scholarly journals Metagenomic insight into the plant growth-promoting potential of a diesel-degrading bacterial consortium for enhanced rhizoremediation application

2021 ◽  
Author(s):  
Michael O Eze ◽  
Volker Thiel ◽  
Grant C Hose ◽  
Simon C George ◽  
Rolf Daniel

The slow rate of natural attenuation of organic pollutants, together with unwanted environmental impacts of traditional remediation strategies, has necessitated the exploration of plant-microbe systems for enhanced bioremediation applications. The identification of microorganisms capable of promoting both plant growth and hydrocarbon degradation is crucial to the success of plant-based remediation techniques. Through successive enrichments of a soil sample from a historic oil-contaminated site in Wietze, Germany, we isolated a plant growth-promoting and hydrocarbon-degrading bacterial consortium. Metagenome analysis of the consortium led to the identification of genes and taxa putatively associated with these processes. The majority of the coding DNA sequences involved in these reactions were affiliated to Acidocella aminolytica and Acidobacterium capsulatum. In microcosm experiments performed in association with Medicago sativa L., the consortium achieved 91% rhizodegradation of diesel fuel hydrocarbons within 60 days, indicating its potential for biotechnological applications in the remediation of sites contaminated by organic pollutants.

2015 ◽  
Vol 81 (19) ◽  
pp. 6700-6709 ◽  
Author(s):  
Maria Isabel Stets ◽  
Sylvia Maria Campbell Alqueres ◽  
Emanuel Maltempi Souza ◽  
Fábio de Oliveira Pedrosa ◽  
Michael Schmid ◽  
...  

ABSTRACTAzospirillumis a rhizobacterial genus containing plant growth-promoting species associated with different crops worldwide.Azospirillum brasilensestrains exhibit a growth-promoting effect by means of phytohormone production and possibly by N2fixation. However, one of the most important factors for achieving an increase in crop yield by plant growth-promoting rhizobacteria is the survival of the inoculant in the rhizosphere, which is not always achieved. The objective of this study was to develop quantitative PCR protocols for the strain-specific quantification ofA. brasilenseFP2. A novel approach was applied to identify strain-specific DNA sequences based on a comparison of the genomic sequences within the same species. The draft genome sequences ofA. brasilenseFP2 and Sp245 were aligned, and FP2-specific regions were filtered and checked for other possible matches in public databases. Strain-specific regions were then selected to design and evaluate strain-specific primer pairs. The primer pairs AzoR2.1, AzoR2.2, AzoR5.1, AzoR5.2, and AzoR5.3 were specific for theA. brasilenseFP2 strain. These primer pairs were used to monitor quantitatively the population ofA. brasilensein wheat roots under sterile and nonsterile growth conditions. In addition, coinoculations with other plant growth-promoting bacteria in wheat were performed under nonsterile conditions. The results showed thatA. brasilenseFP2 inoculated into wheat roots is highly competitive and achieves high cell numbers (∼107CFU/g [fresh weight] of root) in the rhizosphere even under nonsterile conditions and when coinoculated with other rhizobacteria, maintaining the population at rather stable levels for at least up to 13 days after inoculation. The strategy used here can be applied to other organisms whose genome sequences are available.


Proceedings ◽  
2021 ◽  
Vol 66 (1) ◽  
pp. 20
Author(s):  
Marika Pellegrini ◽  
Daniela M. Spera ◽  
Claudia Ercole ◽  
Maddalena del Gallo

The present work was aimed at investigating the effects of a four strains consortium—Azospirillum brasilense, Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, and Burkholderia ambifaria—on crops of Allium cepa L. and its soil health. The bacterial consortium was inoculated on seeds of two different onion varieties; inoculated seeds and control ones (treated with autoclaved inoculum) were sown in open-field and followed until harvest. Plant growth development parameters, as well as soil physico-chemical and molecular profiles (DNA extraction and 16S community sequencing on the Mi-Seq Illumina platform), were investigated. The results showed a positive influence of bacterial application on plant growth, with increased plant height (+18%), total chlorophylls (+42%), crop yields (+13%), and bulbs dry matter (+3%) than the control. The differences between control and treated experimental conditions were also underlined in the bulb extracts in terms of total phenolic contents (+25%) and antioxidant activities (+20%). Soil fertility and microbial community structure and diversity were also positively affected by the bacterial inoculum. At harvest, the soil with the presence of the bacterial consortium showed an increase of total organic carbon, organic matter, and available P and higher concentrations of nutrients than control. The ecological indexes calculated on the molecular profiles showed that community diversity was positively affected by the bacterial treatment. The present work allowed to remark the effective use of plant growth-promoting bacteria as a valid fertilization strategy to improve yield in productive landscapes, whilst safeguarding soil biodiversity.


2021 ◽  
Vol 10 (3) ◽  
Author(s):  
Pooja Ramadas ◽  
Dhruv Pathak ◽  
Prabhjeet Kaur

In today’s largely populated modern world, crop yield is becoming increasingly important. To increase crop yield, new modern technologies for farming are continuously being innovated. The aim of this study is the identification of Plant Growth Promoting Bacteria (PGPBs) and their properties. In order to conduct the experiment, soil samples were collected from the community garden LEAF (Local Ecology and Agriculture Fremont). These samples were grown in Luria Bertani agar plates, and the two bacterial strains that grew from them were analyzed to determine the species of the bacteria. Using a DNA extraction kit, DNA was extracted from the bacteria and then amplified versions were sent to RF Biotech for DNA sequencing. The DNA sequences were then used to determine that the two bacterial species in question are Bacillus cereus and Morganella morganii. Afterwards, multiple assays were used to measure the efficiency of each bacterial species to absorb various substances that would be helpful for plant growth. The aim of this research is to better understand which bacterial strains are beneficial for plants, and which are harmful. Through having greater zones of inhibition, the bacterial species M. morganii proved to be more efficient in the siderophore and phosphate solubilization assays. In contrast, the bacterial species B. cereus proved to be more efficient in the cellulase and amylase production assays. These results will assist LEAF in enriching their soil in order to increase their crop yields by creating an increase in concentration of advantageous bacteria and decrease that of detrimental bacteria.


2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Jinjin Ma ◽  
Chengqiang Wang ◽  
Haide Wang ◽  
Kai Liu ◽  
Tongrui Zhang ◽  
...  

Bacillus atrophaeusGQJK17 was isolated from the rhizosphere ofLycium barbarumL. in China, which was shown to be a plant growth-promoting rhizobacterium as a new biological agent against pathogenic fungi and gram-positive bacteria. We present its biological characteristics and complete genome sequence, which contains a 4,325,818 bp circular chromosome with 4,181 coding DNA sequences and a G+C content of 43.3%. A genome analysis revealed a total of 8 candidate gene clusters for producing antimicrobial secondary metabolites, including surfactin, bacillaene, fengycin, and bacillibactin. Some other antimicrobial and plant growth-promoting genes were also discovered. Our results provide insights into the genetic and biological basis ofB. atrophaeusstrains as a biocontrol agent for application in agriculture.


2021 ◽  
Vol 9 (3) ◽  
pp. 639
Author(s):  
Marika Pellegrini ◽  
Daniela M. Spera ◽  
Claudia Ercole ◽  
Maddalena Del Gallo

The present work was aimed at investigating the effects of a four bacterial strain consortium—Azospirillum brasilense, Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, and Burkholderia ambifaria—on Allium cepa L. and on soil health. The bacterial consortium was inoculated on seeds of two different onion varieties; inoculated and Control seeds (treated with autoclaved inoculum) were sown in an open-field and followed until harvest. Plant growth development parameters, as well as soil physico–chemical and molecular profiles (DNA extraction and 16S community sequencing on the Mi-Seq Illumina platform), were investigated. The results showed a positive influence of bacterial application on plant growth, with increased plant height (+18%), total chlorophylls (+42%), crop yields (+13%), and bulb dry matter (+3%) with respect to the Control. The differences between Control and treatments were also underlined in the bulb extracts in terms of total phenolic contents (+25%) and antioxidant activities (+20%). Soil fertility and microbial community structure and diversity were also positively affected by the bacterial inoculum. At harvest, the soil with the presence of the bacterial consortium showed an increase in total organic carbon, organic matter, and available phosphorus, as well as higher concentrations of nutrients than the Control. The ecological indexes calculated from the molecular profiles showed that community diversity was positively affected by the bacterial treatment. The present work showed the effective use of plant growth-promoting bacteria as a valid fertilization strategy to improve yield in productive landscapes whilst safeguarding soil biodiversity.


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