Cooperative interactions between invader and resident microbial community members weaken the negative diversity-invasion relationship.

The negative diversity-invasion relationship observed in microbial invasion studies is commonly explained by competition between the invader and resident populations. However, whether this relationship is affected by invader-resident cooperative interactions is unknown. Using ecological and mathematical approaches, we examined the survival and functionality of Aminobacter niigataensis MSH1 to mineralize 2,6-dichlorobenzamide (BAM), a groundwater micropollutant affecting drinking water production, in sand microcosms when inoculated together with synthetic assemblies of resident bacteria. The assemblies varied in richness and in strains that interacted pairwise with MSH1, including cooperative and competitive interactions. While overall, the negative diversity-invasion relationship was retained, residents engaging in cooperative interactions with the invader had a positive impact on MSH1 survival and functionality, highlighting the dependency of invasion success on community composition. No correlation existed between community richness and the delay in BAM mineralization by MSH1. The findings suggest that the presence of cooperative residents can alleviate the negative diversity-invasion relationship.

Interaction Between Chronic Endometritis Caused Endometrial Microbiota Disorder and Endometrial Immune Environment Change in Recurrent Implantation Failure.

Objective: To investigate the Interaction between chronic endometritis (CE) caused endometrial microbiota disorder and endometrial immune environment change in recurrent implantation failure (RIF). Method: Transcriptome sequencing analysis of the endometrial of 112 patients was preform by using High-Throughput Sequencing. The endometrial microbiota of 43 patients was analyzed by using 16s rRNA sequencing technology. Result: In host endometrium, CD4 T cell and macrophage exhibited significant differences abundance between CE and non-CE patients. The enrichment analysis indicated differentially expressed genes mainly enriched in immune-related functional terms. Phyllobacterium and Sphingomonas were significantly high infiltration in CE patients, and active in pathways related to carbohydrate metabolism and/or fat metabolism. The increased synthesis of lipopolysaccharide, an important immunomodulator, was the result of microbial disorders in the endometrium. Conclusion: The composition of endometrial microorganisms in CE and non-CE patients were significantly different. Phyllobacterium and Sphingomonas mainly regulated immune cells by interfering with the process of carbohydrate metabolism and/or fat metabolism in the endometrium. CE endometrial microorganisms might regulate Th17 response and the ratio of Th1 to Th17 through lipopolysaccharide (LPS).

Bactericera cockerelli resistance in the wild tomato Solanum habrochaites is polygenic and influenced by the presence of Candidatus Liberibacter solanacearum.

The tomato-potato psyllid (TPP), Bactericera cockerelli, is a vector for the phloem-limited bacterium Candidatus Liberibacter solanacearum (Lso), the causative agent of economically important diseases including tomato vein-greening and potato zebra chip. Here, we screened 11 wild tomato relatives for TPP resistance as potential resources for tomato (Solanum lycopersicum) cultivar development. Six accessions with strong TPP resistance (survival <10%) were identified within S. habrochaites, S. pennelli, S. huaylasense, S. chmielewskii, S. corneliomulleri, and S. galapagense. Two S. pennelli and S. corneliomulleri accessions also showed resistance to Lso. We evaluated recombinant inbred lines (RILs) carrying resistance from S. habrochaites accession LA1777 in the S. lycopersicum background and identified major quantitative trait loci (QTLs) responsible for adult TPP mortality and fecundity in several RILs carrying insertions in different chromosomes, indicating the polygenic nature of these traits. Analysis of a major resistance QTL in RIL LA3952 on chromosome 8 revealed that the presence of Lso is required to increase adult TPP mortality. By contrast, the reduced TPP oviposition trait in LA3952 is independent of Lso. Therefore, resistance traits are available in wild-tomato species, although their complex inheritance and modes of action require further characterisation to optimise their utilisation for tomato improvement.

Pseudaminobacter granuli sp. nov., isolated from granules used in a wastewater treatment plant.

A Gram negative, aerobic, non-motile and rod-shaped bacterial strain designated as Gr-2T was isolated from granules used in a wastewater treatment plant in Korea, and its taxonomic position was investigated using a polyphasic approach. Strain Gr-2T grew at 18-37°C (optimum temperature, 30°C) and a pH of 6.0-8.0 (optimum pH, 7.0) on R2A agar medium. Based on 16S rRNA gene phylogeny, the novel strain showed a new branch within the genus Pseudaminobacter of the family Phyllobacteriaceae, and formed clusters with Pseudaminobacter defluvii THI 051T (98.9%) and Pseudaminobacter salicylatoxidans BN12T (98.7%). The G+C content of the genomic DNA was 63.6%. The predominant respiratory quinone was ubiquinone-10 (Q-10) and the major fatty acids were cyclo-C19:0 ω8c, C18:1 ω7c, and iso-C17:0. The overall polar lipid patterns of Gr-2T were similar to those determined for the other Pseudaminobacter species. DNA-DNA relatedness values between strain Gr-2T and its closest phylogenetically neighbors were below 18%. Strain Gr-2T could be differentiated genotypically and phenotypically from the recognized species of the genus Pseudaminobacter. The isolate therefore represents a novel species, for which the name Pseudaminobacter granuli sp. nov. is proposed with the type strain Gr-2T (=KACC 18877T =LMG 29567T).

Aquamicrobium soli sp. nov., a bacterium isolated from a chlorobenzoate-contaminated soil.

An aerobic, Gram-stain negative, short rod-shaped, asporogenous, non-motile bacterium designated strain NK8T was isolated from a chlorobenzoate contaminated soil in China. Strain NK8T was observed to grow optimally at pH 7.0, 30 °C and in the absence of NaCl in LB medium. The G + C content of the total DNA of strain NK8T was found to be 65.5 mol%. The 16S rRNA gene sequence of strain NK8T showed high similarity to that of Aquamicrobium aerolatum Sa14T (97.3%), followed by Aquamicrobium lusatiense S1T (96.7%) and Mesorhizobium sangali SCAU7T (96.6%). The DNA-DNA relatedness between strain NK8T and A. aerolatum Sa14T was 35.5 ± 0.9%. The major fatty acids of strain NK8T were determined to be C19:0 cyclo ω8c (45.6%), C18:1 ω7c (33.4%) and C16:0 (8.4%). The respiratory quinone was found to be ubiquinone Q-10. The major polyamine was found to be spermidine. The polar lipid profile include the major compounds phosphatidylcholine and diphosphatidylglycerol, and moderate amounts of phosphatidylethanolamine, phosphatidylmonomethylethanolamine, aminolipid and phospholipid. Based on the differential biochemical and physiological characteristics, the geno-, chemo- and phenotypic characteristics, strain NK8T is proposed to represent a novel species of the genus Aquamicrobium, Aquamicrobium soli sp. nov. The type strain is NK8T (=KCTC 52165T=CCTCC AB2016045T).

Surface modification of an organic hessian substrate leads to shifts in bacterial biofilm community composition and abundance.

Antifouling strategies to limit biofilms on submerged surfaces in the marine environment are of particular interest due to the economic and environmental impacts in industries such as shipping and aquaculture. Here, we investigate the influence of chemically modified hessian bag surfaces on the bacterial abundance and community composition of biofilm formation using flow cytometry and 16S rRNA pyrosequencing. Hessian bags were coated with 5% and 10% Propyl(trimethoxy)silane (PTMS) and half of the bags had their lignin and hemicellulose removed via NaOH mercerisation. Significantly lower bacterial abundance was observed on mercerised bags treated with 5% PTMS (p<0.01). Significant shifts in bacterial taxa were also observed (p=0.0004), whereby unmercerised bags exhibited higher relative abundances of the anaerobic family Desulfovibrionaceae (4.5±1.7%), while mercerised bags displayed higher relative abundances of the aerobic family Phyllobacteriaceae (3.6±1.7%). This suggests that the mercerisation process may lower colonization rates and subsequently produce a thinner biofilm. This hypothesis is strengthened by the lower abundance of bacteria on mercerised bags, particularly on the 5% PTMS coating. Our results show that modifying a hessian surface via non-toxic coating and mercerisation reduces biofilm formation and also shifts the dominant taxa, increasing our understanding of antifouling strategies in the marine environment.

Nitratireductor soli sp. nov., isolated from phenol-contaminated soil.

Strain ZZ-1(T), a Gram-negative, rod-shaped bacterium, motile by flagella, was isolated from phenol-contaminated soil. Strain ZZ-1(T) was found to grow at 15-37 °C (optimum 25-30 °C), at pH 6.0-10.0 (optimum pH 7.5) and with 0-8.0% (w/v) NaCl (optimum 0.5%). The isolate was found to be able to reduce nitrate to nitrite, but not to nitrogen. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain ZZ-1(T) is a member of the genus Nitratireductor, and shows high sequence similarities to Nitratireductor pacificus MCCC 1A01024(T) (98.5%) and lower (<97%) sequence similarities to all other Nitratireductor species. Chemotaxonomic analysis revealed that strain ZZ-1(T) possesses Q-10 as the predominant ubiquinone and Summed feature 8(C(18:1) ω6c and/or C(18:1) ω7c; 66.6%), C(19:0) ω8c cyclo (23.3%), C(18:0) (3.4%), iso-C(17:0) (2.3%) and C(17:0) (1.0%) as the major fatty acids. The polar lipids of strain ZZ-1(T) were determined to be diphosphatidylglycerol, phosphatidylcholine, phospholipids, aminolipids, a glycolipid and an aminophospholipid. The DNA G+C content was determined to be 64.1 mol%. Based on the draft genome sequence, the DNA-DNA hybridization estimate value between strain ZZ-1(T) and N. pacificus MCCC 1A01024(T) was 46.5 ± 3.0% and ANI was 75.9 %. The combination of phylogenetic analysis, phenotypic characteristics, chemotaxonomic data and DNA-DNA hybridization supports the conclusion that strain ZZ-1(T) represents a novel species of the genus Nitratireductor, for which the name Nitratireductor soli sp. nov. is proposed. The type strain is ZZ-1(T) (=JCM 30640(T) = MCCC 1K00508(T)).

Plants probiotics as a tool to produce highly functional fruits: the case of phyllobacterium and vitamin C in strawberries.

The increasing interest in the preservation of the environment and the health of consumers is changing production methods and food consumption habits. Functional foods are increasingly demanded by consumers because they contain bioactive compounds involved in health protection. In this sense biofertilization using plant probiotics is a reliable alternative to the use of chemical fertilizers, but there are few studies about the effects of plant probiotics on the yield of functional fruits and, especially, on the content of bioactive compounds. In the present work we reported that a strain of genus Phyllobacterium able to produce biofilms and to colonize strawberry roots is able to increase the yield and quality of strawberry plants. In addition, the fruits from plants inoculated with this strain have significantly higher content in vitamin C, one of the most interesting bioactive compounds in strawberries. Therefore the use of selected plant probiotics benefits the environment and human health without agronomical losses, allowing the production of highly functional foods.

Arsenite oxidation by the phyllosphere bacterial community associated with Wolffia australiana.

Speciation is a key determinant in the toxicity, behavior, and fate of arsenic (As) in the environment. However, little is known about the transformation of As species mediated by floating macrophytes and the phyllosphere bacteria in aquatic and wetland environment. In this study, Wolffia australiana, a rootless floating duckweed, was cultured with (W+B) or without (W-B) phyllosphere bacteria to investigate its ability in arsenite (As(III)) oxidation. Results showed that sterile W. australiana did not oxidize As(III) in the growth medium or in plant tissue, whereas W. australiana with phyllpsphere bacteria displayed substantial As(III) oxidation in the medium. Quantitative PCR of As redox-related functional genes revealed the dominance of the arsenite oxidase (aioA) gene in the phyllosphere bacterial community. These results demonstrate that the phyllosphere bacteria were responsible for the As(III) oxidation in the W+B system. The rapid oxidation of As(III) by the phyllosphere bacterial community may suppress As accumulation in plant tissues under phosphate rich conditions. The aioA gene library showed that the majority of the phyllosphere arsenite-oxidizing bacteria related either closely to unidentified bacteria found in paddy environments or distantly to known arsenite-oxidizing bacteria. Our research suggests a previously overlooked diversity of arsenite-oxidizing bacteria in the phyllosphere of aquatic macrophytes which may have a substantial impact on As biogeochemistry in water environments, warranting further exploration.

Aquamicrobium terrae sp. nov., isolated from the polluted soil near a chemical factory.

A Gram-negative, aerobic, non-motile bacterial strain hun6(T) isolated from the polluted soil near a chemical factory in northern Nanjing, China was investigated to clarify its taxonomic position. Growth of strain hun6(T) occurred between 10 and 45 °C (optimum, 30 °C) and between pH 6.0 and 8.0 (optimum, pH 7.0). No growth occurred at NaCl concentrations greater than 5 % (w/v). The 16S rRNA gene sequence analysis indicated that strain hun6(T) belongs to the genus Aquamicrobium. The sequence similarities of strain hun6(T) to other type strains of Aquamicrobium genus were all below 98.5 %. The presence of ubiquinone-10, the predominant fatty acid summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) and C19:0 cyclo ω8c, a polar lipid pattern with phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, phosphatidylethanolamine and phophatidylmonomethylethanoamine were in accord with the characteristics of the genus Aquamicrobium. The G+C content of the genomic DNA was determined to be 63.5 mol%. The results of DNA-DNA hybridization, physiological and biochemical tests and chemotaxonomic properties allowed genotypic and phenotypic differentiation of strain hun6(T) from all known Aquamicrobium species. Therefore, strain hun6(T) can be assigned to a new species of this genus for which the name Aquamicrobium terrae sp. nov. is proposed. The type strain is hun6(T) (= CICC 10733(T) = DSM 27865(T)).

Using 2,6-dichlorobenzamide (BAM) degrading Aminobacter sp. MSH1 in flow through biofilters--initial adhesion and BAM degradation potentials.

Micropollutants in groundwater are given significant attention by water companies and authorities due to an increasing awareness that they might be present even above the legal threshold values. As part of our investigations of the possibility to remove the common groundwater pollutant 2,6-dichlorobenzamide (BAM) by introducing the efficient BAM degrader Aminobacter sp. MSH1 into biologically active sand filters, we investigated if the strain adheres to filters containing various filter materials and if the initial adherence and subsequent degradation of BAM could be optimized. We found that most of the inoculated MSH1 cells adhered fast and that parameters like pH and ionic strength had only a minor influence on the adhesion despite huge influence on cell surface hydrophobicity. At the given growth protocol, the MSH1 strain apparently developed a subpopulation that had lost its ability to adhere to the filter materials, which was supported by attempted reinoculation of non-adhered cells. Analysis by quantitative PCR showed that most cells adhered in the top of the filters and that some of these were lost from the filters during initial operation, while insignificant losses occurred after 1 day of operation. The inoculated filters were found to degrade 2.7 µg/L BAM to below 0.1 µg/L at a 1.1-h residence time with insignificant formation of known degradation products. In conclusion, most filter materials and water types should be feasible for inoculation with the MSH1 strain, while more research into degradation at low concentrations and temperatures is needed before this technology is ready for use at actual waterworks.

The PGPR strain Phyllobacterium brassicacearum STM196 induces a reproductive delay and physiological changes that result in improved drought tolerance in Arabidopsis.

Understanding how biotic interactions can improve plant tolerance to drought is a challenging prospect for agronomy and ecology. Plant growth-promoting rhizobacteria (PGPR) are promising candidates but the phenotypic changes induced by PGPR under drought remain to be elucidated. We investigated the effects of Phyllobacterium brassicacearum STM196 strain, a PGPR isolated from the rhizosphere of oilseed rape, on two accessions of Arabidopsis thaliana with contrasting flowering time. We measured multiple morphophysiological traits related to plant growth and development in order to quantify the added value of the bacteria to drought-response strategies of Arabidopsis in soil conditions. A delay in reproductive development induced by the bacteria resulted in a gain of biomass that was independent of the accession and the watering regime. Coordinated changes in transpiration, ABA content, photosynthesis and development resulted in higher water-use efficiency and a better tolerance to drought of inoculated plants. Our findings give new insights into the ecophysiological bases by which PGPR can confer stress tolerance to plants. Rhizobacteria-induced delay in flowering time could represent a valuable strategy for increasing biomass yield, whereas rhizobacteria-induced improvement of water use is of particular interest in multiple scenarios of water availability.

Phytoextraction of heavy metal polluted soils using Sedum plumbizincicola inoculated with metal mobilizing Phyllobacterium myrsinacearum RC6b.

The aim of this study was to investigate the effects of metal mobilizing plant-growth beneficial bacterium Phyllobacterium myrsinacearum RC6b on plant growth and Cd, Zn and Pb uptake by Sedum plumbizincicola under laboratory conditions. Among a collection of metal-resistant bacteria, P. myrsinacearum RC6b was specifically chosen as a most favorable metal mobilizer based on its capability of mobilizing high concentrations of Cd, Zn and Pb in soils. P. myrsinacearum RC6b exhibited a high degree of resistance to Cd (350 mg L(-1)), Zn (1000 mg L(-1)) and Pb (1200 mg L(-1)). Furthermore, P. myrsinacearum RC6b showed multiple plant growth beneficial features including the production of 1-aminocyclopropane-1-carboxylic acid deaminase, indole-3-acetic acid, siderophore and solubilization of insoluble phosphate. Inoculation of P. myrsinacearum RC6b significantly increased S. plumbizincicola growth and organ metal concentrations except Pb, which concentration was lower in root and stem of inoculated plants. The results suggest that the metal mobilizing P. myrsinacearum RC6b could be used as an effective inoculant for the improvement of phytoremediation in multi-metal polluted soils.

The NRT2.5 and NRT2.6 genes are involved in growth promotion of Arabidopsis by the plant growth-promoting rhizobacterium (PGPR) strain Phyllobacterium brassicacearum STM196.

The Phyllobacterium brassicacearum STM196 strain stimulates Arabidopsis thaliana growth and antagonizes high nitrate inhibition of lateral root development. A previous study identified two STM196-responsive genes, NRT2.5 and NRT2.6 (Mantelin et al., 2006, Planta 223: 591-603). We investigated the role of NRT2.5 and NRT2.6 in the plant response to STM196 using single and double Arabidopsis mutants. The single mutants were also crossed with an nrt2.1 mutant, lacking the major nitrate root transporter, to distinguish the effects of NRT2.5 and NRT2.6 from potential indirect effects of nitrate pools. The nrt2.5 and nrt2.6 mutations abolished the plant growth and root system architecture responses to STM196. The determination of nitrate content revealed that NRT2.5 and NRT2.6 do not play an important role in nitrate distribution between plant organs. Conversely, NRT2.5 and NRT2.6 appeared to play a role in the plant response independent of nitrate uptake. Using a nitrate reductase mutant, it was confirmed that the NRT2.5/NRT2.6-dependent plant signalling pathway is independent of nitrate-dependent regulation of root development. Our findings demonstrate that NRT2.5 and NRT2.6, which are preferentially expressed in leaves, play an essential role in plant growth promotion by the rhizospheric bacterium STM196.

Hoeflea halophila sp. nov., a novel bacterium isolated from marine sediment of the East Sea, Korea.

A Gram-negative, aerobic, motile, straight or curved rod-shaped marine bacterium was isolated from marine sediment of the East Sea, Korea. The isolated strain, JG120-1(T), grows with 0-5 % (w/v) NaCl and at 15-30 °C and pH 6-9. α-galactosidase activity test was positive. Comparative 16S rRNA gene sequence studies showed that this strain belonged to the Alphaproteobacteria and was the most closely related to Hoeflea alexandrii AM1 V30(T), Hoeflea phototrophica DFL-43(T) and Hoeflea marina LMG 128(T) (98.9, 97.9 and 97.0 % 16S rRNA gene sequence similarities, respectively). Strain JG120-1(T) was found to possess summed feature 8 (C18:1ω7c/C18:1ω6c, 71.11 %) as the major cellular fatty acid. The major ubiquinone was determined to be Q-10. Polar lipids include phosphatidylglycerol, phosphatidylethanolamine, sulfoquinovosyl diacylglycerol, phosphatidylcholine and phosphatidylmonomethylethanolamine. The G+C content of the genomic DNA of strain JG120-1(T) was determined to be 57.8 mol %. DNA-DNA relatedness data indicated that strain JG120-1(T) represents a distinct species that is separate from H. phototrophica DFL-43(T), H. marina LMG128(T) and H. alexandrii AM1 V30(T). On the basis of polyphasic evidences, it is proposed that strain JG120-1(T) (= KCTC 23107(T) = JCM 16715(T)) represents the type strain of a novel species, Hoeflea halophila sp. nov.

[Isolation and identification of aerobic denitrifying bacterium Defluvibacter lusatiensis strain DN7 and its heterotrophic nitrification ability].

An aerobic denitrifying bacterium strain DN7 with excellent nitrate removal ability was isolated from the bio-contact oxidation reactor treating bamboo process wastewater. The strain had a nitrate removal efficiency of 99.4% in 72 h. Cell microscopic observation demonstrated that the strain was a gram-negative bacillus with an average size of 0.5 microm x 1.5 microm, and the colony was ivory. Based on its biochemical/morphological characteristics and its 16S rDNA sequence homologic analysis, this strain was identified as Defluvibacter lusatiensis. Its optimal carbon sources were small molecular organic compounds such as sodium citrate and glucose, and its nitrogen removal efficiency reached 99.0% when the medium C/N ratio was 9. The nitrogen removal efficiency could reach more than 96% when the nitrate concentration was below 138.48 mg x L(-1) and the nitrite concentration was lower than 1.0 mg x L(-1). The strain was not sensitive to DO, and the denitrification was favored under neutral or a bit alkaline condition. The DN7 also had good ability in degrading ammonim nitrogen, with the removal efficiency being 84.7% in 72 h.

The ethylene pathway contributes to root hair elongation induced by the beneficial bacteria Phyllobacterium brassicacearum STM196.

In Arabidopsis roots, some epidermal cells differentiate into root hair cells. Auxin regulates root hair positioning, while ethylene controls cell elongation. Phyllobacterium brassicacearum STM196, a beneficial strain of plant growth promoting rhizobacteria (PGPR) isolated from the roots of field-grown oilseed rape, stimulates root hair elongation in Arabidopsis thaliana seedlings. We investigated the role of ethylene in the response of root hair cells to STM196 inoculation. While we could not detect a significant increase in ethylene biosynthesis, we could detect a slight activation of the ethylene signalling pathway. Consistent with this, an exhaustive survey of the root hair elongation response of mutants and transgenic lines affected in the ethylene pathway showed contrasting root hair sensitivities to STM196. We propose that local ethylene emission contributes to STM196-induceed root hair elongation.