Genetic Transfer in Action: Uncovering DNA Flow in an Extremophilic Microbial Community.

Horizontal genetic transfer (HGT) is a significant driver of genomic novelty in all domains of life. HGT has been investigated in many studies however, the focus has been on conspicuous protein-coding DNA transfers that often prove to be adaptive in recipient organisms and are therefore fixed longer-term in lineages. These results comprise a subclass of HGTs and do not represent exhaustive (coding and non-coding) DNA transfer and its impact on ecology. Uncovering exhaustive HGT can provide key insights into the connectivity of genomes in communities and how these transfers may occur. In this study, we use the term frequency-inverse document frequency (TF-IDF) technique, that has been used successfully to mine DNA transfers within real and simulated high-quality prokaryote genomes, to search for exhaustive HGTs within an extremophilic microbial community. We establish a pipeline for validating transfers identified using this approach. We find that most DNA transfers are within-domain and involve non-coding DNA. A relatively high proportion of the predicted protein-coding HGTs appear to encode transposase activity, restriction-modification system components, and biofilm formation functions. Our study demonstrates the utility of the TF-IDF approach for HGT detection and provides insights into the mechanisms of recent DNA transfer.