Comparative Microbiota Analysis in Healthy and Diseased Leeches: A Preliminary Study

Background: Microbiota analysis can provide important information about health status by analyzing the microbial community of a specific organism. Aim: This study aims to determine microbiota changes in healthy and morphologically deformed leeches. Methods: Microbiota analysis was conducted at the SU Genomics Biotechnology Laboratory (Ankara, Türkiye). Leeches were homogenized, and genomic DNA was extracted with the SuSpin kit and quantified by Qubit 3.0. The 16S rRNA V5–V7 regions were PCR-amplified (799F–1191R), purified, and libraries prepared with Illumina Nextera XT for sequencing on the MiSeq platform (PE 2×150). Raw reads were classified taxonomically using Kraken2 with RefSeq, Silva, Greengenes, and GTDB databases. Results: According to the findings, leeches with morphological deformities were predominantly associated with Dactylococcopsis salina, Corynebacterium glucuronolyticum, Pectobacterium parmentieri, Burkholderia pseudomallei and Enterococcus faecalis, whereas healthy leeches were mainly associated with Pelagovum pacificum, Halorhabdus sp. BNX81, Staphylococcus aureus, Halorubrum sp. SS7 and Klebsiella pneumoniae. Discussion and Conclusion: The bacterial composition of diseased leeches consists of species that carry a serious risk of pathogenic and opportunistic infections. In healthy leeches, however, species that are mostly environmentally sourced or found in normal flora predominate. This finding suggests that deformities may be directly related to this serious imbalance in the microbiota and pathogen invasion. Acknowledgment: This study is derived from the project supported by the Scientific and Technological Research Council of Türkiye with project number 123O439.