Serratia montpellierensis sp. nov., isolated from laboratory reared parasitic wasps Psyttalia lounsburyii and Psyttalia ponerophaga (Hymenoptera: Braconidae)

Authors: Blackburn, Michael - Mike; TANNIERES, MELANIE - European Biological Control Laboratory (EBCL); Sparks, Michael; Gundersen-Rindal, Dawn; MARIE-CLAUDE, BON - European Biological Control Laboratory (EBCL)

Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2024
Publication Date: 4/18/2024
Citation: Blackburn, M.B., Tannieres, M., Sparks, M., Gundersen, D.E., Marie-Claude, B. 2024. Serratia montpellierensis sp. nov., isolated from laboratory reared parasitic wasps Psyttalia lounsburyii and Psyttalia ponerophaga (Hymenoptera: Braconidae). Current Microbiology. 81:146. https://doi.org/10.1007/s00284-024-03666-0.
DOI: https://doi.org/10.1007/s00284-024-03666-0

Interpretive Summary: Bacteria of genus Serratia are often found associated with insects, and some species, like Serratia marcescens, cause disease in insects and are commonly found associated with laboratory-reared insects. They can also infect humans, usually in hospital settings. Scientists at the USDA ARS European Biological Control Laboratory in Montpellier, France, isolated several strains of bacteria from colonies of parasitic wasps being evaluated for control of the olive fruit fly that they identified as Serratia. Their ARS colleagues sequenced the genomes of these strains and evaluated biochemical phenotypic properties, finding they were a new species of Serratia that had not been described previously, naming the new species Serratia montpellierensis. The new species was most closely related to Serratia nevei, which like S. marcescens, has been isolated from insects and can cause human infections in hospitals. The research is of interest to entomologists involved in mass rearing of insects, and microbiologists studying bacteria associated with insects.

Technical Abstract: Two strains of bacteria, PsyLou2AT and PsyPon4B, were isolated from adult braconid wasps Psyttalia lounsburyii and Psyttalia ponerophaga, respectively. These laboratory-reared wasps were being investigated for biological control of olive fruitfly, Bactrocera oleae. Analysis of 16S rRNA genes of the two isolates demonstrated that they were highly related and belonged to the genus Serratia. Genomic sequencing of these isolates revealed genomes of 5,152,551bp and 5,154,385 bp for PsyLou2AT and PsyPon4B, respectively, and both genomes had a G+C content of 59.6 mol%. Phylogenetic analyses using BLAST-basaed average nucleotide identity (ANIb) and digital DNA-DNA hybrization methods idicated that PsyLou2AT was most closely related to Serratia nevei S15T, producing ANIb and dDDH values of 96.11% and 70.2%, respectively. Since these values were literally on the species cutoff level, an additional 65 S. nevei genome assemblies were analyzed using ANIb and dDDH calculations. This revealed that among assemblies that are legitimately identified as S. nevi, S. nevei S15T was the most closely related to PsyLou2AT, and that a majority of assemblies produced dDDH values of 68.3-68.7% relatve to PsyLou2AT. Additionally, PsyLou2AT differed from S. nevei S15T in that it produced positive Voges Proskauer tests, produced protease, lacked arginine dihydrolase, and did not utilize D-lactose. Hence, PsyLou2AT represents a novel taxon within the Serratia, for which we propse the name Serratia montpellierensis sp. nov. The type strain is PsyLou2AT (=LMG 32817T).