Bacteria Belonging to Pseudomonas typographi sp. nov. from the Bark Beetle Ips typographus Have Genomic Potential to Aid in the Host Ecology
by
, , and
Ezequiel Peral-Aranega
1,2
,
Zaki Saati-Santamaría
1,2,
Miroslav Kolařik
3,4,
Raúl Rivas
1,2,5
and
Paula García-Fraile
1,2,4,5,* 1
Microbiology and Genetics Department, University of Salamanca, 37007 Salamanca, Spain
2
Spanish-Portuguese Institute for Agricultural Research (CIALE), 37185 Salamanca, Spain
3
Department of Botany, Faculty of Science, Charles University, Benátská 2, 128 01 Prague, Czech Republic
4
Laboratory of Fungal Genetics and Metabolism, Institute of Microbiology of the Academy of Sciences of the Czech Republic, 142 20 Prague, Czech Republic
5
Associated Research Unit of Plant-Microorganism Interaction, University of Salamanca-IRNASA-CSIC, 37008 Salamanca, Spain
*
Author to whom correspondence should be addressed.
Insects 2020, 11(9), 593; https://doi.org/10.3390/insects11090593
Submission received: 4 July 2020
/
Revised: 23 August 2020
/
Accepted: 1 September 2020
/
Published: 3 September 2020
Simple Summary
European Bark Beetle (Ips typographus) is a pest that affects dead and weakened spruce trees. Under certain environmental conditions, it has massive outbreaks, resulting in 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. During a study of bacterial associates from I. typographus, we isolated three strains identified as Pseudomonas from different beetle life stages. In this work, we aimed to reveal the taxonomic status of these bacterial strains and to sequence and annotate their genomes to mine possible traits related to a role within the bark beetle holobiont. Our study indicates that these bacteria constitute a new species for which the name of Pseudomonas typographi sp. nov. is proposed. Moreover, their genome analysis suggests different metabolic pathways possibly related to the beetle’s ecology. Finally, in vitro tests conclude the capability of these bacteria to inhibit beetle’s fungal pathogens. Altogether, these results suggest that P. typographi aids I. typographi nutrition and resistance to fungal pathogens. These findings might be of interest in the development of integrated methods for pest control.
Abstract
European Bark Beetle Ips typographus is a secondary pest that affects dead and weakened spruce trees (Picea 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. typographus, we isolated three strains identified as Pseudomonas from different beetle life stages. A polyphasic taxonomical approach showed that they belong to a new species for which the name Pseudomonas typographi 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 P. typographi strains to inhibit several Ips beetles’ pathogenic fungi. Altogether, these results suggest that P. typographi aids I. typographi nutrition and resistance to fungal pathogens.
Keywords:
Ips typographus; bark beetle; bacteriome; Pseudomonas; beneficial
