Rhizosphere Of Various Plants Research Articles

Plant-beneficial Bacillus, Pseudomonas, and Staphylococcus spp. from Kumaon Himalayas and their drought tolerance response

Plant growth-promoting rhizobacteria (PGPR) have been shown to augment plant responses against drought and other abiotic stresses. In the present study, we isolated 27 bacteria from the rhizosphere of various plants cultivated in the Kumaon Himalayas., and to measure their abiotic stress tolerance, these 27 isolates were subjected to variations in pH, temperature, and drought. All 27 isolates were also screened for various plant growth-promoting traits. Among these, the four isolates RR1, ASC1, AFS3, and NG4 demonstrated various plant growth promotion activities including the synthesis of indole-3-acetic acid (IAA), siderophores, ammonia, and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase production, and concomitantly high tolerance to abiotic stresses. Moreover, 16S rRNA sequencing of these four isolates validated their identities as Bacillus, Pseudomonas, and Staphylococcus sp. Finally, to assess the in-vivo drought tolerance potential of these four isolates, a pot-trial experiment was undertaken in wheat cultivar VL-892. The results demonstrated that inoculating wheat plants with these four PGPR isolates greatly improved plant growth under drought circumstances by increasing root and shoot length and both fresh and dry weight of root and shoot. This study endeavors to discover the biochemical and molecular diversity of cultivable PGPR in six remotely located districts of Uttarakhand. In conclusion, the drought-tolerant PGPR strains described in this study are plant-beneficial and can effectively mobilize nutrients under drought conditions. Consequently, they could be used as bioinoculants to alleviate drought stress in wheat plants, in a sustainable manner. To the best of our knowledge, this is the first report of exploring the diversity and characterization of PGPR from the Kumaon Himalayas and their drought evaluation.

Bioaugmentation-Enhanced Remediation of Crude Oil Polluted Water in Pilot-Scale Floating Treatment Wetlands

Floating treatment wetlands (FTWs) are cost-effective systems for the remediation of polluted water. In FTWs, the metabolic activity of microorganisms associated with plants is fundamental to treatment efficiency. Bioaugmentation, the addition of microorganisms with pollutant-degrading capabilities, appears to be a promising means to enhance the treatment efficiency of FTWs. Here, we quantified the effect of bioaugmentation with a four-membered bacterial consortium on the remediation of water contaminated with crude oil in pilot-scale FTWs planted with Phragmites australis or Typha domingensis. The bacteria had been isolated from the endosphere and rhizosphere of various plants and carry the alkane hydroxylase gene, alkB, involved in aerobic hydrocarbon degradation. During a treatment period of 36 days, FTWs planted with P. australis achieved a reduction in hydrocarbon concentration from 300 mg/L to 16 mg/L with and 56 mg/L without bioaugmentation. In the FTWs planted with T. domingensis, respective hydrocarbon concentrations were 46 mg/L and 84 mg/L. The inoculated bacteria proliferated in the rhizoplane and in the plant interior. Copy numbers of the alkB gene and its mRNA increased over time in plant-associated samples, suggesting increased bacterial hydrocarbon degradation. The results show that bioaugmentation improved the treatment of oil-contaminated water in FTWs by at least a factor of two, indicating that the performance of full-scale systems can be improved at only small costs.

Myco-metabolites as biological control agents against the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae)

Fungi are a promising source for bioactive secondary metabolites against various agricultural pests. Soil samples were collected from the rhizosphere of various plants at El-Khatatba, Egypt, in May 2016. Sixty-two fungal isolates were locally isolated and screened against Tetranychus urticae Koch (Acari: Tetranychidae). Four fungal strains, showed potent control activities, were morphologically identified. Laboratory evaluation of the crude extracts of the selected strains, Aspergillus melleus, A. terreus, Emericella nidulans, and Chaetomium globosum, exhibited LC50 values of 10.27, 33.05, 14.68, and 22.40 mg/ml against females of T. urticae, respectively. Correspondent LC50 values that exhibited on eggs were 8.81, 23.17, 11.66, and 11.05 mg/ml. Consequently, secondary metabolites of A. melleus were separated by liquid chromatography/mass spectrometry. Compounds separated from the active fraction were identified as mellamide, ochratoxin C, nodulisporic acid, 7-Oxocurvularin, and 6-(4′-hydroxy-2′-methyl phenoxy)-(−)-(3R)-mellein. Obtained secondary metabolites are promising sources for biopesticides to be used in bio-rationale control of T. urticae.

English

Starch degrading bacteria are important for different industries such as food, fermentation, textile, and paper. The aim of this study is to isolate and characterize bacteria able to degrade starch from the rhizospheres of various plants at four sites located in Jimma University main campus. Collected soil samples were labeled as kobo (AJUMC), Avocado (BJUMC), Banana (CJUMC), and Cana indica (DJUMC) respectively. Soil samples were serially diluted in sterilized peptone water, poured on sterilized starch agar plates, and incubated at 32oC for 48 h. The representative colonies showing different morphology was randomly picked up using the streaking method on nutrient agar. A total of 53 bacterial isolates were obtained from the soils rhizospheres. Microscopic characteristics showed that among the 53 isolates, 38 (72%) were Gram-positive rod shaped bacteria, while 15 (28%) were Gram-negative rod shaped bacteria. Based on the biochemical tests, the results revealed that the 38 isolates belonged to the genera Bacillus while the remaining isolates belonged to the genera Pseudomonas. All isolates were catalase positive and only 15 isolates (Pseudomonas) were KOH positive with negative growth at 80°C, while the 38 (Bacillus) isolates have positive growth at 80oC. The highest values of starch degrading index were the Gram positive bacteria isolates. The amylase activity was also carried out with respect to time, temperature and pH of the media. The maximum activity of amylase at different temperatures from 35 to 45°C was recorded at 35°C (0.94 U/ml) within 24 h, while maximum activity at different pH from 5 to 9 was recorded at pH 7 (1 U/ml). Key words: Rhizobacteria, starch degrading, amylase enzyme, Bacillus, Pseudomonas.

Phosphate solubilizing rhizobacteria as alternative of chemical fertilizer for growth and yield of Triticum aestivum (Var. Galaxy 2013).

AimThe presence of Phosphorus as a macronutrient in soil is necessary for plant growth and its deficiency restricts crop yield. Therefore, the aim of current study is to isolate promising rhizospheric phosphate solubilizing bacteria presenting with plant growth promoting (PGP) traits and their utilization as biofertilizers to improve Triticum aestivum (Var. Galaxy 2013) growth and nutrition.MethodOut of 30 isolates obtained from rhizosphere of various plants of different regions, 10 best PSRB strains (WumS-3, WumS-4, WumS-5, WumS-11, WumS-12, WumS-21, WumS-24, WumS-25, WumS-26 and WumS-28) were selected based on their high P solubilization and good PGP (auxin, psiderphore, HCN, Nitrogen fixation) activities. Triticum aestivum (Var. Galaxy 2013) was used as an experimental crop under laboratory and field conditions.ResultsIn this study, P solubilization capacity of selected strains were found 4–7 solubilization index on agar plate and 30–246 µg/ml in liquid broth respectively. The optimum conditions for phosphate solubilization under in vitro condition were found 35 °C at pH 7, glucose as good carbon source and ammonium nitrate as a good nitrogen source. Furthermore, the selected strains had the ability to produces phytohormones (indole acetic acid), siderophore, ammonia and Hydrogen Cyanide. Finally, PSRB inoculum showed significant (p < 0.05) increase (50%–80%) in seed germination while 10–90% increase in root length and shoot length was found as compared to control in laboratory condition. Under natural conditions, 40–80% increase in seed germination while 5–34.8% increase in shoot length and 5–96% increase in seed weight was also observed.ConclusionIsolated strains are promising PSRB that enhance plant growth and this research is a base for recommending the use of these bacterial strains for biofertilizer, as an alternative of chemical fertilizer, for Triticum aestivum L. production.

Morphological diversity of Bacillus subtilis

&lt;p&gt;&lt;em&gt;Bacillus subtilis&lt;/em&gt; is the most studied bacterium from genus &lt;em&gt;Bacillus&lt;/em&gt; and this microorganism is widespread in nature. &lt;em&gt;B. subtilis&lt;/em&gt; is often found in fresh and seawater, in the rhizosphere, in the soil (especially contaminated with feces and manure). The large variety of strains are available in collections of microorganisms, but strains isolated from the rhizosphere of various plants are particularly interesting for science and practical use. At the same time, the morphological criterion (the form and other features of the colonies) is the main one in the identification of &lt;em&gt;B. subtilis&lt;/em&gt; at the first stages of the study and allows to refuse of extraneous strains before use more expensive methods and materials. The article presents the description of the morphological diversity of &lt;em&gt;B. subtilis&lt;/em&gt; strains that are used in agriculture. Typical R–colonies are characteristic of bacteria &lt;em&gt;B. subtilis&lt;/em&gt;, and we established 2 morphologically diverse forms of these colonies in the studied strains.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Spatial patterns of enzyme activities in the rhizosphere: Effects of root hairs and root radius

The importance of root hairs and root radius for exudation and nutrient acquisition by plants is known mainly from nutrient solution studies. The in situ effects of root hairs and root radius on the spatial distribution of enzyme activity in the rhizosphere of various plants are unknown. Four plants with contrasting root morphology (maize, wheat, lentil and lupine) were chosen to test the effects of root hairs and root radius on the spatial distribution of β-glucosidase, cellobiohydrolase, leucine aminopeptidase and acid phosphatase. We combined zymography with enzyme kinetics to evaluate the effects of root hairs on the rhizosphere extent and on substrate turnover. The extent of enzyme activity in the rhizosphere of four plants ranged from 0.55 to 2 mm. The extent of β-glucosidase was 1.5 times broader (1.2 mm versus 0.8 mm) and the substrate turnover was 2-fold faster around wheat root regions with hairs than hairless locations. The rhizosphere extent relative to root radius and the enzyme activity per root surface area were plant and enzyme specific: the rhizosphere extent was 1.5–2 times broader and the enzyme activity was 2–8-fold higher in wheat (with thin roots and long root hairs) compared to maize, lentil and lupine. The rhizosphere extent of acid phosphatase (1.1–2.0 mm) was 1.5–2-fold broader than that of other enzymes (0.5–1.0 mm). For the first time, we showed that the rhizosphere extent relative to root radius was 20–100% broader and enzyme activity per surface area was 4–7-fold higher around thin roots (wheat) than around thick roots (maize). Moreover, the rhizosphere extent relative to root radius was 10–30% broader and enzyme activity per root area was 2–7 times higher around roots with long and dense hairs (lupine) than around roots with short and sparse hairs (lentil). We conclude that root hairs and root radius shape the rhizosphere: root hairs contributed mainly to the rhizosphere extent, while root radius more strongly affected the enzyme activity per root surface area.

Biocontrol Potentials of Antimicrobial Peptide Producing Bacillus Species: Multifaceted Antagonists for the Management of Stem Rot of Carnation Caused by Sclerotinia sclerotiorum

Bacillus species are widely exploited as biocontrol agents because of their efficiency in impeding various plant pathogens with multifaceted approach. In this study, Bacillus species were isolated from rhizosphere of various plants viz., carnations, cotton, turmeric, and bananas in Tamil Nadu state of India. Their potential to control the mycelial growth of Sclerotinia sclerotiorum was assessed in vitro by dual plate and partition plate techniques. B. amyloliquefaciens strain VB7 was much effective in inhibiting mycelial growth (45% inhibition of over control) and sclerotial production (100%). PCR detection of AMP genes revealed that B. amyloliquefaciens (VB7) had a maximum of 10 diverse antibiotic biosynthesis genes, namely, ituD, ipa14, bacA, bacD, bamC, sfP, spaC, spaS, alba, and albF, that resulted in production of the antibiotics iturin, bacilysin, bacillomycin, surfactin, subtilin, and subtilosin. Further, metabolites from B. amyloliquefaciens strains VB2 and VB7, associated with inhibition of S. sclerotiorum, were identified as phenols and fatty acids by gas chromatography mass spectrometry (GC-MS). Delivery of bacterial suspension of the effective strains of Bacillus spp. as root dip was found promising for the management of stem rot of cultivated carnations. Minimal percent disease incidence (4.6%) and maximum plant growth promotion was observed in the plants treated with B. amyloliquefaciens (VB7).

Selection and evaluation of phosphate-solubilizing bacteria from grapevine rhizospheres for use as biofertilizers

Phosphate-solubilizing bacteria (PSB) have the ability to solubilize insoluble phosphorus (P) and release soluble P. Extensive research has been performed with respect to PSB isolation from the rhizospheres of various plants, but little is known about the prevalence of PSB in the grapevine rhizosphere. In this study, we aimed to isolate and identify PSB from the grapevine rhizosphere in five vineyards of Northwest China, to characterize their plant-growth-promoting (PGP) traits, evaluate the effect of stress on their phosphate-solubilizing activity (PSA), and test their ability to stimulate the growth of Vitis vinifera L. cv. Cabernet Sauvignon. From the vineyard soils, 66 PSB isolates were screened, and 10 strains with high PSA were identified by 16S rRNA sequencing. Sequence analysis revealed that these 10 strains belonged to 4 genera and 5 species: Bacillus aryabhattai, B. megaterium, Klebsiella variicola, Stenotrophomonas rhizophila, and Enterobacter aerogenes. The selected PSB strains JY17 (B. aryabhattai) and JY22 (B. aryabhattai) were positive for multiple PGP traits, including nitrogen fixation and production of indole acetic acid (IAA), siderophores, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, chitinase, and protease. JY17 and JY22 showed strong PSA under stress conditions of high pH, high salt, and high temperature. Therefore, these two isolates can be used as biofertilizers in saline-alkaline soils. The inoculation with PSB significantly facilitated the growth of V. vinifera cv. Cabernet Sauvignon under greenhouse conditions. Use of these PSB as biofertilizers will increase the available P content in soils, minimize P-fertilizer application, reduce environmental pollution, and promote sustainable agriculture.

식물 근권토양에서 분리한 수지상균근균

In this study, arbuscular mycorrhizal fungi (AMF) were isolated and cultivated from rhizospheres of various plants in Korea. Five species belonging to four genus were identified based on spore morphology and 18S rDNA sequence analysis: Acaulospora cavernata Claroideoglomus luteum, Diversispora aurantium, D. trimurales, Rhizophagus irregularis. These fungal species have not been cultivated or reported to date in Korea, Morphological description and phylogenetic analysis for each species were presented. This result could be useful for research of AMF diversity in Korea.

Selection of phytotoxin producing rhizobacteria.

In order to select phytotoxin producing rhizobacteria to control weed plants, twenty five bacterial strains previously isolated from the rhizospheres of various plants were grown in a liquid medium and, after cell removal by centrifugation, the liquid phases were freeze-dried and the products were extracted with ethyl acetate/methanol. The extracts were concentrated to dryness under vacuum and dissolved in water and sucrose solution to be submitted to in vitro assays of lettuce (Lactuca sativa L.) seed germination and wheat (Triticum aestivum L.) coleoptile growth. Although most samples affected coleoptile growth, only those from four strains reduced lettuce seed germination. Two strains of Bacillus cereus, one strain of B. pumilus and one of Stenotrophoonas altophilia were the most promising microorganisms for producing phytotoxin and, consequently, for the development of new weed control products.

Different growth and survival ofRhizobiumspecies in the rhizosphere of various plants in different sorts of soil

Summary The effect of various crop roots on clover bacteria (Rhizobium trifolii) and alfalfa bacteria (R. meliloti) living together was investigated using two kinds of soil: Southern Kantō volcanic ash soil at Tanashi and alluvial clay loam soil at Tachikawa.

ACTINOMYCETES-ANTAGONISTS ISOLATED FROM BULGARIAN SOILS.

A total of 1257 Actinomycetes strains, the majority of which of the albus, griseus and globisporus series, were isolated from 345 samples from the rhizosphere of various plants and soils. According to these observations the cultivation of the soil is not of paramount importance for the quantitative and species composition of the Actinomycetes. The determination of the antibacterial spectrum shows that 45% of the isolated strains have antagonistic properties with respect to Gram positive, Gram negative, acid fast bacteria, yeastlike fungi and moulds.

The effect of rhizosphere of various plants on the growth ofRhizobium

Abstract As elucidated in the previous paper1), the rhizosphere of the host plant maintains more abundant root nodule bacteria than non-rhizosphere soil. The success of seed inoculation of the root nodule bacteria is supported by the multiplication in the vicinity of the host plant.