Microbiological characteristics of a Lysinibacillus strain isolated from Populous euphratica

Abstract:

Abstract:［Objective］The aim of this study was to identify the microbiological characteristics of a Lysinibacillus strain isolated from storage liquid in the stems of Populus euphratica trees． ［Methods］ Bacterial morphology and cultivation characteristics were studied by conventional cultivation and dyeing method． Biochemical characteristics，fatty acid components，menaquinone，polar lipids，phylogenetic analyses of 16S rＲNA，determination of (G+C) mol% content and DNA- DNA hybridization were studied by polyphasic taxonomic approach．［Results］Strain ML-64 is Gram-positive，endospore-forming and rod-shaped． Colonies are pale-yellow，circular and entire margin．Temperature range for growth is between 10 and 45 ℃ (optimum at 37 ℃)．The pH range for growth is between 6. 0 and 9.0 (optimum at 7.0)．NaCl concentration range for growth is between 0 and 6% (optimum 3%)．Cells were positive for lipid esterase，Arginine dihydrolase，urease and Voges-Proskauer test． No sugars were fermented in the API 50CH strips．L-Serine，Methyl Pyruvate，α-Keto-Butyric，Acetoacetic Acid were oxidized．Resistant to polymyxin b (30 μg)，novobiocin (30 μg)，peillin G (10 U)．16S rRNA gene sequence demonstrated that strain ML-64 was closely related to Lysinibacillus chungkukjangi 2RL3-2T (100%)，Lysinibacillus sinduriensis BLB-1T (99.1%)．DNA-DNA relatedness were 82% and 50.9% with Lysinibacillus chungkukjangi 2RL3-2T and Lysinibacillus massiliensis CIP108446T，respectively． The genomic DNA G+C content of strain ML-64 was 36.8% (mol)． Major fatty acids were iso-C15:0 ( 55.05% ) and anteiso-C15:0 (20.70%)．The predominant menaquinone is MK-7．Based on the phenotypic phylogenetic and genotypic analyses，the strain ML-64 is concluded to represent a new mutant strain of the Lysinibacillus chungkukjangi species，GenBank accession number is KC609752．［Conclusion］As an endophytic bacterium of Populus euphratica，genomic structure of the strain ML-64 was greatly differentiated from the closest strain L． chungkukjangi，and suitably adapted to the endophytic environment of Populus euphratica．

Key words:Keywords: genus Lysinibacillus，endophytic bacterium of Populus euphratica，polyphasic taxonomic approach