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  • 1.

    【2hr】The Nitrogen Cycle: A Large, Fast, and Mystifying Cycle

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    机译 氮循环：一个大型，快速而神秘的循环
    • 作者：Ken Takai
    • 刊名：Microbes and Environments
    • 2019年第3期
    摘要：
  • 2.

    【2hr】The Honeybee Gut Microbiota Is Altered after Chronic Exposure to Different Families of Insecticides and Infection by Nosema ceranae

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    机译 长期暴露于不同杀虫剂家族后，蜜蜂肠道菌群发生改变，并被鼻线虫感染
    摘要：The gut of the European honeybee Apis mellifera is the site of exposure to multiple stressors, such as pathogens and ingested chemicals. Therefore, the gut microbiota, which contributes to host homeostasis, may be altered by these stressors. The abundance of major bacterial taxa in the gut was evaluated in response to infection with the intestinal parasite Nosema ceranae or chronic exposure to low doses of the neurotoxic insecticides coumaphos, fipronil, thiamethoxam, and imidacloprid. Experiments were performed under laboratory conditions on adult workers collected from hives in February (winter bees) and July (summer bees) and revealed season-dependent changes in the bacterial community composition. N. ceranae and a lethal fipronil treatment increased the relative abundance of both Gilliamella apicola and Snodgrassella alvi in surviving winter honeybees. The parasite and a sublethal exposure to all insecticides decreased the abundance of Bifidobacterium spp. and Lactobacillus spp. regardless of the season. The similar effects induced by insecticides belonging to distinct molecular families suggested a shared and indirect mode of action on the gut microbiota, possibly through aspecific alterations in gut homeostasis. These results demonstrate that infection and chronic exposure to low concentrations of insecticides may affect the honeybee holobiont.
  • 3.

    【2hr】Density and Diversity of Microbial Symbionts under Organic and Conventional Agricultural Management

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    机译 有机和常规农业管理下微生物共生体的密度和多样性
    摘要：The influence of organic and conventional farming and agroecology on the diversity and functioning of indigenous soil microbial communities was examined using a multifactorial analysis based on an extended minimum data set of classical status and functional tests. Main soil physicochemical properties and selected microbiological indicators, the quantity of heterotrophic or aerobic spore-forming bacteria, basal and substrate-induced respiration, catabolic activity with MicroResp™, and fluorescein diacetate enzyme activity were characterized. A pot experiment applying the most probable number method was designed with soil dilution series using Pisum sativum L. and Triticum spelta L. to assess the symbiotic infectivity and genetic diversity of key indicator groups of the plant microbiome, e.g. nitrogen-fixing bacteria (rhizobia) and arbuscular mycorrhizal fungi. Soil pH, humus content, CFU, enzyme activity, and soil respiration were significantly higher in organic soils. The activity of soil microorganisms was mainly related to clay, humus, calcium, and magnesium parameters. A redundancy analysis test of catabolic activities showed that samples were grouped according to different substrate utilization patterns and land uses were also clearly separated from each other. Farming practice influenced the abundance and diversity of microbial populations. Dark septate endophytic fungi were only found in conventional soils. In addition to confirming soil health improvements by organic management, our results highlight the importance of a complex evaluation including both classical status and functional parameters of soil microbiota, which may more reliably indicate a shift in the quality status of soils.
  • 4.

    【2hr】An Aggregation-defective Mutant of Methanothermobacter sp. CaT2 Reveals Unique Protein-dependent Aggregation

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    机译 甲烷杆菌嗜热菌的聚集缺陷突变体。 CaT2揭示独特的蛋白质依赖性聚集。
    摘要：The thermophilic hydrogenotrophic methanogen, Methanothermobacter sp. CaT2, which possesses an extracellular sugar layer, commonly aggregates by itself or with other microorganisms. To elucidate the molecular mechanisms responsible for this aggregation, the aggregation-defective mutant, CLA160, was isolated. Optical and electron microscopy observations revealed that the mutant exhibited a significant reduction in aggregation. Genomic sequencing showed that CLA160 has a single point mutation, causing a nonsense mutation in MTCT_1020, which encodes a hypothetical protein. Motif and domain analyses indicated that the hypothetical protein bears two membrane-spanning segments at the N- and C-terminal regions and a large middle repeat-containing region. The results of a bioinformatic analysis suggested that the first middle region (RII) of the protein or the whole structure is responsible for the function of the product of MTCT_1020 in the aggregation of CaT2. A treatment with proteinase K suppressed sedimentation in CaT2, indicating a reduction in aggregation, with almost no effect on sedimentation in CLA160. The addition of Ca2+ or Mg2+ ions enhanced sedimentation in CaT2, whereas a DNase treatment had no effect on sedimentation in either strain. These results suggest that the hypothetical protein encoded by MTCT_1020 plays a key role as a membrane-bound adhesion protein in the aggregation of CaT2, which is enhanced by the addition of Ca2+ or Mg2+ ions.
  • 5.

    【2hr】Mode and Structure of the Bacterial Community on Human Scalp Hair

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    机译 人类头皮上细菌群落的模式和结构
    摘要：Bacterial communities on various parts of the human body are distinct. We were the first to report the existence of a stable bacterial community on human scalp hair and demonstrated that an analysis of its structure by terminal restriction fragment length polymorphism (T-RFLP) is helpful for individual discrimination. However, the ecology of the bacterial community on human scalp hair has not yet been elucidated in detail. We herein investigated the mode, quantity, and phylogeny of bacterial communities on the human hair shaft and root and showed the results obtained from one representative individual. Direct SEM observations of hair, without a pretreatment, confirmed the ubiquitous presence of bacteria-like coccoids and rods on the shaft and root of hair from the human scalp, with 105–106 cells cm−2 of hair and 107 cells cm−2 of hair, respectively. These values corresponded to the 16S rRNA gene copy numbers obtained by qPCR. These numbers were not significantly affected by detergent washing. These results represented those obtained from many individuals with different hair lengths, ages, and gender. The major OTUs on the human scalp hair shaft and root were the same and included two species of Pseudomonas (phylum Proteobacteria), Cutibacterium and Lawsonella (phylum Actinobacteria), and Staphylococcus (phylum Firmicutes). These results suggest that major bacteria on the human hair shaft are indigenous and derived from the hair root.
  • 6.

    【2hr】Identification of Genes Regulated by the Antitermination Factor NasT during Denitrification in Bradyrhizobium diazoefficiens

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    机译 重氮根瘤菌缓释过程中反终止因子NasT调控的基因的鉴定。
    摘要：The soybean symbiont Bradyrhizobium diazoefficiens grows anaerobically in the presence of nitrate using the denitrification pathway, which involves the nap, nir, nor, and nos genes. We previously showed that NasT acts as a transcription antitermination regulator for nap and nos gene expression. In the present study, we investigated the targets of NasT in B. diazoefficiens during denitrifying growth by performing transcription profiling with RNA-seq and quantitative reverse-transcription PCR. Most of the genes with altered expression in the absence of NasT were related to nitrogen metabolism, specifically several systems for branched-chain amino acid transport. The present results suggest that the reduced expression of genes involved in nitrogen acquisition leads to the induction of alternative sets of genes with similar functions. The ΔnasT mutant of B. diazoefficiens grew better than the wild type under denitrifying conditions. However, this enhanced growth was completely abolished by an additional loss of the narK or bjgb genes, which encode cytoplasmic systems for nitrite and nitric oxide detoxification, respectively. Since the expression of narK and bjgb was increased in the ΔnasT mutant, the growth of the ΔnasT mutant may be promoted by increased detoxification activity.
  • 7.

    【2hr】Comparative Characterization of Bacterial Communities in Moss-Covered and Unvegetated Volcanic Deposits of Mount Merapi, Indonesia

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    机译 印度尼西亚默拉皮火山青苔覆盖和无​​植被火山岩沉积物中细菌群落的比较特征
    摘要：Microbial colonization, followed by succession, on newly exposed volcanic substrates represents the beginning of the development of an early ecosystem. During early succession, colonization by mosses or plants significantly alters the pioneer microbial community composition through the photosynthetic carbon input. To provide further insights into this process, we investigated the three-year-old volcanic deposits of Mount Merapi, Indonesia. Samples were collected from unvegetated (BRD) and moss-covered (BRUD) sites. Forest site soil (FRS) near the volcanic deposit-covered area was also collected for reference. An analysis of BRD and BRUD revealed high culturable cell densities (1.7–8.5×105 CFU g−1) despite their low total C (<0.01%). FRS possessed high CFU (3×106 g−1); however, its relative value per unit of total C (2.6%) was lower than that of the deposit samples. Based on the tag pyrosequencing of 16S rRNA genes, the BRD bacterial community was characterized by a higher number of betaproteobacterial families (or genus), represented by chemolithotrophic Methylophilaceae, Leptothrix, and Sulfuricellaceae. In contrast, BRUD was predominated by different betaproteobacterial families, such as Oxalobacteraceae, Comamonadaceae, and Rhodocyclaceae. Some bacterial (Oxalobacteraceae) sequences were phylogenetically related to those of known moss-associated bacteria. Within the FRS community, Proteobacteria was the most abundant phylum, followed by Acidobacteria, whereas Burkholderiaceae was the most dominant bacterial family within FRS. These results suggest that an inter-family succession of Betaproteobacteria occurred in response to colonization by mosses, followed by plants.
  • 8.

    【2hr】Geochemical and Metagenomic Characterization of Jinata Onsen, a Proterozoic-Analog Hot Spring, Reveals Novel Microbial Diversity including Iron-Tolerant Phototrophs and Thermophilic Lithotrophs

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    机译 Jinata Onsen是一种元古代模拟温泉的地球化学和超基因组学特征，揭示了新的微生物多样性，包括耐铁性养分和嗜热性养分
    摘要：Hydrothermal systems, including terrestrial hot springs, contain diverse geochemical conditions that vary over short spatial scales due to progressive interactions between reducing hydrothermal fluids, the oxygenated atmosphere, and, in some cases, seawater. At Jinata Onsen on Shikinejima Island, Japan, an intertidal, anoxic, iron-rich hot spring mixes with the oxygenated atmosphere and seawater over short spatial scales, creating diverse chemical potentials and redox pairs over a distance of ~10 m. We characterized geochemical conditions along the outflow of Jinata Onsen as well as the microbial communities present in biofilms, mats, and mineral crusts along its traverse using 16S rRNA gene amplicon and genome-resolved shotgun metagenomic sequencing. Microbial communities significantly changed downstream as temperatures and dissolved iron concentrations decreased and dissolved oxygen increased. Biomass was more limited near the spring source than downstream, and primary productivity appeared to be fueled by the oxidation of ferrous iron and molecular hydrogen by members of Zetaproteobacteria and Aquificae. The microbial community downstream was dominated by oxygenic Cyanobacteria. Cyanobacteria are abundant and active even at ferrous iron concentrations of ~150 μM, which challenges the idea that iron toxicity limited cyanobacterial expansion in Precambrian oceans. Several novel lineages of Bacteria are also present at Jinata Onsen, including previously uncharacterized members of the phyla Chloroflexi and Calditrichaeota, positioning Jinata Onsen as a valuable site for the future characterization of these clades.
  • 9.

    【2hr】Metabolic Potential of As-yet-uncultured Archaeal Lineages of Candidatus Hydrothermarchaeota Thriving in Deep-sea Metal Sulfide Deposits

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    机译 深海金属硫化物矿床中尚存的尚未培养的古生念珠菌的代谢潜能
    摘要：Candidatus Hydrothermarchaeota, formally called Marine Benthic Group E, has often been detected in iron- and sulfur-rich marine environments, such as hydrothermal vents and cold seeps. However, their ecology and physiology remain unclear. Cultivated representatives of this group are still lacking and only several metagenome-assembled genomes (MAGs) and single-amplified genomes (SAGs) are available from two deep-sea hydrothermal areas, the Juan de Fuca Ridge (JdFR) and Guaymas Basin (GB), in the north-east Pacific. We herein report four MAGs of Ca. Hydrothermarchaeota recovered from hydrothermally-inactive metal sulfide deposits at the Southern Mariana Trough (SMT) in the north-west Pacific. A phylogenetic analysis indicated that the MAGs of the SMT were distinct from those of the JdFR and GB at the genus or potentially family level. Ca. Hydrothermarchaeota MAGs from the SMT commonly possessed putative genes for carboxydotrophic and hydrogenotrophic respiration using oxidized chemical species of sulfur as electron acceptors and also for carbon fixation, as reported previously in MAGs/SAGs from the JdFR and GB. This result strongly supports Ca. Hydrothermarchaeota containing anaerobic chemolithoautotrophs using carbon monoxide and/or hydrogen as electron donors. A comparative genome analysis highlighted differences in the capability of nitrogen fixation between MAGs from the SMT and the other fields, which are consistent with environmental differences in the availability of nitrogen sources for assimilation between the fields. Based on the wide distribution in various areas, abundance, and metabolic potential of Ca. Hydrothermarchaeota, they may play a role in the biogeochemical cycling of carbon, nitrogen, sulfur, and iron in marine environments, particularly in deep-sea hydrothermal fields.
  • 10.

    【2hr】Sulfide-dependent Photoautotrophy in the Filamentous Anoxygenic Phototrophic Bacterium, Chloroflexus aggregans

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    机译 丝状厌氧的光养细菌，绿豆弯曲菌中的硫化物依赖性光致自养。
    摘要：Chloroflexus aggregans is a thermophilic filamentous anoxygenic phototrophic bacterium frequently found in microbial mats in natural hot springs. C. aggregans often thrives with cyanobacteria that engage in photosynthesis to provide it with an organic substrate; however, it sometimes appears as the dominant phototroph in microbial mats without cyanobacteria. This suggests that C. aggregans has the ability to grow photoautotrophically. However, photoautotrophic growth has not been observed in any cultured strains of C. aggregans. We herein attempted to isolate a photoautotrophic strain from C. aggregansdominated microbial mats in Nakabusa hot spring in Japan. Using an inorganic medium, we succeeded in isolating a new strain that we designated “ACA-12”. A phylogenetic analysis based on 16S rRNA gene and 16S-23S rRNA gene internal transcribed spacer (ITS) region sequences revealed that strain ACA-12 was closely related to known C. aggregans strains. Strain ACA-12 showed sulfide consumption along with autotrophic growth under anaerobic light conditions. The deposited elemental sulfur particles observed by microscopy indicated that sulfide oxidation occurred, similar to that in photoautotrophic strains in the related species, C. aurantiacus. Moreover, we found that other strains of C. aggregans, including the type strain, also exhibited a slight photoautotrophic growing ability, whereas strain ACA-12 showed the fastest growth rate. This is the first demonstration of photoautotrophic growth with sulfide in C. aggregans. The present results strongly indicate that C. aggregans is associated with inorganic carbon incorporation using sulfide as an electron donor in hot spring microbial mats.
  • 11.

    【2hr】Analyses of the Complete Genome Sequence of the Strain Bacillus pumilus ZB201701 Isolated from Rhizosphere Soil of Maize under Drought and Salt Stress

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    机译 干旱和盐胁迫下玉米根际土壤中分离到的短小芽孢杆菌ZB201701株全基因组序列分析
    摘要：Bacillus pumilus ZB201701 is a rhizobacterium with the potential to promote plant growth and tolerance to drought and salinity stress. We herein present the complete genome sequence of the Gram-positive bacterium B. pumilus ZB201701, which consists of a linear chromosome with 3,640,542 base pairs, 3,608 protein-coding sequences, 24 ribosomal RNAs, and 80 transfer RNAs. Genome analyses using bioinformatics revealed some of the putative gene clusters involved in defense mechanisms. In addition, activity analyses of the strain under salt and simulated drought stress suggested its potential tolerance to abiotic stress. Plant growth-promoting bacteria-based experiments indicated that the strain promotes the salt tolerance of maize. The complete genome of B. pumilus ZB201701 provides valuable insights into rhizobacteria-mediated salt and drought tolerance and rhizobacteria-based solutions for abiotic stress in agriculture.
  • 12.

    【2hr】Pol B, a Family B DNA Polymerase, in Thermococcus kodakarensis is Important for DNA Repair, but not DNA Replication

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    机译 柯达热球菌中的B族DNA聚合酶Pol B对DNA修复很重要，但对DNA复制不重要
    摘要：Thermococcus kodakarensis possesses two DNA polymerases, Pol B and Pol D. We generated a T. kodakarensis strain (DPB1) in which polB was completely deleted and a derivative of DPB1 in which polB was overexpressed; neither of the generated strains exhibited any growth delay, indicating that the lack or overexpression of Pol B in T. kodakarensis did not affect cell growth. We also found that DPB1 showed higher sensitivity to four DNA-damaging agents (ultraviolet C irradiation, γ-ray irradiation, methyl methanesulfonate, and mitomycin C) than the parental strain. The sensitivity of DPB1 was restored to the level of the parent strain by the introduction of a plasmid harboring polB, suggesting that the DNA damage-sensitive phenotype of DPB1 was due to the loss of polB. Collectively, these results indicate that Pol B is involved in DNA repair, but not DNA replication, which, in turn, implies that Pol D is the sole replicative DNA polymerase in Thermococcus species.
  • 13.

    【2hr】Nestedness in Arbuscular Mycorrhizal Fungal Communities in a Volcanic Ecosystem: Selection of Disturbance-tolerant Fungi along an Elevation Gradient

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    机译 火山生态系统中的丛枝菌根真菌群落的嵌套性：沿海拔梯度的耐干扰真菌的选择。
    摘要：Arbuscular mycorrhizal (AM) fungi play a significant role in the establishment and resilience of vegetation in harsh environments, such as volcanic slopes, in which soil is frequently disturbed by ash falling and erosion. We characterized AM fungal communities associated with a pioneer grass in a volcanic slope based on the disturbance tolerance of the fungi, addressing the hypothesis that soil disturbance is a major ecological filter for AM fungi in volcanic ecosystems and, thus, fungi that are more tolerant to soil disturbance are selected at higher elevations (i.e. nearer to the crater). Paired soil-core samples were collected from the rhizosphere of Miscanthus sinensis between the vegetation limit and forest limit on a volcanic slope and used in a trap culture with M. sinensis seedlings, in which one of the paired samples was sieved to destroy hyphal networks (disturbance treatment), while the other was not (intact treatment). Seedlings were grown in a greenhouse for two months, and the roots were subjected to molecular analysis of fungal communities. AM fungal diversity decreased with increasing elevations, in which nested structure was observed. Community dissimilarity between the disturbed and intact communities decreased with increasing elevations, suggesting that communities at higher elevations were more robust against soil disturbance. These results suggest that AM fungi that are more tolerant to soil disturbance are more widely distributed across the ecosystem, that is, they are generalists. The wide distribution of disturbance-tolerant fungi may have significant implications for the rapid resilience of vegetation after disturbance in the ecosystem.
  • 14.

    【2hr】The Earth Is Small for “Leviathans”: Long Distance Dispersal of Giant Viruses across Aquatic Environments

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    机译 “ Leviathans”的地球很小：在水生环境中远距离传播巨型病毒
    摘要：Giant viruses of ‘Megaviridae’ have the ability to widely disperse around the globe. We herein examined ‘Megaviridae’ communities in four distinct aquatic environments (coastal and offshore seawater, brackish water, and hot spring freshwater), which are distantly located from each other (between 74 and 1,765 km), using a meta-barcoding method. We identified between 593 and 3,627 OTUs in each sample. Some OTUs were detected in all five samples tested as well as in many of the Tara Oceans metagenomes, suggesting the existence of viruses of this family in a wide range of habitats and the ability to circulate on the planet.
  • 15.

    【2hr】Weed Roots Facilitate the Spread of Rosellinia necatrix, the Causal Agent of White Root Rot

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    机译 杂草根促进白根腐病的致病菌玫瑰色病的蔓延
    摘要：Rosellinia necatrix causes white root rot in various plants, including the Japanese pear. PCR assays using specific primers for R. necatrix detected the fungus on the roots of nine weed species from infested pear orchards. The soil inoculation experiment revealed that the spread of R. necatrix was similar between weed-mowed and non-weed-mowed treatments under field conditions. The spread of R. necatrix was also observed when rescue grass (Bromus catharticus) was grown in planter boxes under greenhouse conditions, but was limited without the grass, suggesting that some weeds facilitate the spread of R. necatrix in soil.
  • 16.

    【2hr】Ecology of Pathogens and Antibiotic-resistant Bacteria in Environments: Challenges and Opportunities

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    机译 环境中的病原体和耐药细菌生态学：挑战和机遇
    • 作者：Satoshi Ishii
    • 刊名：Microbes and Environments
    • 2019年第1期
    摘要：
  • 17.

    【2hr】Control of the Nitrogen Isotope Composition of the Fungal Biomass: Evidence of Microbial Nitrogen Use Efficiency

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    机译 真菌生物量氮同位素组成的控制：微生物氮利用效率的证据
    摘要：Changes in 15N/14N in the soil microbial biomass during nitrogen (N) mineralization have been hypothesized to influence 15N/14N in soil organic matter among ecosystem sites. However, a direct experimental test of this mechanism has not yet been performed. To evaluate the potential control of microbial N mineralization on the natural N isotope composition, we cultured fungi (Aspergillus oryzae) in five types of media of varying C:N ratios of 5, 10, 30, 50, and 100 for 4 d, and tracked changes in δ15N in the microbial biomass, NH4+, and dissolved organic N (DON: glycine) over the course of the experiment. High rates of NH4+ excretion from A. oryzae were accompanied by an increase in δ15N in the microbial biomass in low C:N media (i.e., C/N<30). In contrast, NH4+ was strongly retained in higher C/N treatments with only minor (i.e., <1 ‰) changes being detected in δ15N in the microbial biomass. Differences in δ15N in the microbial biomass were attributed to the loss of low-δ15N NH4+ in low, but not high C/N substrates. We also detected a negative linear correlation between microbial nitrogen use efficiency (NUE) and Δ15N (δ15N-biomass–δ15N-glycine). These results suggest an isotope effect during NH4+ excretion in relatively N-repleted environments in which microbial NUE is low, which may explain the vertical patterns of organic matter δ15N in soil profiles.
  • 18.

    【2hr】Eelgrass Sediment Microbiome as a Nitrous Oxide Sink in Brackish Lake Akkeshi, Japan

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    机译 淡水咸湖微生物群，作为日本咸淡湖中的一氧化二氮池
    摘要：Nitrous oxide (N2O) is a powerful greenhouse gas; however, limited information is currently available on the microbiomes involved in its sink and source in seagrass meadow sediments. Using laboratory incubations, a quantitative PCR (qPCR) analysis of N2O reductase (nosZ) and ammonia monooxygenase subunit A (amoA) genes, and a metagenome analysis based on the nosZ gene, we investigated the abundance of N2O-reducing microorganisms and ammonia-oxidizing prokaryotes as well as the community compositions of N2O-reducing microorganisms in in situ and cultivated sediments in the non-eelgrass and eelgrass zones of Lake Akkeshi, Japan. Laboratory incubations showed that N2O was reduced by eelgrass sediments and emitted by non-eelgrass sediments. qPCR analyses revealed that the abundance of nosZ gene clade II in both sediments before and after the incubation as higher in the eelgrass zone than in the non-eelgrass zone. In contrast, the abundance of ammonia-oxidizing archaeal amoA genes increased after incubations in the non-eelgrass zone only. Metagenome analyses of nosZ genes revealed that the lineages Dechloromonas-Magnetospirillum-Thiocapsa and Bacteroidetes (Flavobacteriia) within nosZ gene clade II were the main populations in the N2O-reducing microbiome in the in situ sediments of eelgrass zones. Sulfur-oxidizing Gammaproteobacteria within nosZ gene clade II dominated in the lineage Dechloromonas-Magnetospirillum-Thiocapsa. Alphaproteobacteria within nosZ gene clade I were predominant in both zones. The proportions of Epsilonproteobacteria within nosZ gene clade II increased after incubations in the eelgrass zone microcosm supplemented with N2O only. Collectively, these results suggest that the N2O-reducing microbiome in eelgrass meadows is largely responsible for coastal N2O mitigation.
  • 19.

    【2hr】Impact of Introduction of Arbuscular Mycorrhizal Fungi on the Root Microbial Community in Agricultural Fields

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    机译 丛枝菌根真菌的引入对农田根系微生物群落的影响
    摘要：Arbuscular mycorrhizal (AM) fungi are important members of the root microbiome and may be used as biofertilizers for sustainable agriculture. To elucidate the impact of AM fungal inoculation on indigenous root microbial communities, we used high-throughput sequencing and an analytical pipeline providing fixed operational taxonomic units (OTUs) as an output to investigate the bacterial and fungal communities of roots treated with a commercial AM fungal inoculum in six agricultural fields. AM fungal inoculation significantly influenced the root microbial community structure in all fields. Inoculation changed the abundance of indigenous AM fungi and other fungal members in a field-dependent manner. Inoculation consistently enriched several bacterial OTUs by changing the abundance of indigenous bacteria and introducing new bacteria. Some inoculum-associated bacteria closely interacted with the introduced AM fungi, some of which belonged to the genera Burkholderia, Cellulomonas, Microbacterium, Sphingomonas, and Streptomyces and may be candidate mycorrhizospheric bacteria that contribute to the establishment and/or function of the introduced AM fungi. Inoculated AM fungi also co-occurred with several indigenous bacteria with putative beneficial traits, suggesting that inoculated AM fungi may recruit specific taxa to confer better plant performance. The bacterial families Methylobacteriaceae, Acetobacteraceae, Armatimonadaceae, and Alicyclobacillaceae were consistently reduced by the inoculation, possibly due to changes in the host plant status caused by the inoculum. To the best of our knowledge, this is the first large-scale study to investigate interactions between AM fungal inoculation and indigenous root microbial communities in agricultural fields.
  • 20.

    【2hr】Genetic and Physiological Characteristics of a Novel Marine Propylene-Assimilating Halieaceae Bacterium Isolated from Seawater and the Diversity of Its Alkene and Epoxide Metabolism Genes

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    机译 海水中分离的一种新型海洋同化Hal科细菌的遗传，生理特性及其烯和环氧代谢基因的多样性
    摘要：The Gram-negative marine propylene-assimilating bacterium, strain PE-TB08W, was isolated from surface seawater. A structural gene analysis using the 16S rRNA gene showed 96, 94, and 95% similarities to Halioglobus species, Haliea sp. ETY-M, and Haliea sp. ETY-NAG, respectively. A phylogenetic tree analysis showed that strain PE-TB08W belonged to the EG19 (Chromatocurvus)-Congregibacter-Haliea cluster within the Halieaceae (formerly Alteromonadaceae) family. Thus, strain PE-TB08W was characterized as a newly isolated Halieaceae bacterium; we suggest that this strain belongs to a new genus. Other bacterial characteristics were investigated and revealed that strain PE-TB08W assimilated propylene, n-butane, 1-butene, propanol, and 1-butanol (C3 and C4 gaseous hydrocarbons and primary alcohols), but not various other alcohols, including methane, ethane, ethylene, propane, and i-butane. The putative alkene monooxygenase (amo) gene in this strain was a soluble methane monooxygenase-type (sMMO) gene that is ubiquitous in alkene-assimilating bacteria for the initial oxidation of alkenes. In addition, two epoxide carboxylase systems containing epoxyalkane, the co-enzyme M transferase (EaCoMT) gene, and the co-enzyme M biosynthesis gene, were found in the upstream region of the sMMO gene cluster. Both of these genes were similar to those in Xanthobacter autotrophicus Py2 and were inductively expressed by propylene. These results have a significant impact on the genetic relationship between terrestrial and marine alkene-assimilating bacteria.
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