A starch-degrading novel strain, designated as strain ITR2T, was isolated from a soil sample collected from a garden near Dongguk University located in Goyang, Republic of Korea. The strain was identified as Gram-stain-positive, rod-shaped, and motile by means of peritrichous flagella. Moreover, 16S rRNA gene analysis revealed the novel strain to form a separate clade with Tumebacillus permanentifrigoris Eur1 9.5T (98.3 %) while also clustering with Tumebacillus flagellatus GST4T (97.9 %). Strain ITR2T grew optimally at temperatures of 20-30 °C, at pH 6.0-7.0 and at NaCl concentrations of 0-1 %. The sole quinone was menaquinone-7 and the cell-wall peptidoglycan comprised alanine, aspartic acid, glutamic acid, lysine and meso-diaminopimelic acid (type-A1γ peptidoglycan). The major fatty acids (>10%) of the novel strain were C16 : 0, iso-C14 : 0, iso-C15 : 0 and anteiso-C15 : 0, while the major polar lipids were phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol and one unidentified phospholipid. Other polar lipids of the novel strain included, two unidentified glycolipids, three unidentified phospholipids and one unidentified lipid. The in silico DNA-DNA hybridization values between strain ITR2T and its reference strains (T. permanentifrigoris DSM 18773T and T. flagellatus GST4T) were 21.3 and 23.9 %, respectively, while the average nucleotide identity values were 78.5 and 81.2 %, respectively. The genomic DNA G+C content was 54.9 mol%. Based on the phylogenetic, chemotaxonomic and genomic data obtained in the present study, we propose Tumebacillus amylolyticus sp. nov. to be a novel species within the genus Tumebacillus. The type strain is ITR2T (=KCTC 43280T=NBRC 114753T).
Keywords: Tumebacillus; amylolytic bacteria; phylogenetic analysis; starch; starch-degrading.