scholarly journals Synthesis of Biogenic silver nanoparticles using plant growth-promoting bacteria: Potential use as biocontrol agent against phytopathogens

2021 ◽  
Vol 1 (1) ◽  
pp. 22-31
Author(s):  
Divya Mittal ◽  
Arun Kumar ◽  
Bhuvaneshwari Balasubramaniam ◽  
Rahul Thakur ◽  
Samarjeet Singh Siwal ◽  
...  

Biogenic nanoparticles (NPs) derived from microbes present an excellent opportunity to deal with various challenges in medicine, diagnosis, environment and agriculture. In the area of agriculture sciences, researchers are facing challenges related to excessive utilization of pesticides which can be answered by utilizing plant growth-promoting (PGP) microbes. Herein, we have employed the culture filtrate of two PBP bacteria strains, Serratia marcescens and Burkholderia cepacia to prepare biogenic silver NPs. The biogenic silver NPs were characterized by various techniques viz. UV-VIS spectroscopy, SEM, XRD and FTIR. The biogenic AgNPs were able to control the growth of phytopathogenic fungi Aspergillus niger, A. fumigatus, Fusarium oxysporum, Pythium sp., and Rosellinia sp. by more than 80% as examined by in vitro growth reduction on agar medium. Very significantly, the growth inhibition of seedlings by phytopathogenic fungi was efficiently rescued using biogenic AgNPs derived from PGP bacteria. These results indicate the potential use of biogenic NPs to reduce the burden of chemical-based pesticides.

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Mariana S. Santos ◽  
Artur B. L. Rondina ◽  
Marco A. Nogueira ◽  
Mariangela Hungria

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.


2021 ◽  
pp. 100209
Author(s):  
Mariluza Silva Leite ◽  
Tainara Eler Furtado Pinto ◽  
Agda Rabelo Centofante ◽  
Aurélio Rubio Neto ◽  
Fabiano Guimarães Silva ◽  
...  

2021 ◽  
Vol 9 (4) ◽  
pp. 682
Author(s):  
Mohamad Syazwan Ngalimat ◽  
Erneeza Mohd Hata ◽  
Dzarifah Zulperi ◽  
Siti Izera Ismail ◽  
Mohd Razi Ismail ◽  
...  

As a major food crop, rice (Oryza sativa) is produced and consumed by nearly 90% of the population in Asia with less than 9% produced outside Asia. Hence, reports on large scale grain losses were alarming and resulted in a heightened awareness on the importance of rice plants’ health and increased interest against phytopathogens in rice. To serve this interest, this review will provide a summary on bacterial rice pathogens, which can potentially be controlled by plant growth-promoting bacteria (PGPB). Additionally, this review highlights PGPB-mediated functional traits, including biocontrol of bacterial rice pathogens and enhancement of rice plant’s growth. Currently, a plethora of recent studies address the use of PGPB to combat bacterial rice pathogens in an attempt to replace existing methods of chemical fertilizers and pesticides that often lead to environmental pollutions. As a tool to combat bacterial rice pathogens, PGPB presented itself as a promising alternative in improving rice plants’ health and simultaneously controlling bacterial rice pathogens in vitro and in the field/greenhouse studies. PGPB, such as Bacillus, Pseudomonas, Enterobacter, Streptomyces, are now very well-known. Applications of PGPB as bioformulations are found to be effective in improving rice productivity and provide an eco-friendly alternative to agroecosystems.


PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0248274
Author(s):  
Iliana Julieta Cortese ◽  
María Lorena Castrillo ◽  
Andrea Liliana Onetto ◽  
Gustavo Ángel Bich ◽  
Pedro Darío Zapata ◽  
...  

Plant growth-promoting bacteria (PGPB) are a heterogeneous group of bacteria that can exert beneficial effects on plant growth directly or indirectly by different mechanisms. PGPB-based inoculant formulation has been used to replace chemical fertilizers and pesticides. In our previous studies, two endophytic endospore-forming bacteria identified as Bacillus altitudinis were isolated from roots of Ilex paraguariensis St. Hil. seedlings and selected for their plant growth-promoting (PGP) properties shown in vitro and in vivo. The purposes of this work were to assemble the genomes of B. altitudinis 19RS3 and T5S-T4, using different assemblers available for Windows and Linux and to select the best assembly for each strain. Both genomes were also automatically annotated to detect PGP genes and compare sequences with other genomes reported. Library construction and draft genome sequencing were performed by Macrogen services. Raw reads were filtered using the Trimmomatic tool. Genomes were assembled using SPAdes, ABySS, Velvet, and SOAPdenovo2 assemblers for Linux, and Geneious and CLC Genomics Workbench assemblers for Windows. Assembly evaluation was done by the QUAST tool. The parameters evaluated were the number of contigs ≥ 500 bp and ≥ 1000 bp, the length of the longest contig, and the N50 value. For genome annotation PROKKA, RAST, and KAAS tools were used. The best assembly for both genomes was obtained using Velvet. The B. altitudinis 19RS3 genome was assembled into 15 contigs with an N50 value of 1,943,801 bp. The B. altitudinis T5S-T4 genome was assembled into 24 contigs with an N50 of 344,151 bp. Both genomes comprise several genes related to PGP mechanisms, such as those for nitrogen fixation, iron metabolism, phosphate metabolism, and auxin biosynthesis. The results obtained offer the basis for a better understanding of B. altitudinis 19RS3 and T5S-T4 and make them promissory for bioinoculant development.


Author(s):  
CLARA IVETTE RINCON-MOLINA ◽  
FRANCISCO ALEXANDER RINCON-MOLINA ◽  
ADALBERTO ZENTENO-ROJAS ◽  
VICTOR MANUEL RUIZ-VALDIVIEZO ◽  
JOSE MIGUEL CULEBRO-RICALDI ◽  
...  

ABSTRACT Objective: Study the diversity of cultivable rhizospheric bacteria associated to Agave americana, and select native strains with potential as plant growth-promoting bacteria (PGPB). Design/methodology/approach: The isolated bacteria were phenotypically characterized. The genetic diversity and identity of the strains were revealed by genomic fingerprints and by sequencing of 16S rRNA gene. Plant growth promoting ability and plant inoculation assays were evaluated to know the potential as PGPB. Results: A total of 235 strains were isolated from A. americana rhizosphere and were classified within of 10 different bacterial genera. Rhizobium, Pseudomonas, Acinetobacter had high potential as PGPB. Study limitations/implications Cultivable approach was used to study rhizobacteria. A metagenomic study could expand the knowledge about the structure and diversity of bacterial community associated to A. americana. Findings/conclusions Rhizosphere bacteria have potential use as biofertilizer for the cultivation and propagation of A. americana and other agave species.


2020 ◽  
Vol 21 (12) ◽  
Author(s):  
Lamia AOUAR ◽  
INAS BOUKELLOUL ◽  
ABDERRAHMANE BENADJILA

Abstract. Aouar L, Boukelloul I, Benadjila A. 2020. Identification of antagonistic Streptomyces strains isolated from Algerian Saharan soils and their plant growth promoting properties. Biodiversitas 21: 5672-5683. To produce new bioactive substances of agricultural interest, extreme ecosystems can be a source of unexplored microorganisms. Accordingly, in this study, twenty-two actinobacteria strains were obtained from rhizospheric arid soils of palm groves collected from Biskra and El Oued in the Algerian Sahara. All isolates were examined for the in vitro antifungal potential towards phytopathogenic fungi: Aspergillus flavus, Verticillium dahlia, Rhizoctonia solani, Botrytis cinerea and Fusarium oxysporum as well as for their antibacterial property toward phytopathogenic bacteria: Streptomyces scabiei, Pectobacterium carotovorum and Agrobacterium tumefaciens. The three isolates (13%) that inhibited at least five pathogens were then selected, identified and assessed for their attributes to produce indole-3-acetic acid (IAA) and siderophores, to solubilize phosphate, and to antagonize Streptomyces scabiei in vivo. According to phylogenetic analysis performed with 16S rDNA sequence, chemotaxonomy and phenotypic characteristics, the strain SO1, which inhibited all tested pathogens, was assigned to Streptomyces flaveus. While, strains SO2 and SB1 were affiliated to Streptomyces enissocaesilis and Streptomyces albidoflavus, respectively. All strains produced IAA but only SO1 and SB1 were able to elaborate siderophores catecholate-type. Two strains SO1 and SO2 exhibited a capacity to solubilize phosphate and SO1 was able to suppress the pathogenic effect of Streptomyces scabiei on radish seedlings. The findings indicate that SO1 strain may reveal the potential for use as a biocontrol agent and plant growth promoter.


2018 ◽  
Vol 28 (1) ◽  
pp. 25-34
Author(s):  
Waheeda Parvin ◽  
Quazi Shirin Akhter Jahan ◽  
Md Mahbubur Rahman ◽  
Mui Yun Wong

Burkholderia cepacia UPMB3 is an important plant growth promoting rhizobacteria isolated from oil palm rhizosphere which is considered to promote plant growth directly or indirectly. The IAA was extracted, purified, detected and confirmed by thin layer chromatography analyses f r om t h e strain UPMB3 of B. cepacia. Rf value was compared with the authentic IAA. Maximum 50 μg/ml IAA was produced in the medium supplemented with 4 mg/ml L-tryptophan, under shaken conditions at 150 rpm in seven days incubation at pH 7. The bacterial extract significantly influenced the growth of oil palm seedlings producing shoot, root, leaf and leaf length compared to control.Plant Tissue Cult. & Biotech. 28(1): 25-34, 2018 (June)


2020 ◽  
Vol 96 (9) ◽  
Author(s):  
Camila Cristina Vieira Velloso ◽  
Christiane Abreu de Oliveira ◽  
Eliane Aparecida Gomes ◽  
Ubiraci Gomes de Paula Lana ◽  
Chainheny Gomes de Carvalho ◽  
...  

ABSTRACT Plant growth promoting bacteria (PGPB) are an efficient and sustainable alternative to mitigate biotic and abiotic stresses in maize. This work aimed to sequence the genome of two Bacillus strains (B116 and B119) and to evaluate their plant growth-promoting (PGP) potential in vitro and their capacity to trigger specific responses in different maize genotypes. Analysis of the genomic sequences revealed the presence of genes related to PGP activities. Both strains were able to produce biofilm and exopolysaccharides, and solubilize phosphate. The strain B119 produced higher amounts of IAA-like molecules and phytase, whereas B116 was capable to produce more acid phosphatase. Maize seedlings inoculated with either strains were submitted to polyethylene glycol-induced osmotic stress and showed an increase of thicker roots, which resulted in a higher root dry weight. The inoculation also increased the total dry weight and modified the root morphology of 16 out of 21 maize genotypes, indicating that the bacteria triggered specific responses depending on plant genotype background. Maize root remodeling was related to growth promotion mechanisms found in genomic prediction and confirmed by in vitro analysis. Overall, the genomic and phenotypic characterization brought new insights to the mechanisms of PGP in tropical Bacillus.


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