Characterization of Marinilongibacter aquaticus gen. nov., sp. nov., a unique marine bacterium harboring four CRISPR-Cas systems in the phylum Bacteroidota.

A novel bacterium, designated YYF0007, was isolated from an agar-degrading co-culture. The strain was found harboring four CRISPR-Cas systems of two classes in the chromosome and subsequently subjected to a study on polyphasic taxonomy. Pairwise analyses of the 16S rRNA gene sequences indicated that strain YYF0007 had highest 16S rRNA gene sequence similarity (92.2%) to Jiulongibacter sediminis JN-14-9. The phylogenomic trees based on the 16S rRNA gene and 269 single-copy orthologous gene clusters (OCs) indicated that strain YYF0007 should be recognized as a novel genus of the family Spirosomaceae. The cells were Gramstain-negative, nonmotile, strictly aerobic, and straight long rods with no flagellum. Optimum growth occurred at 28°C and pH 7.0 with the presence of NaCl concentration 1.0-3.0% (w/v). The strain showed oxidase and catalase activities. The major fatty acids were Cω5c, iso-C and summed feature 3 (Cω7c and/or Cω6c). The predominant isoprenoid quinone was MK-7. The complete genome size was 4.64 Mb with a DNA G + C content of 44.4%. Further typing of CRISPR-Cas systems in the family Spirosomaceae and the phylum Bacteroidota indicated that it was remarkable for strain YYF0007 featured by such a set of CRISPR-Cas systems. This trait highlights the applications of strain YYF-0007 in studies on the evolutionary dynamics and bacterial autoimmunity of CRISPR-Cas system as a potential model. The name Marinilongibacter aquaticus gen. nov., sp. nov. is proposed, and the type strain is YYF0007 (= MCCC 1K06017 = GDMCC 1.2428 = JCM 34683).