Bacillus aciditolerans sp. nov., isolated from paddy soil.

A Gram-stain-positive, motile, rod-shaped bacterial strain, YN-1T, was isolated from a rice field in the town of Jietou, Yunnan Province, PR China. Colonies were circular, 1-2 mm in diameter, creamy white, with slightly irregular margins. The isolate grew optimally at 37 °C, pH 7.0 and with 1.0 % (w/v) NaCl. On the basis of the results of 16S rRNA gene sequence similarity comparisons, YN-1T clustered together with other species of the genus Bacillus and showed highest similarities with Bacillus onubensis 0911MAR22V3T (98.0 %), Bacillus humi LMG22167T (97.5 %), 'Bacillus timonensis' 10403023 (97.4 %) and 'Bacillussinesaloumensis' P3516 (97.1 %). However, the DNA-DNA hybridization values between YN-1T and closely related strains of species of the genus Bacillus were well below 47 %, indicating that they represent different taxa. The average nucleotide identity and the Genome-to-Genome Distance Calculator also revealed low relatedness (below 95 and 70 %, respectively) between YN-1T and type strains of closely related species of the genus Bacillus. The DNA G+C content of the strain was 40 mol%. The major cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0, and C16 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids, three unidentified aminophospholipids and two other unidentified lipids. Physiological and biochemical test results were also different from those of the most closely related species. On the basis of the phenotypic, genetic and chemotaxonomic data, strain YN-1T is considered to represent a novel species of the genus Bacillus, for which the name Bacillusaciditolerans sp. nov. is proposed, with strain YN-1T (=CCTCC AB 2017280T=JCM 32973T) as the type strain.

Biodegradation of malachite green by an endophytic bacterium Klebsiella aerogenes S27 involving a novel oxidoreductase.

Endophytic microorganisms can metabolize organic contaminants and assist in plant growth, thus facilitating the phytoremediation of polluted environments. An endophytic bacterium capable of decoloring malachite green (MG) was isolated from the leaves of the wetland plant Suaeda salsa and was identified as Klebsiella aerogenes S27. Complete decolorization of MG (100 mg/l) was achieved in 8 h at 30 °C and pH 7.0. Ultraviolet-visible spectroscopy and Fourier-transform infrared spectroscopy analyses indicated the degradation of MG by the isolate. The enzymic assays of the strain showed the triphenylmethane reductase (TMR) activity. A gene encoding putative TMR-like protein (named as KaTMR) was cloned and heterologously expressed in Escherichia coli. KaTMR showed only 42.6-43.3% identities in amino acids compared with well-studied TMRs, and it phylogenetically formed a new branch in the family of TMRs. The degraded metabolites by recombinant KaTMR were detected by liquid chromatography-mass spectrometry, showing differences from the products of reported TMRs. The biotransformation pathway of MG was proposed. Phytotoxicity studies revealed the less-toxic nature of the degraded metabolites compared to the dye. This study presented the first report of an endophyte on the degradation and detoxification of triphenylmethane dye via a novel oxidoreductase, thus facilitating the study of the plant-endophyte symbiosis in the bioremediation processes.

Complete Genome Sequence of the Heavy-Metal-Tolerant Endophytic Type Strain of Salinicola tamaricis.

The first complete genome sequence of a recently described Salinicola tamaricis species was determined for the strain F01T (=CCTCC AB 2015304T =KCTC 42855T). The strain was isolated from the leaves of wetland plant Tamarix chinensis Lour and shows a high tolerance to heavy metals, such as manganese, nickel, lead, and copper ions.