Characterization of Lacinutrix neustonica sp. nov., Isolated from the Sea Surface Microlayer of Brackish Lake Shihwa, South Korea

Abstract

A Gram-negative, strictly aerobic, non-motile, slightly curved rod-shaped bacterial strain, designated as HL-RS19T, was isolated from a sea surface microlayer (SML) sample of the brackish Lake Shihwa. Here, we characterized the new strain HL-RS19T using a polyphasic approach to determine its taxonomic position. A phylogenetic analysis of its 16S rRNA gene sequence revealed that strain HL-RS19T belonged to the genus Lacinutrix and was closely related to L. mariniflava AKS432T (97.9%), L. algicola AKS293T (97.8%), and other Lacinutrix species (<97.3%). The complete genome sequence of strain HL-RS19T comprised a circular chromosome of 3.9 Mbp with a DNA G+C content of 35.2%. Genomic comparisons based on the average nucleotide identity and digital DNA-DNA hybridization showed that strain HL-RS19T was consistently discriminated from its closely related taxa in the genus Lacinutrix. Strain HL-RS19T showed optimal growth at 20–25 °C, pH 6.5–7.0, and 3.0–3.5% (w/v) sea salts. The major fatty acids (>5%) of strain HL-RS19T were identified as iso-C15:1 G (16.5%), iso-C16:0 3-OH (12.9%), anteiso-C15:1 A (9.9%), anteiso-C15:0 (9.7%), iso-C15:0 (9.0%), and iso-C15:0 3-OH (8.3%). The polar lipids consisted of phosphatidylethanolamine, three unidentified aminolipids, an unidentified phospholipid, and two unidentified lipids. The major respiratory quinone was MK-6. Based on phylogenetic, genomic, phenotypic, and chemotaxonomic data, strain HL-RS19T represents a novel species belonging to the genus Lacinutrix, for which the name Lacinutrix neustonica sp. nov. is proposed. The type strain is HL-RS19T (=KCCM 90497T = JCM 35710T). The genome sequence analysis of strain HL-RS19T suggests that it may be well adapted to a harsh SML environment and is likely involved in arsenic cycling, potentially contributing to the bioremediation of anthropogenic arsenic pollution.