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1.
C. Monard F. Martin-Laurent C. Vecchiato A.J. Francez P. Vandenkoornhuyse F. Binet 《Soil biology & biochemistry》2008,40(9):2253-2259
Earthworms, because they change soil physical and chemical properties, are efficient engineers that act on soil microbial community and activity. Thus they may drive pollutant biodegradation in soil such as atrazine mineralization. We hypothesized that earthworms modify the abundance of indigenous soil bacteria and the fate and activity of atrazine-degraders in the soil they engineer by bioturbation. Two bacterial strains were used as bioaugmentation agents: Pseudomonas sp. ADP and Chelatobacter heintzii, which have acquired the capacity to metabolize atrazine by carrying plasmidic atz A, B, C, D, E, F and atzA, B, C, trzD genes, respectively. We analyzed the interactions between earthworms (Lumbricus terrestris) and the indigenous and atrazine-degrading (indigenous and inoculated) bacterial communities by quantifying the 16S rRNA and the atzA gene sequence copies numbers, respectively, in different earthworm microsites. The kinetics of atrazine mineralization were measured to link the bacterial community changes with the degradation function. Digestion by earthworms significantly impacted the number of indigenous bacteria and atrazine mineralization in bioaugmented soils. Regarding the fate of the two atrazine-degraders tested, Pseudomonas sp. strain ADP survived better within the 10 days of experiment than C. heintzii in the bulk soil but the surviving fraction of C. heintzii was still metabolically active and able to mineralize atrazine. A positive “burrow-lining” effect on the atzA sequence copies number was observed in soil whether bioaugmented with C. heintzii or not (i.e. native indigenous atzA) thereby indicating that burrow-linings form a specific ‘hot spot’ for atrazine-degraders. The present study is the first to report the role of earthworms in selecting native catabolic key-genes in soil (indigenous atzA). This catabolic gene selection through earthworm soil bioturbation could be important in sustaining the degradation (detoxification) function of soil. 相似文献
2.
Four strains of bacteria, Rhizobium leguminosarum biovar trifolii, Pseudomonas fluorescens, Pseudomonas cepacia, and Flavobacterium sp., were introduced into loamy sand and then transported by earthworms of the species Lumbricus rubellus to uninoculated soil. Cell densities recovered from the earthworm gut and casts (both expressed per gram dry material) were significantly lower (up to 3 log units) than cell densities recovered from the inoculated soil. Total bacterial counts in casts were similar to those in the inoculated soil. In casts excreted into a sterile environment numbers of colony-forming units (CFU) increased, suggesting a favourable environment for growth. In casts excreted in a non-sterile environment, cell densities of introduced strains decreased. Casts therefore did not offer the introduced bacteria a protective micro-environment for survival in the bulk soil. Transport by worms of R. leguminosarum biovar trifolii and of P. fluorescens appeared to occur mostly by means of cast production; with the Flavobacterium sp. and P. cepacia a large proportion of the cells was possibly transported on the skin of earthworms. 相似文献
3.
Tomoyoshi Hashimoto Kyung-Sook Whang Kazunari Nagaoka 《Biology and Fertility of Soils》2006,42(3):179-185
This is the first investigation to show that oligotrophic denitrifying bacteria are dominant denitrifiers in subsurface upland
soil. We examined the vertical distribution of denitrifying bacterial populations in upland soil using two kinds of enumeration
media. The number of denitrifying bacteria, enumerated in subsurface soil layers by a 100-fold diluted nutrient broth (DNB)
medium with NO3
−, was two to three orders of magnitude greater than those enumerated by a conventional nutrient broth medium with NO3
−, suggesting the dominance of oligotrophic denitrifying bacteria. Seventy-four percent of the total denitrifying bacterial
isolates were DNB organisms of the oligotrophic type, which did not show appreciable growth on a conventional nutrient broth
medium. The isolates were heterogeneous and were categorized as alpha (35 strains) and beta (19 strains) subdivisions of proteobacteria
and high G+C gram-positive bacteria (7 strains) by 16S rRNA gene sequence analysis. The 35-alpha subdivision of proteobacterial
isolates was of oligotrophic type and widely distributed from the surface to subsurface soil layers. Phylogenetic analysis
indicated that some isolates belonged to groups with few or no cultivated representatives, and that one isolate may be a member
of a new genus. This isolation procedure, using diluted media, is valuable in detecting diverse and novel denitrifying bacteria
in the subsurface soil. 相似文献
4.
Jana Rydlová David Püschel Radka Sudová Milan Gryndler Olga Mikanová Miroslav Vosátka 《植物养料与土壤学杂志》2011,174(1):128-134
This study focused on the application of native strains of arbuscular mycorrhizal fungi (AMF) and Sinorhizobium in effective crop production during reclamation of coal‐mine spoil banks. Two greenhouse experiments were conducted in spoil‐bank clay with a low dose of organic amendment to determine whether the microbial inoculation improves growth and utility qualities of two cultivars of Linum usitatissimum L. (oil and fiber flax). Inoculation with two native AMF isolates (Glomus mosseae, G. intraradices, and their mixture) significantly increased growth and shoot phosphorus (P) concentration of both flax cultivars. Inoculated fiber flax plants produced fivefold more fibers than the uninoculated ones. In oil flax, mycorrhizal inoculation significantly but quantitatively to a minor degree decreased the concentration of nonsaturated fatty acids in the seed oil. A mixture of five native Sinorhizobium sp. strains supported growth and P uptake of oil flax only in the absence of AMF. However, these beneficial effects of the bacteria were significantly lower as compared to AMF. No synergic action of Sinorhizobium strains and AMF was observed, and their interactions were often even antagonistic. Inoculation with AMF significantly decreased population density of Sinorhizobium in the soil. These results suggest that a careful selection of suitable bacterial strains is necessary to provide effective AMF combinations and maximize flax‐growth support. 相似文献
5.
Humic substances play a key role in the global carbon cycling and the sequestration of micropollutants in soil. The transformation of these substances by earthworms, the dominant soil macroinvertebrates of many terrestrial ecosystems, and the mechanisms involved are still obscure. We prepared two chemically identical humic model compounds that were specifically 14C-labeled either in the aromatic or the proteinaceous component, and added them to soil incubated with the geophagous earthworm species Metaphire guillelmi (anecic) and Amynthas corrugatus (endogeic). In the absence of the earthworms, both the aromatic and the proteinaceous components were mineralized at similarly low rates (5−8% after 9 days of incubation). In the presence of the earthworms, mineralization rate of the proteinaceous component was strongly stimulated (2-fold by M. guillelmi and 1.4-fold by A. corrugatus). The mineralization rate of the aromatic component was (slightly) stimulated (1.2-fold; P < 0.05) only by A. corrugatus. In all cases, the stimulated mineralization was accompanied by a transformation of radiolabeled humic acids to fulvic acids within the earthworm guts and by an incorporation of radiolabel into the earthworm tissues. Digestion of the proteinaceous component of humic acids by the earthworms was corroborated also by a decrease of extractable humic acids in fresh cast and a stimulated mineralization of soil nitrogen; in the case of M. guillelmi, the fresh cast contained sixfold more NH4+ than the non-ingested soil. Our study provides direct evidence for the selective digestion of humic components by earthworms. Considering the ubiquity of geophagous earthworms and their large biomass, the alteration of the chemical structure of humic substances by the earthworms through their selective digestion of peptidic components may have significant impacts on the stability of humic substances and the bioavailability of micropollutants in soil. 相似文献
6.
Oscar A. Martínez Milko A. Jorquera David E. Crowley María de la Luz Mora 《Biology and Fertility of Soils》2011,47(8):875-885
Plant growth-promoting rhizobacteria (PGPR) naturally occur in the rhizospheres of pasture, but still little is understood
regarding how soil agricultural practices affect them. Here, we examined the effects of long-term nitrogen (N) fertilisation
on the occurrence of potential culturable PGPR in rhizosphere soils from pastures grown in Chilean Andisols. We also evaluated
in vitro the effects of organic acids (citric, malic and oxalic acids), metals (Al and Mn) and N supply (urea and ammonium
sulphate) on indole acetic acid (IAA) production and phosphorus (P) liberation by selected strains. Compared with non-N-fertilised
pasture, N fertilisation significantly increased (30%) the occurrence of culturable phosphobacteria but decreased (7%) the
occurrence of IAA-producing rhizobacteria. Most efficient IAA-producing phosphobacteria were identified as Bacillus, Enterobacter, Pseudomonas and Serratia. At low pH (4.8), the assays showed that the IAA production by Serratia sp. N0-10LB was increased (31–74%) by organic acids. On the other hand, the IAA production by Pseudomonas sp. N1-55PA was increased two- to fivefold by metals. In all strains, the growth and IAA production were significant decreased
by 500 μM of Al, except Serratia sp. N0-10LB, suggesting its potential as PGPR for Chilean Andisols. When urea was added as main N source, the bacterial growth
and P utilisation significantly increased compared with ammonium sulphate. The influence of environmental factors that are
typical of Chilean Andisols on rhizobacterial communities will provide better management practices to enhance their PGPR functions
as well as a better selection biofertilisers to be used in Chilean Andisols. 相似文献
7.
Raeid M. M. Abed Samiha Al-Kharusi Panagiotis Gkorezis Stephane Prigent Tom Headley 《Archives of Agronomy and Soil Science》2018,64(3):360-370
Although Phragmites australis is commonly planted in constructed wetlands, very little is known about its roots-associated bacterial communities, especially in wetlands used for the remediation of oil produced waters. Here, we describe the bacterial diversity, using molecular (illumina MiSeq sequencing) and cultivation techniques, in the rhizosphere soils of P. australis from an oil-polluted wetland in Oman. The obtained isolates were tested for their plant-growth promoting properties. Most sequences belonged to Proteobacteria, Bacteriodetes and Firmicutes. Sequences of potential hydrocarbon-degrading bacteria (e.g. Ochrobactrum, and Pseudomonas) were frequently encountered. All soils contained sequences of known sulfur-oxidizing (e.g. Thiobacillus, Thiofaba, Rhodobacter and Sulfurovum) and sulfate-reducing bacteria, although the latter group made up only 0.1% to 3% of total sequences. The obtained isolates from the rhizosphere soils were phylogenetically affiliated to Serratia, Acinetobacter, Xenorhabdus, Escherichia and Salmonella. All strains were able to solubilize phosphate and about half were capable of producing organic acids and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Around 42% of the strains had the ability to produce indole acetic acid and siderophores. We conclude that the rhizosphere soils of P. australis in oil polluted wetlands harbor diverse bacterial communities that could enhance the wetland performance through hydrocarbon degradation, nutrient cycling and supporting plant growth. 相似文献
8.
The effects of incorporation of elm leaves (Ulmus glabra) into an agricultural sandy loam soil by earthworms (Lumbricus festivus) on the bacterial and protozoan populations were investigated. Three model systems consisting of soil, soil with leaves,
and soil with leaves and earthworms, respectively, were compared. The total, viable, and culturable number of bacteria, the
metabolic potentials of bacterial populations, and the number of protozoa and nematodes were determined in soil size fractions.
Significant differences between soil fractions were shown by all assays. The highest number of microorganisms was found in
microaggregates of 2–53 μm and the lowest in the <0.2μm fraction. A major part of the bacteria in the latter fraction was
viable, but non-culturable, while a relatively higher number of culturable bacteria was found in the macroaggregates. The
number of colony-forming units and 5-cyano-2,3-ditolyl tetrazolim chloride (CTC)-reducing bacteria explained a major part
of the variation in the number of protozoa. High protozoan activity and predation thus coincided with high bacterial activity.
In soil with elm leaves, fungal growth is assumed to inhibit bacterial and protozoan activity. In soil with elm leaves and
earthworms, earthworm activity led to increased culturability of bacteria, activity of protozoa, number of nematodes, changed
metabolic potentials of the bacteria, and decreased differences in metabolic potentials between bacterial populations in the
soil fractions. The effects of earthworms can be mediated by mechanical mixing of the soil constituents and incorporation
of organic matter into the soil, but as the earthworms have only consumed a minor part of the soil, priming effects are believed
partly to explain the increased microbial activity.
Received: 7 January 1996 相似文献
9.
Lorena Belén Guiñazú Javier Alberto Andrés María Florencia Del Papa Mariano Pistorio Susana Beatriz Rosas 《Biology and Fertility of Soils》2010,46(2):185-190
The objectives of this work were to phenotypically and genetically characterize alfalfa rhizosphere bacteria and to evaluate
the effect of single or mixed inoculation upon nodulation and biological nitrogen fixation. Thirty-two strains showed tricalcium
phosphate solubilization ability, and two of them caused bigger or equal solubilization halos than the control strain P. putida SP22. The comparison of the 16S ribosomal DNA sequences indicated that these strains are phylogenetically related to Bacillus spp. and Pseudomonas spp. A beneficial effect of both isolates on alfalfa growth was observed in coinoculation assays. Pseudomonas sp. FM7d caused a significant increase in root and shoot dry weight, length, and surface area of roots, number, and symbiotic
properties of alfalfa plants. The plants coinoculated with Sinorhizobium meliloti B399 and the Bacillus sp. M7c showed significant increases in the measured parameters. Our results indicating that strains Pseudomonas sp. FM7d and Bacillus sp. M7c can be considered for the formulation of new inoculants. 相似文献
10.
Devanshi Hareshbhai Patel Jinal Hardik Naik 《Archives of Agronomy and Soil Science》2018,64(7):1021-1031
Fifty strains of bacteria isolated from banana roots were studied for their plant growth promoting (PGP) activities. Indole -3- acetic acid (IAA) production by root-associated bacteria ranged from 20 to 302 µg ml?1. Seventeen isolates (34%) were positive for siderophore production and 18 isolates (36%) showed phosphate solubilization. None of the isolates showed potassium solubilization. All the isolates showed growth on nitrogen free Jensen medium. Identification of the bacteria based on 16S rRNA gene sequencing revealed that the isolates belonged to genus Bacillus sp, Klebsiella sp, Microbacterium sp and Enterobacter sp. A pot experiment in a greenhouse was conducted to investigate the effect PGP bacteria on banana plant growth and enzyme activities. The results demonstrated a significant (P < 0.05) increase in plant growth, chlorophyll, total phenolics, proline, catalase and ascorbic acid oxidase in banana plants treated with PGP bacteria as compared to control. However, the plant-growth response was variable and dependent on the bacterial strains, enzyme activity, and growth parameter observed. The present study revealed that bacteria showing multiple PGP activity could be used as biostimulants in enhancing banana production. 相似文献
11.
Antagonistic effect of Pseudomonas spp. on pathogenic fungi and enhancement of growth of green gram (Vigna radiata) 总被引:4,自引:0,他引:4
species were isolated from the rhizosphere of green gram [Vigna radiata (L.) Wilczek] and some of the rhizobacterial isolates were found to have a wide range of antifungal activity inhibiting growth
of the phytopathogenic fungi Aspergillus sp., Curvularia sp., Fusarium oxysporum and Rhizoctonia solani in culture. These isolates also showed slight inhibition of the growth of a Bradyrhizobium strain (Vigna) in a spot test which was mainly a result of nutrient competition as culture supernatants of the Pseudomonas isolates did not inhibit the growth of bradyrhizobia but inhibited the growth of fungi. The rhizobacterial isolates produced
siderophores in Fe-deficient succinate medium. However, the inhibition of fungal growth by different Pseudomonas isolates in Luria Bertani and King's medium B which were not limiting in Fe3+ ions suggested that, besides siderophores, other antifungal compounds (antibiotics) produced by these rhizobacteria were
involved in antagonism. On coinoculation of green gram with Pseudomonas strains MRS13 and MRS16 and Bradyrhizobium sp. (Vigna) strain S24, there was a significant increase in nodule weight, plant dry weight and total plant N as compared to inoculation
with Bradyrhizobium strain S24 alone, suggesting that the nodule-promoting effects of Pseudomonas sp. lead to an increase in symbiotic N fixation and plant growth.
Received: 27 October 1997 相似文献
12.
Elisabetta Loffredo Mariagrazia Berloco Fedele Casulli Nicola Senesi 《Biology and Fertility of Soils》2007,43(6):759-769
The effects of four humic substance (HS) samples, a soil humic acid and two humic acids and one fulvic acid isolated from
a composting substrate, were evaluated on the mycelial growth of Fusarium oxysporum f. sp. melonis (FOM) and F. oxysporum f. sp. lycopersici (FOL). In general, any HS treatment reduced significantly the radial growth of the FOM mycelium either in normal [potato
dextrose agar (PDA) medium] or sub-optimal (water–agar medium) nutritional conditions. Differently, the FOL growth, which
was tested only on PDA, was either inhibited or stimulated on dependence of the HS treatment used. The HS fractions isolated
from the composting substrate were the most effective inhibitors of mycelial growth of both fungi. Furthermore, any HS treatment
was also able to alter the germination process of FOL in aqueous medium, not only by reducing significantly the number of
viable germinating conidia but also by generally decreasing the rate of conidial germ-tube elongation. Apparently, the extent
of the inhibitory action was related to some chemical and functional properties of HS, such as the COOH group content and
elemental composition. 相似文献
13.
Changes in soil bacterial communities after toluene and/or toluene degrading bacteria were added were monitored by growth on various media, and by the culture-independent method of Reverse Sample Genome Probing (RSGP). A total of 397 isolates that were cultured from toluene-amended and non-amended soil were identified using fatty acid methyl ester (FAME) analysis. In 75% of the soil samples, gram-positive bacteria dominated, primarily Bacillus sp. and Cellulomonas sp. In contrast, RSGP revealed Proteobacteria (α, β, and γ subgroups) to be the dominant species, with Bacillus sp. dominant in only one soil sample.In toluene-treated soil, FAME and RSGP analyses indicated that by day 5 the major bacterial populations were gram-negative bacteria, in particular, Pseudomonas sp., Acinetobacter sp., and Alcaligenes sp. When toluene and Pseudomonas putida D8 were coincidentally introduced, the proportion of Pseudomonas sp. in the bacterial population recovered using non-selective medium increased from 16 to 62% and then rapidly decreased to about 9%. When we used selective medium to monitor the population of P. putida D8, a rapid initial increase followed by a gradual decline was also observed. In samples analyzed by RSGP, D8 was one of the major species of the bacterial community at day 2, but its signal intensity dropped to 9.5% by day 5.The influence of D8 addition on the bacterial profile was monitored in growth-based examinations. Bacillus sp. and Pseudomonas sp. were initially dominant. By day 5, Bacillus sp. decreased while the Proteobacteria, (including Acinetobacter sp., Agrobacterium sp., Alcaligenes sp., Burkholderia sp., Erwinia sp., and Pseudomonas sp.) increased. At the same time, D8 decreased to a level indistinguishable from background. Conversely, RSGP analysis revealed the population dominance of P. putida (including D8) and Rhizobium fredii at day 2. Populations shifted toward Agrobacterium tumefaciens, Bacillus subtilis, R. fredii, and D8 by day 5.P. putida D8 levels could be monitored using RSGP when cultivation failed. However, cultivation of Bacillus sp. was always successful, while the organism was only occasionally detected by RSGP. While cultivation and RSGP methods comparably detected the same major bacterial populations, the overall bacterial diversity was greater with RSGP than with growth-based testing. 相似文献
14.
G. Vallini A. Pera L. Avio M. Valdrighi M. Giovannetti 《Biology and Fertility of Soils》1993,16(1):1-4
Summary Increasing concentrations of humic acids were tested in order to determine their effects on the microbial rhizosphere and the growth of laurel (Laurus nobilis L.). Plants that were treated with 300 mg kg-1 of humic acids had the heaviest weights of both fresh and dry shoots; however, doses of 3000 mg kg-1 were highly phytotoxic and inhibited the growth of laurel. Total aerobic bacteria and actinomycetes were stimulated by doses of 1500 and 3000 mg kg-1 of humic acids at the first harvest. Nevertheless, at the end of the experiment no significant differences were found among the different doses. The number of fungi living in the laurel rhizosphere was not affected by any concentration of humic acids. Vesicular-arbuscular mycorrhizal (VAM) colonization was only slightly affected by the addition of increasing concentrations of humic substances to the soil, while the hyphal growth of Glomus mosseae was reduced. 相似文献
15.
S. Yu. Gryuntal’ 《Eurasian Soil Science》2009,42(11):1282-1290
In the burozems of the plains, the composition of the invertebrates and saprophages (the prevailing primary destroyers) differed
from that in the mountainous soils only by the absence of millipedes of the Geophilomorpha order. At the same time, the differences
in these characteristics between the burozems and soddypodzolic soils of the neighboring coniferous-broad-leaved forests were
more significant: in the latter, the composition of the ecological groups of earthworms was more diverse. Among the earthworms,
secondary destroyers (detritophages) consuming well-decomposed residues of plants and animals predominated: Aporrectodea caliginosa, A. rosea, and Octolasium lacteum. In the taiga burozems, among the secondary destroyers, very few O. lacteum among the earthworms, and Polyzonium germanicum among the millipede diplopods were found. Primary destroyers that only comminute plant tissues (Dendrobaena octaedra and Dendrodrilus rubidus f. tenuis) were the main representatives in the invertebrate population of these soils. The differences also concerned the group composition
and the proportion between the life forms of the earthworms. In the southern taiga burozems, only the litter (Dendrobaena octaedra and Dendrodrilus rubidus f. tenuis) earthworms and species of the upper soil layer (Octolasium lacteum) were present. In the mountainous burozems of the Transcarpathian region, litter inhabitants (Dendrobaena attemsi and Aporrectodea submontana), soil-litter inhabitants (Dendrobaena alpina—Transcarpathian region), and inhabitants of the upper (Helodrilus cernosvitovianus) and middle (Aporrectodea carpathica and A. sturanyi) soil layers (in the Primorskii region, only the soil-litter Eisenia nordenskioldi) were identified. In the soddy-podzolic soils, dwellers of the middle soil layers (Aporrectodea caliginosa, A. rosea, and Lumbricus terrestris) were constantly present along with the species dwelling in the litter and in the upper soil layers (in the litter—Dendrobaena octaedra, Dendrodrilus rubidus f. tenuis, and L. castaneus; in the litter-soil layer—L. rubellus; in the upper soil layer—Octolasium lacteum). The higher diversity of the earthworm life forms in the soddy-podzolic soils points to the stronger development of their
humus horizons as compared to those horizons in the burozems of the southern taiga and mountains. 相似文献
16.
Beneficial soil bacteria are able to colonize plant root systems promoting plant growth and increasing crop yield and nutrient uptake through a variety of mechanisms. These bacteria can be an alternative to chemical fertilizers without productivity loss. The objectives of this study were to test bacterial inoculants for their ability to promote nutrient uptake and/or plant growth of rice plants subjected to different rates of chemical fertilizer, and to determine whether inoculants could be an alternative to nitrogen fertilizers. To test the interaction between putatively beneficial bacteria and rice plants, field experiments were conducted with two isolates: AC32 (Herbaspirillum sp.) and UR51 (Rhizobium sp.), and different nitrogen fertilization conditions (0%, 50%, and 100% of urea). Satisfactory results were obtained in relation to the nutrient uptake by plants inoculated with both isolates, principally when the recommended amount of nitrogen fertilizer was 50% reduced. These bacterial strains were unable to increase plant growth and grain yield when plants were subjected to the high level of fertilization. This study indicated that the tested inoculant formulations can provide essential nutrients to plants, especially when the levels of nitrogen fertilizers are reduced. 相似文献
17.
Sorghum was inoculated withPseudomonas bacteria, including strains harboring an As-resistance plasmid, pBS3031, to enhance As-extraction by the plants.Pseudomonas strains (P.fluorescens 38a, P.putida 53a, and P.aureofaciens BS1393) were chosen because they are antagonistic to a wide range of phyto-pathogenic fungi and bacteria, and they can stimulate
plant growth. The resistance of natural rhizospheric pseudomonads to sodium arsenite was assessed. Genetically modifiedPseudomonas strains resistant to As(III)/As(V) were obtained via conjugation or transformation. The effects of the strains on the growth
of sorghum on sodium-arsenite-containing soils were assessed. The conclusions from this study are: (1) It is possible to increase
the survivability of sorghum growing in sodium-arsenite-containing soil by using rhizosphere pseudomonads. (2) The presence
of pBS3031 offers the strains a certain selective advantage in arsenite-contaminated soil. (3) The presence of pBS3031 impairs
plant growth, due to the As-resistance mechanism determined by this plasmid: the transformation of the less toxic arsenate
into the more toxic, plant-root-available arsenite by arsenate reductase and the active removal of arsenite from bacterial
cells. (4) Such a mechanism makes it possible to develop a bacteria-assisted phytoremediation technology for the cleanup of
As-contaminated soils and is the only possible way of removing the soil-sorbed arsenates from the environment. 相似文献
18.
Agnieszka Piernik Katarzyna Hrynkiewicz Anna Wojciechowska Sonia Szymańska Marta Izabela Lis Adele Muscolo 《Archives of Agronomy and Soil Science》2017,63(10):1404-1418
The aim of this study was to determine the influence of selected halotolerant endophytic bacteria isolated from the roots of Salicornia europaea on the growth parameters of Beta vulgaris under different concentrations of salinity. Two endophytic strains were selected as inocula for the pot experiment: Pseudomonas sp. ISE-12 (B1) and Xanthomonadales sp. CSE-34 (B2). Surface-sterilised seeds were incubated in the bacterial inoculation suspensions before sowing and cultivated in a sterile mixture of sand and vermiculite (1:1). Six salinity treatments were taken into account: 0, 50, 100, 150, 200 and 300 mM NaCl. Inoculation of seeds with B1 and B2 positively affected germination percentage and germination index and shortened mean germination time, which led to a quickening of the growth stages of seedlings. After 42 days inoculated plants had, in general, a greater root length, higher dry biomass, lower tissue water content and lower specific leaf area compared with the control. While the positive effect of B2 bacteria was visible only at low salinity, strain B1 stimulated plant growth at higher salinities (200 and 300 mM NaCl). We suggest that the superior growth promotion observed for B1 may be related to the higher metabolic activity of these bacteria. 相似文献
19.
Leticia Andrea Fernández Pablo Zalba Marisa Anahí Gómez Marcelo Antonio Sagardoy 《Biology and Fertility of Soils》2007,43(6):805-809
The efficiency of 13 phosphate-solubilizing bacteria (PSB; four Burkholderia sp., five Enterobacter sp., and four Bradyrhizobium sp.) was assessed in a soil plate assay by evaluating soil phosphorus (P) availability. A commercial argentine strain, Pseudomonas
fluorescens, was used for comparing solubilizing activity. Burkholderia sp. PER2F, Enterobacter sp. PER3G, and Bradyrhizobium sp. PER2H strains solubilized the largest quantities of P in the soil plate assay after 60 days as compared with the other
strains, including the commercial one. The effect of PSB inoculation on growth and nutrient uptake of soybean plants was also
studied under greenhouse conditions. Plants inoculated with Burkholderia sp. PER2F had the highest aerial height and showed an appropriate N/P ratio. However, none of the PSB increased P uptake
by plants. This suggests that PSB inoculation does not necessarily improve P nutrition in soybean, nor was there any relationship
between P availability in the soil plate assay and P content in the soybean shoot in the greenhouse. We concluded that the
selection of efficient PSB strains as possible inoculation tools for P-deficient soils should focus on the integral interpretation
of soil assays, greenhouse experiments, and field trials. 相似文献
20.
Humic acids stimulate growth and activity of in vitro tested axenic cultures of soil autotrophic nitrifying bacteria 总被引:2,自引:0,他引:2
In the present study, the effect of humic acids on activity and growth of Nitrosomonas europaea and Nitrobacter agilis was investigated in vitro under axenic conditions. Humates from compost-stabilized vegetable waste or leonardite were added
to the chemolithotrophic culturing medium at concentrations of 0, 5, 50 and 100 mg l–1. It was found that both types of humic acids increased either NH4
+ or NO2
– oxidation and cell growth of nitrifying bacteria in a dose-independent manner. By combining these results with data from
a comparative growth evaluation of N. agilis based on possible utilization of humates or pyruvate in heterotrophic conditions, evidence was obtained that nitrifiers cannot
use humic acids as an alternative carbon and energy source. Thus, the stimulating effect of this fraction of soil organic
matter on chemolithotrophic ammonia and nitrite oxidizers might be attributed to an increase in microbial membrane permeability
favouring a better utilization of nutrients.
Received: 15 April 1996 相似文献