Polyphasic Taxonology Identification Of Four Actinomycetes Isolated From Mangrove Sediments

Mangrove which grows in the coastal intertidal zones of tropical and subtropical areas is a special kind of plant community. As one of the four highest productive marine ecosystems, mangrove is a precious resource for screening and discovering new actinomycetes. In this research, in accordance with the principle of polyphasic taxonomy, a systematic study had been conducted on the identification of four actinomycetes (strain HA11166, HA11164, HA10211and HA11097) isolated from sediment samples at Dongzhaigang Mangrove in Hainan.Strain HA11166T is Gram-positive. Growth occurs with1-5%(w/v) NaCl, at pH6-12and8-43℃. Nitrate reduction-positive. Degrade starch, but not cellulose. Milk coagulation and peptonization are negative. H2S is not produced. The major polar lipid profiles are PE, PIM and GL. Major cellular fatty acids are ant-C15:0, iso-C16:0, iso-C14:0, C16:1ω9c and C16:0. The DNA GC content is73.71mol%. The phylogenetic tree revealed that its16S rRNA gene had highest homology (98.2%) with Nocardiopsis trehalosi VKM Ac-942T, which located on the same branch. Their DNA-DNA hybridization value was35.4%. Strain HA111667represents a novel species of the genus Nocardiopsis, for which the name Nocardiopsis dongzhaigangensis sp. nov is proposed.Strain HA111641is Gram-positive. Growth occurs with1-5%(w/v) NaCl, at pH6-11and14-28℃. Does not reduce nitrate. Can’t degrade starch. Milk coagulation and peptonization are negative. H2S is not produced. The major polar lipid profiles are DPG, PME, PC, PI and PIM. The DNA G+C content is74.9%. It has the highest homology (98.5%) with Pseudonocardia carboxydivorans Y8T based on16S rRNA gene sequence alignment analysis. In the phylogenetic tree, strain HA11164, P. alni DSM44104T, P. tropica YIM61452T, P. antarctica DVS5a1T, P. carboxydivorans Y8T and P. parietis04-St-002T were clusterd into a large brach. The DNA-DNA hybridization values of strain HA11164T were62.3%,60.2%,50.0%,59.1%and46.0%respectively. Strain HA11164T represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia nematocida sp. nov. is proposed.Strain HA10211is Gram-positive, Colonies are golden yellow. Growth occurs at pH6-11and14-43℃, and optimal growth at3%(w/v) NaCl. Nitrate reduction is negative. Degrade starch, but not cellulose. Milk coagulation and peptonization are negative. H2S is not produced. It has the highest homology (99.2%) with Isoptericola chiayiensis06182M-11 based on16S rRNA gene sequence alignment analysis. In the phylogenetic tree, HA10211and I. chiayiensis06182M-1T constituted a branch. The DNA-DNA relatedness values of strain HA10211with I.chiayiensis06182M-1T and I. halotolerans YM07177are80.3%and60.3%, respectively. Thus, strain HA10211is identified as Isoptericola chiayiensis.Strain HA11097is Gram-positive. Growth occurs between pH6-9, between14-37℃, and in1-3%(w/v) NaCl. Reduce nitrate. Degrade cellulose, but not starch, milk coagulation and peptonization are negative. H2S is not produced. It has the highest homology98.9%with Streptomyces aculeolatus NBRC14824T based on16S rRNA gene sequence alignment analysis. In the phylogenetic tree, HA11097and S. aculeolatus NBRC14824T consitituted a branch. The DNA relatedness between strain HA11097and S. aculeolatus NBRC14824Tare94.4%. Thus, strain HA11097is identified as Streptomyces aculeolatus.