Horizontal gene transfer in the evolution of group A streptococcal emm-like genes: gene mosaics and variation in Vir regulons

Most M type 5 group A streptococcal strains were found to contain a single emm-like gene between virR and scpA (the Vir reguion), but two distinct emm-like genes were identified in the Vir regulon of the MS strain NCTC8193. The complete sequences of both of these genes were determined. One, called emm5.8193, was shown to be a minor variant of the previously described emm5 gene from strain Manfredo. The second, designated enn5.8193, expresses an IgG-binding protein when cloned in Escherichia coli. A comparison of enn5.8193 with emm-like gene sequences from other strains indicated that it has a mosaic structure, consisting of distinct segments originating from emm-like genes in different OF⁺ and OF⁻strains. These data provide the first clear evidence that the horizontal transfer of emm-like sequences between distinct strains contributes to the evolution of group A streptococcal emm-like genes and Vir regulons.     

Evaluation of the antibiotic biosynthetic potential of the genus Amycolatopsis and description of Amycolatopsis circi sp. nov., Amycolatopsis equina sp. nov. and Amycolatopsis hippodromi sp. nov

Aims: To describe three new Amycolatopsis strains and assess the antibiotic biosynthetic potential of the genus. Methods and Results: Three strains, designated S1·3^T, S3·6^T and SE(8)3^T, belonging to the genus Amycolatopsis were isolated and found to cluster together by 16S rRNA and gyrB gene‐based phylogenetic analysis. Genetic distance values, based on the gyrB gene, were calculated between the strains and their closest relatives and were all above the threshold value of 0·02 that has been proposed to distinguish Amycolatopsis type strains. DNA–DNA hybridization experiments against related type strains confirmed that strain S3·6^T represents a unique genomic species. Strain S3·6^T was also found to be distinct from strains S1·3^T and SE(8)3^T, the latter two of which were also shown to be distinct from each other. Antibiotic biosynthetic genes were identified from multiple Amycolatopsis strains, and their presence was found to be phylogenetically associated. Conclusions: The data presented in this study indicate that strains S1·3^T, SE(8)3^T and S3·6^T belong to three novel species, for which the names Amycolatopsis circi sp. nov. (= DSM 45561^T = NRRL B‐24841^T), Amycolatopsis equina sp. nov. (= DSM 45563^T = NRRL B‐24842^T) and Amycolatopsis hippodromi sp. nov. (= DSM 45562^T = NRRL B‐24843^T) are proposed. Significance and Impact of the Study: Three new species of Amycolatopsis are described, and the knowledge of the antibiotic biosynthetic potential of the genus has been extended.     

Phylogenetic analysis of the <Emphasis Type="Italic">lux</Emphasis> operon distinguishes two evolutionarily distinct clades of <Emphasis Type="Italic">Photobacterium leiognathi</Emphasis>

The luminous marine bacterium Photobacterium mandapamensis was synonymized several years ago with Photobacterium leiognathi based on a high degree of phenotypic and genetic similarity. To test the possibility that P. leiognathi as now formulated, however, actually contains two distinct bacterial groups reflecting the earlier identification of P. mandapamensis and P. leiognathi as separate species, we compared P. leiognathi strains isolated from light-organ symbiosis with leiognathid fishes (i.e., ATCC 25521^T, ATCC 25587, lequu.1.1 and lleuc.1.1) with strains from seawater originally described as P. mandapamensis and later synonymized as P. leiognathi (i.e., ATCC 27561^T and ATCC 33981) and certain strains initially identified as P. leiognathi (i.e., PL-721, PL-741, 554). Analysis of the 16S rRNA and gyrB genes did not resolve distinct clades, affirming a close relationship among these strains. However, strains ATCC 27561^T, ATCC 33981, PL-721, PL-741 and 554 were found to bear a luxF gene in the lux operon (luxABFE), whereas ATCC 25521^T, ATCC 25587, lequu.1.1 and lleuc.1.1 lack this gene (luxABE). Phylogenetic analysis of the luxAB(F)E region confirmed this distinction. Furthermore, ATCC 27561^T, ATCC 33981, PL-721, PL-741 and 554 all produced a higher level of luminescence on high-salt medium, as previously described for PL-721, whereas ATCC 25521^T, ATCC 25587, lequu.1.1 and lleuc.1.1 all produced a higher level of luminescence on low-salt medium, a characteristic of P. leiognathi from leiognathid fish light organs. These results demonstrate that P. leiognathi contains two evolutionarily and phenotypically distinct clades, P. leiognathi subsp. leiognathi (strains ATCC 25521^T, ATCC 25587, lequu.1.1 and lleuc.1.1), and P. leiognathi subsp. mandapamensis (strains ATCC 27561^T, ATCC 33981, PL-721, PL-741 and 554).Electronic Supplementary Material Supplementary material is available for this article at .     

Aureocin A70 production is disseminated amongst genetically unrelated Staphylococcus aureus involved in bovine mastitis

Aims: The main aim of this study was to analyse the genetic relationship amongst 46 Staphylococcus aureus Bac⁺ strains isolated in Brazil from 12 geographically distant dairy herds, including 34 isolates that produce the antimicrobial peptide aureocin A70. Methods and Results: The comparison of 46 Staph. aureus Bac⁺ strains was performed by pulsed‐field gel electrophoresis (PFGE). Thirteen different pulsotypes were identified, and the subtype A₁ was the most prevalent one. Nine strains belong to pulsotype F, the second most prevalent and mostly confined to a single herd. The PFGE patterns of the 34 Staph. aureus aureocin A70‐producers, isolated in Brazil, were also compared with those of strains isolated from bovine mastitis cases in Argentina and revealed that these strains are not genetically related. Conclusions: Although a previous study has suggested that a prevalent pulsotype of aureocin A70‐producer Staph. aureus involved in bovine mastitis is disseminated in Argentina, this does not occur in Brazil. Additionally, it was possible to demonstrate that closely related staphylococcal strains can produce distinct staphylococcins. Significance and Impact of the Study: This study corroborates the hypothesis of horizontal gene transfer of aureocin A70 genes amongst distinct staphylococcal strains involved in bovine mastitis, giving them a selective advantage when colonizing the mammary glands.     

<Emphasis Type="Italic">Rhizobium helanshanense</Emphasis> sp. nov., a bacterium that nodulates <Emphasis Type="Italic">Sphaerophysa salsula</Emphasis> (Pall.) DC. in China

Studying rhizobia in the root nodules of Sphaerophysa salsula (Pall.) DC in the northwest of China, we obtained five strains classified as genus Rhizobium on the basis of their 16S rRNA gene sequences. The sequence similarity of strain CCNWQTX14^T with the most related species was 99.0%. Further phylogenetic analysis of housekeeping genes (recA and atpD) suggested the five strains comprised a novel lineage within Rhizobium. The nifH and nodD gene sequences of CCNWQTX14^T were phylogenetically closely related with those of Sinorhizobium kummerowiae and R. sphaerophysae, respectively. The five strains isolated from different places were also distinct from related Rhizobium species using ERIC fingerprint profiles. The DNA–DNA hybridization value was 41.8% between CCNWQTX14^T and Rhizobium sphaerophysae CCNWGS0238^T. Our novel strains were only able to form effective nodules on its original host Sphaerophysa salsula. Our data showed that the five Rhizobium strains formed a unique genomic species, for which a novel species Rhizobium helanshanense sp. nov. is proposed. The type strain is CCNWQTX14^T (=ACCC 16237^T =HAMBI 3083^T).     

INTERSTRAIN VARIABILITY IN PHYSIOLOGY AND GENETICS OF HETEROSIGMA AKASHIWO (RAPHIDOPHYCEAE) FROM THE WEST COAST OF NORTH AMERICA1

High levels of intraspecific variability are often associated with HAB species, and this variability is likely an important factor in their competitive success. Heterosigma akashiwo (Hada) Hada ex Y. Hara et M. Chihara is an ichthyotoxic raphidophyte capable of forming dense surface‐water blooms in temperate coastal regions throughout the world. We isolated four strains of H. akashiwo from fish‐killing northern Puget Sound blooms in 2006 and 2007. By assessing numerous aspects of biochemistry, physiology, and toxicity, we were able to describe distinct ecotypes that may be related to isolation location, source population, or bloom timing. Contrasting elements among strains were cell size, maximum growth and photosynthesis rates, tolerance of low salinities, amino acid use, and toxicity to the ciliate grazer Strombidinopsis acuminatum (Fauré‐Fremiet). In addition, the rDNA sequences and chloroplast genome of each isolate were examined, and while all rDNA sequences were identical, the chloroplast genome identified differences among the strains that tracked differences in ecotype. H. akashiwo strain 07A, which was isolated from an unusual spring bloom, had a significantly higher maximum potential photosynthesis rate (28.7 pg C · cell^?1 · h^?1) and consistently exhibited the highest growth rates. Strains 06A and 06B were not genetically distinct from one another and were able to grow on the amino acids glutamine and alanine, while the other two strains could not. Strain 07B, which is genetically distinct from the other three strains, exhibited the only nontoxic effect. Thus, molecular tools may support identification, tracking, and prediction of strains and/or ecotypes using distinctive chloroplast gene signatures.     

Optimized BlaM-transposon shuttle mutagenesis of Helicobacter pylori allows the identification of novel genetic loci involved in bacterial virulence

Helicobacter pylori is an important etiologic agent of gastroduodenal disease in humans. In this report, we describe a general genetic approach for the identification of genes encoding exported proteins in H. pylori. The novel TnMax9 mini-blaM transposon was used for insertion mutagenesis of a H. pylori gene library established in Escherichia coli. A total of 192 E. coli clones expressing active β-lactamase fusion proteins (BlaM⁺) were obtained, indicating that the corresponding target plasmids carry H. pylori genes encoding putative extracytoplasmic proteins. Natural transformation of H. pylori P1 or P12 using the 192 mutant plasmids resulted in 135 distinct H. pylori mutant strains (70%). Screening of the H. pylori collection of mutant strains allowed the identification of mutant strains impaired in motility, in natural transformation competence and in adherence to gastric epithelial cell lines. Motility mutants could be grouped into distinct classes: (i) mutant strains lacking the major flagellin subunit FlaA and intact flagella (class I); (ii) mutant strains with apparently normal flagella, but reduced motility (class II), and (iii) mutant strains with obviously normal flagella, but completely abolished motility (class III). Two independent mutations that exhibited defects in natural competence for genetic transformation mapped to different genetic loci. In addition, two independent mutant strains were isolated by their failure to bind to the human gastric carcinoma cell line Katoill. Both mutant strains carried a transposon in the same gene, 0.8 kb apart, and showed decreased autoagglutination when compared to the wild-type strain.     

<Emphasis Type="Italic">Streptomyces sudanensis</Emphasis> sp. nov., a new pathogen isolated from patients with actinomycetoma

Nine strains isolated from mycetoma patients and received as Streptomyces somaliensis were the subject of a polyphasic taxonomic study. The organisms shared chemical markers consistent with their classification in the genus Streptomyces and formed two distinct monophyletic subclades in the Streptomyces 16S rRNA gene tree. The first subclade contained four organisms, including the type strain of S. somaliensis, and the second clade the remaining five strains which had almost identical 16S rRNA sequences. Members of the two subclades were sharply separated using DNA:DNA relatedness and phenotypic data which also showed that the subclade 1 strains formed an heterogeneous group. In contrast, the subclade 2 strains were assigned to a single genomic species and had identical phenotypic profiles. It is evident from these data that the subclade 2 strains should be recognised as a new species of Streptomyces. The name proposed for this new species is Streptomyces sudanensis sp. nov. The type strain is SD 504^T (DSM = 41923^T = NRRL B-24575^T). Erika T. Quintana and Katarzyna Wierzbicka contributed equally to this work. The GenBank accession numbers for the 16S rRNA gene sequences of Streptomyces somaliensis DSM 40738^T and Streptomyces sudanensis DSM 41607, DSM 41608, DSM 41609, SD 504^T and SD 509 are EF540897, EF540898, EF540999, EF515876 and EF540900.     

Analysis of pristinamycin-resistant Staphylococcus epidermidis isolates in the Tunisian Bone Marrow Transplant Center

Aims: We report the analysis of genetic determinants conferring resistance to pristinamycin in Staphylococcus epidermidis strains and epidemiology typing of these strains by pulsed‐field gel electrophoresis. Methods and Results: Staphylococcus epidermidis (346 isolates) were searched for strains with pristinamycin resistance. Pristinamycin‐resistant strains (seven isolates) were isolated in five patients with haematological cancer in the Bone Marrow Transplant Centre of Tunisia in 2002. Resistance to pristinamycin was observed in 2% of isolates. The seven pristinamycin‐resistant strains shared resistance to oxacillin (MIC = 8–512 μg ml^?1), gentamicin (MIC = 16–512 μg ml^?1), erythromycin (MIC > 1024 μg ml^?1), lincomycin (MIC > 1024 μg ml^?1), pristinamycin (MIC = 4–16 μg ml^?1) and rifampin (MIC = 128–256 μg ml^?1). erm genes were amplified: ermA from six strains and ermC from one. vga gene encoding streptogramins A resistance (pristinamycin résistance) was amplified from all strains and typed as vgaA by analysis after electrophoresis of restriction profiles of vga amplicons (two fragments with Sau3A of 164 and 378 bp; one fragment with EcoRI). Pulsed‐field gel electrophoresis (PFGE) of SmaI chromosomal DNA digests of the seven S. epidermidis isolates divided them into two distinct pattern types: pulsed‐field type A (classified from A1 to A6 subtypes) and type B. The six strains harbouring ermA genes belonged to the PFGE type A while the strain harbouring ermC genes belonged to the PFGE type B. We characterized an epidemic strain carrying the vgaA and ermA genes responsible for the outbreak. Conclusions: Two clones of pristinamycin‐resistant S. epidermidis were isolated in our patients. One of them, isolated in all patients, had expanded over six months suggesting acquisition by cross‐contamination. Significance and Impact of the study: Increasing isolation of pristinamycin resistant S. epidermidis strains is an alarming indicator of nosocomial dissemination. The vector will be determined to establish a system of epidemiological surveillance.     

Role of trehalose synthesis pathways in salt tolerance mechanism of <Emphasis Type="Italic">Rhodobacter sphaeroides</Emphasis> f. sp. <Emphasis Type="Italic">denitrificans</Emphasis> IL106

Two strains of trichloroethylene (TCE)-degrading bacteria were isolated from soils at polluted and unpolluted sites. The isolates, strains TE26^T and K6, showed co-substrate-independent TCE-degrading activity. TCE degradation was accelerated by preincubation with tetrachloroethylene, cis-dichloroethylene (DCE) and 1,1-DCE. TCE-degrading activities of strains TE26^T and K6 were 0.23, 0.24 mol min^–1 g^–1 dry cells, respectively. 16S rDNA sequences of strains TE26^T and K6 were almost identical (99.7% similarity), and most closely related to Ralstonia basilensis (ATCC17697^T) (98.5% similarity). From the results of DNA–DNA hybridizations, strain TE26^T was genetically coherent to strain K6 (94 and 88% hybridization), and exhibited lower relatedness to R. basilensis (DSM11853^T) (44% and 15%). In addition, because of the differences in chemotaxonomic properties, strain TE26^T and strain K6 appear to be distinct from all established species of the Ralstonia group. Based on these results and the proposal of transferring R. basilensis and related species to Wautersia gen. nov., we propose that these strains should be assigned to the genus Wautersia as Wautersia numadzuensis sp. nov.     

Defluviimonas denitrificans gen. nov., sp. nov., and Pararhodobacter aggregans gen. nov., sp. nov., non-phototrophic Rhodobacteraceae from the biofilter of a marine aquaculture

Three Gram-negative bacterial strains were isolated from the biofilter of a recirculating marine aquaculture. They were non-pigmented rods, mesophiles, moderately halophilic, and showed chemo-organoheterotrophic growth on various sugars, fatty acids, and amino acids, with oxygen as electron acceptor; strains D9-3^T and D11-58 were in addition able to denitrify. Phototrophic or fermentative growth could not be demonstrated. Phylogenetic analysis of the 16S rRNA gene sequences placed D9-3^T and D11-58, and D1-19^T on two distinct branches within the alpha-3 proteobacterial Rhodobacteraceae, affiliated with, but clearly separate from, the genera Rhodobacter, Rhodovulum, and Rhodobaca. Based on morphological, physiological, and 16S rRNA-based phylogenetic characteristics, the isolated strains are proposed as new species of two novel genera, Defluviimonas denitrificans gen. nov., sp. nov. (type strain D9-3^T = DSM 18921^T = ATCC BAA-1447^T; additional strain D11-58 = DSM19039 = ATCC BAA-1448) and Pararhodobacter aggregans gen. nov., sp. nov (type strain D1-19^T = DSM 18938^T = ATCC BAA-1446^T).     

Phylogenetic analysis of alkaline proteinase producing fluorescent pseudomonads associated with green gram (<Emphasis Type="Italic">Vigna radiata</Emphasis> L.) rhizosphere

Fifty fluorescent pseudomonads were isolated from rhizospheric soil of green gram from nearby area of Kaziranga, Assam, India and assayed for their extracellular proteinase production. Out of these isolates, 20 were found to be prominent in proteinase production. Genetic diversity of the 20 isolates were analyzed through BOX-PCR fingerprinting and 16S rDNA-RFLP along with three reference strains, viz., Pseudomonas fluorescens (NCIM2099^T), Pseudomonas aureofaciens (NCIM2026^T), and Pseudomonas aeruginosa (MTCC2582^T). BOX-PCR produced two distinct clusters at 56% similarity coefficient and seven distinct BOX profiles. 16S rDNA-RFLP with three tetra-cutters restriction enzymes (HaeIII, AluI, and MspI) revealed two major clusters A and B; cluster A contained only single isolate FPS9 while the rest of 22 isolates belonged to the cluster B. Based on phenotypic characters and 16S rDNA sequence similarity, all the eight highly proteinase-producing strains were affiliated with P. aeruginosa. The proteinase was extracted from two most prominent strains (KFP1 and KFP2), purified by a three-step process involving (NH₄)₂SO₄ precipitation, gel filtration, and ion exchange chromatography. The enzyme had an optimal pH of 8.0 and exhibit highest activity at 60°C and 37°C by KFP1 and KFP2 respectively. The specific activities were recorded as 75,050 (for KFP1) and 81,320 U/mg (for KFP2). The purified enzyme was migrated as a single band on native and SDS-PAGE with a molecular mass of 32 kDa. Zn²⁺, Cu²⁺, and Ni²⁺ ion inhibited the enzyme activity. Enzyme activity was also inhibited by EDTA established as their metallo-proteinase nature.     

Isolation and characterization of alachlor-degrading actinomycetes from soil

Alachlor (2-cloro-N-(methoxymethyl)-N-(2,6-diethylphenyl)-acetamide) is an extremely toxic and highly mobile herbicide that is widely used for pre-emergence control of grasses and weeds in many commercial crops in Brazil. In order to select soil actinomycetes able to degrade this herbicide, fifty-three actinomycete strains were isolated from soil treated with alachlor using selective conditions and subjected to in vitro degradation assays. Sixteen isolates were shown to be tolerant to high concentrations of the herbicide (up to 720 mg L^-1), and six of these were able to grow and degrade 50 alachlor (72 mg L^-1) in mineral salts medium. Morphological and phylogenetic analysis enabled the assignment of the alachlor-degrading strains to the genus Streptomyces. Strain LS151 was related to the type strains of Streptomyces capoamus/Streptomyces galbus, whereas strains LS143 and LS153 were related to Streptomyces bikiniensis. The remaining strains, LS166, LS177 and LS182, were similar in morphological features and recovered in a single cluster based on 16S rDNA sequence analysis, but shown to be distinct on the basis of genomic fingerprint data (rep-PCR). Though a definitive taxonomic assignment of alachlor-degrading strains was not possible, these data indicate that ability to degrade this pesticide was detected in different Streptomyces taxa.     

Tilletiopsis derxii, Tilletiopsis oryzicola and Tilletiopsis penniseti, three new species of the ustilagionomycetous anamorphic genus Tilletiopsis isolated from leaves in Thailand

Four strains of ballistoconidium-forming yeast-like fungi (K-95, K-125, K-132 and K139), isolated from plants collected in Bangkok, Thailand, were assigned to the genus Tilletiopsis based on morphological and chemotaxonomical characteristics. On the basis of sequence data of 18S rDNA and the D1/D2 region of 26S rDNA, strains K-95, K-125 and K-132 were close to T. flava and T. fulvescens, and strain K-139 each formed related to T. minor. DNA-DNA reassociation experiments with related species revealed that strains K-125, K-132 and K-139 each formed a new and distinct species whereas strain K-95 was identified as T. flava. Tilletiopsis derxii Takashima et Nakase sp. nov. (JCM 10217^T; K-125), Tilletiopsis oryzicola Takashima et Nakase sp. nov. (JCM 10218^T; K-132), and Tilletiopsis penniseti Takashima et Nakase sp. nov. (JCM 10216^T; K-139) are the names proposed for the new taxa.     

Intraspecific variability in Karlodinium veneficum: Growth rates, mixotrophy, and lipid composition

We isolated eleven strains of the harmful algal bloom (HAB)-forming dinoflagellate Karlodinium veneficum during a bloom event in the NW Mediterranean coastal waters and we studied the inter-strain variability in several of their physiological and biochemical traits. These included autotrophic growth parameters, feeding capabilities (mixotrophy), lipid composition, and, in some cases, their responses to biotic and abiotic factors. The strains were found to differ in their growth rates (0.27–0.53 d⁻¹) and in the maximum cell concentrations achieved during stationary phase (6.1 × 10⁴–8.6 × 10⁴ cells mL⁻¹). Their ingestion performance, when offered Rhodomonas salina as prey, was also diverse (0.22–1.3 cells per K. veneficum per day; 8–52% of their daily ration). At least two strains survived for several months under strict heterotrophic conditions (no light, low inorganic nutrients availability, and R. salina as food source). These strains also showed very distinct fatty acid compositions, with very low contents of monounsaturated and polyunsaturated fatty acids. According to a Bray Curtis similarity analysis, three or four strain groups able to perform different roles in bloom development were identified. We further analyzed one strain from each of the two most distinct groups with respect to prey concentration, light intensity, nutrient availability, and we determined the functional responses (growth and feeding rates) to food concentration. Taken together, the results served to highlight the role of mixotrophy and clone variability in the formation of HABs.     

Cohabitation of KP and full-length P elements in the genome of MR strains inducing P-M-like hybrid dysgenesis in Drosophila melanogaster

Summary P strains of Drosophila melanogaster are characterized by the presence of both full-length and deletion derivatives of the transposable element P in their genome, and by their ability to induce the syndrome of hybrid dysgenesis among the progeny of certain intra-strain crosses, when introduced through the male parents. In contrast, strains belonging to the M' class, and which were also found to bear P element-homologous sequences, lack this ability and this has been attributed to the presence in the genome of most of these strains of a distinct class of deletion derivatives termed KP, which can suppress the action of functional P factors. Here we demonstrate that KP elements are present, next to full-length ones, in the genome of at least three strains which induce P-M-like dysgenic symptoms, including GD sterility. KP elements form the majority of the P-homologous sequences in the strains MR-h12, 23.5/CyL ⁴ and the latter's derivative 23.5 ^*/Cy. While the first one is a genuine P strain and the second one depicts a strong P cytotype, the third is a genuine M' strain. The hybrid dysgenesis induced by the two 23.5 MRF strains seems to be due, not primarily to the P elements, but to the action of hobo elements.     

Taxonomic characterisation of ceftazidime-resistant Brevundimonas isolates and description of Brevundimonas faecalis sp. nov

Three ceftazidime-resistant strains isolated from the sewage water of a municipal hospital in Palma de Mallorca, Spain, were analysed phenotypically and genotypically to clarify their taxonomic positions. Sequence determinations and phylogenetic analyses of the 16S rRNA genes indicated that strains CS20.3^T, CS39 and CS41 were affiliated with the species of the alphaproteobacterial genus Brevundimonas, most closely related to B. bullata, B. diminuta, B. naejangsanensis and B. terrae. Additional sequences analyses of the ITS1 region of the rRNA operon and the genes for the housekeeping enzymes DNA gyrase β-subunit and RNA polymerase β-subunit, genomic DNA–DNA hybridisation similarities, cell fatty acid profiles and physiological and biochemical characterizations supported the recognition of CS20.3^T (CCUG 58127^T = CECT 7729^T) as a distinct and novel species, for which the name Brevundimonas faecalis sp. nov. is proposed. Strains CS39 and CS41 were ascribed to the species B. diminuta.     

Alexandriicola marinus gen. nov., sp. nov., a new member of the family Rhodobacteraceae isolated from marine phycosphere

Two yellow-pigmented bacterial strains, LZ-14 ^T and ABI-LZ29, were isolated from the cultivable phycosphere microbiota of the highly toxic marine dinoflagellate Alexandrium catenella LZT09 and demonstrated obvious microalgae growth-promoting potentials toward the algal host. To elucidate the taxonomic status of the two bioactive bacterial strains, they were subjected to a polyphasic taxonomic characterization. Both strains were found to be Gram-negative, aerobic, rod-shaped and motile; to contain Q-10 as the predominant ubiquinone; summed feature 8, C_16:0, C_18:1 ω7c 11-methyl and summed feature 3 as the major fatty acids; and diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and two unidentified phospholipids as the predominant polar lipids. Based on the phylogenetic analysis, phylogenomic inferences and phenotypic characteristics, the strains could be clearly distinguished from phylogenetically closely related species and formed a distinct monophyletic lineage in the family Rhodobacteraceae. The size of the draft genome of strain LZ-14 ^T is 4.615 Mb, with a DNA G?+?C content of 63.3 mol%. It contains ten predicted secondary metabolite biosynthetic gene clusters and core genes for bacterial exopolysaccharide biosynthesis. Therefore, strain LZ-14 ^T (= CCTCC AB 2017230 ^T?=?KCTC 62342 ^T) represents a novel species of a new genus, for which the name Alexandriicola marinus gen. nov., sp. nov., is proposed.

     

Molecular and phenotypic characterization of Leptospira johnsonii sp. nov., Leptospira ellinghausenii sp. nov. and Leptospira ryugenii sp. nov. isolated from soil and water in Japan

In a previous study, 50 of 132 soil samples collected throughout Japan were found to be Leptospira‐positive. In the present study, three strains identified in the collected specimens, three, E8, E18 and YH101, were found to be divergent from previously described Leptospira species according to 16S ribosomal RNA gene sequence analysis. These three strains have a helical shape similar to that of typical Leptospira and were not re‐isolated from experimental mice inoculated with the cultured strains. Upon 16S ribosomal RNA gene sequence analysis, E8 was found to belong to the intermediate Leptospira species clade and E18 and YH101 to belong to the saprophytic Leptospira species clade. Based on analyses of genome‐to‐genome distances and average nucleotide identity in silico using whole genome sequences and DNA–DNA hybridization in vitro, these isolates were found to be distinct from previously described Leptospira species. Therefore, these three isolates represent novel species of the genus Leptospira for which the names Leptospira johnsonii sp. nov., (type strain E8 ^T, = JCM 32515 ^T = CIP111620 ^T), Leptospira ellinghausenii sp. nov., (type strain E18 ^T, = JCM 32516 ^T = CIP111618 ^T) and Leptospira ryugenii sp. nov., (type strain YH101 ^T, = JCM 32518 ^T = CIP111617 ^T) are proposed.