*3.1. Genome Sequencing and Assembly*

Genomic DNA was isolated from stationary phase cultures of *Z. amurskyensis* KMM 3526<sup>Т</sup> and *Z. laminariae* KMM 3676<sup>Т</sup> using a NucleoSpin kit (Macherey-Nagel, Düren, Germany) following manufacturer's instructions. The quantity and quality of isolated DNA were analyzed using NanoPhotometer Pearl (IMPLEN, Munich, Germany). The shotgun DNA libraries were constructed according to the methodological recommendations described in the GS Junior Titanium Rapid Library Preparation Method Manual, GS Junior Titanium emPCR Amplification Method Manual—Lib-L, GS Junior Titanium Sequencing Method Manual, NEBNextR dsDNA FragmentaseR, NEXTflex™ DNA-Sequencing Kit for Ion Platforms, KAPA Library Quantification Kit Ion Torrent™ Platforms, Ion 520™ & Ion 530™ Kit-Chef. Libraries of both flavobacteria were sequenced on the 454 GS Junior (454 Life Sciences, Branford, CT, USA); additional library of the KMM 3676<sup>Т</sup> was sequenced at Far Eastern Federal University, School of Biomedicine, on the Ion Torrent IonS5 XL platform (Thermo Fisher Scientific, Waltham, MA, USA). All sequencing reads were preprocessed with FastQC (https://www.bioinformatics.babraham.ac.uk/projects/fastqc/) and Prinseq

(http://edwards.sdsu.edu/cgi-bin/prinseq/prinseq.cgi) to remove the adaptor sequences and low-quality data. A de novo assembly of filtered reads was performed using Newbler version 3.0 (454 Life Sciences, Branford, CT, USA and SPAdes version 3.11.1 [66]; validation of an assembly was done by remapping filtered reads to the contigs by using Bowtie2 (Galaxy version 2.3.4.3+galaxy0) [67]; metrics were calculated with the help of QUAST (Galaxy version 5.0.2+galaxy0) [68].
