas typographi</i> sp nov. is proposed. Genome sequences show their potential to hydrolyze wood compounds and synthesize several vitamins; screening for enzymes production was verified using PNP substrates. Assays in Petri dishes confirmed cellulose and xylan hydrolysis. Moreover, the genomes harbor genes encoding chitinases and gene clusters involved in the synthesis of secondary metabolites with antimicrobial potential. In vitro tests confirmed the capability of the three <i>P. typographi</i> strains to inhibit several <i>Ips</i> beetles’ pathogenic fungi. Altogether, these results suggest that <i>P. typographi</i> aids <i>I. typographi</i> nutrition and resistance to fungal pathogens.