Isolation of "Methylopumilus profundus" was conducted using dilution-to-extinction cultivation in 96-well-plates containing 1.5ml of medium (Salcher and Karel Šimek, 2016) . The culture, once established, was grown in 400ml of medium until late stationary phase. Growth was checked by flow cytometry. The large volume was filtered through 0.22 µm polysulfone filters (Millipore express PLUS, Germany). DNA was isolated using Quick-DNA HMW MagBead Kit (Zymo Research) and pair end libraries (PE150) were sequenced on a NovaSeq 6000 instrument (Illumina, NOVOGENE, HK.). Raw reads were trimmed using BBMap v36.x (https://github.com/BioInfoTools/BBMap/) and assembled using SPAdes v3.12.0 (using kmers 29,49,59,69,79,89,99,109,119,127) (Prjibelski et al., 2020). One contig was obtained from this genome that was sequentially curated into a circular genome manually using geneious to extend the ends until an overlap was detected. (Layoun et al., 2024)