Genomic insights into Candidatus Argioplasma dusa, a bacterial symbiont of the wasp spider Argiope bruennichi

Abstract

Bacterial symbionts were shown to have significant beneficial impacts on the fitness of their host in insects, but little is known on the symbionts of spiders and their interactions with their hosts. Here, we assembled and investigated the circular 575 kb genome of Candidatus Argioplasma dusa, a novel bacterial symbiont of the wasp spider Argiope bruennichi. Phylogenomic analysis placed this species within the phylum Tenericutes, in a poorly characterized clade that may represent a new order-level lineage or affiliate with the Mycoplasmatales order. With 559 predicted genes, the genome is relatively small compared to other Tenericutes genomes (on average 969 genes) and has a low GC content of ~24%. While the genome encodes genes for proteins involved in glycolysis and fermentative acetate production, it revealed minimal biosynthetic capabilities with pathways for nucleotide, amino acid and vitamin biosynthesis being absent in Ca. Argioplasma dusa. This suggests an intracellular endosymbiotic lifestyle within the spider host. The symbiont was detected in A. bruennichi populations across the distribution range of the spider but appears to be absent in certain populations.