Fig. 4: Relationships between Inocles and host bacteria.

A Abundance of Inocles in the intracellular and extracellular particle fractions. Comparative abundance of 15 Inocles (Inocle_001, 002, 003, 004, 005, 006, 007, 008, 010, 017, 018, 019, 023, 024, and 028) in the bacterial pellets and 0.45 μm filtered fraction of saliva samples. B The distribution of the number of ORFs of 29 Inocles aligned to genus-defined genes in the UniRef90 database. Box plots represent the inter-quartile range (IQR), and lines inside the box indicate the median. Whiskers show 1.5 IQR. C Experimental workflow for the isolation of Streptococcus strains, including Inocle_004. The saliva sample, which contained Inocle_004, was streaked onto the MRS agar plate. The five colonies were subjected to Sanger sequencing of the colony PCR product, amplified using Inocle_004 specific primers. Three colonies were identified as positive for Inocle_004, as their PCR products perfectly matched with Inocle_004. Subsequently, three Inocle_004-positive colonies (colony-1, − 2, and − 3) were subjected to liquid culturing in the MRS medium. The absence of Inocle_004 in the colony-1 strain cultured in the liquid medium was verified using whole-genome sequencing. The absence of Inocle_004 in colony-2 and − 3 strains cultured in liquid media was confirmed via PCR using Inocle_004-specific primers. The bacterial taxonomic classification of colony-1 was obtained using GTDBtk based on whole genome sequences, while that of colony-2 and − 3 was obtained from the sequences of the 16S rRNA (V1-V2 region) PCR product. The red spectrum figure depicts the PCR product size (bp). N/A; not available. D Comparison of the tetranucleotide frequency between Inocles and chromosomes, plasmids, and phages of Streptococcus. The heatmap presents the tetranucleotide frequency, and the dendrogram was obtained based on the similarity of tetranucleotide frequency. E Comparison of the codon usage between Inocles and chromosomes, plasmids, and phages of Streptococcus. The heatmap depicts the relative synonymous codon usage, and the dendrogram was obtained based on the similarity of synonymous codon usage.