scholarly journals Microbiological quality analysis of inoculants based on Bradyrhizobium spp. and Azospirillum brasilense produced “on farm” reveals high contamination with non-target microorganisms

2022 ◽  
Author(s):  
Camila Rafaeli Bocatti ◽  
Eduara Ferreira ◽  
Renan Augusto Ribeiro ◽  
Ligia Maria de Oliveira Chueire ◽  
Jakeline Renata Marçon Delamuta ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Culture Media ◽  
Microbiological Quality ◽  
Quality Analysis ◽  
Rrna Gene ◽  
Plant Growth Promoting Bacteria ◽  
Intrinsic Resistance ◽  
Farm Production ◽  
Plant Growth Promoting ◽  
On Farm

Abstract The use of inoculants carrying diazotrophic and other plant growth–promoting bacteria plays an essential role in the Brazilian agriculture, with a growing use of microorganism-based bioproducts. However, in the last few years, some farmers have multiplied microorganisms in the farm, known as “on farm” production, including inoculants of Bradyrhizobium spp. for soybean (Glycine max L. Merrill.) and Azospirillum brasilense for corn (Zea mays L.) or co-inoculation in soybean. The objective was to assess the microbiological quality of such inoculants concerning the target microorganisms and contaminants. In the laboratory, 18 samples taken in five states were serial diluted and spread on culture media for obtaining pure and morphologically distinct colonies of bacteria, totaling 85 isolates. Molecular analysis based on partial sequencing of the 16S rRNA gene revealed 25 genera of which 44% harbor species potentially pathogenic to humans; only one of the isolates was identified as Azospirillum brasilense, whereas no isolate was identified as Bradyrhizobium. Among 34 isolates belonging to genera harboring species potentially pathogenic to humans, 12 had no resistance to antibiotics, six presented intrinsic resistance, and 18 presented non-intrinsic resistance to at least one antibiotic. One of the samples analyzed with a shotgun-based metagenomics approach to check for the microbial diversity showed several genera of microorganisms, mainly Acetobacter (~ 32% of sequences) but not the target microorganism. The samples of inoculants produced on farm were highly contaminated with non-target microorganisms, some of them carrying multiple resistances to antibiotics.

scholarly journals Effect of Pyroligneous Acid on the Microbial Community Composition and Plant Growth-Promoting Bacteria (PGPB) in Soils

Soil Systems ◽  
2022 ◽  
Vol 6 (1) ◽  
pp. 10
Author(s):  
Anithadevi Kenday Sivaram ◽  
Logeshwaran Panneerselvan ◽  
Kannappar Mukunthan ◽  
Mallavarapu Megharaj
Keyword(s):  
Microbial Community ◽  
Plant Growth ◽  
Microbial Diversity ◽  
Growth And Yield ◽  
Rrna Gene ◽  
Plant Growth Promoting Bacteria ◽  
Microbial Composition ◽  
Pyroligneous Acid ◽  
Plant Growth Promoting ◽  
Growth Promoting

Pyroligneous acid (PA) is often used in agriculture as a plant growth and yield enhancer. However, the influence of PA application on soil microorganisms is not often studied. Therefore, in this study, we investigated the effect of PA (0.01–5% w/w in soil) on the microbial diversity in two different soils. At the end of eight weeks of incubation, soil microbial community dynamics were determined by Illumina-MiSeq sequencing of 16S rRNA gene amplicons. The microbial composition differed between the lower (0.01% and 0.1%) and the higher (1% and 5%) concentration in both PA spiked soils. The lower concentration of PA resulted in higher microbial diversity and dehydrogenase activity (DHA) compared to the un-spiked control and the soil spiked with high PA concentrations. Interestingly, PA-induced plant growth-promoting bacterial (PGPB) genera include Bradyrhizobium, Azospirillum, Pseudomonas, Mesorhizobium, Rhizobium, Herbaspiriluum, Acetobacter, Beijerinckia, and Nitrosomonas at lower concentrations. Additionally, the PICRUSt functional analysis revealed the predominance of metabolism as the functional module’s primary component in both soils spiked with 0.01% and 0.1% PA. Overall, the results elucidated that PA application in soil at lower concentrations promoted soil DHA and microbial enrichment, particularly the PGPB genera, and thus have great implications for improving soil health.

scholarly journals Alone Yet Not Alone: Frankia Lives Under the Same Roof With Other Bacteria in Actinorhizal Nodules

2021 ◽  
Vol 12 ◽  
Author(s):  
Faten Ghodhbane-Gtari ◽  
Timothy D’Angelo ◽  
Abdellatif Gueddou ◽  
Sabrine Ghazouani ◽  
Maher Gtari ◽  
...  
Keyword(s):  
16S Rrna ◽  
Plant Growth ◽  
16S Rrna Gene ◽  
Root Nodules ◽  
Actinorhizal Plants ◽  
Rrna Gene ◽  
Plant Growth Promoting Bacteria ◽  
Metagenomic Sequencing ◽  
Plant Growth Promoting ◽  
Growth Promoting

Actinorhizal plants host mutualistic symbionts of the nitrogen-fixing actinobacterial genus Frankia within nodule structures formed on their roots. Several plant-growth-promoting bacteria have also been isolated from actinorhizal root nodules, but little is known about them. We were interested investigating the in planta microbial community composition of actinorhizal root nodules using culture-independent techniques. To address this knowledge gap, 16S rRNA gene amplicon and shotgun metagenomic sequencing was performed on DNA from the nodules of Casuarina glauca. DNA was extracted from C. glauca nodules collected in three different sampling sites in Tunisia, along a gradient of aridity ranging from humid to arid. Sequencing libraries were prepared using Illumina NextEra technology and the Illumina HiSeq 2500 platform. Genome bins extracted from the metagenome were taxonomically and functionally profiled. Community structure based off preliminary 16S rRNA gene amplicon data was analyzed via the QIIME pipeline. Reconstructed genomes were comprised of members of Frankia, Micromonospora, Bacillus, Paenibacillus, Phyllobacterium, and Afipia. Frankia dominated the nodule community at the humid sampling site, while the absolute and relative prevalence of Frankia decreased at the semi-arid and arid sampling locations. Actinorhizal plants harbor similar non-Frankia plant-growth-promoting-bacteria as legumes and other plants. The data suggests that the prevalence of Frankia in the nodule community is influenced by environmental factors, with being less abundant under more arid environments.

scholarly journals Association of Indolebutyric Acid with Azospirillum brasilense in the Rooting of Herbaceous Blueberry Cuttings

Horticulturae ◽  
2019 ◽  
Vol 5 (4) ◽  
pp. 68 ◽  
Author(s):  
Koyama ◽  
Aparecido Ribeiro Júnior ◽  
Mariani Zeffa ◽  
Tadeu Faria ◽  
Mitsuharu Saito ◽  
...  
Keyword(s):  
Root Length ◽  
Azospirillum Brasilense ◽  
Dry Mass ◽  
Plant Growth Promoting Bacteria ◽  
Indolebutyric Acid ◽  
Rooted Cuttings ◽  
Plant Growth Promoting ◽  
Rooting Of Cuttings ◽  
Mist Chamber ◽  
Root Growth And Development

Association between auxins and plant growth-promoting bacteria can stimulate root growth and development of fruit crop nursery plants, and can be a promising biological alternative to increase the rooting of cuttings. The objective of this study was to assess the viability of producing ‘Powderblue’ blueberry nursery plants from cuttings using different doses of indolebutyric acid (IBA) in association with Azospirillum brasilense. The following treatments were tested: 0 (control); 500 mg L−1 of IBA; 1000 mg L−1 of IBA; A. brasilense; 500 mg L−1 of IBA + A. brasilense; and 1000 mg L−1 of IBA + A. brasilense. The experimental design was completely randomized, with six treatments and four replicates, and each plot (box) consisted of 10 cuttings. The boxes were arranged in a mist chamber with an intermittent regimen controlled by a timer and solenoid valve. After 90 days, the following variables were assessed: rooted cuttings; survival of cuttings; foliar retention; sprouting; cuttings with callus; root dry mass per cutting; number of roots per cutting; and root length. It was observed that the application of IBA with the A. brasilense rhizobacteria increased the number of roots of ‘Powderblue’ blueberry cuttings, while the treatments with IBA alone and IBA 1000 mg L−1 + A. brasilense increased the root length of cuttings. However, treatments with IBA and A. brasilense had no impact on % rooted cuttings and % survival of cuttings.

scholarly journals Amelioration of Saline Stress on Chia (Salvia hispanica L.) Seedlings Inoculated With Halotolerant Plant Growth-Promoting Bacteria Isolated From Hypersaline Environments

2021 ◽  
Vol 3 ◽  
Author(s):  
María Florencia Yañez-Yazlle ◽  
Neli Romano-Armada ◽  
Verónica Beatriz Rajal ◽  
Verónica Patricia Irazusta
Keyword(s):  
Plant Growth ◽  
Culture Media ◽  
Saline Stress ◽  
Plant Growth Promoting Bacteria ◽  
Initial Growth ◽  
Hypersaline Environments ◽  
Salvia Hispanica ◽  
Plant Growth Promoting ◽  
Pgp Activities ◽  
Growth Promoting

The rhizosphere and microbiome of halotolerant plants could be crucial for alleviating salinity stress during plant growth. The aims of this work were (1) to isolate bacteria from rhizosphere and bulk soil samples from the Salar del Hombre Muerto (Catamarca, Argentina), (2) to characterize different plant growth-promoting (PGP) activities produced by these bacterial isolates, and (3) to evaluate their effect on the initial growth of chia (Salvia hispanica L.) under saline stress. A total of 667 microorganisms were isolated, using different culture media with NaCl, and their abilities for nitrogen fixation, phosphate solubilization, siderophores production, and indole-3-acetic acid production were evaluated. Thirteen strains were selected for showing all the tested PGP activities; they belonged to the genera Kushneria, Halomonass, Pseudomonas, Planomicrobium, and Pseudarthrobacter. The strains Kushneria sp. and Halomonas sp. showed the highest salinity tolerance (from 50 to 2,000 mM NaCl) and biomass and biofilm production. Chia seeds were treated with six of the first 13 selected strains to evaluate their plant growth-promoting effect under saline stress (without and with 50 and 100 mM NaCl). Halomonas sp. 3R.12 and Kushneria sp. T3.7 produced heavier seedlings with a balanced shoot/root length ratio, while Pseudomonas sp. AN23 showed the best effect upon chia seedlings, with a morphological response similar to non-stressed seedlings. On the other hand, seedlings displayed no responses when inoculated with Planomicrobium sp. 3S.31 and Pseudarthrobacter sp. ER25. This study contributes to the knowledge on microorganisms from hypersaline environments as plant growth promoters for their use in the production of salt-sensitive crops, among other potential uses.

scholarly journals Compatibility of Azospirillum brasilense with Pesticides Used for Treatment of Maize Seeds

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Mariana S. Santos ◽  
Artur B. L. Rondina ◽  
Marco A. Nogueira ◽  
Mariangela Hungria
Keyword(s):  
Plant Growth ◽  
Root Hair ◽  
Azospirillum Brasilense ◽  
Plant Protection ◽  
Plant Growth Promoting Bacteria ◽  
Root Volume ◽  
Maize Seeds ◽  
Plant Growth Promoting ◽  
Growth Promoting

Seed treatment with chemical pesticides is commonly used as an initial plant protection procedure against pests and diseases. However, the use of such chemicals may impair the survival and performance of beneficial microorganisms introduced via inoculants, such as the plant growth-promoting bacterium Azospirillum brasilense. We assessed the compatibility between the most common pesticide used in Brazil for the treatment of maize seeds, composed of two fungicides, and one insecticide, with the commercial strains Ab-V5 and Ab-V6 of A. brasilense, and evaluated the impacts on initial plant development. The toxicity of the pesticide to A. brasilense was confirmed, with an increase in cell mortality after only 24 hours of exposure in vitro. Seed germination and seedling growth were not affected neither by the A. brasilense nor by the pesticide. However, under greenhouse conditions, the pesticide affected root volume and dry weight and root-hair incidence, but the toxicity was alleviated by the inoculation with A. brasilense for the root volume and root-hair incidence parameters. In maize seeds inoculated with A. brasilense, the pesticide negatively affected the number of branches, root-hair incidence, and root-hair length. Therefore, new inoculant formulations with cell protectors and the development of compatible pesticides should be searched to guarantee the benefits of inoculation with plant growth-promoting bacteria.

scholarly journals Quantification of Azospirillum brasilense FP2 Bacteria in Wheat Roots by Strain-Specific Quantitative PCR

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 ◽  
...  
Keyword(s):  
Plant Growth ◽  
Quantitative Pcr ◽  
Dna Sequences ◽  
Azospirillum Brasilense ◽  
Plant Growth Promoting Bacteria ◽  
Genome Sequences ◽  
Wheat Roots ◽  
Content Type ◽  
Plant Growth Promoting ◽  
Growth Promoting

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.

scholarly journals Bacteria Isolated from Wastewater Irrigated Agricultural Soils Adapt to Heavy Metal Toxicity While Maintaining Their Plant Growth Promoting Traits

2021 ◽  
Vol 13 (14) ◽  
pp. 7792
Author(s):  
Abdul Wahab Ajmal ◽  
Saleha Saroosh ◽  
Shah Mulk ◽  
Muhammad Nadeem Hassan ◽  
Humaira Yasmin ◽  
...  
Keyword(s):  
Plant Growth ◽  
Agricultural Soils ◽  
Culture Media ◽  
Growth Promotion ◽  
Metal Resistance ◽  
Rrna Gene ◽  
Gene Sequence Analysis ◽  
Plant Growth Promoting ◽  
Growth Promoting

The present study explored the plant growth promotion and bioremediation potential of bacteria inhabiting wastewater irrigated agricultural soils. Thirty out of 75 bacterial isolates (40%), 29/75 (39%) and 28/75 (37%) solubilized Zn, K and PO4 during plate essays respectively. Fifty-six percent of the isolates produced siderophores, while 30% released protease in vitro. Seventy-four percent of bacteria resisted Pb, Ni and Cd at various concentrations added to the culture media plates. Sixteen out of 75 (26%) isolates were able to fix N in Nbf medium. Among these 16 N fixers, N fixing nifH, nifD and nifK genes was detected through PCR in 8, 7 and 1 strain respectively using gene specific primers designed in the study with Enterobacter sp. having all three (nifHKD) genes. Isolated bacteria showed resemblance to diverse genera such as Bacillus, Pseudomonas, Enterobacter, Citrobacter, Acinetobacter, Serratia, Klebsiella and Enterococcus based on 16S rRNA gene sequence analysis. In addition to showing the best mineral solubilization and metal resistance potential, Citrobacter sp. and Enterobacter sp. also removed 87%, 79% and 43% and 86%, 78% and 51% of Ni, Cd and Pb, respectively, from aqueous solution. These potent bacteria may be exploited both for bioremediation and biofertilization of wastewater irrigated soils leading to sustainable agriculture.

scholarly journals Mineral Phosphate Solubilizing Bacteria Isolated from Various Plant Rhizosphere under Different Aluminum Content

2015 ◽  
Vol 10 (2) ◽  
Author(s):  
Dolly Iriani Damarjaya ◽  
Jaka Widada ◽  
Keishi Senoo ◽  
Masaya Nishiyama ◽  
Shigeto Otsuka
Keyword(s):  
Dry Weight ◽  
Rrna Gene ◽  
Plant Growth Promoting Bacteria ◽  
Phosphate Solubilizing Bacteria ◽  
Gene Sequence Analysis ◽  
Mineral Phosphate ◽  
Plant Growth Promoting ◽  
The Media ◽  
Formation Method ◽  
Phosphate Solubilizing

The objectives of this study was to isolate and characterize the mineral phosphate solubilizing bacteriafrom rhizosphere and evaluate their potential as plant growth promoting bacteria in Al-toxic soils. The halozone formation method was used to isolate PSB using the media containing insoluble phosphates (Ca-P or Al-P)as a source of phosphate. Eight of acid and Al-tolerant PSB isolates that were able to solubilize Ca-P wereobtained from rhizosphere of clover, wheat, corn, and sunflower grown in Al-toxic soil. Identification of theisolates based on the 16S rRNA gene sequence analysis demonstrated that the isolates were strains of Burkholderia(5 strains), Pseudomonas (1 strain), Ralstonia (1 strain), and unidentified bacterium (1 strains). All PSB isolatesshowed the capability to dissolve Ca-P, and only 1 strain (Ralstonia strain) was able to dissolve Al-P in agar platemedium. The P-solubilization by these isolates was correlated with pH of medium. Inoculation of the bacterialstrains on clover on Al-toxic medium showed that all isolates increased the plant dry weight compared withuninoculated treatment. Our results showed that those PSB isolates have potential to be developed as a biofertilizerto increase the efficiency of P-inorganic fertilizer used in Al-toxic soils.

scholarly journals POLYPHASIC CHARACTERIZATION OF Bacillus STRAINS ISOLATED FROM MAIZE

2020 ◽  
Vol 19 ◽  
pp. 18
Author(s):  
ELIANE APARECIDA GOMES ◽  
UBIRACI GOMES DE PAULA LANA ◽  
MARINA ELEUTÉRIO GÓI DE MORAES RODRIGUES ◽  
SYLVIA MORAIS DE SOUSA ◽  
CHRISTIANE ABREU DE OLIVEIRA ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Restriction Analysis ◽  
16S Rrna Gene Sequencing ◽  
Production Quality ◽  
Rrna Gene ◽  
Plant Growth Promoting Bacteria ◽  
Agricultural Practice ◽  
Production Quality Control ◽  
Plant Growth Promoting ◽  
Bacillus Strains

The use of bioinoculants with plant growth-promoting bacteria (PGPB) is a sustainable agricultural practice that has been expanding worldwide. Thus, it is fundamental to characterize these bacteria molecularly to provide better security and traceability for bioinoculants production. This work aimed to identify, characterize and develop specific molecular markers for Bacillus strains related to plant-growing promotion. Five strains were identified as B. pumillus (B32), B. thuringiensis (B116), B. megaterium (B119) and B. subitilis (B2082 and B2084) using 16S rRNA gene sequencing and MALDI-TOF mass spectrometry. Repetitive element palindromic (Rep-PCR) and amplified ribosomal DNA restriction analysis (ARDRA) techniques allowed the discrimination of the strains, except B2082 and B2084 that presented identical genetic profiles, indicating that they are same or genetically close isolates. Moreover, specific molecular markers were developed for B116 and B119 strains and may be used for microbial inoculants production quality control, strains traceability and to detail PGPB colonization.

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