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1.
Sci Total Environ ; 752: 142223, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33207502

RESUMO

Microplastics pollution poses a new threat to the environment of intertidal zone. The sea forest, mangrove, has been polluted by a large number of plastic debris worldwide. To fill the gaps in knowledge of mangrove rhizosphere microbes connected with the 'plasticsphere', a semi-controlled in situ exposure experiment for nine different types of microplastics were conducted in mangrove ecosystem. A sign of biodegrading was observed on polyethylene, polyamide 6 and polyvinyl chloride microplastics surface after 3 months exposure. We discovered that the metabolic activities of the dominant bacteria on certain microplastics were related to the specific groups on polymers molecule. The selective colonization may be driven by the chemotaxis of bacteria. Specially, microplastics biofilms of polyethylene, polyamide 6, polyvinyl chloride and expanded polystyrene possess distinctive dominant bacteria assemblages which have great significance in ecosystem processes involving carbon cycle or sulfur cycle. Community of mangrove soil microorganism and microplastic biofilm varies as the seasons changes. As a new niche, microplastics has higher inclusivity to bacteria than surrounding soil. Additionally, pathogens for human beings (Vibrio parahaemolyticus and Escherichia-Shigella) were detected both in microplastics and soil. We stress that the interaction between microplastics and rhizosphere microorganisms may affect the growth and health of mangrove plants. Besides, we point out that mangrove rhizosphere microorganism can be an ideal candidate for plastics-degradation.


Assuntos
Plásticos , Poluentes Químicos da Água , Quimiotaxia , Ecossistema , Monitoramento Ambiental , Microplásticos , Rizosfera , Poluentes Químicos da Água/análise
2.
Sci Total Environ ; 751: 141701, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32889460

RESUMO

Excessive Cd in crop grains is toxic to humans. We conducted a field experiment to investigate the effects of intercropping on rice yield and grain Cd content as well as a pot experiment to compare the rhizosphere redox potentials of low-Cd 'Zhuliangyou 189' and the neighboring high-Cd 'Changxianggu' that mediated Cd uptake in a flooded or a ridge-furrow system. In the field experiment, Cd removal from contaminated soil in intercropping was 1.44 times higher than that in monoculture of Zhuliangyou 189. In both Zhuliangyou 189 and Changxianggu, intercropping improved the grain yield and decreased grain Cd content. In the pot experiment, Fe plaque amount was strongly and positively correlated with bulk soil Fe(II) content, root H2O2 concentration, and Fe(II)-oxidizing ability of root bacteria but negatively correlated with Fe(II)-oxidizing ability of bulk soil bacteria and root Cd content. In Zhuliangyou 189, intercropping increased root H2O2 concentration, rhizosphere redox potential, iron plaque amount but decreased Cd bioavailability, Fe(II)-oxidizing ability of bulk soil bacteria, and organ Cd content. In the flooded system, Zhuliangyou 189 showed higher bulk soil Fe(II) content than Changxianggu. In the ridge-furrow system, ridges decreased the Fe(II)-oxidizing ability of root and bulk soil bacteria, thereby decreasing Fe plaque amount and increasing organ Cd content of rice. In both monoculture and intercropping systems, rice cultivars planted on ridges showed higher Cd bioavailability and lower bulk boil Fe(II) content than those planted in furrows.


Assuntos
Oryza , Poluentes do Solo , Cádmio/análise , Peróxido de Hidrogênio , Oxirredução , Raízes de Plantas/química , Rizosfera , Solo , Poluentes do Solo/análise , Água , Abastecimento de Água
3.
Zhongguo Zhong Yao Za Zhi ; 45(18): 4373-4381, 2020 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-33164365

RESUMO

Comparison of total organic carbon(TOC), total nitrogen(TN), total phosphorus(TP), soil microbial biomass carbon(MBC), nitrogen(MBN), phosphorus(MBP) and their stoichiometric ratios measuring from understory planting of Paris polyphylla and Panax japonicus rhizosphere soil with the data of the original forest soil will help us to understand the influence of different planting patterns between soil traits and soil microbial interaction and nutrient cycle characteristics. The results showed that the contents of TOC, TN and MBN were the highest in the rhizosphere soil of P. japonicus, while the highest values of TP, MBC and MBP were found in the rhizosphere soil of P. polyphylla. The changes of TOC∶TN, TOC∶TP, TN∶TP, MBC∶MBN, MBC∶MBP and MBN∶MBP of P. polyphylla and P. japonicus rhizosphere soil compared with the data of the original forest soil were 3.65 and 37.32%,-14.89 and 82.23%,-17.87 and 32.76%, 25.67 and-50.60%,-75.95 and-16.33% as well as-80.79 and 69.76%, respectively. TN and TP were significantly correlated with MBN and MBP respectively. Although, monoculture of P. polyphylla and P. japonicus changed soil nutrient level, it did not reach the state of nutrient deficiency. The demands for nitrogen and phosphorus between P. polyphylla and P. japonicus were quite different. According to their different habits, monoculture of P. polyphylla and P. japonicus could change the understory soil traits, resulting in allometric changes in part of soil nutrient stoichiometry and soil microbial stoichiometry, and then the disappearance of internal stability. The variations in the understory soil caused by P. polyphylla and P. japonicus is developing in completely different directions, whether this phenomenon indicates that the two species have less niche overlap needs further study.


Assuntos
Liliaceae , Panax , Biomassa , Carbono , China , Nitrogênio/análise , Fósforo/análise , Rizosfera , Solo , Microbiologia do Solo
4.
Huan Jing Ke Xue ; 41(11): 5143-5150, 2020 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124258

RESUMO

Cadmium (Cd) contamination in the agricultural soils of China is a serious and growing environmental problem that urgently needs to be controlled and completely remediated. The biogeochemical cycles of nitrogen (N), sulfur (S), and iron (Fe), and the coupled cycles of Fe-N and Fe-S have been reported to control Cd transportation in the soil-rice system. Exploring practical remediation strategies for Cd from the perspective of the application of nutrients such as N, S, and Fe for rice growth is expected to obtain farm-specific and state-of-the-art technologies and products to reduce the accumulation of Cd in rice grains. Using our earlier study as a basis, the rhizosphere bag-pot experiment with ferrous sulfate (FeSO4) and ferric nitrate[Fe(NO3)3] treatments was conducted to investigate Cd bioavailability in rhizosphere soil and Cd translocation in rice plants, and to highlight some possible factors and mechanisms controlling Cd accumulation in rice grains. The results showed that both FeSO4 and Fe(NO3)3 treatments reduced the bioavailable Cd (NH4Ac-Cd) content in rhizosphere soil, with the decreasing extent being significantly lower in the former (55.6%) than in the latter (76.0%). Both FeSO4 and Fe(NO3)3 treatments changed the distribution characteristics of Cd in rice tissues, and the FeSO4 treatment increased the Cd content in brown rice (0.6 mg·kg-1), but the Fe(NO3)3 treatment decreased the Cd content in brown rice (0.1 mg·kg-1). Adsorption or co-precipitation of Cd by iron plaque, increased accumulations of Cd in root, stem, and leaf, and enhanced translocations of Cd from root, stem, and nodule to brown rice occurred with the increased Cd content in brown rice of the FeSO4 treatment. However, the decreased Cd content in brown rice with the Fe(NO3)3 treatment was ascribed to adsorption or co-precipitation of Cd by poorly crystalline Fe oxides and solid Fe sulfides, decreased accumulations of Cd in stem and nodule, and weakened translocations of Cd from root, leaf, and nodule to brown rice. These findings provide a scientific basis for the exploration and application of nutritive soil amendment, and will have significance in regards to the remediation of Cd-contaminated agricultural soils in China.


Assuntos
Oryza , Poluentes do Solo , Cádmio/análise , China , Compostos Férricos , Compostos Ferrosos , Nitratos , Rizosfera , Solo , Poluentes do Solo/análise
5.
Huan Jing Ke Xue ; 41(11): 5193-5200, 2020 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124264

RESUMO

There are complex interrelationships between plant microorganisms (phyllosphere and rhizosphere) and host plants, which can promote plant growth and enhance the tolerance of host plants to stress. In this study, we selected the dominant species Bothriochloa ischaemum as the research subject in a copper tailings dam. Using high-throughput sequencing, we investigated the structures of the fungal communities and diversities in the phyllosphere and rhizosphere of B. ischaemum. This study also explored the effects of heavy metal content on fungal community characteristics. The results showed that Ascomycota and Basidiomycota were the dominant phyla in the phyllosphere and rhizosphere of B. ischaemum. The diversities and richness of the rhizosphere fungal community were higher than that of the phyllosphere fungal community. The diversities of rhizosphere and phyllosphere fungal communities was affected by different heavy metals. Phyllosphere fungal diversity was mainly affected by the content of Zn and Cu in leaves, and the content of Pb in roots was the key factor affecting the diversity of the rhizophere fungal community. Furthermore, Pleosporaceae had a very significant positive correlation with Cd in the phyllosphere, and Nectriaceae had a significant positive correlation with Zn in the rhizosphere. These fungal communities could be used as indicators of ecological recovery in areas with heavy metal pollution. The results could provide an ecological basis for the exploration and utilization of phyllosphere or rhizosphere fungi resources during ecological restoration processes. This study also provides guidance for selecting the plant-microbial symbionts during ecological restoration in areas with heavy metal pollution.


Assuntos
Metais Pesados , Micobioma , Poluentes do Solo , Cobre/análise , Metais Pesados/análise , Rizosfera , Solo , Microbiologia do Solo , Poluentes do Solo/análise
6.
Huan Jing Ke Xue ; 41(8): 3846-3854, 2020 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124362

RESUMO

To study the effects of cotton stalk biochar on the regulation of fungal diversity, the structure and function of alkaline rice rhizosphere soil under cadmium pollution was investigated. An outdoor pot experiment was conducted by adding cotton stalk biochar (0%, 1%, and 5%) to an alkaline paddy soil with a cadmium concentration of 0.1 and 8 mg·kg-1. Taking rice rhizosphere soil as the research object, Illumina HiSeq sequencing was used to analyze the effects of cotton stalk biochar and cadmium pollution on the diversity, structure, abundance, and function of fungi in an alkaline rhizosphere soil, and to explore the correlation between soil environmental factors and the fungal community under the control of cotton stalk biochar. The results showed that:① the application of cotton stalk biochar significantly increased the soil pH, available nutrients, and organic matter, and reduced the content of reducible cadmium in the soil (P<0.05). ② The distribution of rice rhizosphere soil fungi was mainly Ascomycota, Aphelidiomycota, and Chytridiomycota, which accounted for 57% of all mycophytes. The genus was mainly Mortierella, Alternaria, and Fusarium. There was a significant difference in the α-diversity of the fungal community among the treatments (P<0.05). In the absence of cotton stalk biochar (C0), the increase in the cadmium concentration reduced the relative abundance and fungal diversity index (Shannon index) of Chytridiomycota, Mortierella, and Alternaria in the soil. Under different concentrations of cadmium (Cd0, Cd1, and Cd8), increasing cotton stalk biochar reduced the fungal community richness index (Chao1 index) and Shannon index. Cadmium pollution resulted in an increase in the relative abundance of Chytridiomycota in the soil, but decreased the abundance of Alternaria. The application of cotton stalk biochar could significantly increase the relative abundance of Chytridiomycota (P<0.05). Cadmium pollution reduced the abundance of Mortierella and Alternaria, but the application of cotton stalk biochar could increase the relative abundance of Alternaria. Increasing cotton stalk biochar means that soil will have more endophytes, plant pathogens, and saprophytes; while increasing cadmium pollution will reduce endophytes, plant pathogens, and saprophytes in the soil. ③ The main environmental factors affecting the diversity and structure of fungal communities are the available potassium, organic matter, and pH of the soil. The reducible cadmium content, which comprises the largest proportion of cadmium in rice soil, was significantly positively correlated to Rotifera, Aphelidiomycota, and Ascomycota (P<0.05), but negatively correlated to other mycophytes (P<0.05). The results indicate that cotton stalk biochar plays a certain role in the microecological regulation of alkaline cadmium-contaminated soil.


Assuntos
Micobioma , Oryza , Poluentes do Solo , Cádmio/análise , Cádmio/toxicidade , Carvão Vegetal , Fungos , Rizosfera , Solo , Microbiologia do Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
7.
Huan Jing Ke Xue ; 41(10): 4682-4689, 2020 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124401

RESUMO

To study the characteristics of soil nutrients and fungal community composition under different rotation patterns in the arid zone of central Ningxia, we used millet rotation soybean (MRG), rotation grain amaranth (MRA), rotation quinoa (MRQ), and continuous millet rotation (CK) as the objects. The soil nutrient content was determined, and the sequence of the ITS variation region of soil fungi was determined using the Illumina MiSeq high-throughput sequencing platform. The results showed that the effects of different rotation patterns on the soil nutrients were different. The soil pH and electrical conductivity decreased under three rotation patterns, and the soil total nitrogen, total potassium, total phosphorus, and organic matter contents increased. The number of OTUs and α diversity index was higher than those of continuous millet rotation. The results of the fungal community composition study showed that Ascomycota was the dominant flora in 4 patterns. The cluster analysis showed that the fungal genus composition of MRA and MRG was the most similar, followed by MRQ, and that of CK was significantly different with the other three rotation patterns. A correlation analysis showed that the soil nutrients were significantly correlated with several dominant fungal genera (P<0.05 or P<0.01). Further, the soil total nitrogen, total potassium, nitrate nitrogen, and organic matter contents were the most important factors influencing the soil fungal communities. Principal component analysis (PCA) showed that the MRG rotation patterns were better than those of the MRA and MRQ patterns. In summary, crop rotation improved the polytrophic index of the fungal community, changed the soil fungal community structure, and improved soil fertility. Among, the millet and soybean rotation were the best, and we have suggested to promote cereal rotation as one of the main rotation patterns in the cereal industry in the central dry zone.


Assuntos
Micobioma , Nutrientes , Rizosfera , Solo , Microbiologia do Solo
8.
Mol Plant Microbe Interact ; 33(11): 1283-1285, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33000998

RESUMO

Rhizobium (Agrobacterium) is one genus in the family Rhizobiaceae. Most of the species are epi- or endophytic bacteria which include tumorigenic or rhizogenic pathogens, root nodule bacteria, and commensal endosymbionts. Rhizobium vitis strain VAR06-30 is a commensal bacterium without pathogenicity which was isolated from a rootstock of grapevine in Japan. It also does not have antagonistic activity to the pathogenic strain of R. vitis. Here, we show the complete genome sequence data with annotation of R. vitis VAR06-30 which was analyzed by sequence reads obtained from both PacBio and Illumina platforms. This genome sequence would contribute to the understanding of evolutionary lineage and characteristics of Rhizobium commensal bacteria.[Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.


Assuntos
Genoma Bacteriano , Tumores de Planta/microbiologia , Rhizobium , Vitis/microbiologia , Filogenia , Rhizobium/genética , Rizosfera
9.
J Environ Qual ; 49(1): 74-84, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016354

RESUMO

Plants release carbon-based exudates from their roots into the rhizosphere to increase phosphorus (P) supply to the soil solution. However, if more P than required is brought into solution, additional P could be available for leaching from riparian soils. To investigate this further, soil columns containing a riparian arable and buffer strip soil, which differed in organic matter contents, were sown with three common agricultural and riparian grass species. The P loads in leachate were measured and compared with those from unplanted columns, which were 0.17 ± 0.01 and 0.89 ± 0.04 mg kg-1 for the arable and buffer strip soil, respectively. A mixture of ryegrass and red fescue significantly (p ≤ .05) increased dissolved inorganic P loads in leachate from the arable (0.23 ± 0.01 mg kg-1 ) and buffer strip soil (1.06 ± 0.05 mg kg-1 ), whereas barley significantly reduced P leaching from the buffer strip soil (0.53 ± 0.08 mg kg-1 ). This was dependent on the dissolved organic C released under different plant species and on interactions with soil management history and biogeochemical conditions, rather than on plant uptake of P and accumulation into biomass. This suggested that the amount and forms of P present in the soil and the ability of the plants to mobilize them could be key factors in determining how plants affect leaching of soil P. Selecting grass species for different stages of buffer strip development, basing species selection on root physiological traits, and correcting soil nutrient stoichiometry in riparian soils through vegetative mining could help to lower this contribution.


Assuntos
Fósforo , Poaceae , Carbono , Rizosfera , Solo
10.
Oecologia ; 194(1-2): 237-250, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33009940

RESUMO

Climate change causes species range expansions to higher latitudes and altitudes. It is expected that, due to differences in dispersal abilities between plants and soil biota, range-expanding plant species will become associated with a partly new belowground community in their expanded range. Theory on biological invasions predicts that outside their native range, range-expanding plant species may be released from specialist natural enemies, leading to the evolution of enhanced defence against generalist enemies. Here we tested the hypothesis that expanded range populations of the range-expanding plant species Centaurea stoebe accumulate fewer root-feeding nematodes than populations from the original range. Moreover, we examined whether Centaurea stoebe accumulates fewer root-feeding nematodes in expanded range soil than in original range soil. We grew plants from three expanded range and three original range populations of C. stoebe in soil from the original and from the new range. We compared nematode communities of C. stoebe with those of C. jacea, a congeneric species native to both ranges. Our results show that expanded range populations of C. stoebe did not accumulate fewer root-feeding nematodes than populations from the original range, but that C. stoebe, unlike C. jacea, accumulated fewest root-feeding nematodes in expanded range soil. Moreover, when we examined other nematode feeding groups, we found intra-specific plant population effects on all these groups. We conclude that range-expanding plant populations from the expanded range were not better defended against root-feeding nematodes than populations from the original range, but that C. stoebe might experience partial belowground enemy release.


Assuntos
Nematoides , Rizosfera , Animais , Biota , Plantas , Solo
11.
Chemosphere ; 261: 128122, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113643

RESUMO

Heavy metals in soil are harmful to human health via the food chain, but little is known about the mechanism of reducing bioavailability of Cd or Pb to maize (Zea mays L.) by applying complex amendments to soil. A field experiment was conducted at a tropical site in Hainan Province, China, that had been subjected to soil pollution by Cd and Pb from past mining activities. There were ten treatment groups comprising a mixture of biochar, hydroxyapatite (HAP), manure, and plant ash in varying proportions and at three different rates. Compared with untreated soil, all treatments increased pH by 2-3 units in bulk soil or 1-2 units in rhizosphere soil. For all amendments, the concentration of Cd in all parts of maize plants was decreased compared with unamended soil, but this effect was much smaller for Pb. The greatest effect was found with a mixture containing the ratio of HAP:manure:biochar:plant ash as 6:4:2:1 when applied at 20.1 t ha-1. The dominant microbial group in contaminated soil was Proteobacteria. There is evidence that this group can immobilize Cd by mechanisms that include biosorption and bioprecipitation. It was concluded that the mixed amendments containing biochar, HAP, manure, and plant ash can be useful in decreasing Cd uptake by maize. The amendment in this study likely operates through a combination of soil chemical changes and by influencing the soil-microbe-plant interaction.


Assuntos
Fertilizantes/análise , Metais Pesados/análise , Poluentes do Solo/análise , Zea mays/química , Disponibilidade Biológica , Carvão Vegetal/química , China , Durapatita/química , Humanos , Esterco/análise , Mineração , Modelos Teóricos , Rizosfera , Solo/química , Zea mays/metabolismo
12.
Mar Environ Res ; 162: 105174, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33099080

RESUMO

Seagrasses represent high primary productivity and provide important ecosystem services to the marine environment. Seagrass-associated microbial communities are playing essential ecological functional roles in biogeochemical cycles. However, little is known about the effect of seagrass vegetation on microbial communities in sediment. In the present study, the sediment cores of seagrass bed (dominated by Zostera japonica and Zostera marine) and degradation area in Swan Lake (China) were sampled; then, biogeochemical parameters were analyzed, and microbial community composition was investigated by using high-throughput sequencing of the 16S rRNA gene. The results showed that the presence of seagrass could lead to a decrease in the richness and diversity of the microbial community. In the vertical direction, a pronounced shift from Proteobacteria-dominated upper layers to Chloroflexi and Crenarchaeota-dominated deep layers in all sediment cores were observed. Besides, Bathyarchaeia is more abundant at degradation area, while Vibrionaceae, Sulfurovum and Lokiarchaeial overrepresent at the seagrass bed area. Vibrionaceae was abundant in the rhizosphere of Z. marina and Z. japonica, and the proportions reached 84.45% and 63.89%, respectively. This enrichment of Vibrio spp. may be caused by the macrobenthic species near the seagrass rhizosphere, and these Vibrio spp. reduced the diversity and stability of microbial community, which may lead to the degradation of seagrass. This study would provide clues for the distribution patterns and niche preferences of seagrass microbiome. The conservation strategy of seagrass would be further elucidated from the perspective of the microbiome.


Assuntos
Microbiota , Zosteraceae , China , Ecossistema , RNA Ribossômico 16S/genética , Rizosfera
13.
PLoS One ; 15(9): e0238537, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32886707

RESUMO

In this study, we characterized, identified, and determined the effect of salt-tolerant PGPR isolated from coastal saline areas on rice growth and yield. A total of 44 bacterial strains were isolated, and 5 were found to be tolerant at high salt concentration. These isolates were further characterized for salinity tolerance and beneficial traits through a series of quantitative tests. Biochemical characterization showed that bacterial survivability decreases gradually with the increase of salt concentration. One of the strains, UPMRB9, produced the highest amount of exopolysaccharides when exposed to 1.5M of NaCl. Moreover, UPMRB9 absorbed the highest amount of sodium from the 1.5M of NaCl-amended media. The highest floc yield and biofilm were produced by UPMRE6 and UPMRB9 respectively, at 1M of NaCl concentration. The SEM observation confirmed the EPS production of UPMRB9 and UPMRE6 at 1.5M of NaCl concentration. These two isolates were identified as Bacillus tequilensis and Bacillus aryabhattai based on the 16S rRNA gene sequence. The functional group characterization of EPS showed the presence of hydroxyl, carboxyl, and amino groups. This corresponded to the presence of carbohydrates and proteins in the EPS and glucose was identified as the major type of carbohydrate. The functional groups of EPS can help to bind and chelate Na+ in the soil and thereby reduces the plant's exposure to the ion under saline conditions. The plant inoculation study revealed significant beneficial effects of bacterial inoculation on photosynthesis, transpiration, and stomatal conductance of the plant which leads to a higher yield. The Bacillus tequilensis and Bacillus aryabhattai strains showed good potential as PGPR for salinity mitigation practice for coastal rice cultivation.


Assuntos
Bacillus/fisiologia , Oryza/crescimento & desenvolvimento , Oryza/microbiologia , Tolerância ao Sal , Bacillus/isolamento & purificação , Bactérias/isolamento & purificação , Fenômenos Fisiológicos Bacterianos , Biofilmes , Oryza/fisiologia , Rizosfera , Salinidade , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Plantas Tolerantes a Sal/microbiologia , Plantas Tolerantes a Sal/fisiologia
14.
Int J Syst Evol Microbiol ; 70(10): 5382-5388, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32877325

RESUMO

A novel fibrillar matrix-producing, rod-shaped, red-orange, asporogenous, aerobic bacterium, designated DK36T, was isolated from roots of a rice plant in the Ilsan region near Dongguk University, South Korea. Cells of strain DK36T were Gram-stain-negative and motile by means of gliding. The temperature and pH ranges for growth were 7-35 °C (optimum: 30 °C) and pH 5-10 (optimum: pH 7.0). The strain did not require NaCl for growth but tolerated up to 8 % (w/v) NaCl. Phylogenetic anlaysis of the 16S rRNA gene sequence revealed that DK36T formed a monophyletic clade with Adhaeribacter aerophilus 6425 S-25T, Adhaeribacter aerolatus 6515 J-31T and Adhaeribacter swui 17mud1-7T with sequence similarities of 96.3, 95.5 and 95.2%, respectively. The average nucleotide identity and in silico DNA-DNA hybridization values of strain DK36T with the most closely related strains whose whole genomes are publicly available were 72.5-83.6% and 19-28 %, respectively. The strain showed the typical chemotaxonomic characteristics of the genus Adhaeribacter, with the presence of menaquinone MK-7 as the respiratory quinone, and C16 : 1ω5c, iso-C15 : 0 and summed feature 4 (composed of iso-C17 : 1 I/anteiso-C17 : 1 B) as the major fatty acids. The polar lipid profile consisted of phosphatidylethanolamine, one unidentified aminophosphoglycolipid, one unidentified phospholipid, two unidentified aminolipids and five unidentified polar lipids. The genomic DNA G+C content based on the draft genome sequence was 43.4 mol%. The results of physiological and biochemical tests and 16S rRNA gene sequence analysis clearly revealed that strain DK36T represents a novel species of the genus Adhaeribacter, for which the name Adhaeribacter rhizoryzae sp. nov. is proposed. The type strain is DK36T (=KACC 19902T=NBRC 113689T).


Assuntos
Bacteroidetes/classificação , Oryza/microbiologia , Filogenia , Rizosfera , Microbiologia do Solo , Técnicas de Tipagem Bacteriana , Bacteroidetes/isolamento & purificação , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Fosfolipídeos/química , Pigmentação , RNA Ribossômico 16S/genética , República da Coreia , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
15.
Int J Syst Evol Microbiol ; 70(10): 5425-5431, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32886594

RESUMO

An actinobacterial strain, designated KUDC0627T, was isolated from rhizospheric soil that contained Elymus tsukushiensis on the Dokdo Islands, Republic of Korea. Cells were Gram-stain-positive, facultative anaerobic, non-motile and non-endospore-forming cocci. Results of phylogenetic analysis based on 16S rRNA gene sequences indicated that strain KUDC0627T belongs to the genus Microlunatus and is most closely related to Microlunatus soli DSM 21800T (98.5 %), Microlunatus endophyticus DSM 100019T (97.7 %) and Microlunatus ginsengisoli Gsoil 633T (96.5 %). The average nucleotide identity scores and average amino acid identity values were all below the 95.0 % cut-off point. In silico DNA-DNA hybridization, using the Genome-to-Genome Distance Calculator, estimated that there is 22.3 % DNA relatedness between KUDC0627T and M. soli DSM 21800T. The genomic DNA G+C content was 66.9 mol%. The major menaquinone was MK-9(H4) and the major diagnostic diamino acid in the cell-wall peptidoglycan was ll-diaminopimelic acid. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipids, unidentified glycolipids and unidentified lipids. The major cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and iso-C16 : 0. Based on phenotypic, chemotaxonomic, and phylogenetic data, strain KUDC0627T (=KCTC 39853T=JCM 32702T) represents a novel species, for which the name Microlunatus elymi sp. nov. is proposed.


Assuntos
Elymus/microbiologia , Filogenia , Propionibacteriaceae/classificação , Rizosfera , Microbiologia do Solo , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Fosfolipídeos/química , Propionibacteriaceae/isolamento & purificação , RNA Ribossômico 16S/genética , República da Coreia , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
16.
Int J Syst Evol Microbiol ; 70(10): 5531-5538, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32915126

RESUMO

Two nifH gene-harbouring bacterial strains were isolated from rhizospheres of different vegetable plants grown in different regions of northern PR China. The two strains possessed almost identical 16S rRNA gene sequences. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 99.21 and 93.6% respectively, suggesting they belong to one species. Based on 16S rRNA gene phylogeny, the two strains were clustered together with Paenibacillus rhizophilus 7197T, Paenibacillus sabinae T27T and Paenibacillus forsythiae T98T, but on a separate branch. Novelty of the species was confirmed by ANI and dDDH comparisons between the type strain 7124T and its closest relatives, since the obtained values were considerably below the proposed thresholds for the species delineation. The genome size of strain 7124T was 5.40 Mb, comprising 5050 predicted genes with a DNA G+C content of 52.3 mol%. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and three unidentified lipids. The major cellular fatty acids were anteiso-C15  :  0 (52.9%) and C16  :  0 (23.4 %). Menaquinone-7 was reported as the major respiratory quinone. The diamino acid in the cell-wall peptidoglycan was found to be meso-diaminopimelic acid. Based on phylogenetic, genomic, chemotaxonomic and phenotypic data, the two isolates are considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus apii sp. nov. is proposed, with 7124T (=DSM 103172T=CGMCC 1.15689T) as type strain.


Assuntos
Paenibacillus/classificação , Filogenia , Rizosfera , Microbiologia do Solo , Verduras/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Paenibacillus/isolamento & purificação , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
17.
Sci Total Environ ; 741: 140494, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32886976

RESUMO

Here, we examined the effects of low and high concentrations of perfluorooctanesulfonate (PFOS) on rhizosphere soil N cycling processes in the presence of Lythrum salicaria and Phragmites communis over 4 months. Compared with the control group, the nitrate nitrogen (NO3--N) content of the bulk soil in the low PFOS (0.1 mg kg-1) treatment significantly decreased (27.7%), the ammonium nitrogen (NH4+-N) content significantly increased (8.7%), and the pH value and total organic carbon (TOC) content slightly increased (0.3% and 1.1%, respectively). Compared with the low PFOS treatment, the content of NO3-N, NH4+-N and pH value in the bulk soil of the high PFOS treatment (50 mg kg-1) significantly increased (1.0%, 53.8% and 61.8%, respectively), and the TOC content significantly decreased (8.2%). Soil protease levels were high in the low PFOS treatment, but low in the high PFOS treatment. PFOS produced inverted U-shaped responses in the potential nitrification (1.5, 3.0, and 1.1 mg N d-1 kg-1 in no, low, and high PFOS, respectively), denitrification (0.19, 0.30, and 0.22 mg N d-1 kg-1 in no, low, and high PFOS, respectively), and N2O emission rates (0.01, 0.03, and 0.02 mg N d-1 kg-1 in no, low, and high PFOS, respectively) of bulk soil. The abundance of the archaea amoA gene decreased with increasing PFOS concentration, whereas that of bacterial amoA increased; inverted U-shaped responses were observed for narG, nirK, nirS, and nosZ. In the PFOS-contaminated rhizosphere soil, the observed changes differed from those in the bulk soil and differed between treatments. P. communis tended to upregulate each step of the nitrogen cycle under low PFOS conditions, whereas L. salicaria tended to inhibit them. Under high PFOS conditions, both test plants tended to act as inhibitors of the soil N-cycle; thus, the effects of PFOS on soil N transformation were plant-specific.


Assuntos
Rizosfera , Solo , Ácidos Alcanossulfônicos , Desnitrificação , Fluorcarbonetos , Nitrificação , Nitrogênio/análise , Ciclo do Nitrogênio , Microbiologia do Solo
18.
Sci Total Environ ; 740: 140137, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32927575

RESUMO

Phytoremediation is a promising inexpensive method of detoxifying arsenic (As) contaminated soils using plants and associated soil microorganisms. The potential of Pteris vittata to hyperaccumulate As contamination has been investigated widely. Since As(V) is efficiently taken up by P. vittata than As(III), As speciation by associated rhizobacteria could offer enormous possibility to enhance As phytoremediation. Specifically, increased rhizobacteria mediated As(III) to As(V) conversion appeared to be a crucial step in As mobilization and translocation. In this study, Pseudomonasvancouverensis strain m318 with the potential to improve As phytoremediation was inoculated to P. vittata in a field trial for three years to evaluate its long-term efficacy and stability for enhancing As phytoextraction. The biomass, As concentration, and As accumulation of ferns showed to be increased by inoculation treatment. Although this trend occasionally declined which may be accounted to lower As concentration in soil and amount of precipitation during experiments, the potential of inoculation was observed in increased enrichment coefficients. Further, the arsenite oxidase (aioA-like) genes in the rhizosphere were detected to evaluate the influence of inoculation on As phytoremediation. The findings of this study suggested the potential application of rhizosphere regulation to improve phytoremediation technologies for As contaminated soils. However, the conditions which set the efficacy of this method could be further optimized.


Assuntos
Arsênico/análise , Pteris , Poluentes do Solo/análise , Biodegradação Ambiental , Rizosfera
19.
Ecotoxicol Environ Saf ; 205: 111333, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32979802

RESUMO

Plant growth-promoting rhizobacteria (PGPR) are a specific category of microbes that improve plant growth and promote greater tolerance to metal stress through their interactions with plant roots. We evaluated the effects of phytoremediation combining the cadmium accumulator Solanum nigrum L. and two Cd- and Pb-resistant bacteria isolates. To understand the interaction between PGPR and their host plant, we conducted greenhouse experiments with inoculation treatments at Nanjing Agricultural University (Jiangsu Province, China), in June 2018. Two Cd- and Pb-resistant PGPR with various growth-promoting properties were isolated from heavy metal-contaminated soil. 16S rRNA analyses indicated that the two isolates were Bacillus genus, and they were named QX8 and QX13. Pot experiments demonstrated that inoculation may improve the rhizosphere soil environment and promote absorption of Fe and P by plants. Inoculation with QX8 and QX13 also enhanced the dry weight of shoots (1.36- and 1.7-fold, respectively) and roots (1.42- and 1.96-fold) of plants growing in Cd- and Pb-contaminated soil, and significantly increased total Cd (1.28-1.81 fold) and Pb (1.08-1.55 fold) content in aerial organs, compared to non-inoculated controls. We also detected increases of 23% and 22% in the acid phosphatase activity of rhizosphere soils inoculated with QX8 and QX13, respectively. However, we did not detect significant differences between inoculated and non-inoculated treatments in Cd and Pb concentrations in plants and available Cd and Pb content in rhizosphere soils. We demonstrated that PGPR-assisted phytoremediation is a promising technique for remediating heavy metal-contaminated soils, with the potential to enhance phytoremediation efficiency and improve soil quality.


Assuntos
Cádmio/análise , Chumbo/análise , Rhizobiaceae/metabolismo , Microbiologia do Solo , Poluentes do Solo/análise , Solanum nigrum/efeitos dos fármacos , Biodegradação Ambiental , Cádmio/metabolismo , China , Chumbo/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , RNA Ribossômico 16S , Rizosfera , Solo/química , Poluentes do Solo/metabolismo , Solanum nigrum/crescimento & desenvolvimento , Solanum nigrum/metabolismo
20.
Proc Natl Acad Sci U S A ; 117(38): 23823-23834, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32900931

RESUMO

By analyzing successive lifestyle stages of a model Rhizobium-legume symbiosis using mariner-based transposon insertion sequencing (INSeq), we have defined the genes required for rhizosphere growth, root colonization, bacterial infection, N2-fixing bacteroids, and release from legume (pea) nodules. While only 27 genes are annotated as nif and fix in Rhizobium leguminosarum, we show 603 genetic regions (593 genes, 5 transfer RNAs, and 5 RNA features) are required for the competitive ability to nodulate pea and fix N2 Of these, 146 are common to rhizosphere growth through to bacteroids. This large number of genes, defined as rhizosphere-progressive, highlights how critical successful competition in the rhizosphere is to subsequent infection and nodulation. As expected, there is also a large group (211) specific for nodule bacteria and bacteroid function. Nodule infection and bacteroid formation require genes for motility, cell envelope restructuring, nodulation signaling, N2 fixation, and metabolic adaptation. Metabolic adaptation includes urea, erythritol and aldehyde metabolism, glycogen synthesis, dicarboxylate metabolism, and glutamine synthesis (GlnII). There are 17 separate lifestyle adaptations specific to rhizosphere growth and 23 to root colonization, distinct from infection and nodule formation. These results dramatically highlight the importance of competition at multiple stages of a Rhizobium-legume symbiosis.


Assuntos
Rhizobium leguminosarum , Rizosfera , Simbiose/genética , Fabaceae/microbiologia , Genes Bacterianos/genética , Fixação de Nitrogênio/genética , Rhizobium leguminosarum/genética , Rhizobium leguminosarum/fisiologia , Nódulos Radiculares de Plantas/genética , Nódulos Radiculares de Plantas/microbiologia
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