Role of Bacillus licheniformis in phytoremediation of nickel contaminated soil cultivated with rice.

Heavy metal contamination in soil is an important environmental problem and it has negative effect on agriculture. Bacteria play a major role in phytoremediation of heavy metals contaminated soil. In this study, the effect of Bacillus licheniformis NCCP-59, a halophilic bacterium isolated from salt mines near Karak, Pakistan, were determined on a three week old greenhouse grown seedling and germinating seeds of two rice varieties (Basmati-385 (B-385) and KSK-282) in soil contaminated with different concentrations (0, 100, 250, 500, and 1000 ppm) of Nickel. Nickel significantly reduced the germination rate and germination percentage mainly at 500 and 1000 ppm. Significant decrease in ion contents (Na, K, and Ca) was observed while Ni ion concentration in the plant tissues increases as the concentration of Ni applied increases. The photosynthetic pigments (chlorophyll a (chl a), chlorophyll b (chl b), and carotenoids) were also decreased by the application of different concentrations of Ni. Total protein and organic nitrogen were found to be reduced at higher concentrations of Nickel. Inoculation of Bacillus licheniformis NCCP-59 improved seed germination and biochemical attribute of the plant under Ni stress. It is clear from the results that the Bacillus Licheniformis NCCP-59 strain has the ability to protect the plants from the toxic effects of nickel and can be used for the phytoremediation of Ni contaminated soil.

Bacillus pakistanensis sp. nov., a halotolerant bacterium isolated from salt mines of the Karak Area in Pakistan.

A rod shaped, non-motile, endospore forming, Gram-stain positive and moderately halotolerant strain, designated as NCCP-168(T), was isolated from salt mines sampled in the Karak district of Khyber Pakhtunkhwa Province in Pakistan. To delineate its taxonomic position, the strain was subjected to polyphasic characterization. Cells of strain NCCP-168(T) can grow at 10-40 (○)C (optimum at 30-35 (○)C), in a pH range of 5.0-9.0 (optimum at pH 8.0) and in 0-17 % (w/v) NaCl on agar medium. The phylogenetic analysis based on the 16S rRNA gene sequence showed that strain NCCP-168(T) belongs to the genus Bacillus with the highest similarity to Bacillus seohaeanensis BH724(T) (97.1 %), and less than 97 % similarity with other closely related taxa (95.6 % with B. subtilis subsp. subtilis NCIB3610(T)). DNA-DNA relatedness between strain NCCP-168(T) and the type strains of closely related species was lower than 30 %. Chemotaxonomic data (major menaquinone, MK-7; cell wall peptidoglycan type, A1γ [meso-diaminopimelic acid]; major fatty acids, iso-C15:0 29.9 %, anteiso-C15:0 29.3 %, iso-C16:0 11.4 %, iso-C14:0 8.9 % and anteiso-C17:0 7.0 %; major polar lipids, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine) support the affiliation of strain NCCP-168(T) with genus Bacillus. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain NCCP-168(T) can be distinguished from the closely related taxa and thus represents a novel species in the genus Bacillus, for which the name Bacillus pakistanensis sp. nov. is proposed, with the type strain NCCP-168(T) (= KCTC 13786(T) = DSM 24834(T) = JCM 18975(T)).