Tick microbial communities within enriched extracts of Amblyomma maculatum

Abstract

Our objective of this study was to explore the bacterial microbiome in fresh or fresh-frozen adult Amblyomma maculatum (Gulf Coast ticks) using extracts enriched for microbial DNA. We collected 100 questing adult A. maculatum, surface disinfected them, and extracted DNA from individual ticks collected the same day or after storage at -80 °C. Because only extracts with microbial DNA concentrations above 2 ng/μL were considered suitable for individual analysis, we expected fewer samples to meet these requirements. Of individual ticks extracted, 48 extracts met this minimum concentration. We pooled 20 additional extracts that had lower concentrations to obtain seven additional pools that met the minimum DNA concentration. Libraries created from these 55 samples were sequenced using an Illumina MiSeq platform, and data sets were analyzed using QIIME to identify relative abundance of microorganisms by phylum down to genus levels. Proteobacteria were in greatest abundance, followed by Actinobacteria, Firmicutes, and Bacteroidetes, at levels between 1.9% and 6.4% average relative abundance. Consistent with the Francisella-like endosymbiont known to be present in A. maculatum, the genus Francisella was detected at highest relative abundance (72.9%; SE 0.02%) for all samples. Among the top ten genera identified (relative abundance ≥ 0.5%) were potential extraction kit contaminants, Sphingomonas and Methylobacterium, the soil bacterium Actinomycetospora, and the known A. maculatum-associated genus, Rickettsia. Four samples had Rickettsia at greater than 1% relative abundance, while nine additional samples had Rickettsia at low (0.01-0.04%) relative abundance. In this study, we used the entire microbe-enriched DNA extract for whole ticks for microbiome analysis. A direct comparison of the microbiome in microbe-enriched DNA and total genomic DNA extracts from halves of the same tick would be useful to determine the utility of this extraction method in this system. We anticipate that future tick microbiome studies will be valuable to explore the influence of microbial diversity on pathogen maintenance and transmission, and to evaluate niche-specific microbiomes within individual tick tissues.

A Pilot Study on the Microbiome of Amblyomma hebraeum Tick Stages Infected and Non-Infected with Rickettsia africae

“…From the fourteen phyla, Firmicutes, Proteobacteria and Bacteroidetes dominated the samples in this study, and this agrees with previous studies, which showed that tick microbiota found in A. hebraeum mainly consists of the same three phyla in varying amounts [ 9 , 13 , 14 , 24 ]. Similar results have also been reported regarding the microbiome of A. americanum [ 19 , 20 ] and of Amblyomma maculatum [ 25 ].…”

Microbial diversity in the tick Argas japonicus (Acari: Argasidae) with a focus on Rickettsia pathogens

“…Proteobacteria represent the largest group of bacteria that contain many pathogens of medical importance (Marín, ). In the tick A. japonicus , bacteria in this phylum were in great abundance in nymphs, females and males, followed by bacteria in Firmicutes and Actinobacteria, and this result was similar to that found in A. maculatum (Varela‐Stokes et al , ). At the genus level, Staphylococcus was the most abundant genus among the 107 genera characterized from A. japonicus .…”

Update on the intricate tango between tick microbiomes and tick‐borne pathogens

“…ticks, as highlighted in recent studies. 36,[45][46][47][48][49] At a finer scale, FLEs have been detected in large numbers in the ovaries and Malpighian tubules of the host ticks. 44…”