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

Saira Abbas, Iftikhar Ahmed, Takuji Kudo, Muhammad Iqbal, Yong-Jae Lee, Toru Fujiwara, Moriya Ohkuma

The taxonomic position of a Gram-stain positive and heavy metal tolerant bacterium, designated strain NCCP-662(T), was investigated by polyphasic characterisation. Cells of strain NCCP-662(T) 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-662(T) 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 4T19(T) and Bacillus halosaccharovorans E33(T). 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-662(T) with the genus Bacillus. The level of DNA-DNA relatedness between strain NCCP-662(T) and B. niabensis JCM 16399(T) was 20.5 ± 0.5 %. On the basis of physiological and biochemical characteristics, phylogenetic analyses and DNA-DNA hybridization data, strain NCCP-662(T) 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-662(T) (= LMG 28369(T) = DSM 29005(T) = JCM 30192(T)).