scholarly journals Salix purpurea and Eleocharis obtusa Rhizospheres Harbor a Diverse Rhizospheric Bacterial Community Characterized by Hydrocarbons Degradation Potentials and Plant Growth-Promoting Properties

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1987
Author(s):  
Fahad Alotaibi ◽  
Soon-Jae Lee ◽  
Marc St-Arnaud ◽  
Mohamed Hijri

Phytoremediation, a method of phytomanagement using the plant holobiont to clean up polluted soils, is particularly effective for degrading organic pollutants. However, the respective contributions of host plants and their associated microbiota within the holobiont to the efficiency of phytoremediation is poorly understood. The identification of plant-associated bacteria capable of efficiently utilizing these compounds as a carbon source while stimulating plant-growth is a keystone for phytomanagement engineering. In this study, we sampled the rhizosphere and the surrounding bulk soil of Salixpurpurea and Eleocharis obusta from the site of a former petrochemical plant in Varennes, QC, Canada. Our objectives were to: (i) isolate and identify indigenous bacteria inhabiting these biotopes; (ii) assess the ability of isolated bacteria to utilize alkanes and polycyclic aromatic hydrocarbons (PAHS) as the sole carbon source, and (iii) determine the plant growth-promoting (PGP) potential of the isolates using five key traits. A total of 438 morphologically different bacterial isolates were obtained, purified, preserved and identified through PCR and 16S rRNA gene sequencing. Identified isolates represent 62 genera. Approximately, 32% of bacterial isolates were able to utilize all five different hydrocarbons compounds. Additionally, 5% of tested isolates belonging to genera Pseudomonas, Acinetobacter, Serratia, Klebsiella, Microbacterium, Bacillus and Stenotrophomonas possessed all five of the tested PGP functional traits. This culture collection of diverse, petroleum-hydrocarbon degrading bacteria, with multiple PGP traits, represents a valuable resource for future use in environmental bio- and phyto-technology applications.

Author(s):  
R. Thamizh Vendan ◽  
D. Balachandar

Background: Symbiotic associations between legumes and Rhizobia are ancient and fundamental. However, the plant growth-promoting endophytes other than Rhizobia are not yet fully explored for pulses productivity. The present study was aimed to isolate efficient endophytic bacteria from pulses, assess their diversity, screen their plant growth-promoting activities and to test their potential as bio inoculants for pulses.Methods: We have isolated several endophytic bacteria from pulse crops more specifically from blackgram (Vigna mungo) and greengram (Vigna radiata). After careful screening, 15 promising endophytic isolates were selected for this study. The identification of endophytic bacterial isolates was performed by 16S rRNA gene sequencing. The isolates were tested for their potential for the plant growth-promoting traits such as nitrogen fixation, phosphate solubilization, indole-3-acetic acid production, siderophore secretion and antifungal activity. Pot culture experiments were conducted with the screened potential endophytic cultures.Result: The 16S rRNA gene sequencing revealed that species of Enterobacter, Bacillus, Pantoea, Pseudomonas, Acromobacter, Ocrobacterium were found as endophytes in blackgram and greengram. The in vitro screening identified Bacillus pumilus (BG-E6), Pseudomonas fluorescens (BG-E5) and Bacillus licheniformis (BG-E3) from blackgram and Pseudomonas chlororaphis (GG-E2) and Bacillus thuringiensis (GG-E7) from greengram as potential plant growth-promoting endophytes. These strains showed antagonism against plant pathogenic fungi. Upon inoculation of these endophytic PGPR strains, the blackgram and greengram growth and yield got increased. Among the strains, BG-E6 recorded 14.7% increased yield in blackgram and GG-E2 accounted for a 19.5% yield increase in greengram compared to respective uninoculated control. The experimental results showed that there was a host specificity found among the endophytic bacterial cultures with pulses. The cross inoculation of endophytic strains did not perform well to enhance the growth and yield of their alternate hosts. 


2015 ◽  
Vol 64 (4) ◽  
pp. 339-349 ◽  
Author(s):  
Pooja Shrivastava ◽  
Rajesh Kumar ◽  
Mahesh Yandigeri ◽  
Nityanand Malviya ◽  
Dilip Arora

A total of 66 actinomycetes isolates were isolated from mangroves of Andhra Pradesh, India, using various enrichment techniques and pre-treatments. The samples were collected from Coringa mangrove ecosystem and pre-treated by enrichment with CaCO3, sodium dodecyl sulphate and phenol, plated on the media supplemented with cycloheximide (50 mg/ml), nystatin (25 mg/ml) and nalidixic acid (50 mg/ml). The population count of actinomycetes fluctuated from 1.9×105 to 8.0×105/g soil. Out of the isolated 66 actinomycetes, 8 isolates possessing plant growth promoting potential were further studied and characterized by physiological and biochemical traits and identified by 16S rRNA gene sequencing as different species of Streptomycetes genera.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sangeeta Pandey ◽  
Shikha Gupta

Abstract1-Aminocyclopropane-1-carboxylate (ACC) deaminase activity is one of the most beneficial traits of plant growth promoting (PGP) rhizobacteria responsible for protecting the plants from detrimental effects of abiotic and biotic stress. The strain S3 with ACC deaminase activity (724.56 nmol α-ketobutyrate mg−1 protein hr−1) was isolated from rhizospheric soil of turmeric (Curcuma longa), a medicinal plant, growing in Motihari district of Indian state, Bihar. The halotolerant strain S3, exhibited optimum growth at 8% (w/v) NaCl. It also exhibited multiple PGP traits such as indole acetic acid production (37.71 μg mL−1), phosphate solubilization (69.68 mg L−1), siderophore, hydrocyanic acid (HCN) and ammonia production as well as revealed antagonism against Rhizoctonia solani. The potential of isolated strain to alleviate salinity stress in tomato plants was investigated through pots trials by inoculating strain S3 through-seed bacterization, soil drenching, root dipping as well as seed treatment + soil drenching. The strain S3 inoculated through seed treatment and soil drenching method led to improved morphological attributes (root/shoot length, root/shoot fresh weight and root/shoot dry weight), photosynthetic pigment content, increased accumulation of osmolytes (proline and total soluble sugar), enhanced activities of antioxidants (Catalase and Peroxidase) and phenolic content in salt stressed tomato plants. The biochemical characterisation, FAMEs analysis and 16S rRNA gene sequencing revealed that strain S3 belongs to the genus Pseudomonas. The overall findings of the study revealed that Pseudomonas sp. strain S3 can be explored as an effective plant growth promoter which stimulate growth and improve resilience in tomato plants under saline condition.


2019 ◽  
Vol 65 (5) ◽  
pp. 377-386 ◽  
Author(s):  
Sandhya Dhiman ◽  
Ramesh Chand Dubey ◽  
Dinesh Kumar Maheshwari ◽  
Sandeep Kumar

This study aimed to harness the benefits of sulfur-oxidizing beneficial bacteria from buffalo dung to improve crop yields of Foeniculum vulgare. A total of 61 bacterial isolates were screened from buffalo dung, of which 40 isolates exhibited plant-growth-promoting attributes, such as phosphate solubilization, indole-3-acetic acid production, and hydrogen cyanide production. Of these 40, four bacterial isolates, viz., BUFF12, BUFF14, BUFF23, and BUFF38, were the most potent, having plant-growth-promoting and sulfur-oxidizing properties. These four isolates produced phytase by solubilizing calcium phytate and sodium phytate. They solubilized potassium besides oxidizing the sulfur, causing an increase in soil fertility and crop production. All four isolates were nonpathogenic in nature, as demonstrated by a negative haemolysis test. According to the 16S rRNA gene sequence, the isolate BUFF14 was identified as Proteus mirabilis. Proteus mirabilis BUFF14 maximized seed germination with enhanced vegetative and reproductive parameters during pot and field trial studies, compared with the other isolates.


2021 ◽  
Vol 913 (1) ◽  
pp. 012022
Author(s):  
N A Saryanah ◽  
Y P Roswanjaya ◽  
S Himawati ◽  
Sulastri ◽  
I S Bidara ◽  
...  

Abstract Bacterial endophyte and rhizobacteria were reported to associate with medicinal plants including Zingiberaceae plants and involved in growth promotion. These beneficial bacteria are promising candidates as biostimulants because of their ability in promoting plant growth. This study aims to evaluate the activity of endophytic and rhizosphere bacteria isolated from Curcuma xanthorrhiza (Javanese turmeric) in promoting rice seedling and Javanese turmeric growth. Fifty-seven of 150 total bacterial isolates with negative hemolysis and hypersensitivity reactions were characterized to investigate their plant growth-promoting (PGP) traits. Ten selected bacteria (two bacterial endophytes and eight rhizobacteria) with multiple PGP traits were inoculated to rice seed with seed treatment and inoculated to Javanese turmeric rhizome with seed treatment and seed treatment+soil soil drenching. Our results showed that bacterial isolates tested on rice seed promoted rice seedling growth significantly. A total of five, three, six, and three bacterial isolates could increase leaf number, root length, fresh shoot weight, and fresh root weight of rice seedling (p<0.05), respectively. In contrast, all of the bacterial isolates tested on Javanese turmeric rhizomes showed a non-significant effect on the plant growth. Further studies should be considered to investigate the effect of formulated potential bacterial isolates with different application frequencies and environmental conditions on the harvest yield of rice and Javanese turmeric as well as active compounds of Javanese turmeric.


2019 ◽  
Vol 6 ◽  
pp. 1-9
Author(s):  
Pramod Poudel ◽  
Ashish Nepal ◽  
Rashmi Roka Magar ◽  
Pratibha Rauniyar ◽  
Lil Buda Magar

Objectives: To isolate arsenic resistant Bacillus spp. and to determine plant growth promoting activities.  Methods: Eighteen soil samples were collected from the agricultural soil of Terai region of Nepal. Selective isolation of Bacillus species was done by heating the soil at 80 ºC for 15 minutes before the isolation. Nutrient agar was used as an isolation medium. Screening of arsenic resistant Bacillus species was done using nutrient agar supplemented with 100 ppm sodium arsenate and sodium arsenite. For plant growth promoting activity; IAA production was detected taking 0.1% tryptophane and measuring absorbance at 540 nm, NH3 production was tested by Nessler’s reagent and phosphate solubilization activity was detected by growing colonies on Pikovskaya’s agar. Sugar assimilation test was performed to identify the isolates. Most potent arsenic resistant isolate was identified by 16S rRNA gene sequencing. Results: Among 54 randomly selected isolates, 42 were found to be Gram-positive rod-shaped, spore-forming while 12 isolates were Gram-negative bacteria. The isolates IN12a, M12a and BG34a showed growth on 100 ppm sodium arsenite containing NA. Only isolate M12a tolerated up to 1000 ppm and 15000 ppm of sodium arsenite and sodium arsenate respectively, while other isolates could not grow above 400 ppm sodium arsenite. The isolates IN12a and M12a were able to produce IAA and solubilize phosphate while BG34a could not. Both the isolates IN12a and M12a were able to utilize the sugars glucose, fructose, lactose, sucrose, galactose, mannose, mannitol, maltose and xylose.  Based on the 16S rRNA gene sequencing, isolate M12a was identified to be Bacillus flexus with highest similarity of 99.2%. Conclusion: Arsenic resistant and plant growth promoting Bacillus spp. was isolated from the agricultural soil of Terai region of Nepal


2021 ◽  
Author(s):  
Lalit K. Chaurasia ◽  
Ranjan K. Tirwa ◽  
Buddhiman Tamang

Abstract The lipopeptide biosurfactants' chemical characteristics from the lactic acid bacteria isolated from milk and milk products were studied and their effect on maize plant growth. The oil displacement test was performed as a primary screening method to select the BS producing bacteria. Enterococcus faecium LM5.2 had the maximum emulsification index of 45.1±3 and reduced the surface tension to 32.98 ± 0.23% among all the isolates. E. faecium LM5.2 efficiently produced 945.26 ± 4.62 mg/l biosurfactants within 48 hours in MRS broth under the optimum conditions. The confirmation of the identity of the isolate LM5.2 was done with physiochemical tests and 16S rRNA gene sequencing. The molecular phylogenetic relationship was evaluated by the Neighbour-Joining phylogenetic method. The biosurfactant was purified by TLC and identified as lipopeptide-like iturines and surfactins based on Rf values. Mass spectroscopy, NMR, and FTIR analysis also confirmed the biosurfactant's identity as the derivatives of iturin and surfactin. Both the biosurfactant and its producer bacterium were evaluated for their plant growth-promoting activity, and it was found that the biosurfactant and the bacterium could enhance plant growth. To the best of our knowledge, this is the first report of lipopeptide biosurfactant production from Enterococcus faecium. Moreover, the study also showed that the biosurfactant and biosurfactant producing E. faecium LM5.2 could be an eco-friendly plant growth-promoting agent.


2016 ◽  
Vol 68 (2) ◽  
pp. 363-374 ◽  
Author(s):  
Pankaj Kumar ◽  
Ramesh Dubey ◽  
Dinesh Maheshwari ◽  
Yong-Ha Park ◽  
Vivek Bajpai

In vitro screening of plant growth-promoting (PGP) traits was carried out using eight Pseudomonas spp., PPR1 to PPR8, isolated from the rhizosphere of Phaseolus vulgaris growing on the Uttarakhand Himalayan range in India. All the isolates were fast growers, positive for catalase, oxidase and urease activities, and utilized lactose and some amino acids. All the isolates were indole acetic acid (IAA) positive, however PPR8 solubilized potassium and zinc along with various other types of inorganic (tricalcium, dicalcium and zinc phosphate) and organic (calcium phytate) phosphates, as well as producing siderophore and ACC deaminase. PPR8 also produced cyanogens, extracellular chitinase, ?-1,3-glucanase, ?-1,4-glucanase and oxalate oxidase. Based on the PGP traits of all isolates, PPR8 was found to be the most potent plant growth-promoting rhizobacteria (PGPR). Further, PPR8 was identified as Pseudomonas sp. PPR8, based on 16S rRNA gene sequencing analysis. Moreover, the PGP activities of PPR8 confirmed it to be a potent biocontrol agent, inhibiting the growth of various plant pathogenic fungi. This study reveals the potential of Pseudomonas sp. PPR8 to be used as a good bioinoculant for growth promotion of common bean and for the protection of important legume crops from various deleterious phytopathogens.


2018 ◽  
Author(s):  
Madhusmita Borah ◽  
Saurav Das ◽  
Himangshu Baruah ◽  
Robin C. Boro ◽  
Madhumita Barooah

AbstractIn this paper, we report the endophytic microbial diversity of cultivated and wild Oryza sativa plants including their functional traits related to multiple traits that promote plant growth and development. Around 255 bacteria were isolated out of which 70 isolates were selected for further studies based on their morphological differences. The isolates were characterized both at biochemical and at the molecular level by 16s rRNA gene sequencing. Based on 16S rRNA gene sequencing the isolates were categorized into three major phyla, viz, Firmicutes (57.1 %), Actinobacteria (20.0 %) and Proteobacteria (22.8 %). Firmicutes was the dominant group of bacteria of which the most abundant genus was Bacillus. The isolates were further screened in vitro for plant growth promoting activities which revealed a hitherto unreported endophytic bacterial isolate, Microbacteriaceae bacterium RS01 11 as the highest secretor of a phytohormone, IAA (28.39 ± 1.39 μg/ml) and GA (67.23 ± 1.83 μg/ml). Bacillus subtilis RHS 01 displayed highest phosphate solubilizing activity (81.70 ± 1.98 μg/ml) while, Microbacterium testaceum MK LS01, and Microbacterium trichothecenolyticum MI03 L05 exhibited highest potassium solubilizing activity (53.42±0.75μg/ml) and zinc solubilizing efficiency (157.50%) respectively. Bacillus barbaricus LP20 05 produced highest siderophore units (64.8 %). Potential plant growth promoting isolated were tested in vivo in pot culture under greenhouse conditions. A consortium consisting of Microbacteriaceae bacterium RS01 11, Bacillus testaceum MK LS01 and Bacillus subtilis RHS promoted plant growth and increased the yield 3.4 fold in rice when compared to control T0 when tested in pot culture and reduce application rates of chemical fertilizer to half the recommended dose. Our study confirms the potentiality of the rice endophytes isolated as good plant growth promoter and effective biofertilizer.


Diversity ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 665
Author(s):  
Zhibin Zhang ◽  
Tingting Liu ◽  
Xiao Zhang ◽  
Jing Xie ◽  
Ya Wang ◽  
...  

Dongxiang wild rice (Oryza rufipogon Griff.) germplasm is a precious resource for the improvement of agronomic traits in rice. Rice seeds also harbor a diverse endophytic bacterial community, and their interactions with their hosts and each other can influence plant growth and adaptability. Here, we investigated the community composition of cultivable endophytic bacteria obtained from the surface-sterilized seeds of Dongxiang wild rice and screened them for plant growth-promoting traits. Phylogenetic analysis of 16S rRNA gene sequences indicated that the 47 isolates were affiliated with five classes and 13 discrete genera, and Bacillus and Microbacterium predominated. Evaluations of plant growth promoting (PGP) traits showed that 45 endophytic bacteria isolates produced between 3.37 and 90.11 μg mL−1 of Indole-3-acetic acid (IAA), with the highest yield of 90.11 μg mL−1 (Fse28). Further, 37 of the isolates were able to solubilize mineral phosphate, while 28 other isolates had the ability of N2-fixation, 17 isolates possessed 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity with the highest yield of 20.72 μmol mg−1 protein h−1 (Fse35), and 17 isolates were also able to produce siderophores. The two strains Fse28 and Fse35 had multiple PGP traits that significantly improved the agronomic traits (root length, shoot length, dry matter, and chlorophyll content) of cultivated rice seedlings. Our results illustrate the rich diversity of seed endophytic bacteria in Dongxiang wild rice and their potential for developing novel efficient bioinoculants to enhance soil fertility and favor seedling growth.


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