Tumebacillus flagellatus sp. nov., an α-amylase/pullulanase-producing bacterium isolated from cassava wastewater

Abstract

A novel α-amylase/pullulanase-producing bacterium, designated strain GST4T, was isolated from samples collected from the wastewater of a cassava starch factory in Nanning, Guangxi Autonomous Region, southern China. Cells of strain GST4T were rod-shaped bacilli containing ellipsoidal terminal spores and found to be Gram-reaction-positive, aerobic, motile, oxidase-positive, catalase-negative and formed light yellow colonies on agar plates. Strain GST4T was able to grow at pH 4.5–8.5 (optimum at pH 5.5), temperatures ranging from 20 to 42 °C (optimum at 37 °C) and salt concentrations of 0–1 % (w/v) NaCl (optimum at 0.5 %, w/v) on R2A medium. Strain GST4T grew heterotrophically on complex carbon substrates and chemolithoautotrophically on inorganic sulfur compounds, as demonstrated by growth on sodium thiosulfate and sulfite as sole electron donors. It can reduce nitrate and nitrite. Strain GST4T contained iso-C15 : 0 and anteiso-C15 : 0 as the major cellular fatty acids and menaquinone 7 (MK-7) as the major respiratory quinone. The cell-wall peptidoglycan was of type A1γ. The genomic DNA G+C content of strain GST4T was 53.7 mol%. Physiological and chemotaxonomic characteristics combined with phylogenetic analysis based on 16S rRNA gene sequences revealed that strain GST4T was a member of the genus Tumebacillus and most closely related to Tumebacillus permanentifrigoris DSM 18773T and Tumebacillus ginsengisoli DSM 18389T with 97.3 and 94.5 % sequence similarity, respectively. The DNA–DNA relatedness values between strain GST4T and T. permanentifrigoris DSM 18773T, and strain GST4T and T. ginsengisoli DSM 18389T were 44.0 and 60.4 %, respectively. The new isolate differed from those species of the genus Tumebacillus in that it has peritrichous flagella for motility. Based on the evidence obtained from this study, strain GST4T represents a novel species of the genus Tumebacillus , for which the name Tumebacillus flagellatus sp. nov. is proposed. The type strain is GST4T ( = CGMCC 1.12170T = DSM 25748T).