J. P. W. Young

Burkholderia diazotrophica sp. nov., isolated from root nodules of Mimosa spp.

Five strains, JPY461(T), JPY359, JPY389, DPU-3 and STM4206 were isolated from nitrogen-fixing nodules on the roots of Mimosa spp. and their taxonomic positions were investigated using a polyphasic approach. All five strains grew at 15-40 °C (optimum, 30-37 °C), at pH 4.0-8.0 (optimum, pH 6.0-7.0) and with 0-1u200a% (w/v) NaCl [optimum, 0u200a% (w/v)]. On the basis of 16S rRNA gene sequence analysis, a representative strain (JPY461(T)) showed 97.2u200a% sequence similarity to the closest related species Burkholderia acidipaludis SA33(T), a similarity of 97.2u200a% to Burkholderia terrae KMY02(T), 97.1u200a% to Burkholderia phymatum STM815(T) and 97.1u200a% to Burkholderia hospita LMG 20598(T). The predominant fatty acids of the five novel strains were summed feature 2 (comprising C(16u200a:u200a1) iso I and/or C(14u200a:u200a0) 3-OH), summed feature 3 (comprising C(16u200a:u200a1)ω7c and/or C(16u200a:u200a1)ω6c), C(16u200a:u200a0) , C(16u200a:u200a0) 3-OH, C(17u200a:u200a0) cyclo, C(18u200a:u200a1)ω7c and C(19u200a:u200a0) cyclo ω8c. The major isoprenoid quinone was Q-8 and the DNA G+C content of the strains was 63.0-65.0 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, an unidentified aminophospholipid, an unidentified aminolipid and several unidentified phospholipids. The DNA-DNA relatedness of the novel strain with respect to recognized species of the genus Burkholderia was less than 54u200a%. On the basis of 16S rRNA and recA gene sequence similarities, chemotaxonomic and phenotypic data, the five strains represent a novel species in the genus Burkholderia, for which the name Burkholderia diazotrophica sp. nov. is proposed with the type strain, JPY461(T) (u200a=u200aLMG 26031(T)u200a=u200aBCRC 80259(T)u200a=u200aKCTC 23308(T)).

Burkholderia symbiotica sp. nov., isolated from root nodules of Mimosa spp. native to north-east Brazil

Four strains, designated JPY-345(T), JPY-347, JPY-366 and JPY-581, were isolated from nitrogen-fixing nodules on the roots of two species of Mimosa, Mimosa cordistipula and Mimosa misera, that are native to North East Brazil, and their taxonomic positions were investigated by using a polyphasic approach. All four strains grew at 15-43 °C (optimum 35 °C), at pH 4-7 (optimum pH 5) and with 0-2 % (w/v) NaCl (optimum 0 % NaCl). On the basis of 16S rRNA gene sequence analysis, strain JPY-345(T) showed 97.3 % sequence similarity to the closest related species Burkholderia soli GP25-8(T), 97.3 % sequence similarity to Burkholderia caryophylli ATCC25418(T) and 97.1 % sequence similarity to Burkholderia kururiensis KP23(T). The predominant fatty acids of the strains were C(18 : 1)ω7c (36.1 %), C(16 : 0) (19.8 %) and summed feature 3, comprising C(16 : 1)ω7c and/or C(16 : 1)ω6c (11.5 %). The major isoprenoid quinone was Q-8 and the DNA G+C content of the strains was 64.2-65.7 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and several uncharacterized aminophospholipids and phospholipids. DNA-DNA hybridizations between the novel strain and recognized species of the genus Burkholderia yielded relatedness values of <51.8 %. On the basis of 16S rRNA and recA gene sequence similarities and chemotaxonomic and phenotypic data, the four strains represent a novel species in the genus Burkholderia, for which the name Burkholderia symbiotica sp. nov. is proposed. The type strain is JPY-345(T) (= LMG 26032(T) = BCRC 80258(T) = KCTC 23309(T)).

International committee on systematics of prokaryotes; subcommittee on the taxonomy of agrobacterium and rhizobium: minutes of the meetings, 31 August 2008, Gent, Belgium.

Minute 3. Membership issues. The new subcommittee member Gehong Wei, China, was welcomed. It was proposed to invite Dr Kemanthie Nandasena, Australia, to the subcommittee. She has published descriptions of rhizobial species and made discoveries of the role of horizontal gene transfer in rhizobial speciation and diversification. During the online-phase of this meeting, Dr Nandasena was subsequently unanimously elected a new member of the subcommittee.

Mesorhizobium alhagi sp. nov., isolated from wild Alhagi sparsifolia in north-western China

Eleven strains that formed symbiotic root nodules on Alhagi sparsifolia, designated previously as genospecies II, were identified as a new lineage of Mesorhizobium (Alphaproteobacteria) that could be differentiated from all previously recognized species of the genus Mesorhizobium by using 16S rRNA gene sequences (<97.8 % similarity), DNA-DNA hybridization (<45 %), dnaJ, dnaK, recA, glnA, nifH, nodA and nodC gene sequences, fatty acid profiles (C(18 : 1)omega7c, 35 %;11-methyl C(18 : 1)omega7c, 30 %) and numerical taxonomy. These strains are therefore considered to represent a novel species, for which the name Mesorhizobium alhagi sp. nov. is proposed, with isolate CCNWXJ12-2(T) (=ACCC 15461(T)=HAMBI 3019(T)) as the type strain.

Rhizobium anhuiense sp. nov., isolated from effective nodules of Vicia faba and Pisum sativum.

Four rhizobia-like strains, isolated from root nodules of Pisum sativum and Vicia faba grown in Anhui and Jiangxi Provinces of China, were grouped into the genus Rhizobium but were distinct from all recognized species of the genus Rhizobium by phylogenetic analysis of 16S rRNA and housekeeping genes. The combined sequences of the housekeeping genes atpD, recA and glnII for strain CCBAU 23252(T) showed 86.9 to 95% similarity to those of known species of the genus Rhizobium. All four strains had nodC and nifH genes and could form effective nodules with Pisum sativum and Vicia faba, and ineffective nodules with Phaseolus vulgaris, but did not nodulate Glycine max, Arachis hypogaea, Medicago sativa, Trifolium repens or Lablab purpureus in cross-nodulation tests. Fatty acid composition, DNA-DNA relatedness and a series of phenotypic tests also separated these strains from members of closely related species. Based on all the evidence, we propose a novel species, Rhizobium anhuiense sp. nov., and designate CCBAU 23252(T) (u2009= CGMCC 1.12621(T) = LMG 27729(T)) as the type strain. This strain was isolated from a root nodule of Vicia faba and has a DNA G+C content of 61.1 mol% (Tm).

Mesorhizobium camelthorni sp. nov., isolated from Alhagi sparsifolia.

Nine strains isolated from symbiotic root nodules on Alhagi sparsifolia were previously designated as representing genospecies I. Phylogenetic analyses indicated that genospecies I was related closely to Mesorhizobium alhagi (genospecies II), and clearly formed a new lineage within the genus Mesorhizobium. In this study, we differentiated genospecies I from recognized species of the genus Mesorhizobium based on phylogenetic analyses of additional core genes (recA, glnA), levels of DNA-DNA relatedness (<43.3u200a%), fatty acid profile (58u200a% C₁₈:₁ω7c, 19u200a% 11-methyl C₁₈:₁ω7c), and biochemical and physiological characteristics. The nine strains are therefore considered to represent a novel species of the genus Mesorhizobium, for which the name Mesorhizobium camelthorni sp. nov. is proposed. The type strain is CCNWXJ 40-4(T) (=HAMBI 3020(T) =ACCC 14549(T)).

Average nucleotide identity of genome sequences supports the description of Rhizobium lentis sp. nov., Rhizobium bangladeshense sp. nov. and Rhizobium binae sp. nov. from lentil (Lens culinaris) nodules.

Rhizobial strains isolated from effective root nodules of field-grown lentil (Lens culinaris) from different parts of Bangladesh were previously analysed using sequences of the 16S rRNA gene, three housekeeping genes (recA, atpD and glnII) and three nodulation genes (nodA, nodC and nodD), DNA fingerprinting and phenotypic characterization. Analysis of housekeeping gene sequences and DNA fingerprints indicated that the strains belonged to three novel clades in the genus Rhizobium. In present study, a representative strain from each clade was further characterized by determination of cellular fatty acid compositions, carbon substrate utilization patterns and DNA-DNA hybridization and average nucleotide identity (ANI) analyses from whole-genome sequences. DNA-DNA hybridization showed 50-62% relatedness to their closest relatives (the type strains of Rhizobium etli and Rhizobium phaseoli) and 50-60% relatedness to each other. These results were further supported by ANI values, based on genome sequencing, which were 87-92% with their close relatives and 88-89% with each other. On the basis of these results, three novel species, Rhizobium lentis sp. nov. (type strain BLR27(T) = LMG 28441(T) = DSM 29286(T)), Rhizobium bangladeshense sp. nov. (type strain BLR175(T) = LMG 28442(T) = DSM 29287(T)) and Rhizobium binae sp. nov. (type strain BLR195(T) = LMG 28443(T) = DSM 29288(T)), are proposed. These species share common nodulation genes (nodA, nodC and nodD) that are similar to those of the symbiovar viciae.

Bradyrhizobium guangdongense sp. nov. and Bradyrhizobium guangxiense sp. nov., isolated from effective nodules of peanut.

Seven slow-growing rhizobia isolated from effective nodules of Arachis hypogaea were assigned to the genus Bradyrhizobium based on sharing 96.3-99.9u2009% 16S rRNA gene sequence similarity with the type strains of recognized Bradyrhizobium species. Multilocus sequence analysis of glnII, recA, gyrB and dnaK genes indicated that the seven strains belonged to two novel species represented by CCBAU 51649T and CCBAU 53363T. Strain CCBAU 51649T shared 94, 93.4, 92.3 and 94.9u2009% and CCBAU 53363T shared 91.4, 94.5, 94.6 and 97.7u2009% sequence similarity for the glnII, recA, gyrB and dnaK genes, respectively, with respect to the closest related species Bradyrhizobium manausense BR 3351T and Bradyrhizobium yuanmingense CCBAU 10071T. Summed feature 8 and C16u2009:u20090 were the predominant fatty acid components for strains CCBAU 51649T and CCBAU 53363T. DNA-DNA hybridization and analysis of phenotypic characteristics also distinguished these strains from the closest related Bradyrhizobium species. The strains formed effective nodules on Arachis hypogaea, Lablab purpureus and Aeschynomene indica, and they had identical nodA genes to Bradyrhizobium sp. PI237 but were phylogenetically divergent from other available nodA genes at less than 66u2009% similarity. Based in these results, strains CCBAU 51649T (u2009=u2009CGMCC 1.15034Tu2009=u2009LMG 28620T) and CCBAU 53363T (u2009=u2009CGMCC 1.15035Tu2009=u2009LMG 28621T) are designated the type strains of two novel species, for which the names Bradyrhizobium guangdongense sp. nov. and Bradyrhizobium guangxiense sp. nov. are proposed, respectively.

Abstraction and Representation in Living Organisms: When Does a Biological System Compute?

Even the simplest known living organisms are complex chemical processing systems. But how sophisticated is the behaviour that arises from this? We present a framework in which even bacteria can be identified as capable of representing information in arbitrary signal molecules, to facilitate altering their behaviour to optimise their food supplies, for example. Known as Abstraction/Representation theory (AR theory), this framework makes precise the relationship between physical systems and abstract concepts. Originally developed to answer the question of when a physical system is computing, AR theory naturally extends to the realm of biological systems to bring clarity to questions of computation at the cellular level.

Increased sequencing depth does not increase captured diversity of arbuscular mycorrhizal fungi

The arrival of 454 sequencing represented a major breakthrough by allowing deeper sequencing of environmental samples than was possible with existing Sanger approaches. Illumina MiSeq provides a further increase in sequencing depth but shorter read length compared with 454 sequencing. We explored whether Illumina sequencing improves estimates of arbuscular mycorrhizal (AM) fungal richness in plant root samples, compared with 454 sequencing. We identified AM fungi in root samples by sequencing amplicons of the SSU rRNA gene with 454 and Illumina MiSeq paired-end sequencing. In addition, we sequenced metagenomic DNA without prior PCR amplification. Amplicon-based Illumina sequencing yielded two orders of magnitude higher sequencing depth per sample than 454 sequencing. Initial analysis with minimal quality control recorded five times higher AM fungal richness per sample with Illumina sequencing. Additional quality control of Illumina samples, including restriction of the marker region to the most variable amplicon fragment, revealed AM fungal richness values close to those produced by 454 sequencing. Furthermore, AM fungal richness estimates were not correlated with sequencing depth between 300 and 30,000 reads per sample, suggesting that the lower end of this range is sufficient for adequate description of AM fungal communities. By contrast, metagenomic Illumina sequencing yielded very few AM fungal reads and taxa and was dominated by plant DNA, suggesting that AM fungal DNA is present at prohibitively low abundance in colonised root samples. In conclusion, Illumina MiSeq sequencing yielded higher sequencing depth, but similar richness of AM fungi in root samples, compared with 454 sequencing.