Analysis of the structural and functional diversity of bacterial microbiota carried by ticks suggests a potential threat of Rickettsia in Liaoning Province, China

Abstract Objectives To conduct polymorphism analysis of the tick microbiota in Liaoning Province, explore the tick-borne microbial populations that cause zoonotic diseases. Methods In this study, 241 tick specimens were collected from forests and pastures in different areas of the eastern, southern, western, and northern Liaoning Province from May to June, 2023. The four groups of tick specimens were analyzed using microbial 16S amplicon sequencing. The specimens were analyzed for the presence of rickettsiae in their own microbiota environments and subsequently analyzed for the genetic evolution of their 16S, ompA, and ompB genes. Rickettsiae were successfully isolated by infecting a baby hamster kidney (BHK) cell line and staining with Swiss-Giemsa composite stain. Results Sequencing of the LNW, LNE, LNN, and LNS 16S amplicons yielded 140,027, 132,756, 133,476, and 133,331 sequences, respectively. Diversity analysis showed that the LNN group higher microbial community richness, and more uniform species distribution. A total of 1,671 amplicon sequence variants (ASVs) were identified through sequence comparison and species annotation. Among these sequences, 92.46% of ASVs could be annotated to the database, with genus being the most abundant in all four groups of samples, followed by species. The homology of the Rickettsia 16S, ompA, and ompB genes obtained from the LNW and LNS groups was 99.3%, 93.9%, and 96.2%, respectively. The successfully isolated and purified rickettsiae-infected BHK cells could cause cellular lesions. Conclusion Ticks of multiple genera in Liaoning Province carry a rich bacterial microbiota. The severe infection of Rickettsia poses a potential threat to both humans and animals.