RESUMEN
A thermotolerant, Gram-positive, aerobic, endospore-forming, acidophilic bacterium (strain Kr1T) was isolated from the pulp of a gold-containing sulfide concentrate processed at 40 degrees C in a gold-recovery plant (Siberia). Cells of strain Kr1(T) were straight to slightly curved rods, 0.8-1.2 microm in diameter and 1.5-4.5 microm in length. Strain Kr1T formed spherical and oval, refractile, subterminally located endospores. The temperature range for growth was 20-60 degrees C, with an optimum at 40 degrees C. The pH range for growth on medium containing ferrous iron was 1.2-2.4, with an optimum at pH 2.0; the pH range for growth on medium containing S0 was 2.0-5.0, with an optimum at pH 2.5. Strain Kr1T was mixotrophic, oxidizing ferrous iron, S0, tetrathionate or sulfide minerals as energy sources in the presence of 0.02 % yeast extract or other organic substrates. The G+C content of the DNA of strain Kr1T was 48.2+/-0.5 mol%. Strain Kr1T showed a low level of DNA-DNA reassociation with the known Sulfobacillus species (11-44 %). 16S rRNA gene sequence analysis revealed that Kr1T formed a separate phylogenetic group with a high degree of similarity between the nucleotide sequences (98.3-99.6 %) and 100 % bootstrap support within the phylogenetic Sulfobacillus cluster. On the basis of its physiological properties and the results of phylogenetic analyses, strain Kr1T can be affiliated to a novel species of the genus Sulfobacillus, for which the name Sulfobacillus thermotolerans sp. nov. is proposed. The type strain is Kr1T (=VKM B-2339T=DSM 17362T).
Asunto(s)
Bacilos Grampositivos Formadores de Endosporas/clasificación , Bacilos Grampositivos Formadores de Endosporas/aislamiento & purificación , Composición de Base , Metabolismo de los Hidratos de Carbono , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Microbiología Ambiental , Compuestos Ferrosos/metabolismo , Genes de ARNr , Ácido Glutámico/metabolismo , Glutatión/metabolismo , Oro , Bacilos Grampositivos Formadores de Endosporas/citología , Bacilos Grampositivos Formadores de Endosporas/fisiología , Concentración de Iones de Hidrógeno , Datos de Secuencia Molecular , Hibridación de Ácido Nucleico , Oxidación-Reducción , Filogenia , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Sulfuros/metabolismo , Azufre/metabolismo , Temperatura , Ácido Tetratiónico/metabolismoRESUMEN
Comparative analysis of 16S rRNA gene sequences, DNA-DNA hybridization data and phenotypic properties revealed that 'Sulfobacillus thermosulfidooxidans subsp. thermotolerans' strain K1 is not a member of the genus Sulfobacillus. Phylogenetically, strain K1 is closely related to unclassified strains of the genus Alicyclobacillus: the 16S rRNA gene sequence of strain K1 is similar to that of Alicyclobacillus sp. AGC-2 (99.6 %), Alicyclobacillus sp. 5C (98.9 %) and Alicyclobacillus sp. CLG (98.6 %) and bacterium GSM (99.1 %). The 16S rRNA gene sequence similarity values for strain K1 and species of the genus Alicyclobacillus with validly published names were in the range 92.1-94.6 %, and for S. thermosulfidooxidans VKM B-1269(T) the value was 87.7 %. Sulfobacillus disulfidooxidans SD-11(T) was also phylogenetically related to strain K1 (92.6 % sequence similarity) and thus belonged to the genus Alicyclobacillus. Chemotaxonomic data, such as the major cell-membrane lipid components of strains K1 and SD-11(T) (omega-alicyclic fatty acids) and the major isoprenoid quinone (menaquinone MK-7) of strain K1, supported the affiliation of strains K1 and SD-11(T) to the genus Alicyclobacillus. Physiological and molecular biological tests allowed genotypic and phenotypic differentiation of strains K1 and SD-11(T) from the nine Alicyclobacillus species with validly published names. The G+C content of the DNA of strain K1 was 48.7+/-0.6 mol%; that of strain SD-11(T) was 53+/-1 mol%. DNA-DNA reassociation studies showed low relatedness (22 %) between strains K1 and SD-11(T), and even lower relatedness (3-5 %) between these strains and Alicyclobacillus acidocaldarius subsp. acidocaldarius ATCC 27009(T), DSM 446(T). DNA reassociation of strains K1 and SD-11(T) with Alicyclobacillus cycloheptanicus DSM 4006(T) gave values of 15 and 21, respectively. Based on the phenotypic and phylogenetic characteristics of strains K1 and SD-11(T), Alicyclobacillus tolerans sp. nov. (type strain, K1(T)=VKM B-2304(T)=DSM 16297(T)) and Alicyclobacillus disulfidooxidans comb. nov. (type strain, SD-11(T)=ATCC 51911(T)=DSM 12064(T)) are proposed.
Asunto(s)
Bacilos Grampositivos Formadores de Endosporas/clasificación , Bacilos Grampositivos Formadores de Endosporas/genética , ADN Bacteriano/análisis , ADN Ribosómico/análisis , Genes de ARNr , Bacilos Grampositivos Formadores de Endosporas/química , Datos de Secuencia Molecular , Hibridación de Ácido Nucleico , Fenotipo , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADNRESUMEN
Polyphasic genotypic analysis of 25 Acidithiobacillus ferrooxidans strains isolated from ores and ore concentrates collected in different regions of the world showed considerable strain heterogeneity. Restriction patterns of the chromosomal DNA of these strains obtained by PFGE were specific for each strain. According to the degree of DNA relatedness, 17 of the 23 strains studied were divided into four genomovars. Six independent, considerably divergent strains could not be assigned to any of the genomovars. A comparison of nearly complete nucleotide sequences of the 16S rDNA of five representatives of the genomovars (including the type strain of A. ferrooxidans, ATCC 23270T) with those of species of the genus Acidithiobacillus available from GenBank showed that most of the A. ferrooxidans strains, together with the type strain and some other strains of the species Acidithiobacillus thiooxidans, comprised a monophyletic cluster. Within this major cluster, A. ferrooxidans strains fell into four phylogenetic groups that were equidistant from the phylogenetic group of A. thiooxidans strains. In general, the distribution of strains among the phylogenetic groups correlated with their distribution among the genomovars, except that the representatives of two different genomovars fell into one phylogenetic group. Thus, at least two levels of phylogenetic heterogeneity for A. ferrooxidans have been found. The phylogenetic heterogeneity of A. ferrooxidans strains, which are phenotypically indistinguishable, suggests the occurrence of microevolutionary processes in different econiches. This should be taken into account in the biohydrometallurgical applications of A. ferrooxidans strains.