Hormesis of glyphosate on ferulic acid metabolism and antifungal volatile production in rice root biocontrol endophyte Burkholderia cepacia LS-044.

Glyphosate (GP, N-phosphonomethyl glycine) is one of the most popular organophosphate herbicides widely used in agricultural practices worldwide. There have been extensive reports on the biohazard attributes and hormetic impacts of GP on plant and animal systems. However, the effects of GP on plant growth-promoting microbes and its ecological relevance remain unknown. Here, we show that GP does exert a hormetic impact on Burkholderia cepacia LS-044, a rice (Oryza sativa ssp. japonica cv. Tainung 71) root endophytic isolate. We used increasing doses of ferulic acid (FA, 1-25 mM) and GP (0.5-5 mM) to test the growth and antifungal volatile production in LS-044 by electrochemical, liquid chromatographic, gas chromatographic and spectrophotometric means. GP treatment at a low dose (0.5 mM) increased FA utilization and significantly (P < 0.0001) enhanced antifungal volatile activity in LS-044. Although FA (1 mM) was rapidly utilized by LS-044, no chromatographically detectable utilization of GP was observed at tested doses (0.5-5 mM). LS-044 emitted predominant amounts of tropone in addition to moderate-to-minor amounts of diverse ketones and/or their derivatives (acetone, acetophenone, 2-butanone, 1-propanone, 1-(2-furanyl-ethanone, 1-phenyl-1-propanone and 1-(3-pyridinyl)-1-propanone), d-menthol, 2-methoxy-3-(1-methylethyl)-pyrazine, dimethyl disulfide, pyridine and ammonium carbamate when grown under GP supplement. GP hormesis on LS-044 induced phenotypic variations in O. sativa ssp. japonica cv. Tainan 11 as evident through seed germination assay. Genes involved in the transformation of FA, and a key gene encoding 5-enolpyruvylshikimate 3-phosphate synthase (EPSPS) with Gly-94 and Tyr-95 residues localized at active site most likely rendering EPSPS sensitivity to GP, were detected in LS-044. This is the first report on the GP hormesis influencing morphological and metabolic aspects including volatile emission in a biocontrol bacterium that could modulate rice plant phenotype.

Differential visible spectral influence on carbon metabolism in heterotrophic marine flavobacteria.

The visible spectrum of solar radiation is known to stimulate photoheterotrophic bacterial carbon metabolism. However, its impact on 'strictly' heterotrophic bacteria remains less explored. Here, we show that heterotrophic flavobacteria exhibit enhanced uptake and mineralization of dissolved organic carbon with increasing wavelengths of visible light, without employing any 'known' light-harvesting mechanisms. RNA sequencing identified blue light as a major constraint in the extracellular enzymatic hydrolysis of polymeric carbohydrates and acquisition of sugars, despite acting as a stimulus for inorganic carbon sequestration. In contrast, green-red and continuous full-spectrum lights activated diverse hydrolytic enzymes and sugar transporters, but obstructed inorganic carbon fixation. This 'metabolic switching' was apparent through limited nutrient uptake, suppressed light-sensitivity, oxidative stress response and promotion of inorganic carbon sequestration pathways under blue light. The visible light impact on metabolism may be of significant ecological relevance as it appears to promote cell-mediated mineralization of organic carbon in 'green-colored' chlorophyll-rich copiotrophic coastal seawater and inorganic carbon sequestration in 'blue-colored' oligotrophic open ocean. Thus, a novel regulatory role played by light on heterotrophic metabolism and a hidden potential of flavobacteria to sense and respond differentially to monochromatic lights influencing marine carbon cycling were unraveled.

Draft genome sequence reveals co-occurrence of multiple antimicrobial resistance and plant probiotic traits in rice root endophytic strain Burkholderia sp. LS-044 affiliated to Burkholderia cepacia complex.

OBJECTIVES: Members of the Burkholderia cepacia complex (Bcc) have been isolated from various environmental and clinical samples and reportedly pose a threat to human health. Here we examine the draft genome sequence of Burkholderia sp. LS-044, an antibiotic-resistant endophytic strain affiliated to the Bcc (ST895) inhabiting rice (Oryza sativa ssp. japonica cv. Tainung 71) root. METHODS: Antimicrobial susceptibility of LS-044 was evaluated comparatively with other Burkholderia sp. (CC-Al74 and CC-3XP9) using commercial ATB PSE 5 test strips. The genome of LS-044 was sequenced using an Illumina MiSeq platform. Plant probiotic and antimicrobial resistance genes were screened by Rapid Annotation using Subsystem Technology (RAST), CARD 2017, NCBI and/or UniProt. RESULTS: Plant-associated members of Bcc (LS-044 and CC-Al74) exhibited greater resistance to the majority of antibiotics tested. The draft genome sequence of LS-044 contained 8.78 Mbp in 62 contigs having a G + C content of 66.5%, 8868 coding sequences and 75 RNAs. The genome harboured genes coding for LysR-type ß-lactamase transcription regulator, classes A, C and D ß-lactamases, several metal-dependent ß-lactamases, antibiotic efflux proteins, and proteins conferring resistance to colistin, streptothricin, colicin and fluoroquinolones. Similarly, it also possessed genes for copper homeostasis, copper-cobalt-zinc-cadmium-chromium resistance and reduction of mercury. Genes involved in flagellar motility, hydrolysis of murein and chitin, production of siderophore and auxin, and metabolism of aromatic compounds were also found. CONCLUSION: Genome sequence data revealed an interlinked occurrence of plant probiotic traits and antimicrobial resistance in the rice root endophyte LS-044.

Actibacterium ureilyticum sp. nov., isolated from seawater.

A polyphasic approach was used to characterize a novel marine bacterial strain, designated LS-811T, isolated from seawater of the South China Sea (Taiwan). Cells of strain LS-811Twere Gram-staining negative, aerobic and rod-shaped with polar flagella. The 16S rRNA gene sequence analysis of strain LS-811T showed highest sequence similarity to Actibacterium mucosum (96.5 %) and Actibacterium atlanticum (95.6 %), and lower sequence similarity (<96.0 %) to members of all other related genera. Strain LS-811Twas able to grow at 15-40 °C and pH 5.0-9.0. The quinone system was ubiquinone (Q-10), and the DNA G+C content was 60.1 mol%. The major fatty acids (>5 %) found in strain LS-811T were C18 : 0, C10 : 0 3-OH, C19 : 0 cyclo ω8c and C18 : 1ω7c/C18 : 1ω6c. The major polar lipid profile consisted of glycolipids, phosphatidylglycerol and one unidentified aminolipid. Based on the distinct phylogenetic, phenotypic and chemotaxonomic traits together with results of comparative 16S rRNA gene sequence analysis, strain LS-811T is considered to represent a novel species in the genus Actibacterium, for which the name Actibacterium ureilyticum sp. nov. is proposed. The type strain is LS-811T (=BCRC 80823T=JCM 30681T).

Thalassocola ureilytica gen. nov., sp. nov., of the family Phyllobacteriaceae isolated from seawater.

A Gram-stain-negative, aerobic, rod-shaped, non-flagellated marine bacterium, designated strain LS-861T, was isolated from seawater of the South China Sea (Taiwan). Strain LS-861T grew optimally at pH 7.0 and 30 °C in the presence of 3 % (w/v) NaCl. The novel strain shared highest 16S rRNA gene sequence similarity (91.5 % each) with 'Nitratireductor shengliensis' CGMCC 1.12519 and Hoeflea halophila JG120-1T and lower sequence similarity ( < 91.5 %) with other species. Phylogenetic analyses based on 16S rRNA gene sequences revealed a distinct taxonomic position attained by strain LS-861T within the clade that accommodated members of the family Phyllobacteriaceae. The major fatty acids were C16 : 0, iso-C17 : 1ω10c, C18 : 0 3-OH and C18 : 1ω7c/C18 : 1ω6c. The polar lipid profile was relatively simple as compared with other representatives of Phyllobacteriaceae, by having major amounts of diphosphatidylglycerol, phosphatidylglycerol and an unidentified glycolipid, and moderate amounts of three unidentified phospholipids and an unidentified aminolipid. The DNA G+C content was 61.2 mol%. The predominant quinone system was ubiquinone-10 (Q-10). The data in general and phylogenetic and polar lipid data in particular clearly distinguish the novel strain from related species at the genus level. Thus, strain LS-861T is suggested to represent a novel species of a new genus of the family Phyllobacteriaceae, for which the name Thalassocola ureilytica gen. nov., sp. nov. is proposed. The type strain of Thalassocola ureilytica is LS-861T ( = BCRC 80818T = JCM 30682T).

Oricola cellulosilytica gen. nov., sp. nov., a cellulose-degrading bacterium of the family Phyllobacteriaceae isolated from surface seashore water, and emended descriptions of Mesorhizobium loti and Phyllobacterium myrsinacearum.

A Gram-stain negative, strictly aerobic, rod-shaped, non-spore-forming, motile cellulolytic bacterium, designated strain CC-AMH-0(T), was isolated from surface seashore water of Hualien, Taiwan and subjected to polyphasic taxonomy. Strain CC-AMH-0(T) exhibited enzymatic saccharification of cellulose and active growth particularly during log-phase under nutrient-limited conditions, whereas enhanced saccharification was found in the declining growth phase under copiotrophic conditions. The novel strain shared high pairwise 16S rRNA gene sequence similarities to Mesorhizobium loti USDA 3471(T) (96.2 %), Phyllobacterium myrsinacearum IAM 13584(T) (95.9 %), Hoeflea marina LMG 128(T) (94.0 %) and other Phyllobacteriaceae members. However, phylogenetic analyses based on 16S rRNA, atpD and recA gene sequences clearly distinguished strain CC-AMH-0(T) from other representatives of related genera. In addition, strain CC-AMH-0(T) was distinguished from the above mentioned species by significantly lacking phosphatidylcholine besides accommodating major amounts of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmonomethylethanolamine and sulfoquinovosyldiacylglycerol; moderate amounts of phosphatidylethanolamine and trace amounts of an unidentified phospholipid, an unidentified aminolipid and an unidentified phosphoglycolipid. Strain CC-AMH-0(T) possessed C18:1 ω7c and/or C18:1 ω6c (summed feature 8) as predominant fatty acids, 63.3 mol% DNA G+C content and ubiquinone-10 (Q-10) as the sole respiratory quinone. On the basis of polyphasic taxonomic evidences, strain CC-AMH-0(T) is proposed to represent a novel genus and species of the family Phyllobacteriaceae, for which the name Oricola cellulosilytica gen. nov., sp. nov. is proposed. The type strain of the type species is CC-AMH-0(T) (=JCM 19534(T) =BCRC 80694(T)). Emended descriptions of M. loti and P. myrsinacearum are also proposed.

Pseudomonas matsuisoli sp. nov., isolated from a soil sample.

An aerobic, Gram-stain-negative, rod-shaped and polar-flagellated bacterium, designated strain CC-MHH0089(T), was isolated from a soil sample taken on Matsu Island (Taiwan). Strain CC-MHH0089(T) grew at 15-30 °C and pH 5.0-10.0 and tolerated ≤8 % (w/v) NaCl. 16S rRNA gene sequence analysis showed high pairwise sequence similarity to Pseudomonas azotifigens 6H33b(T) (97.3 %) and Pseudomonas balearica SP1402(T) (96.7 %) and lower sequence similarity to other strains (<96.0 %). In DNA-DNA reassociation experiments, the relatedness of strain CC-MHH0089(T) to P. azotifigens JCM 12708(T) was 38.3 % (reciprocal value 19.5 %). Evolutionary trees reconstructed on the basis of 16S rRNA, gyrB and rpoB gene sequences revealed a varying phylogenetic neighbourhood of strain CC-MHH0089(T) with regard to the most closely related type strains. The predominant quinone system was ubiquinone 9 (Q-9) and the DNA G+C content was 63.6 mol%. The major fatty acids were C12 : 0, C16 : 0, C17 : 0, C19 : 0 cyclo ω8c and summed features 2 (C14 : 0 3-OH/iso-C16 : 1 I), 3 (C16 : 1ω7c/C16 : 1ω6c) and 8 (C18 : 1ω7c/C18 : 1ω6c). The major polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. According to its distinct phylogenetic, phenotypic and chemotaxonomic features, strain CC-MHH0089(T) is proposed to represent a novel species within the genus Pseudomonas, for which the name Pseudomonas matsuisoli sp. nov. is proposed. The type strain is CC-MHH0089(T) ( = BCRC 80771(T) = JCM 30078(T)).

Impacts of industrial waste resources on maize (Zea mays L.) growth, yield, nutrients uptake and soil properties.

Discharging untreated highly acidic (pH<4.0), organic and nutrients rich monosodium glutamate wastewater (MW), and highly alkaline (pH>10.0) paper-mill wastewater (PW) causes environmental pollution. When acidity of MW neutralized (pH 6.5±0.1) with PW and lime (treatments represented as MW+PW and MW+Lime), then MW may be utilized as a potential source of nutrients and organic carbon for sustainable food production. Objectives of this study were to compare the effects of PW and lime neutralized MW and chemical fertilizers on maize (Zea mays L. cv. Snow Jean) plant growth, yield, nutrients uptake, soil organic matter and humic substances. The field experiment was carried out on maize using MW at 6000 L ha(-1). Impacts of the MW application on maize crop and soil properties were evaluated at different stages. At harvest, plant height, and plant N and K uptake were higher in MW treatment. Leaf area index at 60 days after sowing, plant dry matter accumulation at harvest, and kernels ear(-1) and 100-kernel weight were higher in MW+Lime treatment. Kernel N, P, K, Mn, Fe and Zn, and plant Zn uptake were highest in MW+Lime. Plant Fe uptake, and soil organic matter and humic substances were highest in MW+PW. The MW+PW and MW+Lime treatments exhibited comparable results with chemically fertilized treatment. The MW acidity neutralized with lime showed positive impacts on growth, yield and nutrients uptake; nevertheless, when MW pH neutralized with PW has an additional benefit on increase in soil organic matter and humic substances.

Pseudomonas guguanensis sp. nov., a gammaproteobacterium isolated from a hot spring.

An aerobic, Gram-stain-negative, rod-shaped bacterium (designated strain CC-G9A(T)), motile by a polar-flagellum, was isolated from a hot spring water sample in Taiwan. Strain CC-G9A(T) could grow at 20-42 °C, pH 6.0-10.0 and tolerate up to 7% (w/v) NaCl. The 16S rRNA gene sequence analysis of strain CC-G9A(T) showed pairwise sequence similarity to Pseudomonas mendocina LMG 1223(T) (97.7%), Pseudomonas alcaligenes ATCC 14909(T) (97.8 %), Pseudomonas alcaliphila DSM 17744(T) (97.8 %), Pseudomonas toyotomiensis JCM 15604(T) (97.6 %), Pseudomonas oleovorans subsp. lubricantis DSM 21016(T) (97.6 %) and Pseudomonas argentinensis BCRC 17807(T) (97.5 %), and lower sequence similarity to other species of the genus Pseudomonas. According to DNA-DNA association analysis, the relatedness of strain CC-G9A(T) to P. mendocina BCRC 10458(T), P. alcaliphila DSM 17744(T), P. alcaligenes BCRC 11893(T), P. oleovorans subsp. lubricantis DSM 21016(T), P. argentinensis BCRC 17807(T) and P. oleovorans subsp. oleovorans BCRC 11902 was 55.1±3.1, 13.7±1.5, 14.1±1.8, 58.5±1.1, 28.9±2.0 and 28.6±1.8 %, respectively. The evolutionary trees reconstructed based on 16S rRNA, gyrB and rpoB gene sequences revealed varying phylogenetic neighbourhoods of strain CC-G9A(T) with regard to the most closely related type strains. The predominant quinone system was ubiquinone (Q-9) and the DNA G+C content was 64.3±1.3 mol%. The major fatty acids were C10 : 0 3-OH, C12 : 0, C12 : 0 3-OH, C16 : 0 and summed features 3 and 8 consisting of C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω7c/C18 : 1ω6c, respectively. The major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine and phosphatidylglycerol. According to distinct phylogenetic, phenotypic and chemotaxonomic features, strain CC-G9A(T) is proposed to represent a novel species within the genus Pseudomonas for which the name Pseudomonas guguanensis sp. nov. is proposed. The type strain is CC-G9A(T) ( = BCRC 80438(T) = JCM 18416(T)).

Chiayiivirga flava gen. nov., sp. nov., a novel bacterium of the family Xanthomonadaceae isolated from an agricultural soil, and emended description of the genus Dokdonella.

A novel Gram-reaction-negative, yellow-pigmented, aerobic, non-motile and rod-shaped bacterium designated strain CC-YHH031(T) was isolated from an agricultural soil collected at Chiayi County, Taiwan. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CC-YHH031(T) formed a discrete monophyletic lineage in the family Xanthomonadaceae, sharing high pairwise sequence similarity of 93.5-95.2 and 94.8% with species of the genus Dokdonella (94.9% similarity to the type strain of the type species) and Aquimonas voraii GPTSA 20(T), respectively. The genomic DNA G+C content of strain CC-YHH031(T) was 68.6 ± 0.7 mol% and the predominant respiratory quinone was ubiquinone Q-8. Spermidine was the principal polyamine, with minor amounts of putrescine. Major fatty acids (>5% of total fatty acids) were iso-C(16:00, iso-C(15:0), C(16:1)ω7c and/or C(16:1)ω6c (summed feature 3), iso-C(17:1)ω9c, iso-C(14:0), iso-C(11:0) and iso-C(11:0) 3-OH. The polar lipid profile of strain CC-YHH031(T) included phosphatidylethanolamine, phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, two unidentified aminophospholipids (APL1-2) and four unidentified phospholipids (PL1-4). Strain CC-YHH031(T) was distinguished particularly from the type species of the genus Dokdonella (Dokdonella koreensis) by the presence of major amounts of iso-C(14:0) and summed feature 3 and minor amounts of iso-C(17:0) and by the complete absence of anteiso-C(17:0), the presence of PL1-3 and APL1-2, the absence of APL3 and the presence of putrescine in the former. On the basis of distinguishing genotypic and phenotypic evidence, strain CC-YHH031(T) is proposed to represent a novel genus and species within the family Xanthomonadaceae, for which the name Chiayiivirga flava gen. nov., sp. nov. is proposed. The type strain of Chiayiivirga flava is CC-YHH031(T) ( =BCRC 80274(T) =DSM 24163(T)).

Cohnella formosensis sp. nov., a xylanolytic bacterium isolated from the rhizosphere of Medicago sativa L.

A Gram-positive, spore-forming, aerobic, rod-shaped, xylanolytic bacterium designated strain CC-Alfalfa-35(T) was isolated from the rhizosphere of Medicago sativa L. in Taiwan. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain CC-Alfalfa-35(T) was affiliated to the genus Cohnella. Strain CC-Alfalfa-35(T) shared 95.3 % pairwise 16S rRNA gene sequence similarity to the type strain of the type species of the genus Cohnella (Cohnella thermotolerans DSM 17683(T)) besides showing a similarity of 97.4-93.6 % with other recognized species of the genus Cohnella. The DNA-DNA hybridization value between CC-Alfalfa-35(T) and Cohnella thailandensis KCTC 22296(T) was 37.7 % ± 1.7 % (reciprocal value, 55.7 % ± 3.0 %). Predominant cellular fatty acids were iso-C16 : 0 and anteiso-C15 : 0. The polar lipid profile constituted diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, lysyl-phosphatidylglycerol, three unidentified phospholipids and three unidentified aminophospholipids. The major respiratory quinone was MK-7 and the DNA G+C content was 58.3 mol%. Strain CC-Alfalfa-35(T) contained meso-diaminopimelic acid as the major diamino acid in the cell-wall peptidoglycan. Based on the polar lipid and fatty acid profiles, which were in line with those of C. thermotolerans DSM 17683(T), coupled with additional distinguishing genotypic, phenotypic and chemotaxonomic features, strain CC-Alfalfa-35(T) is proposed to represent a novel species within the genus Cohnella, for which the name Cohnella formosensis sp. nov. is proposed. The type strain is CC-Alfalfa-35(T) ( = JCM 18405(T) = BCRC 80428(T)).

Aureimonas ferruginea sp. nov. and Aureimonas rubiginis sp. nov., two siderophore-producing bacteria isolated from rusty iron plates.

Two novel siderophore-producing strains designated CC-CFT023(T) and CC-CFT034(T), isolated from a rusty iron plate, are characterized in this study. Cells of both strains were catalase- and oxidase-positive. Strain CC-CFT023(T) showed a high pairwise 16S rRNA gene sequence similarity to Aureimonas altamirensis LMG 23375(T) (96.0 %), whereas, strain CC-CFT034(T) shared a maximum similarity to Aureimonas ureilytica DSM 18598(T) (95.8 %). The predominant quinone system was ubiquinone (Q-10) and the DNA G+C contents of CC-CFT023(T) and CC-CFT034(T) were 69.5 mol% and 67.7 mol%, respectively. The major fatty acids of these strains were C16 : 0, C18 : 0, C19 : 0 cyclo ω8c, C18 : 1 2-OH and summed features 3 and 8, consisting of C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω7c/C18 : 1ω6c, respectively. Polar lipid profiles of both of these isolates include diphosphatidylglycerol (DPG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and most importantly sulfoquinovosyldiacylglycerol (SQDG), which is one of the typical molecular features reported to delineate the members of the genus Aureimonas from their closest relatives, species of the genus Aurantimonas. Based on the phylogenetic, phenotypic and chemotaxonomic features, strains CC-CFT023(T) and CC-CFT034(T) represent two novel species within the genus Aureimonas, for which the names Aureimonas ferruginea sp. nov. (type strain CC-CFT023(T) = BCRC 80439(T) = JCM 18444(T)) and Aureimonas rubiginis sp. nov. (type strain CC-CFT034(T) = BCRC 80440(T) = JCM 18445(T)) are proposed.

Siansivirga zeaxanthinifaciens gen. nov., sp. nov., a novel zeaxanthin-producing member of the family Flavobacteriaceae isolated from coastal seawater of Taiwan.

A strictly aerobic, Gram-negative, rod-shaped bacterium (strain CC-SAMT-1(T)) showing gliding motility was isolated from coastal seawater of China Sea, Taiwan. Strain CC-SAMT-1(T) synthesizes all-trans-zeaxanthin (6.5 ± 0.5 mg g(-1) dry biomass) as a predominant xanthophyll carotenoid. As determined by 16S rRNA gene analysis, strain CC-SAMT-1(T) shared very high sequence similarity to the members of the genera Mariniflexile (96.1-95.3%) and Gaetbulibacter (96.0-95.9%); however, it formed a distinct phyletic lineage distantly associated with Mariniflexile species. Polar lipid profile constitutes phosphatidylethanolamine, four unidentified aminolipids, four unidentified lipids, and an unidentified glycolipid. Strain CC-SAMT-1(T) contains excessive unidentified aminolipid lipid (AL2-4) and glycolipid contents, and therefore clearly distinct from Mariniflexile species. Major fatty acids (> 5% of total fatty acids) were iso-C(15:0) (14.8%), iso-C(17:0) 3-OH (11.8%), iso-C(15:1) G (10.6%), anteiso-C(15:0) (9.7%), C(16:0) (8.1%), iso-C(16:0) 3-OH (7.9%), iso-C(15:0) 3-OH (7.5%), and summed feature 3 (containing C(16:1) ω6c and/or C(16:1) ω7c) (7.5%). Menaquinone-6 (MK-6) was major respiratory quinone. DNA G+C content was 33.7 mol%. Based on polyphasic taxonomy, strain CC-SAMT-1(T) represents a novel genus and species in the family Flavobacteriaceae for which the name Siansivirga zeaxanthinifaciens gen. nov., sp. nov. is proposed. The type strain is CC-SAMT-1(T) (= BCRC 80315(T) = JCM 17682(T)).

Azospirillum formosense sp. nov., a diazotroph from agricultural soil.

A gram-negative, spiral or rod-shaped, non-spore-forming diazotrophic bacterium, designated CC-Nfb-7(T), was isolated from agricultural soil in Yunlin County, Taiwan. 16S rRNA gene sequence analysis showed that strain CC-Nfb-7(T) was most closely related to Azospirillum brasilense DSM 1690(T) (97.4 % 16S rRNA gene sequence similarity), Azospirillum rugosum IMMIB AFH-6(T) (96.8 %) and Azospirillum oryzae JCM 21588(T) (96.6 %); <96.5 % 16S rRNA gene sequence similarity was found with all other members of the genus Azospirillum. DNA-DNA relatedness between strain CC-Nfb-7(T) and A. brasilense DSM 1690(T), A. rugosum DSM 19657(T) and A. oryzae JCM 21588(T) was 38.9, 30.1 and 31.8 %, respectively. The respiratory quinone was ubiquinone Q-10. The major fatty acids were summed feature 8 (consisting of C(18 : 1)ω7c and/or C(18 : 1)ω6c), summed feature 3 (consisting of C(16 : 1)ω7c and/or C(16 : 1)ω6c), summed feature 2 (consisting of C(14 : 0) 3-OH and/or iso-C(16 : 1) I), C(16 : 0), C(18 : 0) 2-OH and C(16 : 0) 3-OH. The polar lipids consisted mainly of phosphatidylglycerol, phosphatidylcholine and one unidentified phospholipid. Furthermore, moderate amounts of phosphatidylethanolamine, phosphatidyldimethylethanolamine and one unidentified aminophospholipid were also detected. Strain CC-Nfb-7(T) could be distinguished from members of phylogenetically related species by differences in phenotypic properties. On the basis of morphological, chemotaxonomic and phylogenetic data, strain CC-Nfb-7(T) represents a novel species within the genus Azospirillum, for which we propose the name Azospirillum formosense sp. nov. The type strain is CC-Nfb-7(T) ( = BCRC 80273(T) = JCM 17639(T) = DSM 24137(T)).

Molecular detection and phylogenetic analysis of the alkane 1-monooxygenase gene from Gordonia spp.

The alkB gene encodes for alkane 1-monooxygenase, which is a key enzyme responsible for the initial oxidation of inactivated alkanes. This functional gene can be used as a marker to assess the catabolic potential of bacteria in bioremediation. In the present study, a pair of primers was designed based on the conserved regions of the AlkB amino acid sequences of Actinobacteria, for amplifying the alkB gene from the genus Gordonia (20 Gordonia strains representing 13 species). The amplified alkB genes were then sequenced and analyzed. In the phylogenetic tree based on the translated AlkB amino acid sequences, all the Gordonia segregated clearly from other closely related genera. The sequence identity of the alkB gene in Gordonia ranged from 58.8% to 99.1%, which showed higher sequence variation at the inter-species level compared with other molecular markers, such as the 16S rRNA gene (93.1-99.8%), gyrB gene (77.5-97.3%) or catA gene (72.4-99.5%). The genetic diversity of four selected loci also showed that the alkB gene might have evolved faster than rrn operons, as well as the gyrB or catA genes, in Gordonia. All the available actinobacterial alkB gene sequences derived from the whole genome shotgun sequencing projects are phylogenetically characterized here for the first time, and they exclude the possibility of horizontal gene transfer of the alkB gene in these bacterial groups.

Agaricicola taiwanensis gen. nov., sp. nov., an alphaproteobacterium isolated from the edible mushroom Agaricus blazei.

A Gram-negative, beige-pigmented, aerobic, motile, club-shaped bacterium, designated strain CC-SBABM117(T), was isolated from the stipe of the edible mushroom Agaricus blazei Murrill. 16S rRNA gene sequence analysis demonstrated that the strain shared <93 % similarity with the type strains of species in the genera Pannonibacter, Methylopila, Nesiotobacter and Stappia. The organism was unable to produce acid from carbohydrates, but utilized a number of organic acids and amino acids. Ubiquinone 10 (Q-10) was the major respiratory quinone and C(18 : 1) ω 7c, C(19 : 0) cyclo ω 8c, C(16 : 0) and C(18 : 0) were the predominant fatty acids. The predominant polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content of strain CC-SBABM117(T) was 62.7 mol%. On the basis of 16S rRNA gene sequence analysis and chemotaxonomic and physiological data, strain CC-SBABM117(T) is considered to represent a novel species of a new genus, for which the name Agaricicola taiwanensis gen. nov., sp. nov. is proposed. The type strain of Agaricicola taiwanensis is CC-SBABM117(T) (=BCRC 17964(T) =CCM 7684(T)).

Molecular detection and phylogenetic analysis of the catechol 1,2-dioxygenase gene from Gordonia spp.

The C12O gene (catA gene) encodes for catechol 1,2-dioxygenase, which is a key enzyme involved in the first step catalysis of the aromatic ring in the ortho-cleavage pathway. This functional gene can be used as a marker to assess the catabolic potential of bacteria in bioremediation. C12OF and C12OR primers were designed based on the conserved regions of the CatA amino acid sequence of Actinobacteria for amplifying the catA gene from the genus Gordonia (16 Gordonia representing 11 species). The amplified catA genes (382bp) were sequenced and analyzed. In the phylogenetic tree based on the translated catA amino acid sequences, all the Gordonia segregated clearly from other closely related genera. The sequence similarity of the catA gene in Gordonia ranged from 72.4% to 99.5%, indicating that the catA gene might have evolved faster than rrn operons or the gyrB gene at the inter-species level. A single nucleotide deletion of the catA gene was observed in Gordonia amicalis CC-MJ-2a, Gordonia rhizosphera and Gordonia sputi at nucleotide position 349. This deletion led to an encoding frame shift downstream of 11 amino acid residues, from WPSVAARAPAP to GHPWRPAHLHL, which was similar to most of the non-Gordonia Actinobacteria. Such variations might influence the catabolic activities or substrate utilization patterns of catechol 1,2-dioxygenase among Gordonia.

Adenosine kinase modulates root gravitropism and cap morphogenesis in Arabidopsis.

Adenosine kinase (ADK) is a key enzyme that regulates intra- and extracellular levels of adenosine, thereby modulating methyltransferase reactions, production of polyamines and secondary compounds, and cell signaling in animals. Unfortunately, little is known about ADK's contribution to the regulation of plant growth and development. Here, we show that ADK is a modulator of root cap morphogenesis and gravitropism. Upon gravistimulation, soluble ADK levels and activity increase in the root tip. Mutation in one of two Arabidopsis (Arabidopsis thaliana) ADK genes, ADK1, results in cap morphogenesis defects, along with alterations in root sensitivity to gravistimulation and slower kinetics of root gravitropic curvature. The kinetics defect can be partially rescued by adding spermine to the growth medium, whereas the defects in cap morphogenesis and gravitropic sensitivity cannot. The root morphogenesis and gravitropism defects of adk1-1 are accompanied by altered expression of the PIN3 auxin efflux facilitator in the cap and decreased expression of the auxin-responsive DR5-GUS reporter. Furthermore, PIN3 fails to relocalize to the bottom membrane of statocytes upon gravistimulation. Consequently, adk1-1 roots cannot develop a lateral auxin gradient across the cap, necessary for the curvature response. Interestingly, adk1-1 does not affect gravity-induced cytoplasmic alkalinization of the root statocytes, suggesting either that ADK1 functions between cytoplasmic alkalinization and PIN3 relocalization in a linear pathway or that the pH and PIN3-relocalization responses to gravistimulation belong to distinct branches of the pathway. Our data are consistent with a role for ADK and the S-adenosyl-L-methionine pathway in the control of root gravitropism and cap morphogenesis.

Gravity signal transduction in primary roots.

AIMS: The molecular mechanisms that correlate with gravity perception and signal transduction in the tip of angiosperm primary roots are discussed. SCOPE: Gravity provides a cue for downward orientation of plant roots, allowing anchorage of the plant and uptake of the water and nutrients needed for growth and development. Root gravitropism involves a succession of physiological steps: gravity perception and signal transduction (mainly mediated by the columella cells of the root cap); signal transmission to the elongation zone; and curvature response. Interesting new insights into gravity perception and signal transduction within the root tip have accumulated recently by use of a wide range of experimental approaches in physiology, biochemistry, genetics, genomics, proteomics and cell biology. The data suggest a network of signal transduction pathways leading to a lateral redistribution of auxin across the root cap and a possible involvement of cytokinin in initial phases of gravicurvature. CONCLUSION: These new discoveries illustrate the complexity of a highly redundant gravity-signalling process in roots, and help to elucidate the global mechanisms that govern auxin transport and morphogenetic regulation in roots.