Pleionea litopenaei sp. nov., isolated from the gastric tract of juvenile Pacific white shrimp Litopenaeus vannamei

Abstract

A Gram-stain-negative, aerobic, rod-shaped and motile strain HL-JVS1^T, was isolated from the gastric tract of a juvenile Pacific white shrimp. Molecular phylogenetic analysis based on 16S rRNA gene sequences of strain HL-JVS1^T revealed its affiliation with the genus Pleionea, with close relatives including Pleionea mediterranea MOLA115^T (97.5%) and Pleionea sediminis S1-5-21^T (96.2%). The complete genome of strain HL-JVS1^T consisted of a circular 4.4 Mb chromosome and two circular plasmids (6.6 and 35.0 kb) with a G + C content of 43.1%. The average nucleotide identity and digital DNA-DNA hybridization values between strain HL-JVS1^T and the type strains of described Pleionea species were 69.7–70.4% and 18.3–18.6%, respectively. Strain HL-JVS1^T grew at 10–40 °C (optimum, 30 °C) in the presence of 0.5 − 9.0% (w/v) sea salts (optimum, 2.0 − 2.5%), and at pH range of 5.5 − 10.0 (optimum, pH 6.5). The major fatty acids (> 10%) were summed feature 9 (iso-C_17:1 ω9c and/or C_16:0 10-methyl) (23.3%), iso-C_16:0 (14.5%), iso-C_11:0 3-OH (13.8%) and iso-C_15:0 (11.0%). The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, an unidentified aminophospholipid, two unidentified aminolipids, and two unidentified lipids. The respiratory quinone was ubiquinone-8. The comprehensive phylogenetic, phylogenomic, phenotypic and chemotaxonomic results showed that strain HL-JVS1^T is distinct from other Pleionea species. Hence, we propose strain HL-JVS1^T as a novel species belonging to the genus Pleionea, for which the name Pleionea litopenaei sp. nov. is proposed with HL-JVS1^T (= KCCM 90514^T = JCM 36490^T) as the type strain.