A heavy metal tolerant novel bacterium, Bacillus malikii sp. nov., isolated from tannery effluent wastewater

Abstract

The taxonomic position of a Gram-stain positive and heavy metal tolerant bacterium, designated strain NCCP-662T, was investigated by polyphasic characterisation. Cells of strain NCCP-662T were observed to be rod to filamentous shaped, motile and strictly aerobic, and to grow at 10–50 °C (optimum 30–37 °C) and at pH range of 6–10 (optimum pH 7–8). The strain was found to be able to tolerate 0–12 % NaCl (w/v) and heavy metals (Cr 1200 ppm, Pb 1800 ppm and Cu 1200 ppm) in tryptic soya agar medium. The phylogenetic analysis based on the 16S rRNA gene sequence of strain NCCP-662T showed that it belongs to the genus Bacillus and showed high sequence similarity (98.2 and 98.0 %, respectively) with the type strains of Bacillus niabensis 4T19T and Bacillus halosaccharovorans E33T. The chemotaxonomic data showed that the major quinone is MK-7; the predominant cellular fatty acids are anteiso-C15 :0, iso-C14:0, iso-C16:0 and C16:0 and iso-C15:0; the major polar lipids are diphosphatidylglycerol, phosphatidylglycerol along with several unidentified glycolipids, phospholipids and polar lipids. The DNA G+C content was determined to be 36.9 mol%. These data also support the affiliation of strain NCCP-662T with the genus Bacillus. The level of DNA–DNA relatedness between strain NCCP-662T and B. niabensis JCM 16399T was 20.5 ± 0.5 %. On the basis of physiological and biochemical characteristics, phylogenetic analyses and DNA–DNA hybridization data, strain NCCP-662T can be clearly differentiated from the validly named Bacillus species and thus represents a new species, for which the name Bacillus malikii sp. nov. is proposed with the type strain NCCP-662T (= LMG 28369T = DSM 29005T = JCM 30192T).