Accessing the Functional Capabilities of the Tick Microbiome Through Metagenomics

The black-legged tick Ixodes scapularis is a common ectoparasite of animals and an obligate blood feeder, attaching to a host animal and taking a blood meal once per life stage (i.e. 3 times during its life). Unfortunately for the tick, blood represents a nutrient poor diet largely consisting of lipids and proteins but notably lacking in essential nutrients such a B vitamins (e.g., biotin, riboflavin, niacin) Other exclusive blood feeders such as the tsetse fly harbor symbiotic bacteria that provision B-complex vitamins to their host. I. scapularis harbors Rickettsia buchneri an endoparasitic bacterium that intriguingly possesses two copies of a complete biotin synthesis operon; however, there is no evidence that R. buchneri is required for I. scapularis fitness, or that it provisions biotin to its host. Consequently, it remains an open question how I. scapularis and other ticks without endosymbionts thrive on nutrient-poor blood alone. In the current work, I present a method to isolate the tick microbiome away from host cells to interrogate the complete microbial metagenome for metabolic capabilities related to nutrient supplementation. This method will allow us to analyze the entire microbial metagenome of small arthropods such as ticks – previously inaccessible due to overwhelming amounts of host DNA – and enable characterization of host-microbiome metabolic interdependency, providing novel insight into microbial ecology within ticks and other hematophagous arthropods