Acinetobacter strains IH9 and OCI1, two rhizospheric phosphate solubilizing isolates able to promote plant growth, constitute a new genomovar of Acinetobacter calcoaceticus.

During a screening of phosphate solubilizing bacteria (PSB) in agricultural soils, two strains, IH9 and OCI1, were isolated from the rhizosphere of grasses in Spain, and they showed a high ability to solubilize phosphate in vitro. Inoculation experiments in chickpea and barley were conducted with both strains and the results demonstrated their ability to promote plant growth. The 16S rRNA gene sequences of these strains were nearly identical to each other and to those of Acinetobacter calcoaceticus DSM 30006(T), as well as the strain CIP 70.29 representing genomospecies 3. Their phenotypic characteristics also coincided with those of strains forming the A. calcoaceticus-baumannii complex. They differed from A. calcoaceticus in the utilization of l-tartrate as a carbon source and from genomospecies 3 in the use of d-asparagine as a carbon source. The 16S-23S intergenic spacer (ITS) sequences of the two isolates showed nearly 98% identities to those of A. calcoaceticus, confirming that they belong to this phylogenetic group. However, the isolates appeared as a separate branch from the A. calcoaceticus sequences, indicating their molecular separation from other A. calcoaceticus strains. The analysis of three housekeeping genes, recA, rpoD and gyrB, confirmed that IH9 and OCI1 form a distinct lineage within A. calcoaceticus. These results were congruent with those from DNA-DNA hybridization, indicating that strains IH9 and OCI1 constitute a new genomovar for which we propose the name A. calcoaceticus genomovar rhizosphaerae.

Paenibacillus castaneae sp. nov., isolated from the phyllosphere of Castanea sativa Miller.

A bacterial strain, designated Ch-32(T), was isolated from the phyllosphere of Castanea sativa in Spain. Phylogenetic analysis based on 16S rRNA gene sequences placed the isolate in the genus Paenibacillus within the same subgroup as Paenibacillus xinjiangensis and Paenibacillus glycanilyticus, with similarities of 96.3 and 96.8 %, respectively. DNA-DNA hybridization values for strain Ch-32(T) with these two species were lower than 20 %. The novel isolate was a Gram-variable, motile, sporulating rod. It produced catalase and oxidase and hydrolysed cellulose, gelatin and aesculin. Acetoin and urease production, nitrate reduction and starch hydrolysis were negative. Growth was supported by many carbohydrates and organic acids as carbon sources. MK-7 was the only menaquinone detected and anteiso-C(15 : 0), iso-C(16 : 0) and C(16 : 0) were the major fatty acids. The DNA G+C content was 46 mol%. Phylogenetic, DNA relatedness and phenotypic analyses showed that strain Ch-32(T) should be classified as a novel species of the genus Paenibacillus, for which the name Paenibacillus castaneae sp. nov. is proposed; the type strain is Ch-32(T) (=CECT 7279(T)=DSM 19417(T)).

Reclassification of Pseudomonas aurantiaca as a synonym of Pseudomonas chlororaphis and proposal of three subspecies, P. chlororaphis subsp. chlororaphis subsp. nov., P. chlororaphis subsp. aureofaciens subsp. nov., comb. nov. and P. chlororaphis subsp. aurantiaca subsp. nov., comb. nov.

Pseudomonas chlororaphis, Pseudomonas aureofaciens and Pseudomonas aurantiaca were considered as separate species until 1989, when P. aureofaciens was proposed as a later heterotypic synonym of P. chlororaphis with P. aurantiaca remaining as a separate species. Nevertheless, analysis of the almost complete 16S rRNA gene sequences revealed that the type strain of P. aurantiaca, NCIMB 10068(T), shows gene sequence similarities close to 99.5 % with respect to P. chlororaphis DSM 50083(T) and P. aureofaciens DSM 6698(T). DNA-DNA hybridization experiments among strains of P. aurantiaca, P. chlororaphis and P. aureofaciens showed values higher than 70 %, confirming that they represent members of the same species. The results of fatty acid analysis and phenotypic traits showed that these strains are closely related, although there are some differences among the strains belonging to P. aurantiaca, those from P. chlororaphis and those from P. aureofaciens. All these results confirm the previous reclassification of P. aureofaciens into P. chlororaphis and support the reclassification of P. aurantiaca as a synonym of P. chlororaphis. Phenotypic and molecular data permit the description of three novel subspecies within this last species, for which the following names are proposed: P. chlororaphis subsp. chlororaphis subsp. nov. [with the type strain DSM 50083(T) (=ATCC 9446(T)=NCIMB 9392(T))], P. chlororaphis subsp. aureofaciens subsp. nov., comb. nov. [with the type strain DSM 6698(T) (=ATCC 13985(T)=NCIMB 9030(T))] and P. chlororaphis subsp. aurantiaca subsp. nov., comb. nov. [with the type strain NCIMB 10068(T) (=ATCC 33663(T)=CIP 106718(T))].

Climate vs. soil factors in local adaptation of two common plant species.

Evolutionary theory suggests that divergent natural selection in heterogeneous environments can result in locally adapted plant genotypes. To understand local adaptation it is important to study the ecological factors responsible for divergent selection. At a continental scale, variation in climate can be important while at a local scale soil properties could also play a role. We designed an experiment aimed to disentangle the role of climate and (abiotic and biotic) soil properties in local adaptation of two common plant species. A grass (Holcus lanatus) and a legume (Lotus corniculatus), as well as their local soils, were reciprocally transplanted between three sites across an Atlantic-Continental gradient in Europe and grown in common gardens in either their home soil or foreign soils. Growth and reproductive traits were measured over two growing seasons. In both species, we found significant environmental and genetic effects on most of the growth and reproductive traits and a significant interaction between the two environmental effects of soil and climate. The grass species showed significant home site advantage in most of the fitness components, which indicated adaptation to climate. We found no indication that the grass was adapted to local soil conditions. The legume showed a significant home soil advantage for number of fruits only and thus a weak indication of adaptation to soil and no adaptation to climate. Our results show that the importance of climate and soil factors as drivers of local adaptation is species-dependent. This could be related to differences in interactions between plant species and soil biota.

Burkholderia ferrariae sp. nov., isolated from an iron ore in Brazil.

A Gram-negative, non-spore-forming bacterial strain with the ability to solubilize highly insoluble phosphatic minerals was isolated from a high-phosphorous iron ore from Minas Gerais State, Brazil. This strain, designated FeGl01(T), was subjected to a polyphasic taxonomic investigation. Comparative 16S rRNA gene sequence analysis indicated that it formed a distinct phylogenetic lineage within the genus Burkholderia together with several other species of the genus, e.g. Burkholderia sacchari, Burkholderia tropica and Burkholderia unamae. Partial nucleotide sequencing and analysis of the recA gene roughly corroborated the phylogenetic position of strain FeGl01(T) within the genus Burkholderia. The chemotaxonomic properties of strain FeGl01(T), such as ubiquinone Q-8 as the predominant quinone system and C(16 : 0), C(17 : 0) cyclo, C(18 : 1)omega7c and C(19 : 0)omega8c cyclo as the major fatty acids, were also consistent with its classification within the genus Burkholderia. DNA-DNA hybridization experiments between strain FeGl01(T) and the type strains of B. unamae, B. sacchari and B. tropica yielded reassociation values of 40 % or lower, which, together with qualitative and quantitative differences in fatty acid composition and with differences in several phenotypic traits, support the separation of the new isolate from the phylogenetically most closely related species. Therefore, it is suggested that strain FeGl01(T) represents a novel species of the genus Burkholderia, for which the name Burkholderia ferrariae sp. nov. is proposed. The type strain is FeGl01(T) (=LMG 23612(T)=CECT 7171(T)=DSM 18251(T)).

Pseudomonas lutea sp. nov., a novel phosphate-solubilizing bacterium isolated from the rhizosphere of grasses.

A phosphate-solubilizing bacterial strain designated OK2(T) was isolated from rhizospheric soil of grasses growing spontaneously in a soil from Spain. Cells of the strain were Gram-negative, strictly aerobic, rod-shaped and motile. Phylogenetic analysis of the 16S rRNA gene indicated that this bacterium belongs to the gamma-subclass of Proteobacteria within the genus Pseudomonas and that the closest related species is Pseudomonas graminis. The strain produced catalase but not oxidase. Cellulose, casein, starch, gelatin and urea were not hydrolysed. Aesculin was hydrolysed. Growth was observed with many carbohydrates as carbon sources. The main non-polar fatty acids detected were hexadecenoic acid (16 : 1), hexadecanoic acid (16 : 0) and octadecenoic acid (18 : 1). The hydroxy fatty acids detected were 3-hydroxydecanoic acid (3-OH 10 : 0), 3-hydroxydodecanoic acid (3-OH 12 : 0) and 2-hydroxydodecanoic acid (2-OH 12 : 0). The G+C DNA content determined was 59.3 mol%. DNA-DNA hybridization showed 48.7 % relatedness between strain OK2(T) and P. graminis DSM 11363(T) and 26.2 % with respect to Pseudomonas rhizosphaerae LMG 21640(T). Therefore, these results indicate that strain OK2(T) (=LMG 21974(T)=CECT 5822(T)) belongs to a novel species of the genus Pseudomonas, and the name Pseudomonas lutea sp. nov. is proposed.

Pseudomonas rhizosphaerae sp. nov., a novel species that actively solubilizes phosphate in vitro.

A bacterial strain (designated IH5(T)), isolated from rhizospheric soil of grasses growing spontaneously in Spanish soil, actively solubilized phosphates in vitro when bicalcium phosphate was used as a phosphorus source. This strain was Gram-negative, strictly aerobic, rod-shaped and motile. The strain produced catalase, but not oxidase. Cellulose, casein, starch, gelatin, aesculin and urea were not hydrolysed. Growth was observed with many carbohydrates as the carbon source. The main non-polar fatty acids detected were hexadecenoic acid (C(16 : 1)), hexadecanoic acid (C(16 : 0)) and octadecenoic acid (C(18 : 1)). The hydroxy fatty acids detected were 3-hydroxydecanoic acid (C(10 : 0) 3-OH), 3-hydroxydodecanoic acid (C(12 : 0) 3-OH) and 2-hydroxydodecanoic acid (C(12 : 0) 2-OH). Phylogenetic analysis of 16S rRNA indicated that this bacterium belongs to the genus Pseudomonas in the gamma-subclass of the Proteobacteria and that the closest related species is Pseudomonas graminis. The DNA G+C content was 61 mol%. DNA-DNA hybridization showed 23 % relatedness between strain IH5(T) and P. graminis DSM 11363(T). Therefore, strain IH5(T) belongs to a novel species from the genus Pseudomonas, for which the name Pseudomonas rhizosphaerae sp. nov. is proposed (type strain, IH5(T)=LMG 21640(T)=CECT 5726(T)).