A Novel Carotenoid-Producing Bacterium, Paenibacillus aurantius sp. nov., Isolated from Korean Marine Environment

The novel bacterial strain MBLB1776(T) was isolated from marine mud in Uljin, the Republic of Korea. Cells were Gram-positive, spore-forming, non-motile, and non-flagellated rods. Growth was observed at a temperature range of 10–45 °C, pH range of 6.0–8.0, and NaCl concentrations of 0–4% (w/v). Phylogenetic analysis of the 16S rRNA gene sequence revealed that MBLB1776(T) belonged to the genus Paenibacillus and was closely related to Paenibacillus cavernae C4-5(T) (94.83% similarity). Anteiso-C(15:0), iso-C(16:0), C(16:0), and iso-C(15:0) were the predominant fatty acids. Menaquinone 7 was identified as the major isoprenoid quinone. The major polar lipids included diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. Its whole genome was 6.3 Mb in size, with a G+C content of 55.8 mol%. Average nucleotide identity and in silico DNA–DNA hybridization values were below the species delineation threshold. Gene function analysis revealed the presence of a complete C(30) carotenoid biosynthetic pathway. Intriguingly, MBLB1776(T) harbored carotenoid pigments, imparting an orange color to whole cells. Based on this comprehensive polyphasic taxonomy, the MBLB1776(T) strain represents a novel species within the genus Paenibacillus, for which the name Paenibacillus aurantius sp. nov is proposed. The type strain was MBLB1776(T) (=KCTC 43279(T) = JCM 34220(T)). This is the first report of a carotenoid-producing Paenibacillus sp.