A Endosymbiont Is a Potential Source of Essential B-Vitamins for the Poultry Red Mite, .

Many obligate blood-sucking arthropods rely on symbiotic bacteria to provision essential B vitamins that are either missing or at sub-optimal levels in their nutritionally challenging blood diet. The poultry red mite , an obligate blood-feeding ectoparasite, is a serious threat to the hen egg industry. Poultry red mite infestation has a major impact on hen health and welfare and causes a significant reduction in both egg quality and production. Thus far, the identity and biological role of nutrient provisioning bacterial mutualists from are little understood. Here, we demonstrate that an obligate intracellular bacterium of the genus is detected in mites collected from 63 sites (from 15 countries) across Europe. In addition, we report the genome sequence of from ( endosymbiont; DGE). DGE has a circular 1.89Mbp genome that encodes 1,973 proteins. Phylogenetic analysis confirms the placement of DGE within the genus, related to a facultative endosymbiont from the pea aphid and -like endosymbionts (CLEs) from blood feeding ticks. Analysis of the DGE genome reveals that many protein-coding sequences are either pseudogenized or lost, but DGE has retained several B vitamin biosynthesis pathways, suggesting the importance of these pathways in evolution of a nutritional symbiosis with . metabolic pathway reconstruction revealed that DGE is unable to synthesize protein amino acids and, therefore, amino acids are potentially provisioned by the host. In contrast, DGE retains biosynthetic pathways for B vitamins: thiamine (vitamin B1) the salvage pathway; riboflavin (vitamin B2) and pyridoxine (vitamin B6) and the cofactors: flavin adenine dinucleotide (FAD) and coenzyme A (CoA) that likely provision these nutrients to the host.