Actinotalea endophytica sp. nov., a Novel Endophytic Actinobacterium Isolated from Sonneratia apetala.

A Gram-stain-positive, rod-shaped and aerobic actinobacterium, designated strain M2MS4P-6T, was isolated from surface-sterilized bark of Sonneratia apetala. The isolate was able to grow at 15–40 °C (optimum, 30–37 °C), at pH 6–8 (optimum, pH 7) and in the presence of 0–11% (w/v) NaCl (optimum, 2%). Strain M2MS4P-6T showed the high 16S rRNA gene sequence similarities (95.5–98.9%) with the members of the genus Actinotalea. Phylogenetic trees based on 16S rRNA gene sequences and up-to-date bacterial core genes consistently showed that strain M2MS4P-6T clustered tightly with Actinotalea lenta GDMCC 1.3827T and formed an independent evolutionary branch. Digital DNA-DNA hybridization (19.5–21.6%), average nucleotide identity (72.5–78.7%) and average amino acid identity (55.3–75.9%) values between strain M2MS4P-6T and the Actinotalea species were lower than the thresholds for species delineation, indicating that strain M2MS4P-6T was a new species of the genus Actinotalea. The genomic G + C content of strain M2MS4P-6T was 72.9%. The major polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside, one unidentified phospholipid and two unidentified lipids. The predominant respiratory quinone was MK-8(H4), and the major fatty acids were C16:0, anteiso-C15:0 and C14:0. Gene functional analysis revealed that strain M2MS4P-6T harbored an effective osmoregulation system to adapt the mangrove environment. Based on polyphasic taxonomic data, strain M2MS4P-6T is considered to represent a novel Actinotalea species, for which the name Actinotalea endophytica sp. nov. is proposed. The type strain is M2MS4P-6T (= CGMCC 4.7527T =KCTC 49194T).