Study On Polyphasic Taxonomy Approach Of A Novel Species Isolated From Populus Euphratica Leaves

The strain NTA-7~T isolated from Populus euphratica leaves in Tarim river was characterized using a polyphasic Taxonomy approach.The morphological,physiological and biochemical,whole-cell chemochemical properties and molecular characteristics of the strain NTA-7~T were analyzed,and determine its taxonomic status.Almost-complete 16 S rRNA gene sequence(1491bp)of strain NTA-7~T was obtained and sequenced.The 16 S rRNA gene sequence analysis indicated that it closest to Pontibacter toksunensis ZLD-7~T,with a similarity value of 16 S rRNA gene sequence was 94.55%.And the Pontibacter toksunensis ZLD-7~T,Pontibacter actiniarum KMM 6156 T,Nibribacter koreensis GSR3061 T,Rufibacter tibetensis 1351 T,Adhaeribacter aquaticus MBRG1.5T were used as references strains in this study.The similarity values of 16 S rRNA gene sequences of bacterium NTA-7~T with those references strains were 94.55%,92.96%,92.00%,91.99% and91.07%,respectively.The results of phylogenetic tree analysis based on 16 S rRNA gene sequence demonstrated that strain NTA-7~T was a new taxon with a high threshold value of 96%.The results of the polyphasic approach revealed that the strain NTA-7~T was a gram-negative bacterium,aerobic,non-motile,non-spore-forming,shiny,rod-shaped bacteria.Cell size was(0.4-0.7)?m×(1.2-2.6)?m.The strain NTA-7~T cultured on0.3×MA marine culture medium and pink colony was appeared at two days after incubation at 30?.The colon was 1.6 mm in diameter,circular,smooth with entire margins.Growth temperature range of the strain NTA-7~T is 6~40?,optimal growth temperature is 30?.Growth occurs at pH 6.0~9.0,the optimum growth pH value is between7 and 8.The tolerance range of NaCI is 0-6%,and the optimum growth NaCI concentration is(w/v)0~1%.The growth medium of strain NTA-7~T is Luria-Bertant(LB),Water Plate Count Agar(R2A)and Marine Agar 2216 Difco(MA).Strain NTA-7~T does not produce Flexirubin-type pigment.Strain NTA-7~T are negative for Oxidase and positive for catalase activity;canhydrolyze starch,gelatin,casein,but can not hydrolyze cellulose,tween20,tween 60,tween 80.Also API ZYM,API 20 NE,API 20 E and API 50 CH were used to test the biochemical and enzymatic activity of strain NTA-7~T and the activity results were compared with the reference strains.Strain NTA-7~T are susceptible to penicillin,cefotaxime,streptomycin,ampicillin,gentamicin,neomycin,tetracycline,erythromycin,rifampicin,vancomycin,but also to kanamycin,tobramycin,amikacin,chloramphenicol,doxycycline is not sensitive.The major fatty acids were iso C15: 0(31.11%),C16:1 ?5c(13.87%),Summed feature 3(13.00%),Summed feature 4(24.16%),iso C17:0(2.21%),iso C17:0 3-OH(2.15%).The polar lipid of strain NTA-7~T profile consists mainly phosphatidylethanolamine(PE),four unidentified lipids(L1,L2,L3,L4),one unknown aminophospholipid(APL),one unknown phospholipids(PL)and an unknown glycolipid(GL)are also present.The predominant isoprenoid quinone was MK-7.The G+C content of the genomic DNA was 43.2 moL%.Based on phenotypic,chemotaxonomic and phylogenetic properties,strain NTA-7~T represents a novel species of the genus Pontibacter,for which the name Pontibacter Tarimense sp.nov.is proposed,the type strain is NTA-7~T.The Gen Bank accession number for the 16 S rRNA gene sequence of strain NTA-7~Tis KY814729.