Nocardioides piscium sp. nov. , an Epsilon-poly-L-lysine producing actinobacterium isolated from the fish intestine

Abstract A Gram-positive, irregular short-stemmed, non-motile, non-acid-fast, non-spore-forming, aerobic actinomycete strain, designated GXZ039T, was isolated from the fish gut of grouper from the Beibu Gulf, Guangxi, China. Analysis of the growth state and conditions showed that colonies on medium 2216E for 5 days of incubation were light-white, rounded, glossy, smooth, raised, and opaque, diameter 1.0–2.0 mm. Strain growth conditions ranged from pH 6.0–10.0 (optimum pH 7.5), 4–40°C (optimum 30°C)and 0–10% NaCl (w/v) (optimum 3.5%). Chemical histological showed that the major menaquinone of strain GXZ039T was MK-8, with a small amount of MK-7. The main cellular fatty acids were iso-C16:0 (39.2%), C17:1ꞷ6c (11.59%) and anteiso-C15:0 (10.97%). The type of the cell wall peptidoglycan was LL-diaminoheptanedioic acid and the polar lipids consisted of phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), an uncharacterised lipid (L) and two unknown phospholipids (PL1-2). Total cell sugars were xylose, arabinose, glucose and galactose. The DNA G + C ratio of the strain was 71.1 mol%. Sequence comparison of 16S rRNA genes showed that strain GXZ039T belonged to the genus Nocardioides and its close relatives were with Nocardioides plantarum NCIMB 12834T (98.03%),, Nocardioides dongxiaopingii S-1144T (97.54%) and Nocardioides litoris 002-2T(97.54%), respectively. Calculations showed that GXZ039T had ANI values of 77.12–85.13% and dDDH values of 21.6–27.7%. On the basis of phenotypic, chemical components and phylogenetic data, strain GXZ039T was defined as a novel species of the genus Nocardioides under the name Nocardioides piscium sp. nov. The strain type is GXZ039T (= MCCC 1K09118T = KCTC 59248T).