Protaetiibacter mangrovi sp. nov., isolated from mangrove soil

Abstract

A novel Gram-stain-positive, aerobic, non-flagellated and rod-shaped actinobacterium, designated 10F1B-8-1^T, was isolated from mangrove soil sampled at Futian Mangrove Nature Reserve, China. The isolate was able to grow at 10-40 °C (optimum 30-32 °C), at pH 6-8 (optimum 7) and in the presence of 0-6% (w/v) NaCl (optimum 0%). Strain 10F1B-8-1^T shared the highest 16S rRNA gene sequence similarity to Protaetiibacter larvae NBRC 113051^T (98.3%), followed by Protaetiibacter intestinalis NBRC 113050^T (98.2%). Phylogenetic trees based on 16S rRNA gene sequences and the core proteomes exhibited that strain 10F1B-8-1^T formed a new phyletic line in the clade of genus Protaetiibacter, indicating that this strain belonged to the genus Protaetiibacter. Strain 10F1B-8-1^T showed low average nucleotide identity (<84%) and digital DNA-DNA hybridization values (<27%) with closely related taxa, suggesting that strain 10F1B-8-1^T was a hitherto undescribed species of the genus Protaetiibacter. Strain 10F1B-8-1^T contained D-2,4-diaminobutyric acid as the diagnostic diamino acid, and the peptidoglycan type was characterized as type B2β. The major fatty acids were iso-C_16:0, anteiso-C_15:0 and anteiso-C_17:0. The major menaquinones were MK-13 and MK-14. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, an unidentified glycolipid and five unidentified lipids. Notably, the ethyl acetate extracts of strain 10F1B-8-1^T showed effective antibacterial activity against Bacillus subtilis CPCC 100029 and Escherichia coli △tolC. According to the polyphasic data, strain 10F1B-8-1^T should be classified as a novel species of the genus Protaetiibacter, for which the name Protaetiibacter mangrovi sp. nov. is proposed, with the type strain 10F1B-8-1^T (=JCM 33142^T = CPCC 205428^T).